Efficacy and tolerability of tremelimumab in patients with metastatic pancreatic ductal adenocarcinoma.

470 Background: Clinical activity and tolerability of the anti-CTLA-4 antibody, tremelimumab, has yet to be established in metastatic pancreatic ductal adenocarcinoma (mPDAC). In a Phase 2, multicenter, open label study (NCT02527434), tremelimumab was evaluated in pts with advanced solid tumors. We report a planned analysis of the safety and efficacy of tremelimumab monotherapy in a cohort of pts with mPDAC. Methods: Eligible pts were adults with histologically or cytologically confirmed mPDAC with tumor progression following prior standard first-line 5-FU- or gemcitabine-containing chemotherapy. Pts received tremelimumab 750 mg IV Q4W for 7 doses, followed by 750 mg Q12W for 2 doses, for up to a total of 12 mo (total 9 doses in 12 mo) or until disease progression or unacceptable toxicity. Pts were radiographically assessed Q6 wks relative to first dose. The primary endpoints were safety (evaluated by CTCAE v4.0) and objective response rate (ORR) by investigator assessments (evaluated by RECIST v1.1). Results: As of April 5, 2017, 20 mPDAC pts had received treatment and were evaluable for efficacy analysis. Median treatment duration was 1.8 mo. There were no observed objective responses (ORR 0%; 95% CI, 0.0, 16.8%). Of 20 pts, 2 were not evaluable and 18 had progressive disease (PD). Based on the full analysis set (N = 20), progression occurred in target lesions in 14 (70%), non-target lesions in 7 (35%), and new lesions in 13 (65%) pts (not mutually exclusive categories). At the time of progression, 11 (61%) pts were on treatment and 7 (39%) had discontinued treatment. Median overall survival was 4 mo (95% CI 2.83 - 5.42). Two (10%) pts were still in follow up at 12 mo after treatment initiation. Treatment-related AEs (trAEs) occurred in 14 pts (70%); grade ≥3 trAEs occurred in 6 pts (30%). Three pts (15%) discontinued therapy due to trAEs. There were no treatment-related deaths. Conclusions: Tremelimumab monotherapy did not appear to be active in mPDAC pts who had tumor progression following prior standard first-line 5-FU- or gemcitabine-containing chemotherapy. Clinical trial information: NCT02527434.