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The Natural History of BK Polyomavirus and the Host Immune Response After Stem Cell Transplantation

The Natural History of BK Polyomavirus and the Host Immune Response After Stem Cell Transplantation Abstract Background BK polyomavirus (BKPyV) is associated with symptomatic hemorrhagic cystitis after hematopoietic cell transplantation (HCT). Little is known about the host immune response, effectiveness of antiviral treatment, or impact of asymptomatic replication on long-term kidney function. Methods In children and young adults undergoing allogeneic HCT, we quantified BKPyV viruria and viremia (pre-HCT and at Months 1–4, 8, 12, and 24 post-HCT) and tested associations of peak viremia ≥10 000 or viruria ≥109 copies/mL with estimated kidney function (glomerular filtration rate, eGFR) and overall survival at 2 years posttransplant. We examined the factors associated with viral clearance by Month 4, including BKPyV-specific T cells by enzyme-linked immune absorbent spot at Month 3 and cidofovir use. Results We prospectively enrolled 193 participants (median age 10 years) and found that 18% had viremia ≥10 000 copies/mL and 45% had viruria ≥109 copies/mL in the first 3 months post-HCT. Among the 147 participants without cystitis (asymptomatic), 58 (40%) had any viremia. In the entire cohort and asymptomatic subset, having viremia ≥10 000 copies/mL was associated with a lower creatinine/cystatin C eGFR at 2 years post-HCT. Viremia ≥10 000 copies/mL was associated with a higher risk of death (adjusted hazard ratio, 2.2; 95% confidence interval, 1.1–4.2). Clearing viremia was associated with detectable BKPyV-specific T cells and having viremia <10 000 copies/mL, but not cidofovir exposure. Conclusions Screening for BKPyV viremia after HCT identifies asymptomatic patients at risk for kidney disease and reduced survival. These data suggest potential changes to clinical practice, including prospective monitoring for BKPyV viremia to test virus-specific T cells to prevent or treat BKPyV replication. BK polyomavirus, stem cell transplantation, pediatrics, kidney BK polyomavirus (BKPyV) is associated with nephropathy after kidney transplantation and hemorrhagic cystitis after hematopoietic cell transplantation (HCT) [1, 2]. Hemorrhagic cystitis occurs in up to 25% of patients, leading to pain, urinary obstruction, prolonged hospitalizations, and possibly increased mortality [3–5]. In immunosuppressed patients, BKPyV replication is detected by nucleic acid testing of blood (viremia) or urine (viruria). Asymptomatic viruria is common after HCT and solid organ transplant, while viremia, especially high-level replication ≥10 000 copies/mL, is more specific for kidney and bladder disease [1, 4, 6]. Single-center studies have reported viremia or viruria incidences in the first 100 days after HCT [3, 7, 8] but not the longer-term risk of asymptomatic BKPyV replication on kidney function or the host immune response. We defined the natural history of BKPyV replication and outcomes for 2 years after HCT among patients at 2 large children’s hospitals and examined antiviral immunity. We hypothesized that BKPyV was associated with decreased kidney function and that the measurement of BKPyV T cells would predict viral clearance. Consensus guidelines do not recommend screening for BKPyV after HCT [5, 9] perhaps missing a risk factor for reduced kidney function or cystitis. Moreover, antivirals do not have proven efficacy, but third-party BKPyV T cells can be infused to promote viral clearance and more data are needed to define appropriate therapeutic use. METHODS Patient Population We prospectively enrolled children and young adults ≥2 years of age who were undergoing an allogeneic HCT at the Children’s Hospital of Philadelphia (CHOP) or Cincinnati Children’s Hospital Medical Center (CCHMC) from April 2013–May 2018, with follow-up until October 2018. The Institutional Review Boards at CHOP and CCHMC approved the study and participants provided informed consent and assent. Laboratory Methods Plasma, serum, peripheral blood mononuclear cells (PBMCs), and urine were frozen prior to HCT and at Months 1–4, 8, 12, and 24 (the research methods are available in the Supplementary Material). Nucleic acid testing for BKPyV was performed on all plasma and urine samples (Viracor-Eurofins, Lee’s Summit, MO). Blood BKPyV immunoglobulin G (IgG) was measured at baseline and Months 3 and 12 (Viracor-Eurofins). Enzyme-linked immunosorbent spot (ELISPOT) testing to detect BKPyV-specific T cells was performed on Month 3 PBMC samples (Figure 1). Figure 1. Open in new tabDownload slide Study cohort, sampling, and testing frequency and BK polyomavirus (BKPyV) viremia and viruria after hematopoietic cell transplant. A, We tested 193 children and young adults for BK polyomavirus in the blood (viremia) and urine (viruria) in the first 2 years after hematopoietic cell transplant (exclusion criteria in Supplementary Methods). Samples were collected and analyzed prior to transplant and at Months 1, 2, 3, 4, 8, 12, and 24 after transplant. B, Viremia was rare prior to transplant, occurred most frequently in the first 4 months, and, among survivors, was less frequent >8 months after transplant. C, Viruria was common prior to transplant, occurred frequently in the first 4 months, and persisted among a high proportion of survivors >8 months after transplant. Note that the scales are different for viremia and viruria. Abbreviations: CCHMC, Cincinnati Children’s Hospital Medical Center; CHOP, Children’s Hospital of Philadelphia; ELISPOT, enzyme-linked immune absorbent spot; IgG, immunoglobin G; PreTX, pretransplant. Clinical Data Clinical data were abstracted from the medical record, including serum creatinine and absolute lymphocyte counts within ±1 day of when 1049 of the 1070 (98.0%) research blood samples were collected (Supplementary Table 1). We recorded participants receiving cidofovir for any indication. Epstein-Barr virus, cytomegalovirus, adenovirus, and human herpes virus 6 viremia were captured from center-specific monitoring; positivity was defined using ≥2 consecutive nucleic acid results at any time posttransplant. Blood cystatin C was measured clinically or on stored samples at baseline and at Months 8, 12, and 24 [10]. BK Polyomavirus Definitions, Outcome Variables, and Covariates BKPyV replication was defined as a positive nucleic acid test, with or without clinical symptoms, and was categorized as peak viremia ≥10 000 copies/mL [1, 4, 6] and/or viruria ≥109 copies/mL [11, 12] among participants with ≥2 samples during the first 3 months post-HCT. The outcomes included cystitis, estimated glomerular filtration rate (eGFR), dialysis, and all-cause death. Cystitis was defined as grade ≥2 (presence of BKPyV, symptoms, and visible hematuria [2, 5]) and was assessed retrospectively by reviewing clinical documentation. GFR was estimated at baseline and at Months 8, 12, and 24. For participants <18 years of age [13] and ≥18 years of age [14], eGFRs were separately calculated using serum creatinine alone and cystatin C and creatinine together. We analyzed eGFR in the whole cohort and in the subset with asymptomatic viral replication (no cystitis). Covariates included demographic and transplant characteristics, graft-versus-host disease (GVHD), thrombotic microangiopathy (TMA), cidofovir for any indication, and other viremias. TMA was only assessed at CCHMC due to an established screening guideline [15]. As a risk factor for BKPyV replication, other viremias, GVHD, and TMA were not analyzed as time-dependent variables and could have occurred before or after detectable BKPyV. As a risk factor for cystitis, acute GVHD was only considered if it occurred prior to cystitis. Immune Response and Viral Clearance We examined whether the baseline IgG predicted posttransplant replication. We tested the Month 3 PBMC sample for BKPyV-specific T cells, defined as those with ELISPOT counts >5 or >10 above the negative control. We hypothesized that among participants with persistent BKPyV replication (≥2 positive samples) in the first 3 months posttransplant, a positive ELISPOT would predict viral clearance (undetectable viral DNA) at Month 4. We also assessed other factors potentially associated with clearance, including the absolute lymphocyte count, IgG, and cidofovir use. Statistical Analyses Continuous variables were presented as medians and interquartile ranges (IQR) and were examined with the Wilcoxon rank sum or 2-sample t test, as appropriate. Categorical variables were examined with the Chi-square or Fisher’s exact test, as appropriate. Logistic regression examined the factors associated with viral clearance. We excluded those participants developing cystitis prior to their Month 1 sample, to examine whether BKPyV replication predicted later cystitis. Linear regression examined the factors associated with eGFR. Multivariable Cox proportional hazards regression assessed the associations among BKPyV, cystitis, and mortality. Model selection for cystitis was performed with backward elimination using likelihood ratio testing and for mortality included all significant plausible variables. Given the high mortality rate, we also examined cystitis in a competing risk regression with death. We examined the overall survival rate instead of the nonrelapse mortality rate, given the high proportion of nonmalignant transplant indications. The study was originally designed to have 85% power to detect a clinically meaningful difference in a 1-year eGFR of 20 ml/min/1.73m2 between participants with and without BKPyV viremia ≥10 000 copies/mL and assumed a sample size of 100 participants surviving to 1 year and a 10% prevalence of viremia. Analyses were performed using STATA Version 15.1 and R 3.5.1, and a 2-sided P value <.05 was considered statistically significant. RESULTS Cohort We enrolled 193 participants (Figure 1; Table 1), who had a median age of 10 years (IQR, 6–15 years; range, 2–32 years). The most common underlying diagnoses were malignancy (37%), bone marrow failure (27%), or immunodeficiency (21%). At CCHMC (n = 148), a greater proportion of participants had bone marrow failure or immunodeficiency, compared to CHOP (n = 45), where most participants had malignancy. The cohort characteristics by center, specific underlying diagnoses, and conditioning regimens are shown in Supplementary Tables 2–4. Table 1. Cohort Characteristics and Variables Associated with Peak BK Polyomavirus Viremia ≥10 000 Copies/mL in the First 3 Months After Hematopoietic Cell Transplant Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Data are shown as either a median (interquartile range) or n (%). Abbreviation: HLA, human leukocyte antigen. