Study to Estimate Efficacy of Combining Dostarlimab and Niraparib in Relapsed EOC After Treatment With PARPi

In total, 100 patients are planned to be enrolled in 2 cohorts (60 patients cohort A and 40 patients cohort B). Cohort A: Recurrent ovarian-, fallopian tube, or primary peritoneal cancer with relapse after more than 6 months of PARPi maintenance therapy. Cohort B: Recurrent ovarian-, fallopian tube, or primary peritoneal cancer with relapse within 6 months of PARPi maintenance therapy. All patients must have a known status for BRCA1 and BRCA2 and one or two prior lines of chemotherapy. The last line of chemotherapy should have included platinum. Both cohorts will receive the selective PARP 1/2 inhibitor niraparib in combination with the anti-PD-1 checkpoint inhibitor dostarlimab (TSR-042) for a maximum treatment duration of 2 years. The overall objective of this study is to reveal insights in mechanisms of PARPi resistance in epithelial ovarian cancer (EOC) and to obtain preliminary evidence of the efficacy of sequential and/or simultaneous combined immuno-PARPi therapy.