Amgen said on September 8, 2026, that its Phase 3 DeLLphi-305 trial met its primary endpoint. In extensive-stage small-cell lung cancer, the combination of tarlatamab (Imdelltra) and AstraZeneca’s durvalumab (Imfinzi) improved overall survival by a statistically significant amount compared with durvalumab alone.
The trial enrolled 563 patients whose disease had not progressed after first-line durvalumab, platinum-based chemotherapy and etoposide. Participants were divided evenly between the two groups. According to the American Journal of Managed Care, the combination also improved the secondary endpoints of progression-free survival and response rate.
Tarlatamab is a bispecific T-cell engager that binds DLL3 on tumour cells and CD3 on T cells, directing immune cells toward the tumour. Amgen says this is the first Phase 3 trial in which a drug in this class has shown a survival benefit as first-line maintenance treatment. The company said the safety profile was consistent with known risks and no new safety signal was reported.
Small-cell lung cancer is among the most aggressive cancer types, and survival gains in extensive-stage disease are uncommon. The size of the survival benefit — including how many months — has not been disclosed. Amgen said detailed results will be presented at a medical congress.
Verified: Announcement date, primary-endpoint result, 563 participants and secondary endpoints: Amgen’s press release, AJMC and BioPharm International. Uncertainty: Results currently rely on the company’s interim-analysis announcement; a peer-reviewed publication and numerical survival difference are not yet available. Not available: Median survival figures, adverse-event rates, regulatory filing timeline and approval status in Türkiye were not available in the source material.