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate, comparing viremia with <10 000 copies/mL to those with ≥10 000 copies/mL. bIncludes 178 participants with ≥2 blood tests (n = 10 with <2 blood tests) in the first 3 months and negative pretransplant viremia (n = 5 with detectable pretransplant viremia). cOf 6 cord blood transplant recipients, 5 also received bone marrow–derived cells. dOccurring at any point posttransplant. Open in new tab Table 1. Cohort Characteristics and Variables Associated with Peak BK Polyomavirus Viremia ≥10 000 Copies/mL in the First 3 Months After Hematopoietic Cell Transplant Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Data are shown as either a median (interquartile range) or n (%). Abbreviation: HLA, human leukocyte antigen. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate, comparing viremia with <10 000 copies/mL to those with ≥10 000 copies/mL. bIncludes 178 participants with ≥2 blood tests (n = 10 with <2 blood tests) in the first 3 months and negative pretransplant viremia (n = 5 with detectable pretransplant viremia). cOf 6 cord blood transplant recipients, 5 also received bone marrow–derived cells. dOccurring at any point posttransplant. Open in new tab BK Polyomavirus Replication BKPyV results are shown in Figure 1 and Tables 2 and 3. We tested 1070 blood samples (median, 6 samples/participant; IQR, 5–7 samples). Only 5 of 188 (2.7%) participants had viremia pre-HCT. Of 190 participants, 94 (49.5%) had ≥1 sample with detectable viremia after transplant. Among participants with ≥2 samples in the first 3 months after transplant and with negative pre-HCT viremia, the viral load was ≥10 000 copies/mL in 32 of 178 (18.0%). In univariate analyses, the risk factors significantly associated with viremia ≥10 000 copies/mL included an older recipient age, unrelated donor, older donor age, antithymocyte globulin or cyclophosphamide conditioning (but not alemtuzumab), detectable pre-HCT viruria, and a lower Month 2 absolute lymphocyte count (Table 1). Viremia ≥10 000 copies/mL was associated with acute GVHD grade ≥2 (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.2–5.4; P = .02) at any time relative to transplant (not time-dependent). Among the CCHMC participants, viremia ≥10 000 copies/mL was associated with TMA (OR, 7.0; 95% CI, 2.4–20.0; P < .001) at any time relative to transplant (not time-dependent). At Months 8, 12, and 24, 12 of 85 (14.1%), 9 of 91 (9.9%), and 3 of 44 (6.8%) participants had detectable viremia, respectively. Table 2. BK Polyomavirus Viremia Sample Results by Time Point . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) There were 191 participants with at least 1 blood sample tested for viremia: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab Table 2. BK Polyomavirus Viremia Sample Results by Time Point . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) There were 191 participants with at least 1 blood sample tested for viremia: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab Table 3. BK Polyomavirus Viruria Sample Results by Time Point Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) There were 189 participants with at least 1 urine sample tested for viruria: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab Table 3. BK Polyomavirus Viruria Sample Results by Time Point Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) There were 189 participants with at least 1 urine sample tested for viruria: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab We tested 890 urine samples (median, 5 samples/participant; IQR, 3–6 samples). Pre-HCT, one-third of participants (69 of 174, 39.7%) had detectable viruria, with a median of 3500 copies/mL (IQR, 1000–4 242 400 copies/mL). Of 184 participants, 160 (87.0%) had ≥1 sample with viruria after transplant. The peak urine viral load was ≥109 copies/mL in 70 of 157 (44.6%) participants with ≥2 urine samples in the first 3 months posttransplant. Approximately half of participants with viruria also experienced viremia (90 of 160, 56.3%). Viremic participants essentially all also had viruria, with only 1 participant with viremia (a single value of 112 copies/mL) having no viruria. Clinical Outcomes Hemorrhagic Cystitis BKPyV-associated cystitis was identified in 43 of 193 (22.3%) participants at a median of 34 days (IQR, 25–54 days) post-HCT. Any detectable viremia or viruria ≥109 copies/mL significantly predicted subsequent cystitis (Table 4). Of note, exposure to busulfan was also associated with an increased risk of cystitis (39.3% with no exposure versus 58.1% with exposure; P = .03), but cyclophosphamide was not (54.0% versus 65.1%; P = .2). In a multivariable model adjusting for significant covariates (Table 4), detectable viremia was independently associated with cystitis (adjusted hazard ratio [HR], 7.8; 95% CI, 3.1–19.3; P < .01). The model results were similar when including viruria ≥109 copies/mL instead of viremia (adjusted HR, 5.7; 95% CI, 2.4–13.4; P < .01). In a competing risk regression with death, adjusted for the same covariates as shown in the final Cox models in Table 4, detectable viremia and viruria ≥109 copies/mL remained independently associated with cystitis (adjusted HRs 7.9 [95% CI 3.1–20.4; P < .01] and 5.7 [95% CI, 2.4–13.2; P < .01], respectively.) Table 4. Variables Associated With Grade ≥ 2 Hemorrhagic Cystitis After Hematopoietic Cell Transplant . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … Total N = 193. Univariate data are shown as a median (interquartile range) or n (%) with a univariate P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. Abbreviations: BKPyV, BK polyomavirus; CI, confidence interval; HCT, hematopoietic cell transplant; HHV6, human herpes virus 7; HLA, human leukocyte antigen. a P < .05. bNot receiving alemtuzumab conditioning predicted failure perfectly and therefore was not included in the Cox models. c P < .01. dOccurring at any point posttransplant. eWe excluded participants without an available posttransplant research sample before the diagnosis of cystitis so that the variable had to precede the diagnosis of cystitis or occur at any time after transplant among those without cystitis. Open in new tab Table 4. Variables Associated With Grade ≥ 2 Hemorrhagic Cystitis After Hematopoietic Cell Transplant . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … Total N = 193. Univariate data are shown as a median (interquartile range) or n (%) with a univariate P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. Abbreviations: BKPyV, BK polyomavirus; CI, confidence interval; HCT, hematopoietic cell transplant; HHV6, human herpes virus 7; HLA, human leukocyte antigen. a P < .05. bNot receiving alemtuzumab conditioning predicted failure perfectly and therefore was not included in the Cox models. c P < .01. dOccurring at any point posttransplant. eWe excluded participants without an available posttransplant research sample before the diagnosis of cystitis so that the variable had to precede the diagnosis of cystitis or occur at any time after transplant among those without cystitis. Open in new tab Kidney Outcomes Participants with viremia ≥10 000 copies/mL in the first 3 months after transplant had a significantly lower eGFR at 12 and 24 months (Table 5) and a higher risk of receiving dialysis (OR, 6.2; 95% CI, 1.8–21.6; P = .004). Age, total body irradiation, cyclophosphamide, calcineurin inhibitor prophylaxis, GVHD, cystitis, and cidofovir were not associated with the Month 24 eGFR (Supplementary Table 5). Adjusting for only the baseline eGFR, participants with viremia ≥10 000 copies/mL had a Month 24 creatinine/cystatin C eGFR that was 20.2 ml/min/1.73m2 lower (95% CI, −38.9 to −1.6 ml/min/1.73m2; P = .03), compared to those with viremia <10 000 copies/mL. Viruria ≥109 copies/mL was not associated with Month 8, 12, or 24 eGFR or dialysis (Table 5). Table 5. Kidney Outcomes Associated With BK Polyomavirus Viremia and Viruria After Hematopoietic Cell Transplant . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 Data are shown as a median (interquartile range) or n (%). Data are for the unadjusted, estimated glomerular filtration rate (mL/min/1.73m2) a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bIncludes the 183 participants with at least 2 samples in the first 3 months after transplant. cIncludes the 157 participants with at least 2 urine samples in the first 3 months after transplant. Open in new tab Table 5. Kidney Outcomes Associated With BK Polyomavirus Viremia and Viruria After Hematopoietic Cell Transplant . