Tarlatamab in small cell lung cancer following platinum-based chemotherapy: subgroup analysis of Japanese patients from the DeLLphi-304 study

Abstract Background In the Phase 3 DeLLphi-304 trial, tarlatamab significantly improved overall survival (OS) over chemotherapy for small-cell lung cancer (SCLC) progressed after platinum-based chemotherapy. We report efficacy and safety in the Japanese subpopulation. Methods Patients were randomized to tarlatamab or amrubicin in Japan. The primary endpoint was OS. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), duration of response (DOR), and safety. Results As of 29 Jan 2025 (data cutoff), 35 patients (tarlatamab, n  = 12; amrubicin, n  = 23) were enrolled. Baseline characteristics were generally balanced although fewer tarlatamab-treated patients had chemotherapy-free interval  Conclusion Tarlatamab demonstrated numerically longer OS and DOR, and higher ORR versus amrubicin in Japanese patients with SCLC, with fewer high-grade treatment-related adverse events. These results in Japanese patients support those of the global population.