A pilot study of the combination of checkpoint inhibition with ablation in subjects with biliary tract cancer.

Abstract

e16150 Background: Immune checkpoint inhibition has demonstrated modest activity in biliary tract carcinoma (BTC). Augmentation of the immune response by ablative procedures to improve efficacy of immune checkpoint inhibition has been previously demonstrated in hepatocellular carcinoma, however the outcome of the combination of immune checkpoint inhibition with tremelimumab (anti-CTLA4) and durvalumab (anti-PD1) with ablation in advanced biliary tract carcinoma is unclear. The primary objective of this study was to establish the efficacy via 6-month progression-free survival (PFS) of combining tremelimumab and durvalumab in patients with advanced BTC either alone or with tumor ablation. Secondary objectives were safety and feasibility of combination treatment. An exploratory objective was overall survival (OS). Methods: Eligible patients had histologically confirmed advanced or unresectable BTC (intra- or extrahepatic cholangiocarcinoma, gallbladder cancer, or ampullary cancer) who had progressed on, been intolerant to, or refused prior chemotherapy. Disease had to be technically amenable to cryoablation with at least two measurable lesions. Adequate organ function and an ECOG of 0 or 1 were required. Patients were treated with tremelimumab and durvalumab with or without tumor ablation. Tremelimumab and durvalumab were administered intravenously every 28 days for four cycles followed by durvalumab every 28 days until disease progression. Cryoablation was performed on day 36. Patients were imaged every 8 weeks and response was defined per RECIST v 1.1 criteria. Results: In total, 22 patients have been enrolled into the BTC cohort. Half underwent ablation and half received immunotherapy alone. The median age was 59 years (range 21-80). All patients had received prior systemic chemotherapy, locally advanced disease was present in 68% of patients. Median PFS was 2.1m and median OS was 5.6 m. DCR was 45% (SD). Median OS and PFS was similar in the group that received ablation vs immunotherapy alone with a median OS of 6.8 m vs 6.7 m and 2.0 m vs 2.7 m respectively. The most common grade 3- 4 adverse events were lymphopenia (27%), increased AST (41%), increased alkaline phosphatase (32%) and elevated bilirubin (27%). Conclusions: Combination checkpoint inhibition combined with tumor ablative procedures is a safe and effective treatment strategy for patients with advanced BTC, however the addition of ablative therapy may not enhance efficacy in this small cohort of patients. Results illustrate the poor prognosis of advanced BTC and may represent a non-chemotherapeutic approach to treatment in this patient population. Further studies are warranted to identify patient populations most likely to respond to these interventions. Clinical trial information: NCT02821754.