Pembrolizumab plus axitinib versus sunitinib in metastatic renal cell carcinoma: outcomes of Japanese patients enrolled in the randomized, phase III, open-label KEYNOTE-426 study

Background: In the phase III open-label KEYNOTE-426 (NCT02853331) study, first-line pembrolizumab and axitinib improved overall survival (OS) and progression-free survival (PFS) versus sunitinib for metastatic renal cell carcinoma (mRCC). KEYNOTE-426 evaluated patients enrolled from 25 sites in Japan. Methods: Patients enrolled in Japan were included in this post hoc subgroup analysis. Adults with clear cell mRCC were randomly assigned 1:1 to receive intravenous pembrolizumab 200 mg every 3 weeks plus oral axitinib 5 mg twice daily or oral sunitinib 50 mg once daily (4 weeks on/2 weeks off). Dual primary endpoints were OS and PFS as assessed by blinded independent central review. Objective response rate (ORR) and safety were secondary endpoints. Results: The Japanese subgroup comprised 94 patients (pembrolizumab–axitinib, n = 44; sunitinib, n = 50; 11% of the intent-to-treat population). Median time from randomization to data cutoff (January 6, 2020) was 29.5 months (range 24.6–37.3). Consistent with the intent-to-treat population, the OS, PFS, and ORR suggested improvement with pembrolizumab–axitinib versus sunitinib in the Japanese subgroup. Grade ≥ 3 treatment-related adverse events (TRAEs) occurred in 70% of patients receiving pembrolizumab–axitinib versus 78% receiving sunitinib; 11 (25%) patients receiving pembrolizumab–axitinib and 13 (27%) patients receiving sunitinib discontinued the study medication due to AEs. TRAEs led to the discontinuation of pembrolizumab, axitinib, pembrolizumab–axitinib, or sunitinib in 32%, 34%, 14%, and 20%, respectively. No deaths from TRAEs occurred. Conclusions: Efficacy outcomes for the Japanese subgroup were consistent with those of the global population. Safety in Japanese patients was consistent with the results from the global population.