Niraparib and dostarlimab for the treatment of recurrent platinum-resistant ovarian cancer: results of a Phase II study (MOONSTONE/GOG-3032)

Objective. This study assessed the efficacy, safety, and health-related quality of life (HRQoL) of the treatment regimen of dostarlimab, a programmed death-1 inhibitor, combined with niraparib, a poly (ADP-ribose) polymerase inhibitor, in patients with BRCA wild type (BRCAwt) recurrent platinum-resistant ovarian cancer (PROC) who had previously received bevacizumab treatment. Methods. This Phase II, open-label, single-arm, multicenter study, conducted in the USA, enrolled patients with recurrent PROC to receive niraparib and dostarlimab until disease progression or unacceptable toxicity (up to 3 years). A preplanned interim futility analysis was performed after the first 41 patients had undergone >_1 radiographic evaluation (approximately 9 weeks from the first treatment). Results. The prespecified interim futility criterion was met and the study was therefore terminated. For the 41 patients assessed, the objective response rate (ORR) was 7.3% (95% confidence interval: 1.5-19.9); no patients achieved a complete response, 3 patients (7.3%) achieved a partial response (duration of response; 3.0, 3.8, and 9.2 months, respectively), and 9 patients (22.0%) had stable disease. In total, 39 patients (95.1%) experienced a treatment-related adverse event, but no new safety issues were observed. HRQoL, assessed using FOSI, or Functional Assessment of Cancer Therapy - Ovarian Symptom Index scores, worsened over time compared with baseline scores. Conclusions. The study was terminated due to the observed ORR at the interim futility analysis. This highlights a need for effective therapies in treating patients with recurrent BRCAwt PROC.