Tambotatug Pelitecan in Small-Cell Lung Cancer after Platinum-Based Therapy

BackgroundTambotatug pelitecan (known as Tam-Peli, a new antibody–drug conjugate that targets the immune-checkpoint molecule B7-H3) showed promising clinical efficacy in patients with relapsed extensive-stage small-cell lung cancer in early-phase trials. MethodsIn this phase 3, multicenter, open-label, randomized trial, we assigned eligible patients with small-cell lung cancer that had progressed after first-line platinum-based therapy in a 1:1 ratio to receive tambotatug pelitecan or topotecan. The primary end point was overall survival. The key secondary end points were progression-free survival and objective response as assessed by investigators. Here, we report the results from the prespecified interim analysis. ResultsA total of 451 patients underwent randomization: 225 were assigned to receive tambotatug pelitecan and 226 to receive topotecan. Overall survival was significantly longer with tambotatug pelitecan than with topotecan — a median of 13.3 months (95% confidence interval [CI], 12.1 to could not be estimated), as compared with 9.4 months (95% CI, 7.7 to 10.5); the stratified hazard ratio for death was 0.46 (95% CI, 0.35 to 0.62; P<0.001). Treatment with tambotatug pelitecan also resulted in significantly longer progression-free survival than treatment with topotecan (median, 7.4 months [95% CI, 6.1 to 7.6] vs. 2.8 months [95% CI, 1.8 to 3.0]; stratified hazard ratio, 0.29 [95% CI, 0.23 to 0.37]; P<0.001). A confirmed objective response occurred in 59.1% of the patients in the tambotatug pelitecan group, as compared with 9.7% of those in the topotecan group (P<0.001). The overall incidence of adverse events of grade 3 or higher was lower with tambotatug pelitecan than with topotecan (55.4% vs. 77.9%). ConclusionsAmong patients with relapsed small-cell lung cancer after platinum-based therapy, treatment with tambotatug pelitecan resulted in longer overall survival, longer progression-free survival, and a higher percentage of patients with an objective response than treatment with topotecan, with a lower incidence of adverse events of grade 3 or higher. (Funded by the Innovative Drug Research and Development National Science and Technology Major Project and MediLink Therapeutics; TAISHAN-302 ClinicalTrials.gov number, NCT06612151.)