A Phase II Study of Toripalimab in Combination with Gemcitabine and 5-Fluorouracil as First-Line Therapy for Advanced or Metastatic Biliary Tract Carcinoma.

[BACKGROUND/OBJECTIVES] The anti-PD-L1 antibody has been applied for use in first-line advanced biliary duct cancer patients. However, clinical evidence of toripalimab in combination with biweekly 5-fluorouracil (5-FU) is limited and predictive biomarkers of treatment benefits remain unclear.

[METHODS] This prospective study enrolled patients with unresectable or metastatic BTC who received toripalimab in combination with gemcitabine and biweekly 5-FU. The primary endpoints were progression-free survival (PFS) and objective response rate (ORR). Secondary endpoints included overall survival (OS) and safety. Exploratory analyses evaluated associations between programmed cell death-ligand 1 (PD-L1) expression or tumor mutational burden (TMB) and clinical outcomes.

[RESULTS] A total of 30 patients were enrolled, with a median follow-up duration of 16.0 months. The ORR was 13.0%. The median PFS and OS were 5.3 months (95% CI: 3.59-7.01) and 11.7 months (95% CI: 6.07-17.33), respectively. Subgroup analyses revealed no significant association between PD-L1 status or TMB level and improved PFS. All patients experienced adverse events (AEs), while grade 3-4 AEs occurred in eight patients (26.7%), most commonly anemia (20.0%), leukocytopenia (13.3%), and nausea (6.6%). No grade 5 AEs were observed, and the safety profile was considered manageable.

[CONCLUSIONS] Toripalimab in combination with gemcitabine and 5-fluorouracil showed promising efficacy and was well-tolerated as a first-line therapy in advanced biliary duct cancer patients. Although PD-L1 expression and TMB did not predict treatment benefit, larger studies are needed to validate potential biomarkers and further optimize immunochemotherapy strategies for BTC.