Phase II trial of dual anti-CTLA-4 and anti-PD-1 blockade in rare tumors SWOG/NCI experience: invasive mucinous or non-mucinous lepidic adenocarcinoma of the lung (formerly bronchioloalveolar carcinoma).

Background: Anti-programmed death-1 (PD-1)/cytotoxic T lymphocyte antigen-4 antibodies are efficacious in various malignancies. Objectives: This study presents the first results of ipilimumab-nivolumab in invasive mucinous or non-mucinous lepidic adenocarcinoma (invasive mucinous adenocarcinoma (IMA) or invasive non-mucinous lepidic adenocarcinomas (INLA), respectively) of the lung. Design: Dual anti-CTLA-4 and anti-PD-1 blockade in rare tumors (DART) is a prospective, open-label, multicenter (1016 US sites), multi-cohort phase II trial of ipilimumab (1 mg/kg intravenously (IV) every 6 weeks) plus nivolumab (240 mg IV every 2 weeks). Methods: Participants histologically diagnosed with advanced IMA or INLA, who had not responded to at least one line of therapy, were included in the bronchioloalveolar carcinoma cohort. The primary endpoint was the overall response rate (ORR) by Response Evaluation Criteria in Solid Tumors (confirmed complete and partial responses (CR and PR)). Secondary endpoints were progression-free survival (PFS), overall survival (OS), clinical benefit rate (CBR; stable disease (SD) ⩾ 6 months plus ORR), and toxicity. Results: Eight evaluable patients (median age: 77 years; the number of prior therapies ranged from 0 to 4; one patient with prior exposure to a PD-1 inhibitor; comprising six IMA and two INLA) were treated. One IMA had a 40% regression (PFS 45.2+ months, PD-L1 0%, KRAS G12C mutated, tumor mutational burden [TMB] 13 mut/Mb). One INLA had 66% regression (PFS 23.8 months, PD-L1 unknown, no actionable mutations, TMB 3 mut/Mb). Overall ORR was 25.0% (2/8) and CBR, 62.5% (5/8); PFS for the patients with SD > 6 months was 43.4+, 11.7+, and 8.3 months. The median PFS was 16 months (5.3-not reached) and the median OS was 32.2 months (14.6-not reached). The toxicity profile was similar to previous reports. Conclusion: Ipilimumab plus nivolumab in the bronchioloalveolar carcinoma cohort (IMA, INLA) resulted in a durable ORR of 25.0% and CBR of 62.5% (PFS, 8.3 11.7+. 23.8 (PR), 43.4+ and 45.2+ (PR) months). Correlative studies to determine response and resistance markers are ongoing. Expanded prospective studies are warranted. Trial registration: ClinicalTrials.gov registry: NCT02834013.