Treatment-free survival and partitioned survival analysis of patients with advanced renal cell carcinoma treated with nivolumab plus ipilimumab versus sunitinib: 5-year update of CheckMate 214

Background: Immunotherapy can be associated with prolonged disease control even after cessation of treatment without the need for further cancer-directed therapy. Treatment-related adverse events (TRAEs) can also persist after discontinuation of therapy. Treatment-free survival (TFS) with and without toxicity as a component of a partitioned survival model can characterize patient survival time, which is not captured by standard outcome measures.

Methods: Data from 1096 patients with advanced renal cell carcinoma treated with first-line nivolumab plus ipilimumab (NIVO+IPI) versus sunitinib (SUN) in the CheckMate 214 trial were analyzed. TFS was defined as the area between two Kaplan-Meier curves for time from randomization to protocol therapy discontinuation and time from randomization to subsequent systemic therapy initiation or death, estimated as the difference in 60-month restricted mean times with confidence intervals (CIs) obtained using bootstrap sampling. Time on protocol therapy and TFS were further characterized as time with and without grade 2+ and 3+TRAEs. Survival functions were estimated in subgroups including International Metastatic Renal Cell Carcinoma Database Consortium risk groups using the Kaplan-Meier method.

Results: At 5 years from randomization, 48% of patients treated with NIVO+IPI and 37% of patients treated with SUN were alive. In the intent-to-treat population, 18% of the NIVO+IPI-treated and 5% of SUN-treated patients are surviving treatment-free. For favorable-risk patients, the 60-month mean TFS was 14.4 months for NIVO+IPI versus 5.5 months for SUN (difference 8.9 months (95% CI 4.9 to 12.8)). TFS for NIVO+IPI versus SUN with grade 2+TRAEs was 5.0 and 2.1 months, respectively, and with grade 3+TRAEs was 1.2 and 0.3 months, respectively. For intermediate/poor-risk patients, the 60-month mean TFS was 10.1 months for NIVO+IPI versus 4.1 months for SUN (difference 6.1 months (95% CI 4.2 to 7.9)). TFS for NIVO+IPI versus SUN with grade 2+TRAEs was 4.0 versus 2.0 months, respectively, and 0.6 versus 0.3 months with grade 3+TRAEs.

Conclusions: Although overall survival was similar, favorable-risk patients treated with NIVO+IPI spent more time surviving treatment-free with and without toxicity versus SUN after 60 months of follow-up. Intermediate/poor-risk patients treated with NIVO+IPI had longer survival and longer TFS without toxicity versus SUN.

Trial registration number: NCT02231749.