Imfinzi Plus Imdelltra Shows Interim Survival Benefit in ES-SCLC Maintenance

Durvalumab (Imfinzi, AstraZeneca) plus tarlatamab-dlle (Imdelltra, Amgen) significantly improved overall survival (OS) compared with durvalumab alone as first-line maintenance treatment for extensive-stage small cell lung cancer (ES-SCLC), according to announcements from AstraZeneca and Amgen. The findings came from a prespecified interim analysis of the phase 3 DeLLphi-305 trial.

The global, randomized, open-label trial enrolled 563 patients whose disease had not progressed after induction treatment with durvalumab, platinum chemotherapy, and etoposide. Patients were assigned 1:1 to receive durvalumab plus tarlatamab or durvalumab alone until disease progression or unacceptable toxicity. Platinum treatment consisted of investigator-selected carboplatin or cisplatin. Patients with treated or untreated asymptomatic brain metastases at baseline were eligible. 

The study met its primary endpoint of OS and also showed statistically significant improvements in the secondary endpoints of progression-free survival and objective response rate. The announcements did not report hazard ratios, median survival estimates, response rates, or confidence intervals for DeLLphi-305.

The companies reported that the combination’s safety profile was consistent with the known profiles of the individual drugs, with no new safety signals identified. Detailed trial-specific adverse-event rates were not provided. Tarlatamab’s prescribing information includes boxed warnings for cytokine release syndrome and neurologic toxicity, including immune effector cell-associated neurotoxicity syndrome.

Tarlatamab is a bispecific T-cell engager that binds DLL3 on tumor cells and CD3 on T cells, activating T cells against DLL3-expressing cancer cells. The first-line maintenance combination remains investigational. The companies plan to present detailed DeLLphi-305 results at an upcoming medical meeting and share the findings with regulatory authorities.

Source: AstraZeneca. Imfinzi plus Imdelltra demonstrated a statistically significant and highly clinically meaningful improvement in overall survival and progression-free survival in 1st-line extensive-stage small cell lung cancer. News release. AstraZeneca; September 8, 2026. Accessed September 14, 2026.

Amgen. Imdelltra in combination with Imfinzi demonstrated landmark improvement in overall survival in first-line extensive stage small cell lung cancer. News release. Amgen; September 8, 2026. Accessed September 14, 2026.