A Comparison of Platinum-based Therapy With TSR-042 and Niraparib Versus Standard of Care (SOC) Platinum-based Therapy as First-line Treatment of Stage III or IV Nonmucinous Epithelial Ovarian Cancer

Ovarian Neoplasms Clinical Trial

— FIRST  

Official title:

A Randomized, Double-blind, Phase 3 Comparison of Platinum-based Therapy With TSR-042 and Niraparib Versus Standard of Care Platinum-based Therapy as First-line Treatment of Stage III or IV Nonmucinous Epithelial Ovarian Cancer

Clinical Trial Details — Status: Active, not recruiting

Administrative data

• NCT number: NCT03602859
• Other study ID #: 213350
• Secondary ID: 3000-03-005
• Status: Active, not recruiting
• Phase: Phase 3
• Start date: October 11, 2018
• Est. completion date: June 22, 2026

Study information

• Verified date: May 2024
• Source: Tesaro, Inc.
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Ovarian cancer is a heterogeneous disease, characterized by complex molecular and genetic changes. The high expression of vascular endothelial growth factor (VEGF) receptor, programmed death receptor ligands 1 (PD-L1) expression, and deoxyribonucleic acid (DNA) damage in ovarian tumors provide several targets for treatment and maintenance of disease response. Given the unmet medical need of participants with advanced or metastatic ovarian cancer, this study design will enable investigators to provide participants with current SOC for ovarian cancer for the duration of the study. This is a global, multicenter, randomized, double-blind, controlled Phase 3 study that will primarily compare the progression-free survival (PFS) for participants receiving dostarlimab with SOC chemotherapy +/- bevacizumab followed by niraparib and dostarlimab maintenance +/- bevacizumab versus participants receiving SOC with chemotherapy followed by niraparib maintenance. This comparison will be investigated both in the PD-L1 positive and overall population of newly diagnosed stage III or IV advanced non-mucinous epithelial ovarian cancer participants and also to compare PFS of all participants with Stage III or IV high-grade non-mucinous epithelial ovarian cancer treated with platinum-based combination therapy, dostarlimab (TSR-042), and niraparib to SOC platinum-based combination therapy. The currently recommended SOC therapy for the first line treatment of Stage III or IV ovarian cancer is the combination of paclitaxel and carboplatin, with or without concurrent and maintenance bevacizumab. Participants will receive SOC during the chemotherapy Run-In period (cycle 1) before randomization to study treatment (cycle 2). Concurrent bevacizumab use must be determined prior to randomization at cycle 2.

Recruitment information / eligibility

• Status: Active, not recruiting
• Enrollment: 1402
• Est. completion date: June 22, 2026
• Est. primary completion date: October 25, 2024
• Accepts healthy volunteers: No
• Gender: Female
• Age group: 18 Years and older

Eligibility

Inclusion criteria:

• Participants must be female, >=18 years of age, able to understand the study procedures, and agree to participate in the study by providing written informed consent.

• Participants with a histologically confirmed diagnosis of high-grade nonmucinous epithelial ovarian (serous, endometrioid, clear cell, carcinosarcoma, and mixed pathologies), fallopian tube, or peritoneal cancer that is Stage III or IV according to the International Federation of Gynecology and Obstetrics (FIGO) or tumor, node and metastasis staging criteria.

• All participants with Stage IV disease are eligible. This includes those with inoperable disease, those who undergo primary debulking surgery (PDS) (R0 or macroscopic disease), or those for whom neoadjuvant chemotherapy (NACT) is planned.

• Participants with Stage III are eligible if they meet protocol defined criteria.

• Participants must provide a blood sample for circulating tumor deoxyribonucleic acid (ctDNA) homologous recombinant repair (HRR) testing at pre-screening or screening.

• Participant must provide a minimum of 1 formalin-fixed paraffin embedded (FFPE) block slide at pre-screening or screening for PD-L1, homologous recombinant deficiency (HRD) testing.

• Participants of childbearing potential must have a negative serum or urine pregnancy test (beta human chorionic gonadotropin) within 3 days prior to receiving the first dose of study treatment.

• Participants must be postmenopausal, free from menses for >1 year, surgically sterilized, or willing to use highly effective contraception to prevent pregnancy or must agree to abstain from activities that could result in pregnancy throughout the study, starting with enrollment through 180 days after the last dose of study treatment.

