Leads Biolabs' PD-L1/4-1BB Bispecific Opamtistomig Enters China Priority Review for Rare Neuroendocrine Cancer

China's Center for Drug Evaluation, part of the National Medical Products Administration (NMPA), has accepted the biologics license application (BLA) for opamtistomig (LBL-024) into its priority review and approval procedure. The application covers opamtistomig as a monotherapy for advanced extrapulmonary neuroendocrine carcinoma (EP-NEC) in patients whose disease progressed after two or more prior lines of systemic therapy.¹ Priority review shortens the standard NMPA timeline from 200 working days to 130 working days, giving Leads Biolabs a clearer path toward its first commercial approval.¹

Opamtistomig is a bispecific antibody that simultaneously targets PD-L1 and the co-stimulatory receptor 4-1BB, built on the company's proprietary X-Body platform. The dual mechanism is designed to block PD-1/PD-L1-mediated immune suppression while conditionally activating 4-1BB, a pathway known to reactivate exhausted T cells.¹ That combination approach reflects a broader industry shift toward multi-mechanism antibody design in oncology. Atul Mohindra, head of Biologics R&D at Lonza, has said of the bispecific antibody field, "We're witnessing a surge in BsAb development, particularly in oncology," pointing to novel formats, engineered Fc regions, and computational design tools as key drivers improving performance and reducing immunogenicity across the class, as reported in BioPharm International's "The Benefit of Technological Advancements to BsAb Development."

Why does EP-NEC represent an unmet need?

EP-NEC is a rare, immunologically "cold" tumor for which no therapy has been approved by any regulatory authority worldwide. Platinum-based chemotherapy remains first-line standard of care, with a median overall survival of roughly one year, but options narrow sharply after progression.¹ In later lines of therapy, currently available treatments produce objective response rates of just 0% to 10%, with median overall survival dropping to three to four months.¹ That treatment gap is central to why opamtistomig has already received Breakthrough Therapy Designation from the NMPA, Orphan Drug Designation from the FDA for neuroendocrine carcinoma, and, as of January 2026, Fast Track Designation from the FDA and Orphan Drug Designation from the European Commission specifically for EP-NEC.¹

How does the 4-1BB mechanism address cold tumors?

4-1BB agonism is designed to reactivate exhausted T cells and drive T-cell proliferation, an approach with particular relevance for tumors that resist standard PD-1/PD-L1 checkpoint blockade alone. Pairing checkpoint inhibition with a costimulatory agonist in a single bispecific molecule is intended to produce a more synergistic anti-tumor immune response than either mechanism could achieve individually, while maintaining a safety profile comparable to existing PD-1/PD-L1 inhibitors.¹ Leads Biolabs describes opamtistomig as the first 4-1BB-targeting bispecific antibody globally to advance into a single-arm pivotal trial as monotherapy, with the drug now under evaluation across 13 solid tumor indications in China, including non-small cell lung cancer, small cell lung cancer, and biliary tract cancer alongside EP-NEC.¹

What comes next?

Leads Biolabs said it is actively preparing for commercialization ahead of the anticipated NMPA decision and will continue working with the CDE throughout the review process.¹ Given the drug's broader pipeline positioning across multiple solid tumor types, an EP-NEC approval would serve as the company's first commercial launch and a proof point for the bispecific platform ahead of larger-indication data still to come in NSCLC and biliary tract cancer.

References

1. Priority Review Granted to PD-L1/4-1BB Bispecific Antibody Opamtistomig, Accelerating Commercialization and Addressing Unmet Need in EP-NEC. (2026 Jul 10). PRNewswire. https://www.prnewswire.com/news-releases/priority-review-granted-to-pd-l14-1bb-bispecific-antibody-opamtistomig-accelerating-commercialization-and-addressing-unmet-need-in-ep-nec-302822659.html
2. Marisol, F. (2024 Dec 31). The Benefit of Technological Advancements to BsAb Development. BioPharm International. https://www.biopharminternational.com/view/benefit-technological-advancements-bsab-development