Boehringer Ingelheim and BioNTech partner on ES‑SCLC immunotherapy trial

Trial collaboration

Boehringer Ingelheim will act as regulatory sponsor of a Phase Ib/II study combining obrixtamig (DLL3/CD3 T‑cell engager) with pumitamig (BNT327/BMS‑986545; PD‑L1/VEGF‑A bispecific) in extensive‑stage small cell lung cancer, with dosing expected to begin in H2 2026; BioNTech will supply pumitamig and both companies retain full rights to their assets under a mutually non‑exclusive agreement.

Rationale

The study tests complementary mechanisms: obrixtamig redirects T cells to kill DLL3‑expressing tumor cells, while pumitamig pairs PD‑L1 checkpoint inhibition with anti‑VEGF‑A activity to restore T‑cell function and limit tumor angiogenesis, targeting immune evasion and a pro‑angiogenic microenvironment.

Key clinical data

In DAREON‑8, obrixtamig plus chemo and atezolizumab showed a 68% confirmed objective response rate, 89% disease control rate and a 52% 9‑month PFS rate; obrixtamig is advancing to a global Phase III (DAREON‑Lung‑1, NCT07472517) and has received FDA Fast Track and Orphan Drug designations and EC Orphan status for neuroendocrine carcinomas. Pumitamig showed a 76.3% confirmed ORR, 100% disease control rate and median PFS of 6.8 months in a Phase II first‑line ES‑SCLC study, has progressed to a global Phase III (ROSETTA LUNG‑01, NCT06712355) and received FDA Orphan Drug designation in 2025.

Next steps

The trial will evaluate safety, tolerability and early clinical activity of the combination to explore whether dual targeting can deliver more sustained tumor control in a disease with high unmet need.