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: firstname.lastname@example.org 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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