Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.

Participants with platinum-resistant advanced, relapsed, high-grade ovarian, fallopian tube, or primary peritoneal cancer, and poly(adenosine diphosphate [ADP] ribose) polymerase [PARP] inhibitor naive were administered 500 milligrams (mg) of Dostarlimab (TSR-042) via infusion on Day 1 every 3 weeks (Q3W) for 4 cycles (each cycle is of 21 days), followed by 1000 mg every 6 weeks (Q6W) beginning from Day 1 of Cycle 5 until progressive disease (PD) or toxicity. Participants were administered 15 milligram per kilogram (mg/kg) of Bevacizumab via infusion Q3W for up to 15 months. Participants with screening actual body weight greater than or equal (≥) to 77 kg and screening platelet count ≥ 150000 cells per microliter were administered 300 mg of Niraparib orally once daily throughout each 21-day cycle until PD or toxicity. Participants with screening actual body weight less than 77 kg or screening platelet count less than 150000 cells per microliter were administered 200 mg of niraparib orally, once daily throughout each 21-day cycle until PD or toxicity.