Ingelheim, Germany & Shanghai, China | April 15, 2026

Boehringer Ingelheim and Zai Lab have announced a strategic clinical collaboration to evaluate a novel dual DLL3-targeting combination therapy for the treatment of small cell lung cancer (SCLC) and other neuroendocrine carcinomas (NECs). The collaboration will focus on a Phase Ib/II clinical study combining obrixtamig, a DLL3/CD3 T-cell engager, with zocilurtatug pelitecan (zoci), a DLL3-targeting antibody-drug conjugate (ADC). This innovative approach aims to enhance therapeutic efficacy by leveraging both immune system activation and targeted cytotoxic delivery, addressing a critical unmet need in aggressive cancers with limited treatment options.

Dual DLL3 Targeting Strategy Enhances Immuno-Oncology Approach

The collaboration introduces a cutting-edge immuno-oncology strategy by combining two complementary therapeutic modalities targeting the same antigen, DLL3, which is highly expressed in SCLC and certain NECs. Obrixtamig, a bispecific T-cell engager, is designed to redirect immune cells to attack tumor cells, while zocilurtatug pelitecan (zoci) delivers a potent cytotoxic payload directly to cancer cells through ADC technology.

This dual approach aims to maximize tumor cell killing by integrating immune activation with targeted chemotherapy delivery, potentially improving clinical outcomes in patients with advanced-stage disease. Early clinical data from both agents have shown encouraging efficacy signals and manageable safety profiles, supporting further evaluation in combination settings.

Phase Ib/II Study Targets High Unmet Need in SCLC

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The upcoming Phase Ib/II clinical trial will assess the safety, tolerability, and initial efficacy of the combination therapy in patients with extensive-stage small cell lung cancer (ES-SCLC) and poorly differentiated neuroendocrine carcinomas. These cancers are known for their aggressive nature and poor prognosis, with limited treatment advancements in recent years.

The study will enroll patients globally and aims to generate early clinical evidence that could support future late-stage development and potential regulatory approvals. Notably, both therapeutic agents have already demonstrated strong development momentum, with obrixtamig advancing toward Phase III trials and zoci progressing through pivotal clinical studies, highlighting the strategic importance of this collaboration in accelerating innovation in oncology.

Advancing Next-Generation ADC and T-Cell Engager Therapies

This collaboration reflects a broader industry trend toward combination therapies that integrate multiple mechanisms of action to overcome tumor resistance and improve patient outcomes. Zoci, developed using advanced ADC technology, is engineered to deliver a topoisomerase I inhibitor payload, while minimizing off-target toxicity through a tumor-specific targeting mechanism.

Meanwhile, obrixtamig leverages bispecific antibody technology to engage T-cells directly, enhancing immune-mediated tumor destruction. The synergy between these modalities represents a promising avenue for next-generation cancer therapies, particularly in difficult-to-treat malignancies where single-agent therapies have shown limited success.

Strategic and Regulatory Implications for Oncology Development

Under the terms of the agreement, Zai Lab will supply its ADC candidate while Boehringer Ingelheim will lead clinical trial operations, ensuring efficient execution and regulatory alignment. Both companies retain rights to their respective assets, enabling continued independent development alongside collaborative efforts. The collaboration also aligns with regulatory incentives, as both therapies have received FDA Fast Track and Orphan Drug Designations, supporting accelerated development pathways. This strategic partnership highlights the importance of cross-company collaboration in advancing complex oncology treatments, particularly in areas with high unmet medical need.

The collaboration between Boehringer Ingelheim and Zai Lab marks a significant advancement in the development of innovative combination therapies for aggressive cancers, leveraging the strengths of both T-cell engager and ADC technologies. By targeting DLL3 through complementary mechanisms, this approach has the potential to redefine treatment strategies for small cell lung cancer and neuroendocrine carcinomas. As the Phase Ib/II study progresses, the results could have far-reaching implications for clinical practice, regulatory pathways, and future oncology innovation, offering new hope for patients facing limited therapeutic options.

Source: Boehringer Ingelheim press release