• Participants must have adequate organ function: Absolute neutrophil count (ANC) >=1500/micro liter (µL;) Platelet count >=100000/µL; Hemoglobin >=9 grams per deciliter (g/dL); Serum creatinine <=1.5 × upper limit of normal (ULN) or calculated creatinine clearance >=60 milliliters per minute (mL/min) using the Cockcroft-Gault equation; total bilirubin <=1.5 × ULN or direct bilirubin <=1.5 × ULN; AST and ALT <=2.5 × ULN unless liver metastases are present, in which case they must be <=5 × ULN.

• Participants must have an ECOG score of 0 or 1.

• Participants must have normal blood pressure (BP) or adequately treated and controlled hypertension (systolic BP <=140 millimeters of mercury (mmHg) and/or diastolic BP <=90 mmHg).

• Participants must agree to complete health related quality of life (HRQoL) questionnaires throughout the study.

• Participants must be able to take oral medication.

Exclusion Criteria:

• Participant has mucinous, germ cell, transitional cell, or undifferentiated tumor.

• Participant has low-grade or Grade 1 epithelial ovarian cancer.

• Participant has not adequately recovered from prior major surgery.

• Participant is pregnant or is expecting to conceive children while receiving study drug or for up to 180 days after the last dose of study drug. Participant is breastfeeding or is expecting to breastfeed within 30 days of receiving the final dose of study drug (women should not breastfeed or store breastmilk for use, during niraparib treatment and for 30 days after receiving the final dose of study treatment).

• Participant has known active central nervous system metastases, carcinomatous meningitis, or both.

• Participant has clinically significant cardiovascular disease.

• Participant has a bowel obstruction by clinical symptoms or computed tomography (CT) scan, subocclusive mesenteric disease, abdominal or gastrointestinal fistula, gastrointestinal perforation, or intra-abdominal abscess.

• Participant has any known history or current diagnosis of myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).

• Participant has been diagnosed and/or treated with any therapy for invasive cancer <5 years from study enrollment, completed adjuvant chemotherapy and/or targeted therapy (example, trastuzumab) less than 3 years from enrollment, or completed adjuvant hormonal therapy less than 4 weeks from enrollment.

• Participants with definitively treated non-invasive malignancies such as cervical carcinoma in situ, ductal carcinoma in situ, Grade 1 or 2, Stage I endometrial cancer, or non-melanomatous skin cancer are allowed.

• Participant is at increased bleeding risk due to concurrent conditions (example, major injuries or major surgery within the past 28 days prior to start of study treatment and/or history of hemorrhagic stroke, transient ischemic attack, subarachnoid hemorrhage, or clinically significant hemorrhage within the past 3 months).

• Participant is immunocompromised.

• Participant has known active hepatitis B (example, hepatitis B surface antigen reactive) or hepatitis C (example, hepatitis C virus ribonucleic acid [qualitative] is detected).

• Participant is considered a poor medical risk due to a serious, uncontrolled medical disorder, non-malignant systemic disease, or uncontrolled infection.

• Participant has had investigational therapy administered within 4 weeks or within a time interval less than at least 5 half-lives of the investigational agent, whichever is longer, prior to the first scheduled day of dosing in this study.

• Participant has received a live vaccine within 14 days of planned start of study therapy. Seasonal influenza vaccines that do not contain live viruses are allowed.

• Participant has a known contraindication or uncontrolled hypersensitivity to the components of paclitaxel, carboplatin, niraparib, bevacizumab, dostarlimab, or their excipients.

• Prior treatment for high-grade nonmucinous epithelial ovarian, fallopian tube, or peritoneal cancer (immunotherapy, anti-cancer therapy, radiation therapy).

• Participant has an active autoimmune disease that has required systemic treatment in the past 2 years. Replacement therapy is not considered a form of systemic therapy (example, thyroid hormone or insulin).

• Participant has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of systemic immunosuppressive therapy within 7 days prior to the first dose of study treatment.

Related Conditions & MeSH terms

• Carcinoma, Ovarian Epithelial
• Ovarian Neoplasms

Intervention

Drug:
• Niraparib
Participants will receive oral capsules of niraparib as a unit dosage strength of 100 milligrams (mg).
• Dostarlimab (TSR-042)
Participants will receive 30 minutes intravenous (IV) infusions of 1000 mg dostarlimab on Day 1 every 6 weeks.
• Standard of care
Participants will receive SOC that includes paclitaxel 175 milligrams per square meter (mg/m^2) on day 1 every 21 days + carboplatin area under the curve (AUC) of 5 to 6 milligrams per milliliter per minute (mg/mL/min) on day 1 every 21 days +/- bevacizumab 7.5 milligrams per kilograms (mg/kg) every 21 days or 15 mg/kg every 21 days for a total of 15 months.
• Dostarlimab-Placebo
Participants will receive 1000 mg of dostarlimab-placebo on day 1 every 6 weeks to continue up to 3 years in the absence of disease progression, unacceptable toxicity, participant withdrawal, or investigator decision
• Niraparib-Placebo
Participants will receive oral capsules of niraparib-placebo as a unit dosage strength of 100 mg.

