China’s National Medical Products Administration accepted the new drug application for opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody, as monotherapy for previously treated advanced extrapulmonary neuroendocrine carcinoma (EP-NEC). The Center for Drug Evaluation granted priority review on July 10, 2026, setting the stage for a potential regulatory milestone for the 4-1BB class in solid tumors. Opamtistomig is being developed by Leads Biolabs and supported by results from a registrational study led by Lin Shen, MD, of Peking University Cancer Hospital. The trial completed enrollment of 96 patients across 34 sites in August 2025, and detailed data are expected at a future international medical meeting. The sponsor highlighted opamtistomig as potentially the first agent directly targeting 4-1BB to reach the market and as an agonistic antibody approach intended to conditionally activate 4-1BB signaling alongside PD-L1 blockade. Previously reported data showed an objective response rate of 33.3% in EP-NEC. Regulatory acceptance of the NDA matters for competitors because 4-1BB agonism has been a high-interest but difficult target class in immuno-oncology, making the NMPA pathway closely watched by teams pursuing next-generation costimulatory strategies.