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 Data are shown as a median (interquartile range) or n (%). Data are for the unadjusted, estimated glomerular filtration rate (mL/min/1.73m2) a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bIncludes the 183 participants with at least 2 samples in the first 3 months after transplant. cIncludes the 157 participants with at least 2 urine samples in the first 3 months after transplant. Open in new tab Among those not developing cystitis, 58 of 147 (39.5%) had viremia, including 19 of 58 (32.8%) with viremia ≥10 000 copies/mL. When limiting the data to these participants with asymptomatic viremia, both the creatinine (median, 83 versus 125 ml/min/1.73m2, respectively; P = .01) and creatinine/cystatin C (median, 78 versus 117 ml/min/1.73m2, respectively; P = .004) eGFRs were significantly lower at 24 months among those with viremia ≥10 000 copies/mL (n = 4), compared to those without (n = 32). Adjusting only for the baseline eGFR, participants with asymptomatic viremia ≥10 000 copies/mL in the first 3 months after transplant had a creatinine/cystatin C eGFR that was 29.4 ml/min/1.73m2 lower (95% CI, −55.3 to −3.6 ml/min/1.73m2, respectively; P = .03) than those with viremia <10 000 copies/mL (Supplementary Table 5). Mortality After a median follow-up of 2.2 years (IQR, .8–3.8 years), 49 of 193 (25.4%) participants died. Participants with viremia ≥10 000 copies/mL in the first 3 months after transplant had a 3-fold increased risk of all-cause mortality (HR, 2.8; 95% CI, 1.5–5.2; P = .002). The HR for death associated with grade ≥2 cystitis was 2.0 (95% CI, 1.1–3.6; P = .02). Adjusting for cystitis and other factors associated with mortality, including age, gender, underlying diagnosis, and acute GVHD grade ≥2, viremia ≥10 000 copies/mL was independently associated with mortality (HR, 2.2; 95% CI, 1.1–4.2; P = .02). Immune Response and Clearance of Viremia The distribution of BKPyV IgG is shown in Figure 2. The baseline IgG was not associated with post-HCT viruria or viremia, as participants with both the highest and lowest levels developed viremia after transplant (data not shown). The Month 3 IgG was not associated with viral clearance (Table 6 and below). Table 6. Factors Associated With Clearance of BK Polyomavirus Viremia at 4 Months After Hematopoietic Cell Transplant . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 Data are shown as a median (interquartile range) or n (%). Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bThe included participants had detectable viremia on ≥2 samples in the first 3 months after transplant and had a Month 4 blood sample to assess for viral clearance. Clearance was defined as having undetectable viremia at Month 4. Open in new tab Table 6. Factors Associated With Clearance of BK Polyomavirus Viremia at 4 Months After Hematopoietic Cell Transplant . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 Data are shown as a median (interquartile range) or n (%). Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bThe included participants had detectable viremia on ≥2 samples in the first 3 months after transplant and had a Month 4 blood sample to assess for viral clearance. Clearance was defined as having undetectable viremia at Month 4. Open in new tab Figure 2. Open in new tabDownload slide Distribution of BK polyomavirus immunoglobulin G titers after transplant. There were 8 participants that inadvertently had 2 separate samples run pretransplant with results that differed by one 4-fold dilution, and their titers were averaged. Abbreviations: M, month; PreTX, pretransplant. Month 3 PBMC samples were tested for BKPyV-specific T cells in 104 of 193 (53.9%) participants. We examined factors associated with viral clearance by Month 4 among the subset of 52 participants with persistent viremia in the first 3 months after transplant and with an available Month 4 sample to assess clearance (Tables 6 and 7). Clearance of viremia at Month 4 occurred in 21 of these 52 (40.4%) and was less likely among participants with prior viremia ≥10 000 copies/mL. The Month 3 absolute lymphocyte count did not predict clearance. Receiving cidofovir for any indication (cystitis or adenoviremia) was less likely among participants with a 10/10 matched donor and more common among those developing acute GVHD, BKPyV viremia >10 000, and viruria ≥109 copies/mL (Supplementary Table 6). Participants with BKPyV replication who had received cidofovir were significantly less likely to clear viremia, but those with an ELISPOT >10 spots above the control were more likely to clear viremia (OR, 5.0; 95% CI, 1.3–18.6; P = .02; Table 6). Finally, 6 of 7 participants with persistent viremia at both Months 8 and 12 did not have detectable BKPyV-specific T cells at Month 3 (Supplementary Table 7). Table 7. BK Polyomavirus Viremia Clearance by Month 4 and Enzyme-linked Immune Absorbent Spot Results Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 These 43 selected participants had persistent viremia in the first 3 months after transplant, had a Month 4 sample to assess for clearance, and had a Month 3 ELISPOT result. Participants with peak viremia <10 000 copies/mL and ELISPOT counts >10 above the negative control (bold and highlighted) were more likely to clear viremia by Month 4. Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. Open in new tab Table 7. BK Polyomavirus Viremia Clearance by Month 4 and Enzyme-linked Immune Absorbent Spot Results Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 These 43 selected participants had persistent viremia in the first 3 months after transplant, had a Month 4 sample to assess for clearance, and had a Month 3 ELISPOT result. Participants with peak viremia <10 000 copies/mL and ELISPOT counts >10 above the negative control (bold and highlighted) were more likely to clear viremia by Month 4. Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. Open in new tab DISCUSSION We report the natural history of BKPyV replication in almost 200 children and young adults undergoing HCT at 2 large centers. A number of novel findings have the potential to change practice. First, we identified frequent asymptomatic viremia and found that high levels of viremia, whether symptomatic or not, were associated with significant reductions in later kidney function. Second, we found that children and young adults with BKPyV replication who received cidofovir were not more likely to clear viremia. Last, we identified BKPyV-specific T cells as a marker of clearing viremia but no benefit from antibody responses. The management of BKPyV at most centers currently includes testing for viral reactivation only in symptomatic cases, with the provision of additional intravenous immunoglobulin and cidofovir. While our data suggest that none of these approaches may be beneficial, randomized trials would be needed to validate the effectiveness of treatments. The screening of asymptomatic patients for BKPyV will only be beneficial if a therapy is available. Our data show that the recovery of endogenous BKPyV-specific T cells is associated with viral clearance, similar to prior studies after kidney transplantation [16–19]. To our knowledge, our study is the largest systematic evaluation of cellular responses to BKPyV after HCT [20–22]. The efficacy and safety of third-party BKPyV-specific T cells has recently been reported after HCT [23–25]. Our findings expand on single-center studies examining BKPyV in the first 100 days after HCT, which are generally without a comprehensive assessment of kidney outcomes or immune responses [11, 12, 26, 27]. Hill et al [7, 8] measured the impact of viremia from 5 viruses, including BKPyV, on mortality among 400 HCT recipients. The incidence of BKPyV viremia was 54%, most episodes were persistent, and, similar to our findings, viremia was associated with mortality. BKPyV viremia occurred a median of 10 days before cystitis. Others have reported that viremia or viruria predict cystitis, which we also confirmed [3, 6]. About 25% of our cohort developed cystitis [5, 7, 11]. BKPyV viremia was associated with a higher risk of receiving dialysis and an eGFR that was, on average, 20 ml/min/1.73m2 lower by 2 years after transplant. O’Donnell et al [27] monitored 57 adults after HCT and observed that viremia was independently associated with higher peak creatinine, similar to retrospective studies in children [4]. In contrast to antithymocyte globulin, alemtuzumab was not associated with the risk of BKPyV replication. It is possible that these data are confounded by an unmeasured variable or that qualitative, BKPyV-specific T-cell recovery after alemtuzumab is importantly different than recovery after antithymocyte globulin. Although we and others have shown that BKPyV viremia can predict cystitis, the positive predictive value of viremia remains low, implying that other factors, perhaps related to the host response or viral diversity, are important to determining which patients will develop disease [11]. We observed that BKPyV viremia was associated with dialysis, TMA, acute GVHD, and death. More research is needed to determine whether these associations are causal, time-dependent, associated with poor immune reconstitution, or