Varlitinib in combination with gemcitabine and cisplatin for treatment-naïve advanced biliary tract cancer.

Abstract

439 Background: Standard first-line treatment for advanced biliary tract cancer (BTC) with gemcitabine plus cisplatin confers only modest benefits (objective response rate [ORR], 26%; Valle et al. N Engl J Med 2010;362:1273-1281) and patient prognosis is poor. Therefore, new first-line strategies are urgently required. Human epidermal growth factor receptor (HER) tyrosine kinases are commonly overexpressed in BTC. Varlitinib is a reversible small molecule pan-HER inhibitor. Methods: This was a multicentre, phase 1B/2 study in patients with advanced BTC who had not received prior systemic therapy. Using a modified 3+3+3 escalation design in phase 1B, patients received oral varlitinib twice daily (BID) every day (starting dose 200 mg BID) plus gemcitabine/cisplatin on Days 1 and 8 in a 3-week cycle. The primary objective was to determine the maximum tolerated dose (MTD) and safety profile of varlitinib in combination with gemcitabine plus cisplatin. Patients were evaluable for MTD if they had varlitinib treatment compliance of ≥80% and received 2 doses of chemotherapy in Cycle 1, or if they experienced a dose-limiting toxicity (DLT) in Cycle 1. Preliminary efficacy was a secondary objective. Results: Overall, 23 patients were enrolled in Korea (3 sites), Singapore (1 site), and Taiwan (1 site). Patient characteristics at baseline: male, 52%; median (range) age, 66 (47-82) years; ECOG PS, 0 (43%)/ 1 (57%); primary tumor site, intrahepatic bile duct (43%)/ extrahepatic bile duct (22%)/ gallbladder (22%)/ ampulla of Vater (13%). In total, 11 and 12 patients were included in the varlitinib 200 mg and 300 mg cohorts, of whom 9 and 7 were evaluable for MTD, respectively. DLTs were observed in 2 patients in the 200 mg cohort. Prior to study termination, the 300 mg dose was being assessed with 1 patient experiencing a DLT. In the overall population (n = 23), 36% of patients in the 200 mg cohort and 67% in the 300 mg cohort had at least one grade ≥3 treatment-related adverse event. Grade ≥3 treatment-related investigations abnormalities and blood and lymphatic system disorders were reported in 27% and 18% of patients in the 200 mg cohort, and 25% and 25% of those in the 300 mg cohort, respectively. Among all 23 patients, 8 had a partial response and 12 had stable disease for ≥12 weeks, giving an ORR of 35% and a disease control rate of 87%. The median (Q1-Q3) duration of objective response was 4.0 (2.8-11.0) months. At the time of analysis, 17 patients had progression events and 6 were censored. The median (Q1-Q3) progression-free survival was 6.8 (5.1-10.7) months. Conclusions: Varlitinib combined with gemcitabine plus cisplatin was well tolerated and associated with preliminary anti-tumor activity in patients with treatment-naïve advanced BTC. Clinical trial information: NCT02992340.