NANJING, China — October 12, 2026
Nanjing Leads Biolabs Co., Ltd. announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to opamtistomig (LBL-024), its investigational PD-L1/4-1BB bispecific antibody, for the first-line treatment of advanced or metastatic biliary tract cancer (BTC). This marks the second Fast Track Designation for opamtistomig, following an earlier designation for extrapulmonary neuroendocrine carcinoma (EP-NEC). According to the company, the latest designation was granted nine days after submission and comes alongside the FDA’s recommendation to initiate discussions on a potential U.S. registration strategy for opamtistomig in combination with chemotherapy. The regulatory milestone supports continued development of the investigational immunotherapy for a cancer group associated with poor outcomes and limited treatment options. Opamtistomig is designed to combine PD-L1 immune checkpoint blockade with conditional 4-1BB-mediated T-cell stimulation, potentially enhancing antitumor immune activity within the tumor microenvironment. The designation may facilitate more frequent communication with the FDA during development, but it does not establish efficacy or safety, guarantee approval, or mean that the therapy is available for routine clinical use.
FDA Fast Track Designation Supports BTC Development
The FDA grants Fast Track Designation to investigational drugs intended to treat serious conditions and address unmet medical needs. The program can provide more frequent regulatory interactions and support discussions about clinical development plans, trial design and evidence requirements. Eligible products may also qualify for rolling review of portions of a marketing application, subject to applicable regulatory criteria. For opamtistomig’s first-line advanced or metastatic BTC program, the designation represents a regulatory milestone as Leads Biolabs advances its clinical development strategy. Biliary tract cancer includes malignancies such as gallbladder cancer and intrahepatic and extrahepatic cholangiocarcinoma. Many patients are diagnosed at advanced stages, and outcomes remain poor despite progress in systemic treatment. Although immune checkpoint inhibitors combined with chemotherapy have expanded first-line treatment options, substantial unmet medical needs remain. The FDA’s recommendation that the company promptly initiate discussions about a potential U.S. registration strategy for opamtistomig in combination with chemotherapy could help clarify the evidence and development requirements for future regulatory submissions. However, any registration pathway will depend on discussions with the agency and the clinical evidence generated in ongoing and future studies.
Opamtistomig Targets PD-L1 and 4-1BB Pathways
Opamtistomig is an investigational PD-L1/4-1BB bispecific antibody designed to combine immune checkpoint inhibition with conditional immune costimulation. PD-L1 blockade is intended to reduce tumor-associated immune suppression, while 4-1BB activation is designed to stimulate T-cell activity in the tumor microenvironment. The company is developing this approach for immunologically cold tumors, which may have limited immune-cell infiltration or respond less effectively to some existing immunotherapies. By linking these mechanisms in a single molecule, opamtistomig is intended to promote a more localized antitumor immune response. The clinical potential of this strategy remains under investigation, and its benefits and risks must be established through clinical trials. Leads Biolabs reported that its Phase I/IIa basket study, initiated in 2022, enrolled 175 patients with advanced solid tumors. Preliminary findings across several difficult-to-treat cancers, including BTC, platinum-resistant ovarian cancer, PD-1-refractory advanced hepatocellular carcinoma and previously treated EP-NEC, have shown encouraging signals, according to the company. These early findings are not definitive evidence of clinical benefit, and further evaluation is needed to determine the magnitude and durability of any treatment effects.
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Phase II Combination Study Advances Clinical Program
Leads Biolabs reported continued progress in its first-line BTC clinical program, with a Phase II study of opamtistomig in combination with chemotherapy advancing into the expansion phase in April 2026 following encouraging safety and efficacy findings. The company subsequently completed enrollment across the study, marking a milestone in the evaluation of the combination regimen. The newly granted Fast Track Designation adds regulatory momentum as the company prepares to engage with the FDA on potential U.S. registration planning. Chief Medical Officer Dr. Charles Cai said the designation was an encouraging development for the program and highlighted the need for additional treatment approaches in BTC and other immunologically challenging cancers. The company intends to continue discussions with regulatory authorities and advance its clinical programs with a focus on generating evidence to support future development decisions. Further clinical results will be needed to establish whether combining opamtistomig with chemotherapy can improve outcomes in first-line advanced or metastatic BTC. Opamtistomig remains investigational, and the Fast Track Designation is intended to facilitate development and regulatory interaction rather than indicate that the FDA has approved the therapy.
Source:: Leads Biolabs press release
