A phase II trial of nivolumab followed by ipilimumab and nivolumab in advanced non-clear-cell renal cell carcinoma.

Objective: To evaluate the efficacy of sequential treatment with ipilimumab and nivolumab following progression on nivolumab monotherapy in individuals with advanced, non-clear-cell renal cell carcinoma (nccRCC).

Materials And Methods: UNISoN (ANZUP1602; NCT03177239) was an open-label, single-arm, phase 2 clinical trial that recruited adults with immunotherapy-naïve, advanced nccRCC. Participants received nivolumab 240 mg i.v. two-weekly for up to 12 months (Part 1), followed by sequential addition of ipilimumab 1 mg/kg three-weekly for four doses to nivolumab if disease progression occurred during treatment (Part 2). The primary endpoint was objective tumour response rate (OTRR) and secondary endpoints included duration of response (DOR), progression-free (PFS) and overall survival (OS), and toxicity (treatment-related adverse events).

Results: A total of 83 participants were eligible for Part 1, including people with papillary (37/83, 45%), chromophobe (15/83, 18%) and other nccRCC subtypes (31/83, 37%); 41 participants enrolled in Part 2. The median (range) follow-up was 22 (16-30) months. In Part 1, the OTRR was 16.9% (95% confidence interval [CI] 9.5-26.7), the median DOR was 20.7 months (95% CI 3.7-not reached) and the median PFS was 4.0 months (95% CI 3.6-7.4). Treatment-related adverse events were reported in 71% of participants; 19% were grade 3 or 4. For participants who enrolled in Part 2, the OTRR was 10%; the median DOR was 13.5 months (95% CI 4.8-19.7) and the median PFS 2.6 months (95% CI 2.2-3.8). Treatment-related adverse events occurred in 80% of these participants; 49% had grade 3, 4 or 5. The median OS was 24 months (95% CI 16-28) from time of enrolment in Part 1.

Conclusions: Nivolumab monotherapy had a modest effect overall, with a few participants experiencing a long DOR. Sequential combination immunotherapy by addition of ipilimumab in the context of disease progression to nivolumab in nccRCC is not supported by this study, with only a minority of participants benefiting from this strategy.