Locations

Country	Name	City	State
Belarus	GSK Investigational Site	Minsk
Belgium	GSK Investigational Site	Brasschaat
Belgium	GSK Investigational Site	Brugge
Belgium	GSK Investigational Site	Brussels
Canada	GSK Investigational Site	London	Ontario
Canada	GSK Investigational Site	Montreal	Quebec
Canada	GSK Investigational Site	Montreal	Quebec
Canada	GSK Investigational Site	Sherbrooke	Quebec
Canada	GSK Investigational Site	Toronto	Ontario
Canada	GSK Investigational Site	Vancouver	British Columbia
Czechia	GSK Investigational Site	Prague
Czechia	GSK Investigational Site	Praha 8 - Liben
Denmark	GSK Investigational Site	Copenhagen
Denmark	GSK Investigational Site	Dk-2730 Herlev
Denmark	GSK Investigational Site	Roskilde
Finland	GSK Investigational Site	Helsinki
Finland	GSK Investigational Site	Kuopio
Finland	GSK Investigational Site	Tampere
Finland	GSK Investigational Site	Turku
France	GSK Investigational Site	Angers Cedex 02
France	GSK Investigational Site	Avignon Cedex 9
France	GSK Investigational Site	Besançon Cedex
France	GSK Investigational Site	Bordeaux
France	GSK Investigational Site	Caen
France	GSK Investigational Site	Clermont-Ferrand cedex
France	GSK Investigational Site	Dijon Cedex
France	GSK Investigational Site	Grenoble Cedex
France	GSK Investigational Site	La Tronche
France	GSK Investigational Site	Le Mans
France	GSK Investigational Site	Lille
France	GSK Investigational Site	Lyon
France	GSK Investigational Site	Lyon cedex 08
France	GSK Investigational Site	Marseille Cedex 9
France	GSK Investigational Site	Montpellier
France	GSK Investigational Site	Montpellier Cedex 5
France	GSK Investigational Site	Nancy
France	GSK Investigational Site	Nantes
France	GSK Investigational Site	Nice Cedex 2
France	GSK Investigational Site	Nîmes cedex 9
France	GSK Investigational Site	Paris
France	GSK Investigational Site	Paris
France	GSK Investigational Site	Paris Cedex 05
France	GSK Investigational Site	Paris Cedex 14
France	GSK Investigational Site	Paris Cedex 15
France	GSK Investigational Site	Paris Cedex 20
France	GSK Investigational Site	Pierre-Benite Cedex
France	GSK Investigational Site	Pierre-Bénite cedex
France	GSK Investigational Site	Plerin-sur-mer
France	GSK Investigational Site	Poitiers cedex
France	GSK Investigational Site	Reims Cedex
France	GSK Investigational Site	Rennes Cedex
France	GSK Investigational Site	Saint-Priest en Jarez
France	GSK Investigational Site	Strasbourg Cedex
France	GSK Investigational Site	Toulouse Cedex 9
France	GSK Investigational Site	Tours Cedex 1
France	GSK Investigational Site	Villejuif
Germany	GSK Investigational Site	Berlin
Germany	GSK Investigational Site	Hamburg
Germany	GSK Investigational Site	Kiel	Schleswig-Holstein
Germany	GSK Investigational Site	Muenster	Nordrhein-Westfalen
Germany	GSK Investigational Site	Ravensburg	Baden-Wuerttemberg
Germany	GSK Investigational Site	Wolfsburg	Niedersachsen
Greece	GSK Investigational Site	Athens
Greece	GSK Investigational Site	Athens
Greece	GSK Investigational Site	Athens
Greece	GSK Investigational Site	Haidari, Athens
Greece	GSK Investigational Site	Maroussi
Israel	GSK Investigational Site	Beer Sheva
Israel	GSK Investigational Site	Haifa
Israel	GSK Investigational Site	Haifa
Israel	GSK Investigational Site	Holon
Israel	GSK Investigational Site	Petach Tikva
Israel	GSK Investigational Site	Rehovot
Italy	GSK Investigational Site	Bologna
Italy	GSK Investigational Site	Faenza (RA)	Emilia-Romagna
Italy	GSK Investigational Site	Meldola
Italy	GSK Investigational Site	Napoli	Campania
Italy	GSK Investigational Site	Ravenna	Emilia-Romagna
Netherlands	GSK Investigational Site	Amsterdam
Netherlands	GSK Investigational Site	Groningen
Netherlands	GSK Investigational Site	Maastricht
Netherlands	GSK Investigational Site	Nijmegen
Netherlands	GSK Investigational Site	Rotterdam
Netherlands	GSK Investigational Site	Utrecht
Norway	GSK Investigational Site	Kristiansand
Norway	GSK Investigational Site	Oslo
Norway	GSK Investigational Site	Tromso
Poland	GSK Investigational Site	Olsztyn
Poland	GSK Investigational Site	Szczecin
Poland	GSK Investigational Site	Warszawa
Romania	GSK Investigational Site	Bucuresti
Romania	GSK Investigational Site	Cluj-Napoca
Romania	GSK Investigational Site	Cluj-Napoca
Romania	GSK Investigational Site	Constanta
Romania	GSK Investigational Site	Craiova
Romania	GSK Investigational Site	Timisoara
Spain	GSK Investigational Site	Avila
Spain	GSK Investigational Site	Badalona
Spain	GSK Investigational Site	Barcelona
Spain	GSK Investigational Site	Girona
Spain	GSK Investigational Site	Jaén
Spain	GSK Investigational Site	Madrid
Spain	GSK Investigational Site	San Sebastian de los Reyes
Spain	GSK Investigational Site	Santiago de Compostela
Spain	GSK Investigational Site	Toledo
Spain	GSK Investigational Site	Valencia
