Leads Biolabs Advances Opamtistomig Toward Approval

NANJING, China, August 21, 2026

Opamtistomig Targets PD-L1 and 4-1BB

Opamtistomig is designed to simultaneously target PD-L1 and the immune co-stimulatory receptor 4-1BB, combining immune checkpoint blockade with T-cell activation. According to Leads Biolabs, the bispecific antibody is intended to block PD-1/PD-L1-mediated immune suppression while conditionally activating the 4-1BB pathway, potentially generating a stronger anti-tumor immune response. The candidate was developed using the company’s proprietary X-Body bispecific antibody platform and has been evaluated across multiple solid tumor indications. Leads Biolabs states that Opamtistomig has demonstrated promising anti-tumor activity in clinical studies covering indications including EP-NEC, non-small cell lung cancer, small cell lung cancer, biliary tract cancer, ovarian cancer, hepatocellular carcinoma and esophageal squamous cell carcinoma. The company describes the therapy as a potential next-generation immunotherapy for tumors where conventional immune checkpoint approaches may have limited effectiveness. The NDA submission is supported by a registrational clinical study conducted at 34 clinical sites, led by Professor Shen Lin of Peking University Cancer Hospital. The study completed enrollment of 96 patients with EP-NEC in August 2025, with detailed results expected to be presented at an international medical congress. The NDA acceptance means Chinese regulatory authorities will now formally review the application and its supporting clinical and manufacturing data. Importantly, Opamtistomig remains investigational until regulatory approval is granted.

Potential New Option for Aggressive EP-NEC

Extrapulmonary neuroendocrine carcinoma is an aggressive and difficult-to-treat cancer, and the disease can originate in organs including the gastrointestinal tract, bladder and other sites outside the lung. According to the company, EP-NEC frequently presents at an advanced stage and can progress rapidly. Existing systemic treatment commonly relies on platinum-based chemotherapy, while treatment options following disease progression remain limited. This creates a substantial unmet medical need for new therapies capable of producing more durable responses. The development of Opamtistomig is particularly notable because 4-1BB is being explored as an immune-stimulatory target capable of promoting T-cell proliferation and activity. Leads Biolabs believes this mechanism could be relevant to immunologically “cold” tumors and potentially to cancers that respond poorly to conventional PD-1/PD-L1 therapies. The company has reported that Opamtistomig has been studied in 13 solid-tumor indications in China, including a pivotal registration study and multiple proof-of-concept studies.

Regulatory Milestones Strengthen Development Program

The Opamtistomig development program has received several regulatory designations intended to accelerate development for serious diseases with limited treatment options. The candidate received Breakthrough Therapy Designation from China’s NMPA in October 2024, while the U.S. FDA granted Orphan Drug Designation for neuroendocrine carcinoma in November 2024. In January 2026, the program received Fast Track Designation from the FDA and an Orphan Drug Designation from the European Commission for EP-NEC, according to Leads Biolabs.If ultimately approved, Opamtistomig could represent an important milestone for 4-1BB-targeted immunotherapy and expand the treatment landscape for patients with advanced EP-NEC. However, the current milestone is NDA acceptance rather than approval, and the candidate’s safety, efficacy and benefit-risk profile remain subject to regulatory review. Leads Biolabs is also advancing Opamtistomig in additional oncology indications as it works toward broader clinical development and potential commercialization.

Source: Leads Biolabs press relese