Tarlatamab’s subcutaneous formulation produced a safety and early activity readout in extensive-stage small cell lung cancer (ES-SCLC) during the Phase 1b DeLLphi-308 study. Presented at the International Association for the Study of Lung Cancer 2026 World Conference on Lung Cancer, the data support continued evaluation of a more convenient dosing route than the original schedules used in earlier development. The report adds to a fast-moving small-cell pipeline that has increasingly focused on target engagement and logistics as much as early antitumor effects. The subcutaneous approach, if confirmed in later studies, could reduce infusion burden and broaden accessibility for patients who need repeated dosing. While the update does not establish efficacy outcomes, it provides a clinical “signal check” that can inform dose selection for randomized studies. Developers will watch for durability, safety in combination settings, and how response rates compare with intravenous schedules and other emerging SCLC immunotherapies.