Spain	GSK Investigational Site	Zaragoza
Ukraine	GSK Investigational Site	Chernihiv
Ukraine	GSK Investigational Site	Kharkiv
Ukraine	GSK Investigational Site	Lviv
United Kingdom	GSK Investigational Site	Bebington, Wirral
United Kingdom	GSK Investigational Site	Glasgow
United Kingdom	GSK Investigational Site	London
United Kingdom	GSK Investigational Site	Portsmouth	Hampshire
United Kingdom	GSK Investigational Site	Sutton	Surrey
United Kingdom	GSK Investigational Site	Truro
United States	GSK Investigational Site	Abington	Pennsylvania
United States	GSK Investigational Site	Anchorage	Alaska
United States	GSK Investigational Site	Austin	Texas
United States	GSK Investigational Site	Baltimore	Maryland
United States	GSK Investigational Site	Billings	Montana
United States	GSK Investigational Site	Boston	Massachusetts
United States	GSK Investigational Site	Canton	Ohio
United States	GSK Investigational Site	Charleston	South Carolina
United States	GSK Investigational Site	Charlotte	North Carolina
United States	GSK Investigational Site	Charlottesville	Virginia
United States	GSK Investigational Site	Cincinnati	Ohio
United States	GSK Investigational Site	Covington	Louisiana
United States	GSK Investigational Site	Dallas	Texas
United States	GSK Investigational Site	Eugene	Oregon
United States	GSK Investigational Site	Farmington	Connecticut
United States	GSK Investigational Site	Fort Worth	Texas
United States	GSK Investigational Site	Gainesville	Florida
United States	GSK Investigational Site	Hampton	Virginia
United States	GSK Investigational Site	Hartford	Connecticut
United States	GSK Investigational Site	Hawthorne	New York
United States	GSK Investigational Site	Houston	Texas
United States	GSK Investigational Site	Jacksonville	Florida
United States	GSK Investigational Site	Kennewick	Washington
United States	GSK Investigational Site	Knoxville	Tennessee
United States	GSK Investigational Site	Los Angeles	California
United States	GSK Investigational Site	Los Angeles	California
United States	GSK Investigational Site	Maplewood	Minnesota
United States	GSK Investigational Site	Minneapolis	Minnesota
United States	GSK Investigational Site	Minneapolis	Minnesota
United States	GSK Investigational Site	Nashville	Tennessee
United States	GSK Investigational Site	Nashville	Tennessee
United States	GSK Investigational Site	Neptune	New Jersey
United States	GSK Investigational Site	New Orleans	Louisiana
United States	GSK Investigational Site	New York	New York
United States	GSK Investigational Site	New York	New York
United States	GSK Investigational Site	New York	New York
United States	GSK Investigational Site	New York	New York
United States	GSK Investigational Site	Newport Beach	California
United States	GSK Investigational Site	Newport News	Virginia
United States	GSK Investigational Site	Norfolk	Virginia
United States	GSK Investigational Site	Ogden	Utah
United States	GSK Investigational Site	Oklahoma City	Oklahoma
United States	GSK Investigational Site	Orange	California
United States	GSK Investigational Site	Paoli	Pennsylvania
United States	GSK Investigational Site	Philadelphia	Pennsylvania
United States	GSK Investigational Site	Phoenix	Arizona
United States	GSK Investigational Site	Pittsburgh	Pennsylvania
United States	GSK Investigational Site	Pittsburgh	Pennsylvania
United States	GSK Investigational Site	Portland	Oregon
United States	GSK Investigational Site	Providence	Rhode Island
United States	GSK Investigational Site	Rochester	New York
United States	GSK Investigational Site	San Antonio	Texas
United States	GSK Investigational Site	Scarborough	Maine
United States	GSK Investigational Site	Seattle	Washington
United States	GSK Investigational Site	Seattle	Washington
United States	GSK Investigational Site	Shreveport	Louisiana
United States	GSK Investigational Site	Silver Spring	Maryland
United States	GSK Investigational Site	Silver Spring	Maryland
United States	GSK Investigational Site	Sioux Falls	South Dakota
United States	GSK Investigational Site	Springfield	Massachusetts
United States	GSK Investigational Site	Stony Brook	New York
United States	GSK Investigational Site	Syracuse	New York
United States	GSK Investigational Site	Teaneck	New Jersey
United States	GSK Investigational Site	The Woodlands	Texas
United States	GSK Investigational Site	Tualatin	Oregon
United States	GSK Investigational Site	Tucson	Arizona
United States	GSK Investigational Site	Tucson	Arizona
United States	GSK Investigational Site	Tucson	Arizona
United States	GSK Investigational Site	Tyler	Texas
United States	GSK Investigational Site	Vancouver	Washington
United States	GSK Investigational Site	Warrenville	Illinois
United States	GSK Investigational Site	Worcester	Massachusetts
United States	GSK Investigational Site	Wynnewood	Pennsylvania
United States	GSK Investigational Site	Zion	Illinois

