Tislelizumab in combination with GEMOX and lenvatinib for conversion therapy of unresectable extrahepatic biliary tract carcinoma (eBTC): A prospective, single-arm, phase 2 study.

e16163 Background: Resection is the only possibility for cure but only less than 1/3 patients with BTC are diagnosed at resectable stages. PD-1 monoclonal antibody plus GEMOX and Lenvatinib regimens have shown promising efficacy for intrahepatic cholangiocarcinoma. However, owing to the extrahepatic and intrahepatic BTC are highly heterogeneous, the efficacy of combination regimen on eBTC is not clear. In this study, we explored the efficacy and safety of Tislelizumab plus GEMOX and Lenvatinib for conversion therapy of unresectable eBTC. Methods: In this prospective, single-arm phase 2 study, major eligible criteria were unresectable locally advanced or metastatic extrahepatic BTC, no previous systemic treatment, ECOG PS 0 or 1. Patients received tislelizumab (200 mg, iv, d1, every 3 weeks) in combination with GEMOX (gemcitabine: 1000 mg/m 2 , iv, d1,d8, every 3 weeks; oxaliplatin: 85 mg/m 2 , iv, d1, every 3 weeks) and Lenvatinib (bodyweight ≥ 60 kg: 12 mg/day; 5%) were thrombocytopenia (8.6%), elevated AST/ALT (8.6%), neutropenia (5.7%) and leukopenia (5.7%). No grade 5 AEs. Conclusions: Tislelizumab plus GEMOX and Lenvatinib showed promising efficacy with manageable safety profile for conversion therapy of unresectable extrahepatic BTC. More patients were recruiting to further prove these results. Clinical trial information: ChiCTR2200056808.