Multicenter Phase II Trial of Axitinib Monotherapy for Gemcitabine‐Based Chemotherapy Refractory Advanced Biliary Tract Cancer (AX‐BC Study)

LESSONS LEARNED Axitinib exhibited marginal activity against gemcitabine-refractory unselected biliary tract cancer. Pretreated soluble vascular endothelial growth factor receptor-2 may be a useful biomarker for axitinib treatment outcome. Ascites should be carefully monitored in patients receiving anti-vascular endothelial growth factor receptor therapy including axitinib in advanced biliary tract cancer. BACKGROUND There are no clear options for second-line treatment in patients with gemcitabine (GEM)-refractory biliary tract cancer (BTC). We conducted a multicenter, single-arm, phase II trial to confirm the efficacy and safety of axitinib, a potent selective inhibitor of vascular endothelial growth factor receptor (VEGFR)-1/2/3, in patients with GEM-refractory BTC. METHODS Patients refractory or intolerant to GEM-based chemotherapy were enrolled. Axitinib was administered orally at an initial dose of 5 mg twice daily. The primary endpoint was progression-free survival (PFS), and the threshold and expected values were set at 2 and 3 months, respectively. The target sample size was 32 patients. RESULTS Nineteen patients were enrolled. The trial was interrupted for a total of 13 months for the evaluation of adverse events. Thirteen patients were previously treated with ≥2 regimens. The median PFS was 2.8 months (95% confidence interval [CI]: 2.1-4.1). The median overall survival was 5.8 months (95% CI: 3.3-9.7). The response rate was 5.3% (95% CI: 0.0-15.3). Grade 3 ascites occurred in two patients. Baseline soluble VEGFR-2 levels were significantly associated with PFS. CONCLUSION Axitinib exhibited marginal activity against GEM-refractory BTC. Ascites should be carefully monitored in axitinib-treated patients with advanced BTC.