Sponsors (2)

Lead Sponsor	Collaborator
Tesaro, Inc.	European Network of Gynaecological Oncological Trial Groups (ENGOT)

Countries where clinical trial is conducted

United States,  Belarus,  Belgium,  Canada,  Czechia,  Denmark,  Finland,  France,  Germany,  Greece,  Israel,  Italy,  Netherlands,  Norway,  Poland,  Romania,  Spain,  Ukraine,  United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	PFS for PD-L1 positive participants	To compare the PFS of PD-L1 positive participants with Stage III or IV non-mucinous epithelial ovarian cancer given first-line treatment with the combination of dostarlimab with SOC chemotherapy +/- bevacizumab followed by niraparib and dostarlimab maintenance +/- bevacizumab versus SOC chemotherapy +/- bevacizumab followed by niraparib maintenance +/- bevacizumab. PFS is defined as the time from treatment randomization to the earlier date of assessment of progression or death by any cause in the absence of progression. PFS will be evaluated by investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) version (v.) 1.1 criteria.	Up to 5 years
Primary	PFS for all participants	To compare the PFS of all participants with Stage III or IV high-grade nonmucinous epithelial ovarian cancer given first-line treatment with the combination of dostarlimab with SOC chemotherapy +/- bevacizumab followed by niraparib and dostarlimab maintenance +/- bevacizumab versus SOC chemotherapy +/- bevacizumab followed by niraparib maintenance +/- bevacizumab. PFS is defined as the time from treatment randomization to the earlier date of assessment of progression or death by any cause in the absence of progression. PFS will be evaluated by investigator assessment per RECIST v.1.1 criteria.	Up to 5 years
Secondary	PFS by Blinded Independent Central Review (BICR) per investigator-assessed Response Evaluation Criteria in Solid Tumors (RECIST) criteria for PD-L1 positive participants	BICR determined PFS will be assessed as per RECIST criteria.	Up to 5 years
Secondary	Overall Survival (OS) of PD-L1 positive participants	OS is defined as the date of randomization to the date of death by any cause.	Up to 5 years
Secondary	OS of all the participants	OS is defined as the date of randomization to the date of death by any cause.	Up to 5 years
Secondary	Number of PD-L1 positive participants with treatment-emergent adverse events (TEAEs)	TEAEs are defined as, any event that was not present prior to the initiation of study treatment or any event already present that worsens in either intensity or frequency following exposure to study treatment.	Up to 5 years
Secondary	Number of overall participants with TEAEs	TEAEs are defined as, any event that was not present prior to the initiation of study treatment or any event already present that worsens in either intensity or frequency following exposure to study treatment.	Up to 5 years
Secondary	Number of PD-L1 positive participants with serious adverse events (SAEs)	SAEs are any adverse event that may result in death, is life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability or incapacity, is a congenital abnormality or birth defect, is an important medical event.	Up to 5 years
Secondary	Number of overall participants with SAEs	SAEs are any adverse event that may result in death, is life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability or incapacity, is a congenital abnormality or birth defect, is an important medical event.	Up to 5 years
Secondary	Number of PD-L1 positive participants with treatment discontinuations or dose delays or dose reductions due to adverse events	Adverse events are any untoward medical occurrence that occurs in a participant or clinical investigation participant administered a medicinal product and which does not necessarily have to have a causal relationship with this treatment.	Up to 5 years
Secondary	Number of overall participants with treatment discontinuations or dose delays or dose reductions due to adverse events	Adverse events are any untoward medical occurrence that occurs in a participant or clinical investigation participant administered a medicinal product and which does not necessarily have to have a causal relationship with this treatment.	Up to 5 years
