Tarlatamab in Small-Cell Lung Cancer after Platinum-Based Chemotherapy.

BACKGROUND: Tarlatamab, a bispecific delta-like ligand 3-directed T-cell engager immunotherapy, received accelerated approval for the treatment of patients with previously treated small-cell lung cancer. Whether tarlatamab is more effective than chemotherapy in the treatment of patients whose small-cell lung cancer has progressed during or after initial platinum-based chemotherapy is not known. METHODS: We conducted a multinational, phase 3, open-label trial to compare tarlatamab with chemotherapy as second-line treatment in patients with small-cell lung cancer whose disease had progressed during or after platinum-based chemotherapy. Patients were randomly assigned to receive tarlatamab or chemotherapy (topotecan, lurbinectedin, or amrubicin). The primary end point was overall survival. Key secondary end points were investigator-assessed progression-free survival and patient-reported outcomes. Results of the prespecified interim analysis (data-cutoff date, January 29, 2025) are reported. RESULTS: A total of 509 patients were randomly assigned to receive tarlatamab (254 patients) or chemotherapy (255 patients). Treatment with tarlatamab resulted in significantly longer overall survival than chemotherapy (median, 13.6 months [95% confidence interval {CI}, 11.1 to not reached] vs. 8.3 months [95% CI, 7.0 to 10.2]; stratified hazard ratio for death, 0.60; 95% CI, 0.47 to 0.77; P<0.001). Tarlatamab treatment also had a significant benefit with respect to progression-free survival and cancer-related dyspnea and cough as compared with chemotherapy. The incidence of adverse events of grade 3 or higher was lower with tarlatamab than with chemotherapy (54% vs. 80%), as was the incidence of adverse events resulting in treatment discontinuation (5% vs. 12%). CONCLUSIONS: Treatment with tarlatamab led to longer overall survival than chemotherapy among patients with small-cell lung cancer whose disease had progressed during or after platinum-based chemotherapy. (Funded by Amgen; DeLLphi-304 ClinicalTrials.gov number, NCT05740566.).