are confounded by higher degrees of immunosuppression. In vitro studies indicate that BKPyV infection can induce host endothelial cell production of interferon [28], which may precipitate both TMA and acute GVHD, supporting a possible direct, causative effect of BKPyV viremia on these other, significant posttransplant complications [7]. The strengths of our approach include the multi-center design, collection of samples and clinical data for 2 years after transplant, and centralized lab testing. We assessed both the humoral and cellular host immune response to BKPyV. Finally, we examined the association between BKPyV replication and eGFR for the first time in the HCT population using both serum creatinine and cystatin C, which has advantages in patients with decreased muscle mass [10]. Participants with viremia >10 000 copies/mL had an 18–26% decrease in baseline eGFR by 2 years post-HCT (Table 5). In older adults, a 30% reduction in eGFR over 2 years has been strongly associated with end-stage kidney disease and death [29]. While similar data are not available in children, it is plausible that the eGFR decline we observed would also be associated with poor outcomes in a younger population. Our study was limited by a lack of biopsy data to confirm nephropathy. Nevertheless, BKPyV viremia ≥10 000 copies/mL has been classified as presumptive nephropathy after kidney transplantation, even without a biopsy [30]. Patient characteristics, most notably the high proportion of nonmalignant indications, may not reflect the risk for BKPyV infection at other centers. Not all centers have the resources to perform centralized, quantitative testing for viremia, and semi-quantitative detection of high-level viremia may have produced the same observations. Our monthly sampling frequency may have missed earlier windows of detection associated with clinical outcomes, including TMA and GVHD. The potential benefits and risks of treatments, such as intravenous immune globulin and cidofovir, would need to be tested in randomized trials. Finally, clinical information was abstracted from the medical record, possibly influencing the capture of outcomes, such as cystitis and GVHD. In conclusion, BKPyV viremia was associated with significant kidney and bladder disease and mortality after HCT. Moreover, asymptomatic viremia was common and was associated with decreased kidney function. Assessments of novel interventions, such as the infusion of virus-specific T cells, are needed to determine whether preventing or treating BKPyV infection can improve morbidity and mortality, as our study does not suggest the utility of cidofovir. Patients with persistent, high-level symptomatic or asymptomatic viremia may benefit from infusion of BKPyV-specific T cells, and this hypothesis can be tested in future clinical trials. Supplementary Data Supplementary materials are available at Clinical Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author. Notes Acknowledgement. The authors thank Dr Ulf Beier for his assistance with illustrating the figures. Financial support. This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health (grant numbers K23 DK101600 to B. L. L. and K23 DK093556 to M. R. D.) and the National Center for Advancing Translational Sciences (grant number UL1 TR001878). Viracor-Eurofins tested the samples for BK polyomavirus viremia, viruria, and antibody at no charge. Potential conflicts of interest. B. L. L and S. J. are coinventors of a patent application under review: Compositions and Methods for Treatment of HSCT-Associated Thrombotic Microangiopathy (United States Patent Number PCT/US2014/055922, 2014). B. L. L. has received consulting fees from Jazz Pharmaceuticals and Bioporto. S. K. and M. A. are employees of Viracor-Eurofins. M. R. D. has received research funding from Mallinckrodt, unrelated to this study. S. M. D. has received research support from Alexion Pharmaceuticals, personal fees from Novartis and Anthem, and research grants from Prolacta, outside the submitted work. S. J. has received research support from Alexion Pharmaceuticals; has received grants from the National Institutes of Health; has received personal fees from Omeros, Arcus Medica, and Magnolia Innovations, outside the submitted work; and has the following patents pending: 61/878,119, 62/094,802, 62/172,987, and 62/593,401. T. O. has received personal fees from Bluebird Bio, Miltenyi, and Novartis, outside the submitted work. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed. References 1. Hirsch HH , Knowles W, Dickenmann M, et al. Prospective study of polyomavirus type BK replication and nephropathy in renal-transplant recipients . N Engl J Med 2002 ; 347 : 488 – 96 . Google Scholar Crossref Search ADS PubMed WorldCat 2. Bedi A , Miller CB, Hanson JL, et al. 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The Natural History of BK Polyomavirus and the Host Immune Response After Stem Cell Transplantation

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Oxford University Press
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Copyright © 2022 Infectious Diseases Society of America
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1058-4838
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1537-6591
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10.1093/cid/ciz1194
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Abstract

Abstract Background BK polyomavirus (BKPyV) is associated with symptomatic hemorrhagic cystitis after hematopoietic cell transplantation (HCT). Little is known about the host immune response, effectiveness of antiviral treatment, or impact of asymptomatic replication on long-term kidney function. Methods In children and young adults undergoing allogeneic HCT, we quantified BKPyV viruria and viremia (pre-HCT and at Months 1–4, 8, 12, and 24 post-HCT) and tested associations of peak viremia ≥10 000 or viruria ≥109 copies/mL with estimated kidney function (glomerular filtration rate, eGFR) and overall survival at 2 years posttransplant. We examined the factors associated with viral clearance by Month 4, including BKPyV-specific T cells by enzyme-linked immune absorbent spot at Month 3 and cidofovir use. Results We prospectively enrolled 193 participants (median age 10 years) and found that 18% had viremia ≥10 000 copies/mL and 45% had viruria ≥109 copies/mL in the first 3 months post-HCT. Among the 147 participants without cystitis (asymptomatic), 58 (40%) had any viremia. In the entire cohort and asymptomatic subset, having viremia ≥10 000 copies/mL was associated with a lower creatinine/cystatin C eGFR at 2 years post-HCT. Viremia ≥10 000 copies/mL was associated with a higher risk of death (adjusted hazard ratio, 2.2; 95% confidence interval, 1.1–4.2). Clearing viremia was associated with detectable BKPyV-specific T cells and having viremia <10 000 copies/mL, but not cidofovir exposure. Conclusions Screening for BKPyV viremia after HCT identifies asymptomatic patients at risk for kidney disease and reduced survival. These data suggest potential changes to clinical practice, including prospective monitoring for BKPyV viremia to test virus-specific T cells to prevent or treat BKPyV replication. BK polyomavirus, stem cell transplantation, pediatrics, kidney BK polyomavirus (BKPyV) is associated with nephropathy after kidney transplantation and hemorrhagic cystitis after hematopoietic cell transplantation (HCT) [1, 2]. Hemorrhagic cystitis occurs in up to 25% of patients, leading to pain, urinary obstruction, prolonged hospitalizations, and possibly increased mortality [3–5]. In immunosuppressed patients, BKPyV replication is detected by nucleic acid testing of blood (viremia) or urine (viruria). Asymptomatic viruria is common after HCT and solid organ transplant, while viremia, especially high-level replication ≥10 000 copies/mL, is more specific for kidney and bladder disease [1, 4, 6]. Single-center studies have reported viremia or viruria incidences in the first 100 days after HCT [3, 7, 8] but not the longer-term risk of asymptomatic BKPyV replication on kidney function or the host immune response. We defined the natural history of BKPyV replication and outcomes for 2 years after HCT among patients at 2 large children’s hospitals and examined antiviral immunity. We hypothesized that BKPyV was associated with decreased kidney function and that the measurement of BKPyV T cells would predict viral clearance. Consensus guidelines do not recommend screening for BKPyV after HCT [5, 9] perhaps missing a risk factor for reduced kidney function or cystitis. Moreover, antivirals do not have proven efficacy, but third-party BKPyV T cells can be infused to promote viral clearance and more data are needed to define appropriate therapeutic use. METHODS Patient Population We prospectively enrolled children and young adults ≥2 years of age who were undergoing an allogeneic HCT at the Children’s Hospital of Philadelphia (CHOP) or Cincinnati Children’s Hospital Medical Center (CCHMC) from April 2013–May 2018, with follow-up until October 2018. The Institutional Review Boards at CHOP and CCHMC approved the study and participants provided informed consent and assent. Laboratory Methods Plasma, serum, peripheral blood mononuclear cells (PBMCs), and urine were frozen prior to HCT and at Months 1–4, 8, 12, and 24 (the research methods are available in the Supplementary Material). Nucleic acid testing for BKPyV was performed on all plasma and urine samples (Viracor-Eurofins, Lee’s