Secondary	Number of PD-L1 positive participants with immune-related adverse events (irAEs)	Following events are categorized as irAEs: Diarrhea/colitis, aspartate aminotransferase (AST) or alanine aminotransferase (ALT; >3 and <=5 X upper limit of normal [ULN]), or increased bilirubin, type 1 diabetes mellitus (T1DM) or hyperglycemia, immune-related encephalitis, uveitis, myositis, hypophysitis, adrenal insufficiency, hypo- and hyperthyroidism, infusion-related reaction, pneumonitis, immune-related rash, renal failure or nephritis and recurrence of adverse events after resolution to Grade <=1.	Up to 5 years
Secondary	Number of overall participants with irAEs	Following events are categorized as irAEs: Diarrhea/colitis, AST or ALT (>3 and <=5 X ULN), or increased bilirubin, T1DM or hyperglycemia, immune-related encephalitis, uveitis, myositis, hypophysitis, adrenal insufficiency, hypo- and hyperthyroidism, infusion-related reaction, pneumonitis, immune-related rash, renal failure or nephritis and recurrence of AEs after resolution to Grade <=1.	Up to 5 years
Secondary	Number of PD-L1 positive participants with changes in Eastern Cooperative Oncology Group (ECOG) performance status	Performance status will be assessed using the ECOG performance status scale: ranging from Grade 0 to 5, Grade 0 denoting fully active and Grade 5 denoting death.	Up to 5 years
Secondary	Number of overall participants with changes in ECOG performance status	Performance status will be assessed using the ECOG performance status scale: ranging from Grade 0 to 5, Grade 0 denoting fully active and Grade 5 denoting death.	Up to 5 years
Secondary	Number of PD-L1 positive participants with abnormal hematology results	Blood samples will be collected for the analysis of hematologic parameters including: hemoglobin, platelet count, white blood cell count, differential white blood cell count, coagulation factors-International normalized ratio (INR) and activated partial thromboplastin time.	Up to 5 years
Secondary	Number of all the participants with abnormal hematology results	Blood samples will be collected for the analysis of hematologic parameters including: hemoglobin, platelet count, white blood cell count, differential white blood cell count, coagulation factors-INR and activated partial thromboplastin time.	Up to 5 years
Secondary	Number of PD-L1 positive participants with abnormal clinical chemistry results	Blood samples will be collected for the analysis of clinical chemistry parameters including: amylase, thyroid function (thyroid stimulating hormone [TSH]), urea or blood urea nitrogen, creatinine, albumin, total protein, ALT, AST, total bilirubin, Glucose, Magnesium, Calcium, Chloride, Potassium and Sodium.	Up to 5 years
Secondary	Number of all the participants with abnormal clinical chemistry results	Blood samples will be collected for the analysis of clinical chemistry parameters including: amylase, thyroid function (TSH), urea or blood urea nitrogen, creatinine, albumin, total protein, ALT, AST, total bilirubin, Glucose, Magnesium, Calcium, Chloride, Potassium and Sodium.	Up to 5 years
Secondary	Change from Baseline in the European Quality of Life 5-Dimension 5-Level Scale (EQ-5D-5L) assessment among PD-L1 positive participants	EQ-5D-5L is a validated questionnaire to assess the overall health-related quality of life in participants across diseases. EQ-5D-5L consists of a descriptive section of 5 questions/dimensions, one related to each of: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is measured by 5-point Likert scale (no problems, slight problems, moderate problems, severe problems and extreme problems).	Baseline and up to 5 years
Secondary	Change from Baseline in the EQ-5D-5L assessment among all participants	EQ-5D-5L is a validated questionnaire to assess the overall health-related quality of life in participants across diseases. EQ-5D-5L consists of a descriptive section of 5 questions/dimensions, one related to each of: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is measured by 5-point Likert scale (no problems, slight problems, moderate problems, severe problems and extreme problems).	Baseline and up to 5 years
Secondary	Change from Baseline in the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC-QLQ-C30) assessment among PD-L1 positive participants	EORTC QLQ-C30 is a validated questionnaire to assess the overall health-related quality of life in participants with cancer and is composed of 30 questions including multi-item scales and single item measures. These include five functional scales (physical, role, emotional, cognitive and social), three symptom scales (fatigue, nausea/vomiting, and pain), a global health status/quality of life scale (GHS/QOL), and six single items (dyspnoea, insomnia, appetite loss, constipation, diarrhea and financial difficulties). Response options are 1 to 4. Higher score indicates better health-related quality of life.	Baseline and Up to 5 years
