China’s NMPA accepted the new drug application for opamtistomig (LBL-024), a PD-L1/4-1BB–directed bispecific antibody, as monotherapy for previously treated advanced extrapulmonary neuroendocrine carcinoma. The agency granted priority review, adding regulatory momentum for a highly aggressive cancer subtype that has lacked approved therapies. The NDA is supported by results from a registrational study led by Lin Shen, MD, of Peking University Cancer Hospital, with enrollment of 96 patients across 34 sites completed in August 2025. Previously reported activity included an overall response rate of 33.3% in EP-NEC. If approved, opamtistomig would become the first agent to directly target 4-1BB to reach the market, according to the sponsor’s materials, and the first approved agonistic antibody in this category. The decision will be watched by developers of next-wave immune agonists targeting co-stimulatory pathways.