A Pooled Analysis of Treatment-Free Survival in Advanced Renal Cell Carcinoma

A clinically meaningful attribute of some immune-oncology (IO) regimens is potential durable clinical benefit during a treatment-free interval. We characterize treatment-free survival (TFS) with and without ongoing toxicity in trials of frontline IO-VEGF tyrosine kinase inhibitor (TKI) combinations in patients with advanced renal cell carcinoma (aRCC).

Individual patient data were pooled by treatment arm from randomized trials submitted to the FDA evaluating IO-TKI combination in treatment-naïve aRCC with at least 30 months of median follow-up. OS, TFS, TFS with and without toxicity, and time to all protocol therapy cessation were assessed. TFS was estimated by 30-month restricted mean times, defined as area between Kaplan-Meier curves for two time-to-event endpoints originating at randomization: time to all protocol therapy cessation and time to subsequent systemic therapy initiation or death.

Three trials met criteria for analysis; 1,183 patients received IO-TKI versus 1,184 on control arms receiving TKI alone (sunitinib, SUN). IO-TKI and SUN groups spent 9% {2.7 months [95% confidence interval (CI), 1.8-3.5]} and 10% [2.9 months (95% CI, 2.1-3.8)] of the 30-month period alive and treatment-free, respectively. Mean TFS without grade ≥3 toxicity was 1.7 and 2.3 months in IO-TKI and SUN groups, respectively.

In this post hoc partitioned survival analysis, TFS and TFS without toxicity appeared similar in the IO-TKI group compared with the SUN group. These findings may reflect contin-uation of TKI until progression per protocol design in all trials and discontinuation of IO after 2 years in two trials. See related commentary by Stadler and Karrison, p. 3098.