Secondary	Change from Baseline in the EORTC-QLQ-C30 assessment among all the participants	EORTC QLQ-C30 is a validated questionnaire to assess the overall health-related quality of life in participants with cancer and is composed of 30 questions including multi-item scales and single item measures. These include five functional scales (physical, role, emotional, cognitive and social), three symptom scales (fatigue, nausea/vomiting, and pain), a GHS/QOL, and six single items (dyspnoea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). Response options are 1 to 4. Higher score indicates better health-related quality of life.	Baseline and up to 5 years
Secondary	Change from Baseline in the EORTC-QLQ Ovarian Cancer Module OV28 (EORTC-QLQ-OV28) assessment among PD-L1 positive participants	EORTC QLQ-OV28 is a validated questionnaire to assess the overall health-related quality of life in participants with local or advanced ovarian cancer. EORTC QLQ-OV28 consists of 28 questions evaluated across eight multi-item and 4 single item scales: abdominal/ gastrointestinal (GI) symptoms, peripheral neuropathy, hormonal symptoms, body image, attitude to disease/treatment, chemotherapy side effects, and sexuality, and single items scales for indigestion/heartburn, hair loss, upset due to hair loss, and taste. All questions are rated on a 4 point verbal rating scale: "Not at all," "A little," "Quite a bit," and "Very much."	Baseline and up to 5 years
Secondary	Change from Baseline in the EORTC-QLQ-OV28 assessment among all the participants	EORTC QLQ-OV28 is a validated questionnaire to assess the overall health-related quality of life in all the participants with local or advanced ovarian cancer. EORTC QLQ-OV28 consists of 28 questions evaluated across eight multi-item and 4 single item scales: abdominal/GI symptoms, peripheral neuropathy, hormonal symptoms, body image, attitude to disease/treatment, chemotherapy side effects, and sexuality, and single items scales for indigestion/heartburn, hair loss, upset due to hair loss, and taste. All questions are rated on a 4 point verbal rating scale: "Not at all," "A little," "Quite a bit," and "Very much."	Baseline and up to 5 years
Secondary	Time to symptom worsening in the EQ-5D-5L assessment among the PD-L1 positive participants	EQ-5D-5L is a validated questionnaire to assess the overall health-related quality of life in participants across diseases. EQ-5D-5L consists of a descriptive section of 5 questions/dimensions, one related to each of: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is measured by 5-point Likert scale (no problems, slight problems, moderate problems, severe problems and extreme problems).	Up to 5 years
Secondary	Time to symptom worsening in the EQ-5D-5L assessment among all the participants	EQ-5D-5L is a validated questionnaire to assess the overall health-related quality of life in participants across diseases. EQ-5D-5L consists of a descriptive section of 5 questions/dimensions, one related to each of: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is measured by 5-point Likert scale (no problems, slight problems, moderate problems, severe problems and extreme problems).	Up to 5 years
Secondary	Time to symptom worsening in the EORTC-QLQ-C30 assessment among the PD-L1 positive participants	EORTC QLQ-C30 is a validated questionnaire to assess the overall health-related quality of life in participants with cancer and is composed of 30 questions including multi-item scales and single item measures. These include five functional scales (physical, role, emotional, cognitive and social), three symptom scales (fatigue, nausea/vomiting, and pain), a GHS/QOL, and six single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). Response options are 1 to 4. Higher score indicates better health-related quality of life.	Up to 5 years
