Efficacy and biomarker analysis of second‐line nab‐paclitaxel plus sintilimab in patients with advanced biliary tract cancer

Abstract

Biliary tract cancer (BTC) is a highly aggressive malignancy with limited second‐line therapy. We conducted this phase 2 trial to evaluate the efficacy and safety of second‐line nab‐paclitaxel plus sintilimab in advanced BTC. Histologically confirmed advanced BTC patients with documented disease progression after first‐line chemotherapy were enrolled. Subjects received nab‐paclitaxel 125 mg/m2 on days 1 and 8 plus sintilimab 200 mg on day 1, administered every 3 weeks. The primary end point was the objective response rate (ORR). The secondary end points were progression‐free survival (PFS), overall survival (OS), and adverse reactions. Simultaneously, next‐generation sequencing, programmed cell death ligand 1 immunohistochemistry and multiplex immunofluorescence of tumor‐infiltrating lymphocytes were applied to explore potential biomarkers. Twenty‐six subjects were consecutively enrolled. The ORR was 26.9% (7/26), including two complete responses and five partial responses, which met the primary end point. The disease control rate was 61.5% (16/26). The median PFS was 169 days (about 5.6 months, 95% confidence interval [CI] 60–278 days). The median OS was 442 days (about 14.7 months, 95% CI 298–586 days). Grade 3 treatment‐related adverse events (TRAEs) were mainly anemia (27%), leukopenia (23%), neutropenia (19%), and peripheral sensory neuropathy (8%). No grade 4 or 5 TRAEs occurred. Biomarker analysis suggested that positive PD‐L1 and high proportions of CD8+ T‐cell infiltration were correlated with improved clinical outcome. Nab‐paclitaxel plus sintilimab is a potentially effective and tolerable second‐line regimen for advanced BTC that deserves to be studied in large‐scale trials. PD‐L1 status and CD8+ T cell infiltration might be promising biomarkers for efficacy prediction.