Early tumor shrinkage (eTS) of 10% has been identified as a putative prognostic marker in mRCC, which could serve as an early read-out in clinical trials. We aimed to validate the prognostic role of eTS in first line TKI treatment using data from the COMPARZ study (NCT00720941).
A retrospective analysis on data of 1100 1st line patients treated with sunitinib or pazopanib was performed. Tumor response was measured according to RECIST 1.1. eTS was a priori defined as tumor shrinkage by ≥10%. The Kaplan-Meier method was used to estimate time-to-event outcomes. A landmark analysis was performed on day (d) 42 and d 90 after randomization. Cox proportional hazards regression was performed to evaluate the effect of prognostic factors on overall survival after d 42 and d 90.