SWOG/NCI Phase II Dual Anti-CTLA-4/PD-1 Blockade in Rare Tumors (DART): Non-Epithelial Ovarian Cancer

Abstract Background: The role of dual checkpoint inhibition in advanced rare/ultra-rare non-epithelial ovarian cancers (NEOCs) is yet to be explored. Methods: DART is a prospective, multicenter (1,016 US sites), multi-cohort, single-arm phase II trial conducted through the Early Therapeutics and Rare Cancer SWOG/NCI Committee, assessing ipilimumab (anti-CTLA-4) (1mg/kg every 6 weeks) and nivolumab (anti-PD-1) (240mg every 2 weeks) in adults with advanced NEOCs who lack beneficial standard therapy. Primary outcome was overall response rate [ORR; complete response (CR)/partial response (PR)]; secondary outcomes were progression-free survival (PFS), overall survival (OS), clinical benefit rate [CBR; stable disease (SD) ≥6 months plus ORR], and toxicity. Results: Seventeen patients (median age: 64; number of prior therapies ranged from 0-8 with no immunotherapy exposure; 8 granulosa, 6 carcinosarcomas, 1 Sertoli-Leydig, 1 yolk sac, 1 Wolffian) were evaluated. In granulosa cell tumors, ORR was 25% (n=2/8; 1 CR, 1 PR) and CBR, 50% (n=4/8); PFS of 58.3 (CR), 50.7+ (PR), 30.4 (SD), and 8.7 (SD) months. Median PFS was 3.5 months (95% confidence intervals (CI) 1.7-11.2 months); median OS, 42.5 months (95% CI 10.1 months-not reached). One Sertoli-Leydig cell tumor showed a 22% regression (PFS 11.2 months). Carcinosarcomas had no response. Three participants (18%) discontinued treatment due to grade 3-4 adverse events. Conclusions: Ipilimumab-nivolumab shows activity in treatment-refractory granulosa cell tumors, with 25% (n=2/8) of patients experiencing either CR or PR lasting over 4 years.​