Summit, MO). Blood BKPyV immunoglobulin G (IgG) was measured at baseline and Months 3 and 12 (Viracor-Eurofins). Enzyme-linked immunosorbent spot (ELISPOT) testing to detect BKPyV-specific T cells was performed on Month 3 PBMC samples (Figure 1). Figure 1. Open in new tabDownload slide Study cohort, sampling, and testing frequency and BK polyomavirus (BKPyV) viremia and viruria after hematopoietic cell transplant. A, We tested 193 children and young adults for BK polyomavirus in the blood (viremia) and urine (viruria) in the first 2 years after hematopoietic cell transplant (exclusion criteria in Supplementary Methods). Samples were collected and analyzed prior to transplant and at Months 1, 2, 3, 4, 8, 12, and 24 after transplant. B, Viremia was rare prior to transplant, occurred most frequently in the first 4 months, and, among survivors, was less frequent >8 months after transplant. C, Viruria was common prior to transplant, occurred frequently in the first 4 months, and persisted among a high proportion of survivors >8 months after transplant. Note that the scales are different for viremia and viruria. Abbreviations: CCHMC, Cincinnati Children’s Hospital Medical Center; CHOP, Children’s Hospital of Philadelphia; ELISPOT, enzyme-linked immune absorbent spot; IgG, immunoglobin G; PreTX, pretransplant. Clinical Data Clinical data were abstracted from the medical record, including serum creatinine and absolute lymphocyte counts within ±1 day of when 1049 of the 1070 (98.0%) research blood samples were collected (Supplementary Table 1). We recorded participants receiving cidofovir for any indication. Epstein-Barr virus, cytomegalovirus, adenovirus, and human herpes virus 6 viremia were captured from center-specific monitoring; positivity was defined using ≥2 consecutive nucleic acid results at any time posttransplant. Blood cystatin C was measured clinically or on stored samples at baseline and at Months 8, 12, and 24 [10]. BK Polyomavirus Definitions, Outcome Variables, and Covariates BKPyV replication was defined as a positive nucleic acid test, with or without clinical symptoms, and was categorized as peak viremia ≥10 000 copies/mL [1, 4, 6] and/or viruria ≥109 copies/mL [11, 12] among participants with ≥2 samples during the first 3 months post-HCT. The outcomes included cystitis, estimated glomerular filtration rate (eGFR), dialysis, and all-cause death. Cystitis was defined as grade ≥2 (presence of BKPyV, symptoms, and visible hematuria [2, 5]) and was assessed retrospectively by reviewing clinical documentation. GFR was estimated at baseline and at Months 8, 12, and 24. For participants <18 years of age [13] and ≥18 years of age [14], eGFRs were separately calculated using serum creatinine alone and cystatin C and creatinine together. We analyzed eGFR in the whole cohort and in the subset with asymptomatic viral replication (no cystitis). Covariates included demographic and transplant characteristics, graft-versus-host disease (GVHD), thrombotic microangiopathy (TMA), cidofovir for any indication, and other viremias. TMA was only assessed at CCHMC due to an established screening guideline [15]. As a risk factor for BKPyV replication, other viremias, GVHD, and TMA were not analyzed as time-dependent variables and could have occurred before or after detectable BKPyV. As a risk factor for cystitis, acute GVHD was only considered if it occurred prior to cystitis. Immune Response and Viral Clearance We examined whether the baseline IgG predicted posttransplant replication. We tested the Month 3 PBMC sample for BKPyV-specific T cells, defined as those with ELISPOT counts >5 or >10 above the negative control. We hypothesized that among participants with persistent BKPyV replication (≥2 positive samples) in the first 3 months posttransplant, a positive ELISPOT would predict viral clearance (undetectable viral DNA) at Month 4. We also assessed other factors potentially associated with clearance, including the absolute lymphocyte count, IgG, and cidofovir use. Statistical Analyses Continuous variables were presented as medians and interquartile ranges (IQR) and were examined with the Wilcoxon rank sum or 2-sample t test, as appropriate. Categorical variables were examined with the Chi-square or Fisher’s exact test, as appropriate. Logistic regression examined the factors associated with viral clearance. We excluded those participants developing cystitis prior to their Month 1 sample, to examine whether BKPyV replication predicted later cystitis. Linear regression examined the factors associated with eGFR. Multivariable Cox proportional hazards regression assessed the associations among BKPyV, cystitis, and mortality. Model selection for cystitis was performed with backward elimination using likelihood ratio testing and for mortality included all significant plausible variables. Given the high mortality rate, we also examined cystitis in a competing risk regression with death. We examined the overall survival rate instead of the nonrelapse mortality rate, given the high proportion of nonmalignant transplant indications. The study was originally designed to have 85% power to detect a clinically meaningful difference in a 1-year eGFR of 20 ml/min/1.73m2 between participants with and without BKPyV viremia ≥10 000 copies/mL and assumed a sample size of 100 participants surviving to 1 year and a 10% prevalence of viremia. Analyses were performed using STATA Version 15.1 and R 3.5.1, and a 2-sided P value <.05 was considered statistically significant. RESULTS Cohort We enrolled 193 participants (Figure 1; Table 1), who had a median age of 10 years (IQR, 6–15 years; range, 2–32 years). The most common underlying diagnoses were malignancy (37%), bone marrow failure (27%), or immunodeficiency (21%). At CCHMC (n = 148), a greater proportion of participants had bone marrow failure or immunodeficiency, compared to CHOP (n = 45), where most participants had malignancy. The cohort characteristics by center, specific underlying diagnoses, and conditioning regimens are shown in Supplementary Tables 2–4. Table 1. Cohort Characteristics and Variables Associated with Peak BK Polyomavirus Viremia ≥10 000 Copies/mL in the First 3 Months After Hematopoietic Cell Transplant Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Data are shown as either a median (interquartile range) or n (%). Abbreviation: HLA, human leukocyte antigen. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate, comparing viremia with <10 000 copies/mL to those with ≥10 000 copies/mL. bIncludes 178 participants with ≥2 blood tests (n = 10 with <2 blood tests) in the first 3 months and negative pretransplant viremia (n = 5 with detectable pretransplant viremia). cOf 6 cord blood transplant recipients, 5 also received bone marrow–derived cells. dOccurring at any point posttransplant. Open in new tab Table 1. Cohort Characteristics and Variables Associated with Peak BK Polyomavirus Viremia ≥10 000 Copies/mL in the First 3 Months After Hematopoietic Cell Transplant Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Variable . Entire Cohort . <10 000 Copies/mL . ≥10 000 Copies/mL . P a . N = 193 N = 178b n = 146 n = 32 Age at transplant, years 10 (6–15) 10 (6–14) 12 (9–17) .02 Recipient male gender 112 (58.0%) 82 (56.2%) 21 (65.6%) .33 Diagnosis group .63  Malignancy 72 (37.3%) 52 (35.6%) 12 (37.5%)  Bone marrow failure 52 (26.9%) 38 (26.0%) 11 (34.4%)  Immunodeficiency 40 (20.7%) 30 (20.5%) 6 (18.8%)  Other 29 (15.0%) 26 (17.8%) 3 (9.4%) Unrelated donor, versus related 130 (67.4%) 94 (64.4%) 28 (87.5%) .01 Donor age, years 24 (16–31) 24 (15–29) 28 (23–36) .01 Donor/recipient gender mismatch 86 (44.6%) 68 (46.6%) 15 (46.9%) .98 10/10 HLA match, versus another match 143 (74.1%) 115 (78.8%) 20 (62.5%) .05 Donor HLA C7 allele 107 (55.4%) 80 (54.8%) 15 (46.9%) .42 Cell product ‑ .45  Bone marrow 123 (63.7%) 96 (65.8%) 18 (56.3%)  Peripheral blood stem cells 64 (33.2%) 45 (30.8%) 14 (43.8%)  Cord bloodc 6 (3.1%) 5 (3.4%) 0 (0%) Conditioning chemotherapy  Received alemtuzumab 51 (26.4%) 40 (27.4%) 6 (18.8%) .31  Received antithymocyte globulin 80 (41.5%) 54 (37.0%) 20 (62.5%) .01  Received cyclophosphamide 109 (56.5%) 76 (52.1%) 23 (71.9%) .04  Received busulfan 84 (43.5%) 65 (44.5%) 14 (43.8%) .94  Received total body irradiation 45 (23.3%) 30 (20.5%) 9 (28.1%) .35 Myeloablative conditioning 129 (66.8%) 95 (65.1%) 23 (71.9%) .46 Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 157 (81.4%) 118 (80.8%) 26 (81.3%) .96  Received ex vivo T-cell depletion 55 (28.5%) 40 (27.4%) 12 (37.5%) .26 Epstein-Barr virus viremiad 85 (44.0%) 65 (44.5%) 15 (46.9%) .81 Cytomegalovirus viremiad 60 (31.1%) 49 (33.6%) 9 (28.1%) .55 Adenovirus viremiad 33 (17.1%) 21 (14.4%) 5 (15.6%) .79 Human herpes virus 6 viremiad 12 (6.2%) 8 (5.5%) 1 (3.1%) 1.00 Detectable pretransplant viruria 69 (39.7%) 46 (34.3%) 19 (63.3%) .003 Month 1 absolute lymphocyte count 410 (190–720) 460 (220–790) 383 (195–595) .35 Month 2 absolute lymphocyte count 530 (280–900) 610 (300–1090) 375 (150–620) .01 Month 3 absolute lymphocyte count 726 (400–1140) 740 (430–1270) 695 (260–980) .15 Data are shown as either a median (interquartile range) or n (%). Abbreviation: HLA, human leukocyte antigen. