Amgen said its DLL3/CD3-targeting BiTE Imdelltra (tarlatamab-dlle) plus AstraZeneca's Imfinzi improved overall survival in the Phase III DeLLphi-305 trial of 563 patients with extensive-stage small-cell lung cancer whose disease had not progressed after initial therapy. The study also met key secondary endpoints of progression-free survival and objective response rate, positioning Imdelltra as the first BiTE to show an OS benefit as first-line maintenance in ES-SCLC in a Phase III study.

Why It Matters To Oncology

• ES-SCLC has seen few meaningful advances in the maintenance setting, so an OS-positive Phase III result could reshape first-line treatment sequencing.

• The readout pushes a bispecific T-cell engager earlier in disease course, beyond Imdelltra's current accelerated approval in previously treated ES-SCLC.

• For drug discovery teams, the result strengthens DLL3 as a validated target and supports broader interest in T-cell redirecting strategies in solid tumors.

The Financials

• Amgen did not disclose hazard ratios or topline survival figures, but said the OS benefit was statistically significant and clinically meaningful.

• A positive label expansion into earlier-line ES-SCLC could materially broaden Imdelltra's commercial opportunity.

• The combo regimen builds on existing use of Imfinzi, AstraZeneca's PD-L1 inhibitor, potentially reinforcing combination-based market dynamics in SCLC.

What They're Saying

• Amgen R&D chief Jay Bradner called the findings “landmark results” that could “meaningfully shift the treatment paradigm” earlier in the patient journey.

• Amgen said no new or unexpected safety signals emerged, with Imdelltra's profile consistent with prior studies.

• The company's framing is that earlier use may allow more patients with SCLC to benefit than in the post-platinum setting.

What's Next

• Amgen plans to present detailed DeLLphi-305 data at an upcoming medical meeting and submit findings to global regulators.

• Regulatory success could convert momentum from the drug's accelerated approval, which was based on the Phase II DeLLphi-301 study showing a 40% objective response rate and median OS of more than 13 months.

• Beyond ES-SCLC maintenance, Imdelltra is also being studied in limited-stage disease in the Phase Ib STREAM-SCLC trial.