Nanjing Leads Biolabs Co., Ltd. (Leads Biolabs) has finalized patient recruitment for its Phase II clinical study of Opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody, in first-line treatment of advanced biliary tract cancer (BTC). All 70 participants were enrolled following the trial’s transition to expansion stage in April 2026, a decision driven by safety and efficacy signals that surpassed predefined thresholds.

The multi-centre study, led by Academician Zhou Jian of Zhongshan Hospital, Fudan University, reported a favourable safety profile in the run-in phase, with good tolerability and no emergent safety concerns when LBL-024 was combined with chemotherapy. Initial assessments indicated encouraging tumour shrinkage; detailed results are scheduled for presentation at the European Society for Medical Oncology (ESMO) Annual Meeting in Madrid on 23–27 October 2026.

BTC, encompassing gallbladder cancer and cholangiocarcinoma, accounted for approximately 419,100 new cases worldwide in 2024 and carries a five-year survival rate below 5%. Although PD-1/PD-L1 inhibitors plus chemotherapy have recently become a standard first-line option, current regimens deliver objective response rates under 30% and median overall survival of roughly 12–13 months, underscoring significant unmet clinical need.

Developed on Leads Biolabs’ proprietary X-body™ platform, LBL-024 is designed to relieve PD-1/PD-L1-mediated immunosuppression while conditionally activating the co-stimulatory receptor 4-1BB. The molecule has shown a safety profile comparable to PD-(L)1 monoclonal antibodies and has demonstrated anti-tumour activity across multiple solid tumours, including extrapulmonary neuroendocrine carcinoma (EP-NEC) and small cell lung cancer. Regulatory acknowledgements already include Breakthrough Therapy Designation from China’s CDE (October 2024), U.S. FDA Orphan Drug Designation for NEC (November 2024) and Fast Track Designation for EP-NEC (January 2026), alongside an EU Orphan Drug Designation granted in the same month.

Leads Biolabs notes that LBL-024 is the first 4-1BB-targeting molecule to enter a pivotal single-arm registrational stage globally. The company cautions that successful development and eventual market approval are not guaranteed, in line with Hong Kong Listing Rule 18A.05.