We read with interest the report by Cloughesy et al on the activity of cabozantinib in recurrent glioblastoma (GBM) patients with prior anti-angiogenic therapy.1 In their subset analysis, they reported overall survival (OS) results using 2 different cabozantinib doses: 4.1 months (95% CI: 1.4–16.7) in the 140 mg group (n = 12); 4.6 (95% CI: 2.9–5.6) in the 100 mg group (n = 58); OS for combined groups was 4.6 months. Of the 70 patients in the analysis, 57 (81%) with prior anti-angiogenic therapy had bevacizumab (BEV). In their discussion, the authors raise the issue of “how best to define a meaningful response (eg, objective response rate, progression-free survival).”1 We argue, because of the vagaries in interpreting MRIs in patients receiving BEV or other anti-angiogenic agents, the most meaningful endpoint is OS. Relative to this, we suggest literature can provide a valuable benchmark, as the OS outcome for these patients tends to be relatively uniform. Such a review of the literature2 exemplifies this argument and compares well with the reported results in the cabozantinib study (ie, group 3 below): A total of 2388 patients from 53 arms of 42 studies were analyzed in 3 groups2: Group 1: Thirty-two studies in which survival post-BEV was determined by subtracting PFS from OS (2045 patients); OS post-BEV = 3.36 months (95% CI: 3.12–3.66) Group 2: Two studies (94 patients) in which OS post-BEV is reported: OS = 3.26 (95% CI: 2.394.42) Group 3: Eight studies of salvage therapy after progression on BEV (249 patients): OS post-BEV = 4.46 months (95% CI: 3.68–5.54). Funding This work was supported by the National Institutes of Health National Cancer Institute CORE grant (no. 4P 30 CA014520). References 1. Cloughesy TF, Drappatz J, de Groot J, et al. Phase II study of cabozantinib in patients with progressive glioblastoma: subset analysis of patients with prior antiangiogenic therapy. Neuro Oncol . 2018; 20( 2): 259– 267. Google Scholar CrossRef Search ADS PubMed 2. Tipping M, Eickhoff J, Ian Robins H. Clinical outcomes in recurrent glioblastoma with bevacizumab therapy: an analysis of the literature. J Clin Neurosci . 2017; 44: 101– 106. Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: email@example.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
Neuro-Oncology – Oxford University Press
Published: Mar 27, 2018
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