This is a prospective, single-arm, Phase II study evaluating sacituzumab tirumotecan combined with envafolimab in patients with TROP2-positive advanced biliary tract cancers who have progressed on first-line immunochemotherapy. Up to 28 eligible patients will be enrolled.After screening, eligible patients receive sacituzumab tirumotecan (5 mg/kg IV, d1, Q2W) plus envafolimab (300 mg SC, d1, Q2W) for 3 cycles, with subsequent treatment at the investigator's discretion.
Tumor imaging assessments per RECIST v1.1 are performed at Week 6, then every 6 weeks (up to 48 weeks) and every 12 weeks (thereafter) until disease progression, new therapy, loss to follow-up, or death. Post-treatment survival follow-up is conducted by phone every 3 months.
The study includes a safety run-in (6 patients) followed by an expansion phase using Simon's two-stage design (first stage: 15 patients; second stage: total 28 patients). The safety run-in stops if \>2 DLTs occur; expansion proceeds if ≤2 DLTs. The trial is terminated if ≤1 objective response is observed in the first 15 expansion patients.
The primary endpoint is ORR(investigator-assessed per RECIST v1.1). Secondary endpoints include OS, PFS, DCR, DOR, safety, and tolerability.