Nanjing Leads Biolabs Co., Ltd. announced on October 12, 2026, that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody (BsAb), for the first-line treatment of advanced or metastatic biliary tract cancer (BTC). The FDA previously granted a Fast Track Designation to opamtistomig for extrapulmonary neuroendocrine carcinoma (EP-NEC).
The company noted that the FDA recommended Leads Biolabs should initiate discussions about a registration strategy for opamtistomig in combination with chemotherapy for BTC. Specific efficacy and safety data from the ongoing combination study were not disclosed in the announcement.
Key finding
The FDA granted Fast Track Designation to opamtistomig for first-line advanced or metastatic BTC, though no efficacy data were publicly disclosed.
Study Design
| Trial | Phase II study of opamtistomig in combination with chemotherapy in first-line advanced BTC (expansion phase initiated April 2026; enrollment completed) |
|---|---|
| Population | Patients with advanced or metastatic BTC receiving first-line treatment |
| Treatment | Opamtistomig (PD-L1/4-1BB BsAb) in combination with chemotherapy |
Primary endpoints, key secondary endpoints, and detailed trial design parameters were not disclosed in the company’s announcement. The Phase II study follows a Phase I/IIa basket study of opamtistomig monotherapy initiated in 2022, which enrolled 175 patients with advanced solid tumors, including BTC, and yielded preliminary signals described by the company as encouraging across multiple difficult-to-treat tumor types.
Results and Safety
Leads Biolabs reported that the Phase I/IIa basket study of opamtistomig monotherapy showed potential survival benefits in several tumor types, including BTC, platinum-resistant ovarian cancer, PD-1-refractory advanced hepatocellular carcinoma, and previously treated EP-NEC. The company stated these findings are expected to be published in an international journal, but as of the announcement, have not been publicly disclosed.
Regarding the Phase II combination study in first-line BTC, the company described encouraging safety and efficacy findings that prompted advancement into an expansion phase in April 2026, and noted that enrollment has since been completed. No specific efficacy, response, or safety data from the combination study were reported in the announcement.
Clinical Context
Biliary tract cancer carries a poor prognosis, and available first-line systemic therapies provide limited benefit for many patients. Immunologically cold tumors, such as BTC, have generally shown limited responsiveness to existing checkpoint inhibitor monotherapies, reflecting an immunosuppressive tumor microenvironment with low baseline T-cell infiltration. Opamtistomig’s dual mechanism that combines PD-L1 blockade with conditional 4-1BB-mediated T-cell costimulation localized to the tumor microenvironment is intended to address this barrier. Whether this mechanistic rationale will translate into clinically meaningful outcomes remains to be established in adequately powered trials.
Fast Track Designation does not constitute evidence of clinical efficacy and does not guarantee FDA approval. The designation does afford more frequent FDA interactions and the possibility of rolling review if regulatory criteria are met, which may help streamline development planning. The FDA’s recommendation to initiate U.S. registration discussions signals regulatory interest in the program, but the specific evidence package required for a potential marketing application has not been publicly disclosed.
Sources
- GlobeNewswire / Leads Biolabs Co., Ltd. “Leads Biolabs’ Opamtistomig (PD-L1/4-1BB Bispecific Antibody) Granted FDA Fast Track Designation for First-Line Advanced or Metastatic Biliary Tract Cancer.” Press release. October 12, 2026. View source.
