A Clinical Study Of Tremelimumab Alone Or In Combination With Olaparib In Patients With Advanced Epithelial Ovarian Cancer.

6045 Background: Single agent immunotherapy (IO) has shown only modest clinical activity for the treatment of ovarian cancer. The combination of anti-programmed death-1 and PARP inhibitors showed promising activity in early trials. Here, we report the results of an open-label, parallel arm, dose escalation study of tremelimumab (T) alone or in combination with olaparib (O) in patients (pts) with advanced epithelial ovarian cancer (EOC). Methods: Pts with recurrent/persistent EOC who had progression < 12 months from last platinum exposure were enrolled. Prior therapy with IO (except anti-CTLA-4) or PARP inhibitor was allowed. Pts were randomized to either T 10mg/kg every 4 weeks (wks) x 7 then every 12 wks (Arm A) or T with O twice daily at three planned dose levels (Arm B). The primary objectives were safety, pharmacodynamic (PD) change in CD4+ICOShi peripheral T cells by flow cytometry, and identification of the optimal dose combination of T with O. Secondary objectives included 6-month progression-free survival (PFS6) and objective response rate (ORR). Results: A total of 24 pts were treated, 12 on Arm A, and 12 on two Arm B dose levels. Pts had a median age of 60 years (range 44-81). Histologic subtypes included high-grade serous EOC (20 pts, 83%), clear cell (3 pts, 13%), and moderately-differentiated adenocarcinoma (1 pt, 4%). BRCA1 mutation (mt) was present in 2 cases, BRCA2 mt in 1. Median number of prior regimens was 3.5 (range 1-9). Most adverse events (AEs) were attributable to T, the most common grade 3 toxicities were rash (13%), immune-mediated hepatitis (8%), and colitis (8%). No grade ≥4 toxicities were identified. Immune-mediated AEs also included acute kidney injury, hypophysitis, and hypothyroidism. No dose limiting toxicities were identified on Arm B. Two pts in Arm B had >PFS6. Of 20 pts evaluable for response, there was 1 partial response (Arm B), and 9 pts had stable disease (6 on Arm A, 3 on Arm B). Mean percentage of CD4+ICOShi T cells was significantly increased on Days 15 and 22 compared to Day 1 at both T dose levels (Table).T at 3 mg/kg with O at 150mg is the optimal dose of those tested. Conclusions: T and T with O was tolerable, with modest clinical activity in this pt population. AEs were as expected, and peripheral CD4+ICOShi T cells increased on therapy. Clinical trial information: 02485990. [Table: see text]