China’s NMPA has accepted the new drug application for opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody, for use as monotherapy in pretreated advanced extrapulmonary neuroendocrine carcinoma. The CDE granted priority review, with acceptance tied to registrational development led by investigators at Peking University Cancer Hospital. The application reflects prior EP-NEC data, including an announced objective response rate of 33.3% in earlier reports, and positions opamtistomig as targeting 4-1BB as an agonistic immunotherapy approach. If approved, the agent would be the first 4-1BB-directed therapy to reach the market. The NDA is supported by enrollment completion across 34 sites for 96 patients during August 2025, with additional data slated for later presentation at international meetings. Regulatory acceptance accelerates the company’s path to a potential first-in-class approval for a highly aggressive immunologically “cold” tumor population where there are currently no approved options worldwide.