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate, comparing viremia with <10 000 copies/mL to those with ≥10 000 copies/mL. bIncludes 178 participants with ≥2 blood tests (n = 10 with <2 blood tests) in the first 3 months and negative pretransplant viremia (n = 5 with detectable pretransplant viremia). cOf 6 cord blood transplant recipients, 5 also received bone marrow–derived cells. dOccurring at any point posttransplant. Open in new tab BK Polyomavirus Replication BKPyV results are shown in Figure 1 and Tables 2 and 3. We tested 1070 blood samples (median, 6 samples/participant; IQR, 5–7 samples). Only 5 of 188 (2.7%) participants had viremia pre-HCT. Of 190 participants, 94 (49.5%) had ≥1 sample with detectable viremia after transplant. Among participants with ≥2 samples in the first 3 months after transplant and with negative pre-HCT viremia, the viral load was ≥10 000 copies/mL in 32 of 178 (18.0%). In univariate analyses, the risk factors significantly associated with viremia ≥10 000 copies/mL included an older recipient age, unrelated donor, older donor age, antithymocyte globulin or cyclophosphamide conditioning (but not alemtuzumab), detectable pre-HCT viruria, and a lower Month 2 absolute lymphocyte count (Table 1). Viremia ≥10 000 copies/mL was associated with acute GVHD grade ≥2 (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.2–5.4; P = .02) at any time relative to transplant (not time-dependent). Among the CCHMC participants, viremia ≥10 000 copies/mL was associated with TMA (OR, 7.0; 95% CI, 2.4–20.0; P < .001) at any time relative to transplant (not time-dependent). At Months 8, 12, and 24, 12 of 85 (14.1%), 9 of 91 (9.9%), and 3 of 44 (6.8%) participants had detectable viremia, respectively. Table 2. BK Polyomavirus Viremia Sample Results by Time Point . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) There were 191 participants with at least 1 blood sample tested for viremia: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab Table 2. BK Polyomavirus Viremia Sample Results by Time Point . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) . Pre-HCT . Month 1 . Month 2 . Month 3 . Month 4 . Month 8 . Month 12 . Month 24 . Copies/mL n = 188 n = 185 n = 178 n = 165 n = 134 n = 85 n = 91 n = 44 0 183 (97.3%) 112 (60.5%) 105 (59.0%) 110 (66.7%) 101 (75.4%) 73 (85.9%) 82 (90.1%) 41 (93.2%) 1–9999 3 (1.6%) 67 (36.2%) 52 (29.2%) 30 (18.2%) 20 (14.9%) 10 (11.8%) 8 (8.8%) 3 (6.8%) 10 000–99 999 2 (1.1%) 3 (1.6%) 16 (9.0%) 15 (9.1%) 8 (6.0%) 2 (2.4%) 0 (0%) 0 (0%) ≥100 000 0 (0%) 3 (1.6%) 5 (2.8%) 10 (6.1%) 5 (3.7%) 0 (0%) 1 (1.1%) 0 (0%) There were 191 participants with at least 1 blood sample tested for viremia: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab Table 3. BK Polyomavirus Viruria Sample Results by Time Point Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) There were 189 participants with at least 1 urine sample tested for viruria: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab Table 3. BK Polyomavirus Viruria Sample Results by Time Point Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) Copies/mL Pre-HCT Month 1 Month 2 Month 3 Month 4 Month 8 Month 12 Month 24 n = 174 n = 162 n = 146 n = 128 n = 99 n = 63 n = 81 n = 37 0 105 (60.3%) 17 (10.5%) 23 (15.8%) 20 (15.6%) 26 (26.3%) 43 (68.3%) 52 (64.2%) 24 (64.9%) 1–999 999 999 63 (36.2%) 65 (40.1%) 51 (34.9%) 53 (41.4%) 37 (37.4%) 15 (23.8%) 21 (25.9%) 11 (29.7%) ≥106–109 6 (3.5%) 21 (13.0%) 32 (21.9%) 27 (21.1%) 24 (24.2%) 3 (4.8%) 6 (7.4%) 2 (5.4%) ≥109 0 (0%) 59 (36.4%) 40 (27.4%) 28 (21.9%) 12 (12.1%) 2 (3.2%) 2 (2.5%) 0 (0%) There were 189 participants with at least 1 urine sample tested for viruria: n represents the number of participants tested at each time point. Abbreviation: HCT, hematopoietic cell transplant. Open in new tab We tested 890 urine samples (median, 5 samples/participant; IQR, 3–6 samples). Pre-HCT, one-third of participants (69 of 174, 39.7%) had detectable viruria, with a median of 3500 copies/mL (IQR, 1000–4 242 400 copies/mL). Of 184 participants, 160 (87.0%) had ≥1 sample with viruria after transplant. The peak urine viral load was ≥109 copies/mL in 70 of 157 (44.6%) participants with ≥2 urine samples in the first 3 months posttransplant. Approximately half of participants with viruria also experienced viremia (90 of 160, 56.3%). Viremic participants essentially all also had viruria, with only 1 participant with viremia (a single value of 112 copies/mL) having no viruria. Clinical Outcomes Hemorrhagic Cystitis BKPyV-associated cystitis was identified in 43 of 193 (22.3%) participants at a median of 34 days (IQR, 25–54 days) post-HCT. Any detectable viremia or viruria ≥109 copies/mL significantly predicted subsequent cystitis (Table 4). Of note, exposure to busulfan was also associated with an increased risk of cystitis (39.3% with no exposure versus 58.1% with exposure; P = .03), but cyclophosphamide was not (54.0% versus 65.1%; P = .2). In a multivariable model adjusting for significant covariates (Table 4), detectable viremia was independently associated with cystitis (adjusted hazard ratio [HR], 7.8; 95% CI, 3.1–19.3; P < .01). The model results were similar when including viruria ≥109 copies/mL instead of viremia (adjusted HR, 5.7; 95% CI, 2.4–13.4; P < .01). In a competing risk regression with death, adjusted for the same covariates as shown in the final Cox models in Table 4, detectable viremia and viruria ≥109 copies/mL remained independently associated with cystitis (adjusted HRs 7.9 [95% CI 3.1–20.4; P < .01] and 5.7 [95% CI, 2.4–13.2; P < .01], respectively.) Table 4. Variables Associated With Grade ≥ 2 Hemorrhagic Cystitis After Hematopoietic Cell Transplant . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … Total N = 193. Univariate data are shown as a median (interquartile range) or n (%) with a univariate P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. Abbreviations: BKPyV, BK polyomavirus; CI, confidence interval; HCT, hematopoietic cell transplant; HHV6, human herpes virus 7; HLA, human leukocyte antigen. a P < .05. bNot receiving alemtuzumab conditioning predicted failure perfectly and therefore was not included in the Cox models. c P < .01. dOccurring at any point posttransplant. eWe excluded participants without an available posttransplant research sample before the diagnosis of cystitis so that the variable had to precede the diagnosis of cystitis or occur at any time after transplant among those without cystitis. Open in new tab Table 4. Variables Associated With Grade ≥ 2 Hemorrhagic Cystitis After Hematopoietic Cell Transplant . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … . No Grade ≥ 2 Cystitis n = 150 . Grade ≥ 2 Cystitis n = 43 . Univariate P . Multivariable Cox Models, Data Shown as Hazard Ratios for Cystitis (95% CI) . . . . Detectable BKPyV Viremia Pre-cystitis BKPyV Viruria >109 Copies/mL Pre-cystitis Full Model Final Model Full Model Final Model Age at transplant, years 10 (6–14) 11 (8–17) .04 1.0 (.9–1.1) … 1.0 (.9–1.1) … Male gender 85 (56.7%) 27 (62.8%) .47 … … … … Diagnosis group .83 … … … …  Malignancy 54 (36.0%) 18 (41.9%) … … … …  Bone marrow failure 40 (26.7%) 12 (27.9%) … … … …  Immunodeficiency 33 (22.0%) 7 (16.3%) … … … …  Other 23 (15.3%) 6 (14.0%) … … … … Unrelated donor, versus related 98 (65.3%) 32 (74.4%) .26 … … … … 10/10 HLA match, versus another match 117 (78.0%) 26 (60.5%) .02 .6 (.3–1.3) … .7 (.3–1.7) … Peripheral blood stem cell product, versus bone marrow/cord 43 (28.7%) 21 (48.8%) .01 .5 (.05–5.1) … .4 (.1–3.0) … Conditioning chemotherapy  Received alemtuzumab 48 (32.0%) 3 (7.0%) <.001 .1 (0–.9)a .1 (.01–.7)a b b  Received antithymocyte globulin 56 (37.3%) 24 (55.8%) .03 1.0 (.4–2.6) … 1.7 (.7–4.2) …  Received cyclophosphamide 81 (54.0%) 28 (65.1%) .20 … … … …  Received busulfan 59 (39.3%) 25 (58.1%) .03 2.7 (1.0–7.6) 3.0 (1.3–6.7)c 1.9 (.7–4.9) …  Total body irradiation 35 (23.3%) 10 (23.3%) .99 … … … …  Myeloablative conditioning 92 (61.3%) 37 (86.0%) .002 .7 (.2–3.0) … 5.5 (1.1–27.4)a 11.1 (2.6–48.0)c Graft-versus-host disease prophylaxis  Received calcineurin inhibitor 123 (82.0%) 34 (79.1%) .66 … … … …  Received ex vivo T-cell depletion 36 (24.0%) 19 (44.2%) .01 2.2 (.2–23.8) … 2.6 (.4–18.4) …  Detectable pre-HCT BKPyV viruria 51/135 (37.8%) 18/39 (46.2%) .35 … … … …  Detectable pre-HCT BKPyV viremia 3/146 (2.1%) 2/42(4.8%) .31 … … … …  Epstein-Barr virus viremiad 71 (47.3%) 14 (32.6%) .09 … … … …  Cytomegalovirus viremiad 41 (27.3%) 19 (44.2%) .04 3.4 (1.5–7.9)c 3.4 (1.6–7.4)c 3.2 (1.4–7.3)c 2.9 (1.3–6.5)c  Adenovirus viremiad 28 (18.7%) 5 (11.6%) .36 … … … …  HHV6 viremiad 9 (6.0%) 3 (7.0%) .73 … … … …  Acute graft-versus-host disease pre-cystitise 50 (33.3%) 15 (34.9%) .85 … … … …  BKPyV viruria >109 copies/mL pre-cystitise 48/141 (34.0%) 17/25 (68.0%) .001 … … 6.4 (2.5–15.9)c 5.7 (2.4–13.4)c  Detectable BKPyV viremia pre-cystitise 58/147 (39.5%) 21/28 (75.0%) <.001 7.4 (2.9–19.3)c 7.8 (3.1–19.3)c … …  BKPyV viremia >10 000 copies/mL pre-cystitise 19/147 (12.9%) 2/28 (7.1%) .53 … … … … Total N = 193. Univariate data are shown as a median (interquartile range) or n (%) with a univariate P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. Abbreviations: BKPyV, BK polyomavirus; CI, confidence interval; HCT, hematopoietic cell transplant; HHV6, human herpes virus 7; HLA, human leukocyte antigen. a P < .05. bNot receiving alemtuzumab conditioning predicted failure perfectly and therefore was not included in the Cox models. c P < .01. dOccurring at any point posttransplant. eWe excluded participants without an available posttransplant research sample before the diagnosis of cystitis so that the variable had to precede the diagnosis of cystitis or occur at any time after transplant among those without cystitis. Open in new tab Kidney Outcomes Participants with viremia ≥10 000 copies/mL in the first 3 months after transplant had a significantly lower eGFR at 12 and 24 months (Table 5) and a higher risk of receiving dialysis (OR, 6.2; 95% CI, 1.8–21.6; P = .004). Age, total body irradiation, cyclophosphamide, calcineurin inhibitor prophylaxis, GVHD, cystitis, and cidofovir were not associated with the Month 24 eGFR (Supplementary Table 5). Adjusting for only the baseline eGFR, participants with viremia ≥10 000 copies/mL had a Month 24 creatinine/cystatin C eGFR that was 20.2 ml/min/1.73m2 lower (95% CI, −38.9 to −1.6 ml/min/1.73m2; P = .03), compared to those with viremia <10 000 copies/mL. Viruria ≥109 copies/mL was not associated with Month 8, 12, or 24 eGFR or dialysis (Table 5). Table 5. Kidney Outcomes Associated With BK Polyomavirus Viremia and Viruria After Hematopoietic Cell Transplant . