A phase II basket trial of Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors (DART) SWOG S1609: vaginal cancer sub cohort results

Objective:The SWOG S1609 Dual Anti-CTLA-4 & Anti-PD-1 blockade in Rare Tumors (DART) trial is the first basket study to include a sub-cohort assessing ipilimumab and nivolumab in patients with primary vaginal cancers with differing histology.Methods: DART is a prospective, open-label, multicenter, multi-cohort phase II clinical trial of ipilimumab (1 mg/kg intravenously) 6 weekly plus nivolumab (240 mg intravenously) 2 weekly across multiple rare tumor cohorts, with the vagina cohort (any vaginal histology) reported here.The primary endpoint was objective response rate (ORR) per RECISTv1.1;progression-free survival (PFS), overall survival (OS), clinical benefit rate (CBR; overall response plus stable disease [SD] 6 months), and toxicity are secondary endpoints.Results: Seven evaluable patients (median age, 60 years; performance status 0-1; no prior exposure to immunotherapy) were analyzed, of whom 3 had adenocarcinoma, 2 had squamous cell carcinoma (SCC), one had small-cell carcinoma and one had undifferentiated histology.The ORR was 29%, with 1 patient (14%) with undifferentiated histology achieving complete response (lasting 14.8 months) and 1 patient with SCC histology (14%) attaining a partial response (lasting 45.2 months).The CBR was 43%.The 6-month PFS rate