Clinical outcome of patients with metastatic renal cell carcinoma who interrupted VEGFR-TKI after achieving stable disease or better response.

Abstract

459 Background: The purpose of the this study is to evaluate the clinical outcome of VEGFR-TKIs interruption in patients with metastatic renal cell carcinoma (mRCC) after achieving stable disease (SD) or better response. Methods: A retrospective analysis of medical records and imaging studies was performed on all patients with mRCC treated with VEGFR-TKIs between January 2008 and July 2014 (n=505). Patients who achieved SD or better response under VEGFR-TKI and later discontinued VEGFR-TKIs for any reason with the exception of disease progression were included in the analysis. Outcomes analyzed were progression free survival (PFS) after VEGFR-TKIs discontinuation, patterns of disease progression, time to subsequent therapy (TST), response to VEGFR-TKI resumption, and time to treatment failure (TTF) after TKI resumption. Results: We identified 32 patients (sunitinib=20, sorafenib=7, and pazopanib=5). The responses to VEGFR-TKIs were CR (n=4), PR (n=11), SD (n=15), and controlled but non-measurable (n=2). Median time to interruption from the initiation of VEGFR-TKI therapy was 16.6 months (95% CI, 12.8-20.3). The main causes of VEGFR-TKI interruption was toxicity (n=19, 59.4%), will to have treatment holiday (n=7, 21.8%), patient’s refusal (n=3, 9.4%), and others (n=3, 9.4%). At the time of analysis, 16 patients had disease progression and 1 patient was dead. With a median follow-up duration of 56.6 months (range, 12.6-167.4), median PFS from VEGFR-TKI interruption was 23.8 months (95% CI, 12.5-35.0), and the median TST was 26.2 months (95% CI, 15.9-36.6). The progression was observed in pre-existing lesions in 7 patients (43.7%) or new lesions developed in 9 (56.3%). Among 11 patients who received VEGFR-TKI resumption, 2 patients (18.2%) achieved a PR and the stable disease was observed in 9 (81.8%) with a median TTF of VEGFR-TKI resumption of 6.2 months (95% CI, 4.0-8.4). Conclusions: In patients with mRCC controlled with VEGFR-TKIs, VEGFR-TKI could be interrupted at least temporarily when clinically warranted.