Boehringer Ingelheim has announced a clinical trial collaboration with BioNTech to evaluate a novel immuno-oncology combination therapy for extensive-stage Small Cell Lung Cancer (ES-SCLC), one of the most aggressive and difficult-to-treat cancers.

Under the agreement, BioNTech will supply pumitamig (BNT327/BMS-986545), a bispecific antibody targeting PD-L1 and VEGF-A, while Boehringer Ingelheim will act as the regulatory sponsor of the Phase Ib/II clinical study. The trial will assess the safety, tolerability and early clinical activity of pumitamig in combination with obrixtamig (BI 764532), Boehringer Ingelheim’s investigational DLL3/CD3 T-cell engager.

Small cell lung cancer accounts for approximately 15–20 percent of all lung cancer cases and is characterised by rapid progression, early metastasis and high relapse rates. Despite advances in treatment, including the use of immune checkpoint inhibitors, most patients experience disease progression within months, highlighting the urgent need for more effective therapies.

The combination therapy aims to tackle key challenges in cancer treatment by integrating two complementary mechanisms. Obrixtamig works by redirecting T-cells to target and destroy cancer cells expressing DLL3, a common marker in small cell lung cancer. Pumitamig, on the other hand, is designed to restore immune system activity against tumours while also inhibiting blood vessel formation that supports tumour growth.

Previous studies have shown promising results for both therapies. Obrixtamig demonstrated encouraging response and disease control rates in early trials when used alongside chemotherapy and immunotherapy, while pumitamig has shown strong clinical activity and manageable safety in combination with chemotherapy. Both drugs are currently being evaluated in ongoing global Phase III trials.

The companies stated that the collaboration aims to explore whether combining these two approaches can enhance and sustain anti-tumour immune responses, potentially leading to improved patient outcomes. The trial is expected to begin dosing patients in the second half of 2026.

Both Boehringer Ingelheim and BioNTech will retain full rights to their respective assets under the non-exclusive agreement. The partnership reflects growing industry focus on combination immunotherapies to address unmet needs in oncology.

With this initiative, the companies aim to advance innovative treatment strategies for small cell lung cancer, a disease where survival outcomes remain poor despite recent therapeutic advances.