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 Data are shown as a median (interquartile range) or n (%). Data are for the unadjusted, estimated glomerular filtration rate (mL/min/1.73m2) a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bIncludes the 183 participants with at least 2 samples in the first 3 months after transplant. cIncludes the 157 participants with at least 2 urine samples in the first 3 months after transplant. Open in new tab Table 5. Kidney Outcomes Associated With BK Polyomavirus Viremia and Viruria After Hematopoietic Cell Transplant . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 . Peak Viremia in First 3 Months After Transplant . . . . Peak Viruria in First 3 Months After Transplant . . . . n <10 000 Copies/mL ≥10 000 Copies/mL P a n <109 Copies/mL ≥109 Copies/mL P a n = 149b n = 34b n = 87c n = 70c Baseline  Creatinine 183 131 (112–153) 132 (108–152) .41 157 130 (108–155) 131 (113–145) .77  Creatinine/cystatin 183 125 (110–141) 118 (108–143) .48 156 120 (109–141) 123 (112–140) .42 Month 8  Creatinine 82 121 (104–138) 98 (84–116) .10 74 125 (98–147) 116 (100–132) .35  Creatinine/cystatin 82 106 (92–120) 92 (82–111) .47 74 106 (90–121) 104 (92–119) .53 Month 12  Creatinine 89 126 (104–148) 110 (78–125) .02 77 119 (97–150) 124 (104–134) .70  Creatinine/cystatin 88 110 (97–131) 100 (88–107) .04 76 104 (94–129) 104 (91–126) .74 Month 24  Creatinine 43 125 (110–141) 98 (75–111) .005 35 125 (108–137) 112 (105–131) .34  Creatinine/cystatin 43 113 (100–127) 97 (73–104) .003 35 115 (103–127) 106 (95–118) .39 Received dialysis … 5 (3.4%) 6 (17.7%) .006 … 3 (3.5%) 6 (8.6%) .19 Alive at last follow-up … 122 (81.9%) 19 (55.9%) .001 … 70 (80.5%) 50 (71.4%) .19 Data are shown as a median (interquartile range) or n (%). Data are for the unadjusted, estimated glomerular filtration rate (mL/min/1.73m2) a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bIncludes the 183 participants with at least 2 samples in the first 3 months after transplant. cIncludes the 157 participants with at least 2 urine samples in the first 3 months after transplant. Open in new tab Among those not developing cystitis, 58 of 147 (39.5%) had viremia, including 19 of 58 (32.8%) with viremia ≥10 000 copies/mL. When limiting the data to these participants with asymptomatic viremia, both the creatinine (median, 83 versus 125 ml/min/1.73m2, respectively; P = .01) and creatinine/cystatin C (median, 78 versus 117 ml/min/1.73m2, respectively; P = .004) eGFRs were significantly lower at 24 months among those with viremia ≥10 000 copies/mL (n = 4), compared to those without (n = 32). Adjusting only for the baseline eGFR, participants with asymptomatic viremia ≥10 000 copies/mL in the first 3 months after transplant had a creatinine/cystatin C eGFR that was 29.4 ml/min/1.73m2 lower (95% CI, −55.3 to −3.6 ml/min/1.73m2, respectively; P = .03) than those with viremia <10 000 copies/mL (Supplementary Table 5). Mortality After a median follow-up of 2.2 years (IQR, .8–3.8 years), 49 of 193 (25.4%) participants died. Participants with viremia ≥10 000 copies/mL in the first 3 months after transplant had a 3-fold increased risk of all-cause mortality (HR, 2.8; 95% CI, 1.5–5.2; P = .002). The HR for death associated with grade ≥2 cystitis was 2.0 (95% CI, 1.1–3.6; P = .02). Adjusting for cystitis and other factors associated with mortality, including age, gender, underlying diagnosis, and acute GVHD grade ≥2, viremia ≥10 000 copies/mL was independently associated with mortality (HR, 2.2; 95% CI, 1.1–4.2; P = .02). Immune Response and Clearance of Viremia The distribution of BKPyV IgG is shown in Figure 2. The baseline IgG was not associated with post-HCT viruria or viremia, as participants with both the highest and lowest levels developed viremia after transplant (data not shown). The Month 3 IgG was not associated with viral clearance (Table 6 and below). Table 6. Factors Associated With Clearance of BK Polyomavirus Viremia at 4 Months After Hematopoietic Cell Transplant . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 Data are shown as a median (interquartile range) or n (%). Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bThe included participants had detectable viremia on ≥2 samples in the first 3 months after transplant and had a Month 4 blood sample to assess for viral clearance. Clearance was defined as having undetectable viremia at Month 4. Open in new tab Table 6. Factors Associated With Clearance of BK Polyomavirus Viremia at 4 Months After Hematopoietic Cell Transplant . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 . Did Not Clear Viremia at Month 4 . Cleared Viremia at Month 4 . P a . n = 31b n = 21b Peak viremia ≥10 000 copies/mL in the first 3 months after transplant 21 (67.7%) 3 (14.3%) <.001 Month 3 BK polyomavirus IgG n = 31 n = 20 .49  1:2560 2 (6.5%) 2 (10.0%)  1:10 240 17 (54.8%) 7 (35.0%)  1:40 960 10 (32.3%) 8 (40.0%)  1:163 840 2 (6.5%) 3 (15.0%) Month 3 absolute lymphocyte count, cells/µL 646 (260–880) 780 (500–970) .15 Received cidofovir in first 3 months after transplant 17 (54.8%) 3 (14.3%) .004 Month 3 ELISPOT spots above negative control n = 25 n = 18  Number of spots 1.3 (0–8.4) 20.1 (2.9–48.5) .007  >5 spots 9 (36.0%) 12 (66.7%) .05  >10 spots 6 (24.0%) 11 (61.1%) .01 Data are shown as a median (interquartile range) or n (%). Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. a P value by Wilcoxon rank sum, 2-sample t test, Chi-square, or Fisher’s exact test, as appropriate. bThe included participants had detectable viremia on ≥2 samples in the first 3 months after transplant and had a Month 4 blood sample to assess for viral clearance. Clearance was defined as having undetectable viremia at Month 4. Open in new tab Figure 2. Open in new tabDownload slide Distribution of BK polyomavirus immunoglobulin G titers after transplant. There were 8 participants that inadvertently had 2 separate samples run pretransplant with results that differed by one 4-fold dilution, and their titers were averaged. Abbreviations: M, month; PreTX, pretransplant. Month 3 PBMC samples were tested for BKPyV-specific T cells in 104 of 193 (53.9%) participants. We examined factors associated with viral clearance by Month 4 among the subset of 52 participants with persistent viremia in the first 3 months after transplant and with an available Month 4 sample to assess clearance (Tables 6 and 7). Clearance of viremia at Month 4 occurred in 21 of these 52 (40.4%) and was less likely among participants with prior viremia ≥10 000 copies/mL. The Month 3 absolute lymphocyte count did not predict clearance. Receiving cidofovir for any indication (cystitis or adenoviremia) was less likely among participants with a 10/10 matched donor and more common among those developing acute GVHD, BKPyV viremia >10 000, and viruria ≥109 copies/mL (Supplementary Table 6). Participants with BKPyV replication who had received cidofovir were significantly less likely to clear viremia, but those with an ELISPOT >10 spots above the control were more likely to clear viremia (OR, 5.0; 95% CI, 1.3–18.6; P = .02; Table 6). Finally, 6 of 7 participants with persistent viremia at both Months 8 and 12 did not have detectable BKPyV-specific T cells at Month 3 (Supplementary Table 7). Table 7. BK Polyomavirus Viremia Clearance by Month 4 and Enzyme-linked Immune Absorbent Spot Results Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 These 43 selected participants had persistent viremia in the first 3 months after transplant, had a Month 4 sample to assess for clearance, and had a Month 3 ELISPOT result. Participants with peak viremia <10 000 copies/mL and ELISPOT counts >10 above the negative control (bold and highlighted) were more likely to clear viremia by Month 4. Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. Open in new tab Table 7. BK Polyomavirus Viremia Clearance by Month 4 and Enzyme-linked Immune Absorbent Spot Results Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 Participant . Month 1 Viremia Copies/mL . Month 2 Viremia Copies/mL . Month 3 Viremia Copies/mL . Month 3 ELISPOT Spots Above Control . Month 4 Viremia Copies/mL . Cleared viremia  1 2000 7600 3400 0 0  2 417 168 0 2.9 0  3 1200 51 0 20.4 0  4 3000 500 0 149 0  5 0 6800 196 7 0  6 190 5300 600 65.7 0  7 0 1100 900 44.3 0  8 38 102 0 3.3 0  9 700 172 0 1.7 0  10 5900 11 900 8700 0 0  11 No sample 201 185 1.9 0  12 1 300 000 58 700 98 127.3 0  13 0 2900 148 82.5 0  14 2400 2100 0 48.5 0  15 4200 1500 0 38.2 0  16 16 100 316 0 26.3 0  17 67 1600 1100 19.8 0  18 1300 70 0 14.3 0 Did not clear viremia  1 175 1200 0 0 89  2 1400 26 500 10 400 8.4 109  3 1300 7200 900 153.6 193  4 900 500 429 14.5 800  5 0 1400 339 2.1 1000  6 1100 23 300 42 500 0 2700  7 1700 600 700 1.6 2800  8 900 2100 66 400 0 2900  9 38 No sample 35 000 0 3100  10 800 700 1700 17.4 3300  11 1700 57 500 166 000 .8 3600  12 6400 60 000 800 40.3 4000  13 3000 900 7300 0 5500  14 222 1300 5700 0 6700  15 1500 12 900 93 000 1.3 13 500  16 209 3900 16 400 0 23 500  17 4700 8500 27 800 −3.8 34 500  18 900 21 600 48 800 4.1 57 400  19 600 3600 25 700 1.2 68 900  20 800 1100 1900 −1.7 97 000  21 184 000 496 000 2 000 000 5.9 460 000  22 No sample 574 000 682 000 −1.3 463 000  23 79 900 2 700 000 8 500 000 8.2 1 400 000  24 87 73 000 168 000 22.3 2 400 000  25 26 100 287 000 14 000 000 64.9 13 000 000 These 43 selected participants had persistent viremia in the first 3 months after transplant, had a Month 4 sample to assess for clearance, and had a Month 3 ELISPOT result. Participants with peak viremia <10 000 copies/mL and ELISPOT counts >10 above the negative control (bold and highlighted) were more likely to clear viremia by Month 4. Abbreviation: ELISPOT, enzyme-linked immune absorbent spot. Open in new tab DISCUSSION We report the natural history of BKPyV replication in almost 200 children and young adults undergoing HCT at 2 large centers. A number of novel findings have the potential to change practice. First, we identified frequent asymptomatic viremia and found that high levels of viremia, whether symptomatic or not, were associated with significant reductions in later kidney function. Second, we found that children and young adults with BKPyV replication who received cidofovir were not more likely to clear viremia. Last, we identified BKPyV-specific T cells as a marker of clearing viremia but no benefit from antibody responses. The management of BKPyV at most centers currently includes testing for viral reactivation only in symptomatic cases, with the provision of additional intravenous immunoglobulin and cidofovir. While our data suggest that none of these approaches may be beneficial, randomized trials would be needed to validate the effectiveness of treatments. The screening of asymptomatic patients for BKPyV will only be beneficial if a therapy is available. Our data show that the recovery of endogenous BKPyV-specific T cells is associated with viral clearance, similar to prior studies after kidney transplantation [16–19]. To our knowledge, our study is the largest systematic evaluation of cellular responses to BKPyV after HCT [20–22]. The efficacy and safety of third-party BKPyV-specific T cells has recently been reported after HCT [23–25]. Our findings expand on single-center studies examining BKPyV in the first 100 days after HCT, which are generally without a comprehensive assessment of kidney outcomes or immune responses [11, 12, 26, 27]. Hill et al [7, 8] measured the impact of viremia from 5 viruses, including BKPyV, on mortality among 400 HCT recipients. The incidence of BKPyV viremia was 54%, most episodes were persistent, and, similar to our findings, viremia was associated with mortality. BKPyV viremia occurred a median of 10 days before cystitis. Others have reported that viremia or viruria predict cystitis, which we also confirmed [3, 6]. About 25% of our cohort developed cystitis [5, 7, 11]. BKPyV viremia was associated with a higher risk of receiving dialysis and an eGFR that was, on average, 20 ml/min/1.73m2 lower by 2 years after transplant. O’Donnell et al [27] monitored 57 adults after HCT and observed that viremia was independently associated with higher peak creatinine, similar to retrospective studies in children [4]. In contrast to antithymocyte globulin, alemtuzumab was not associated with the risk of BKPyV replication. It is possible that these data are confounded by an unmeasured variable or that qualitative, BKPyV-specific T-cell recovery after alemtuzumab is importantly different than recovery after antithymocyte globulin. Although we and others have shown that BKPyV viremia can predict cystitis, the positive predictive value of viremia remains low, implying that other factors, perhaps related to the host response or viral diversity, are important to determining which patients will develop disease [11]. We observed that BKPyV viremia was associated with dialysis, TMA, acute GVHD, and death. More research is needed to determine whether these associations are causal, time-dependent, associated with poor immune reconstitution, or are confounded by higher degrees of immunosuppression. In vitro studies indicate that BKPyV infection can induce host endothelial cell production of interferon [28], which may precipitate both TMA and acute GVHD, supporting a possible direct, causative effect of BKPyV viremia on these other, significant posttransplant complications [7]. The strengths of our approach include the multi-center design, collection of samples and clinical data for 2 years after transplant, and centralized lab testing. We assessed both the humoral and cellular host immune response to BKPyV. Finally, we examined the association between BKPyV replication and eGFR for the first time in the HCT population using both serum creatinine and cystatin C, which has advantages in patients with decreased muscle mass [10]. Participants with viremia >10 000 copies/mL had an 18–26% decrease in baseline eGFR by 2 years post-HCT (Table 5). In older adults, a 30% reduction in eGFR over 2 years has been strongly associated with end-stage kidney disease and death [29]. While similar data are not available in children, it is plausible that the eGFR decline we observed would also be associated with poor outcomes in a younger population. Our study was limited by a lack of biopsy data to confirm nephropathy. Nevertheless, BKPyV viremia ≥10 000 copies/mL has been classified as presumptive nephropathy after kidney transplantation, even without a biopsy [30]. Patient characteristics, most notably the high proportion of nonmalignant indications, may not reflect the risk for BKPyV infection at other centers. Not all centers have the resources to perform centralized, quantitative testing for viremia, and semi-quantitative detection of high-level viremia may have produced the same observations. Our monthly sampling frequency may have missed earlier windows of detection associated with clinical outcomes, including TMA and GVHD. The potential benefits and risks of treatments, such as intravenous immune globulin and cidofovir, would need to be tested in randomized trials. Finally, clinical information was abstracted from the medical record, possibly influencing the capture of outcomes, such as cystitis and GVHD. In conclusion, BKPyV viremia was associated with significant kidney and bladder disease and mortality after HCT. Moreover, asymptomatic viremia was common and was associated with decreased kidney function. Assessments of novel interventions, such as the infusion of virus-specific T cells, are needed to determine whether preventing or treating BKPyV infection can improve morbidity and mortality, as our study does not suggest the utility of cidofovir. Patients with persistent, high-level symptomatic or asymptomatic viremia may benefit from infusion of BKPyV-specific T cells, and this hypothesis can be tested in future clinical trials. Supplementary Data Supplementary materials are available at Clinical Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author. Notes Acknowledgement. The authors thank Dr Ulf Beier for his assistance with illustrating the figures. Financial support. This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health (grant numbers K23 DK101600 to B. L. L. and K23 DK093556 to M. R. D.) and the National Center for Advancing Translational Sciences (grant number UL1 TR001878). Viracor-Eurofins tested the samples for BK polyomavirus viremia, viruria, and antibody at no charge. Potential conflicts of interest. B. L. L and S. J. are coinventors of a patent application under review: Compositions and Methods for Treatment of HSCT-Associated Thrombotic Microangiopathy (United States Patent Number PCT/US2014/055922, 2014). B. L. L. has received consulting fees from Jazz Pharmaceuticals and Bioporto. S. K. and M. A. are employees of Viracor-Eurofins. M. R. D. has received research funding from Mallinckrodt, unrelated to this study. S. M. D. has received research support from Alexion Pharmaceuticals, personal fees from Novartis and Anthem, and research grants from Prolacta, outside the submitted work. S. J. has received research support from Alexion Pharmaceuticals; has received grants from the National Institutes of Health; has received personal fees from Omeros, Arcus Medica, and Magnolia Innovations, outside the submitted work; and has the following patents pending: 61/878,119, 62/094,802, 62/172,987, and 62/593,401. T. O. has received personal fees from Bluebird Bio, Miltenyi, and Novartis, outside the submitted work. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed. References 1. Hirsch HH , Knowles W, Dickenmann M, et al. Prospective study of polyomavirus type BK replication and nephropathy in renal-transplant recipients . N Engl J Med 2002 ; 347 : 488 – 96 . Google Scholar Crossref Search ADS PubMed WorldCat 2. Bedi A , Miller CB, Hanson JL, et al. 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Journal

Clinical Infectious Diseases – Oxford University Press

Published: Dec 15, 2020

Keywords: immune response; drug clearance; hematopoietic stem cell transplantation; bk virus; viremia; t-lymphocytes; cidofovir; viruria; cystitis

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