Lenvatinib plus pembrolizumab in Japanese patients with endometrial cancer: Results from Study 309/KEYNOTE‐775

Study 309/KEYNOTE‐775 is a phase 3 open‐label, randomized trial of lenvatinib plus pembrolizumab versus treatment of physician's choice (TPC) in patients with advanced endometrial cancer with progression after platinum‐based therapy. Primary endpoints of superiority for lenvatinib plus pembrolizumab were met for progression‐free survival (PFS) and overall survival (OS) in all‐comers (ie, regardless of mismatch repair [MMR] status) and patients with MMR proficiency (pMMR). We present results for the Japanese subset. Patients were randomized to oral lenvatinib 20 mg/day plus intravenous pembrolizumab 200 mg every 3 weeks (Q3W; up to 35 cycles of pembrolizumab) or TPC (intravenous doxorubicin 60 mg/m(2) Q3W or paclitaxel 80 mg/m(2) QW [3 weeks on/1 week off]). Primary endpoints were PFS by blinded independent central review per RECIST version 1.1 and OS. One hundred four patients were randomized in Japan (data cutoff, October 26, 2020; median follow‐up, 11.8 [range, 1.1–26.9] months). Hazard ratios (HRs) for PFS with lenvatinib plus pembrolizumab versus TPC were 1.04 (95% CI, 0.63–1.73) in patients with pMMR and 0.81 (0.50–1.31) in all‐comers. Hazard ratios for OS were 0.74 (0.41–1.34) with pMMR and 0.59 (0.33–1.04) for all‐comers. Adverse events were manageable and led to discontinuation of one/both study drugs in 36.5% of patients in the lenvatinib plus pembrolizumab group versus 7.8% in the TPC group. Similar to the global Study 309/KEYNOTE‐775 results, this analysis suggested favorable efficacy and manageable safety with lenvatinib plus pembrolizumab after platinum‐based chemotherapy in Japanese patients with advanced endometrial cancer and supports this combination as a new standard of care in this population.