Niraparib plus Dostarlimab in Pleural Mesothelioma or Non–Small Cell Lung Cancer Harboring HRR Mutations: Interim Results of the UNITO-001 Phase II Prospective Trial

Abstract Purpose: Treatment of homologous recombination repair–deficient (HRD)-tumors with PARP inhibitors has the potential to further increase tumor immunogenicity, suggesting a synergistic effect with immunotherapy. Here we present the preliminary results of niraparib in combination with dostarlimab for pleural mesothelioma (PM) or non–small cell lung cancer (NSCLC) harboring HRR mutations. Experimental Design: UNITO-001 is a phase II, prospective, study aiming to investigate the combination of niraparib plus dostarlimab in pretreated patients with HRD and programmed death ligand-1 (PD-L1) ≥1% NSCLC and/or PM. The primary endpoint is progression-free survival (PFS). Results: Seventeen of 183 (10%) screened patients (12 PM and 5 NSCLC) were included. The objective response rate (ORR) was 6% [95% confidence interval (CI): 0.1–28.7] and the disease control rate (DCR) was 53% (95% CI: 27.8–77). Median PFS was 3.1 (95% CI: 2.7–N.A) and median overall survival (OS) was 4.2 (95% CI: 1.58–NA) months. The PFS was 14.1 months in one PM patient harboring a germline BAP1 mutation. The treatment duration was 9.8 months in one PM patient harboring a somatic BRCA2 mutation. The most common adverse events (AE) were grade 1–2 lymphopenia (59%), anemia (35%), hyponatremia (29%), and hypokalemia (29%). Grade ≥3 AEs were reported in 23% of the patients. Conclusions: This preliminary analysis highlighted the lack of antitumor activity for the combination of niraparib and dostarlimab in patients with PM and/or advanced NSCLC harboring BAP1 somatic mutations. A potential antitumor activity emerged for PM with germline BAP1 and/or BRCA2 somatic mutations along with a good tolerability profile.