Obrixtamig is an investigational bispecific DLL3 engager that targets DLL3-expressing cancer cells in SCLC and NECs. Credit: CI Photos / Shutterstock.com.

Boehringer Ingelheim and Zai Lab have entered a clinical collaboration to investigate a dual delta-like ligand 3 (DLL3)-targeting approach for patients with extensive-stage small cell lung cancer (ES-SCLC) and other neuroendocrine carcinomas (NECs).

This Phase Ib/II study will measure the tolerability, safety, and early clinical activity by combining Boehringer Ingelheim’s DLL3 / cluster of differentiation 3 (CD3) T-cell engager, obrixtamig, with Zai Lab’s antibody-drug conjugate (ADC), zocilurtatug pelitecan (zoci).

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Obrixtamig is an investigational bispecific DLL3/CD3 T cell engager that directs immune cells to attack DLL3-expressing cancer cells.

In the global Phase I DAREON 8 study, obrixtamig combined with chemotherapy and atezolizumab showed early clinical efficacy and a manageable safety profile.

The molecule is advancing into a global Phase III trial and has received fast track and orphan drug designations from the US Food and Drug Administration (FDA) for neuroendocrine carcinomas.

Zoci is Zai Lab’s DLL3-targeting ADC for ES-SCLC. Recent global Phase I data showed strong and durable responses in previously treated patients, including those with brain metastases, and a favourable safety profile.

Zoci is advancing into a global Phase III registrational study in SCLC and NECs, with both orphan drug and fast track designations from the FDA.

Under the agreement, Zai Lab will supply zoci for the study while Boehringer Ingelheim will sponsor and manage clinical operations; both companies retain rights to their respective products.

Boehringer Ingelheim oncology global head Itziar Canamasas said: “The strategy to engage the immune system with a specific T cell engager and deliver a potent cytotoxic payload with a DLL3 targeting ADC, aligns with our immuno-oncology strategy and our drive to advance smart combinations for hard-to-treat cancers.

“It’s another step in our mission to expand effective options for people with DLL3-expressing cancers.”

In February 2026, Boehringer Ingelheim India signed a memorandum of understanding to enhance pharmaceutical education and research collaboration.