Adding Imdelltra to Imfinzi as First-Line Maintenance Extends Survival in ES-SCLC

Adding tarlatamab-dlle (Imdelltra, Amgen) to durvalumab (Imfinzi, AstraZeneca) as first-line maintenance therapy reduced the risk of death compared with durvalumab alone in patients with extensive-stage small cell lung cancer (ES-SCLC), according to interim results from the phase 3 DeLLphi-305 trial. Amgen announced the findings, which were presented at the European Society for Medical Oncology Congress 2026 and simultaneously published in the New England Journal of Medicine.

The global, randomized, open-label trial, sponsored by Amgen with partial funding from AstraZeneca, enrolled 563 patients whose disease had not progressed after initial treatment with durvalumab, platinum-based chemotherapy, and etoposide. Patients were randomly assigned 1:1 to tarlatamab-dlle plus durvalumab or durvalumab alone. Patients with treated or untreated asymptomatic brain metastases were eligible. Tarlatamab-dlle binds DLL3 on tumor cells and CD3 on T cells. Overall survival (OS) was the primary endpoint.

At a median follow-up of about 16 months, the combination reduced the risk of death by 58% (hazard ratio, 0.42; 95% CI, 0.32-0.54). Median OS was 21.1 months vs 12.7 months with durvalumab alone, and nearly 80% vs 53% of patients were alive at 1 year. Median progression-free survival (PFS) was 7.4 vs 1.9 months, and objective response rates were 26.4% vs 4.1%.

Amgen reported that OS and PFS benefits were observed across prespecified subgroups, including patients with brain or liver metastases. Grade 3 or higher treatment-related adverse events occurred in 20.9% of patients receiving the combination and 10.8% of those receiving durvalumab alone. In the New England Journal of Medicine report, adverse events of any cause of grade 3 or higher occurred in 46.8% and 40.6%, respectively. Among patients who received tarlatamab-dlle, cytokine release syndrome occurred in 49.6%, with 1 grade 3 event and none higher. Immune effector cell–associated neurotoxicity syndrome occurred in 1.1%, with no events of grade 3 or higher.

Jacob Sands, MD, associate chief of the Lowe Center for Thoracic Oncology at Dana-Farber Cancer Institute and first author of the DeLLphi-305 presentation, said “the magnitude and consistency of benefit in DeLLphi-305 are striking.” Amgen said it is moving to share the results with regulatory authorities worldwide. Tarlatamab-dlle is currently indicated in the US for adults with ES-SCLC that has progressed on or after platinum-based chemotherapy, and Amgen noted that the products are not approved for the investigational use described.

Source: Amgen. Imdelltra in combination with Imfinzi reduced risk of death by an unprecedented 58% in first-line extensive stage small cell lung cancer. Press release. Amgen; October 24, 2026. Accessed October 25, 2026.