Leads Biolabs’ opamtistomig receives FDA Fast Track designation for first-line advanced biliary tract cancer, with US registration strategy discussions recommended.
Written By: Rishabh Sonawane, BPharm
Reviewed By: Pharmacally Editorial Team
Nanjing Leads Biolabs announced on October 12, 2026, that the US Food and Drug Administration (FDA) had granted Fast Track designation to opamtistomig (LBL-024) for first-line treatment of advanced or metastatic biliary tract cancer (BTC). This is the candidate’s second FDA Fast Track designation, following its earlier designation for extrapulmonary neuroendocrine carcinoma (EP-NEC). The company reported that the latest designation was granted nine days after submission. The FDA also recommended that the company initiate discussions on the US registration strategy for opamtistomig combined with chemotherapy. These developments signal regulatory engagement, but do not establish an agreed approval pathway.
Fast Track designation supports the development of investigational therapies for serious conditions with unmet medical needs through more frequent FDA interactions. Eligible products may also qualify for rolling review. The designation does not constitute marketing approval or guarantee accelerated authorisation.
Mechanism of Action and Clinical Evidence
Opamtistomig is a bispecific antibody designed to block PD-L1-mediated immune suppression while conditionally activating 4-1BB, a costimulatory receptor involved in T-cell activation. By combining checkpoint inhibition with immune stimulation in the tumour microenvironment, the candidate is being investigated for its potential to enhance antitumour activity, including in immunologically cold tumours that may respond poorly to existing immunotherapies.
The company’s Phase I/IIa basket study (NCT05170958), initiated in 2022, enrolled 175 patients with advanced solid tumours receiving opamtistomig monotherapy. Investigated indications included BTC, platinum-resistant ovarian cancer, PD-1-refractory advanced hepatocellular carcinoma and previously treated EP-NEC. Leads Biolabs reported preliminary signals of potential survival benefit across these tumour types, but the October announcement did not provide numerical efficacy estimates or comparative results.
These findings support further investigation but do not establish a survival advantage in BTC or demonstrate that the monotherapy results will translate into benefit from the chemotherapy combination.
Phase II Combination Trial Advances
The first-line advanced BTC programme progressed in April 2026, when the Phase II study of opamtistomig plus chemotherapy entered its expansion phase following encouraging safety and preliminary efficacy findings. The study subsequently completed enrolment of all 70 patients, as announced by the company on July 30, 2026. The enrolment milestone establishes the planned study population, not the treatment’s efficacy or readiness for regulatory filing. Detailed clinical data were scheduled for presentation at the ESMO Annual Meeting on October 23–27, 2026, and were not yet available as of October 12.
The FDA’s recommendation to discuss US registration strategy creates an opportunity to clarify the evidence and development requirements for potential registration. However, the company has not disclosed a marketing application submission date or a projected US approval timeline for BTC.
Disease Burden and Treatment Context
BTC includes gallbladder cancer and intrahepatic and extrahepatic cholangiocarcinoma. Leads Biolabs cited approximately 419,100 new cases worldwide in 2024, highlighting the disease burden and the need for additional treatment options.
PD-1/PD-L1 inhibitors combined with chemotherapy are established first-line treatment options for advanced BTC. The company cited median overall survival figures of approximately 11.5 to 12.8 months and objective response rates below 30%. These figures provide context for the unmet medical need but do not demonstrate that opamtistomig improves outcomes over existing regimens.
Regulatory Milestones and Development Outlook
Beyond the latest BTC designation, opamtistomig received Breakthrough Therapy Designation from China’s National Medical Products Administration (NMPA) in October 2024 and FDA Orphan Drug Designation in November 2024. In January 2026, it received FDA Fast Track and European Commission Orphan Drug designations, followed by Japanese Orphan Drug Designation in September 2026.
In China, the company reported priority review in July 2026 and NDA acceptance in August 2026 for the EP-NEC programme. These milestones concern a separate indication and should not be interpreted as evidence of regulatory approval progress for BTC.
The next steps for opamtistomig in BTC will depend on discussions with the FDA and the clinical evidence generated by the combination programme. The designation provides a route for closer regulatory engagement, while the magnitude and durability of clinical benefit remain to be established. Opamtistomig remains investigational for this indication, and its approval prospects will depend on the evidence and applicable regulatory review.
References
Weilizhibo’s PD-L1/4-1BB bispecific antibody for biliary tract cancer has been recognized in the FDA Fast Track designation, and the value of immunocold tumor therapy has been further recognized internationally, Leads Biolabs, 12 October 2026
A Phase I/II Clinical Study of LBL-024 in Patients with Advanced Malignant Tumors, ClinicalTrials.gov ID NCT05170958
About the Writer
Rishabha Sonawane, B.Pharm (LinkedIn) is healthcare writer with a strong interest in medical writing, regulatory affairs, clinical research, and AI-driven drug discovery. He has completed specialized training from the NIH and ICMR in clinical pharmacology, clinical research, and scientific writing. Passionate about evidence-based healthcare communication, he focuses on translating complex scientific research into clear, accurate, and engaging medical content.