Secondary	Time to symptom worsening in the EORTC QLQ-C30 assessment among all the participants	EORTC QLQ-C30 is a validated questionnaire to assess the overall health-related quality of life in participants with cancer and is composed of 30 questions including multi-item scales and single item measures. These include five functional scales (physical, role, emotional, cognitive and social), three symptom scales (fatigue, nausea/vomiting, and pain), a GHS/QOL, and six single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). Response options are 1 to 4. Higher score indicates better health-related quality of life.	Up to 5 years
Secondary	Time to symptom worsening in the EORTC-QLQ-OV28 assessment among the PD-L1 positive participants	EORTC QLQ-OV28 is a validated questionnaire to assess the overall he PFS2, health-related quality of life in participants with local or advanced ovarian cancer. EORTC QLQ-OV28 consists of 28 questions evaluated across eight multi-item and 4 single item scales: abdominal/GI symptoms, peripheral neuropathy, hormonal symptoms, body image, attitude to disease/treatment, chemotherapy side effects, and sexuality, and single items scales for indigestion/heartburn, hair loss, upset due to hair loss, and taste. All questions are rated on a 4 point verbal rating scale: "Not at all," "A little," "Quite a bit," and "Very much."	Up to 5 years
Secondary	Time to symptom worsening in the EORTC-QLQ-OV28 assessment among all the participants	EORTC QLQ-OV28 is a validated questionnaire to assess the overall he PFS2, health-related quality of life in participants with local or advanced ovarian cancer. EORTC QLQ-OV28 consists of 28 questions evaluated across eight multi-item and 4 single item scales: abdominal/GI symptoms, peripheral neuropathy, hormonal symptoms, body image, attitude to disease/treatment, chemotherapy side effects, and sexuality, and single items scales for indigestion/heartburn, hair loss, upset due to hair loss, and taste. All questions are rated on a 4 point verbal rating scale: "Not at all," "A little," "Quite a bit," and "Very much."	Up to 5 years
Secondary	Time to first subsequent therapy (TFST) in PD-L1 positive participants	TFST is defined as the time from randomization until the start date of the first subsequent anti-cancer therapy or death, whichever occurs first.	Up to 5 years
Secondary	TFST in all the participants	TFST is defined as the time from randomization until the start date of the first subsequent anti-cancer therapy or death, whichever occurs first.	Up to 5 years
Secondary	Time to second subsequent therapy (TSST) in PD-L1 positive participants	TSST is defined as the time from randomization until the start date of the second subsequent anti-cancer therapy or death, whichever occurs first.	Up to 5 years
Secondary	TSST in all the participants	TSST is defined as the time from randomization until the start date of the second subsequent anti-cancer therapy or death, whichever occurs first.	Up to 5 years
Secondary	Time to progression on next-line therapy (PFS2,) in PD-L1 positive participants	PFS2 is defined as the time from randomization until PD per investigator's assessment after starting follow-up anti-cancer therapy or death due to any cause, whichever occurs first.	Up to 5 years
Secondary	PFS2 in all the participants	PFS2 is defined as the time from randomization until PD per investigator's assessment after starting follow-up anti-cancer therapy or death due to any cause, whichever occurs first.	Up to 5 years
Secondary	Objective Response Rate (ORR) among PD-L1 positive participants	ORR, defined as the percentage of participants with complete response (CR) or partial response (PR) on study treatment as assessed by RECIST v.1.1 criteria for participants with measurable disease.	Up to 5 years
Secondary	ORR among all the participants	ORR, defined as the percentage of participants with complete response (CR) or partial response (PR) on study treatment as assessed by RECIST v.1.1 criteria for participants with measurable disease.	Up to 5 years
Secondary	Pathologic complete response (pCR) rate among PD-L1 positive participants	pCR rate, per investigator assessment, defined as the rate of pathologic complete responseas assessed by the evaluation of residual microscopic disease at the time of surgery in neoadjuvant participants.	Up to 5 years
Secondary	pCR rate among all the participants	pCR rate, per investigator assessment, defined as the rate of pathologic complete responseas assessed by the evaluation of residual microscopic disease at the time of surgery in neoadjuvant participants.	Up to 5 years
Secondary	Duration of response (DOR) in PD-L1 positive participants	DOR, defined as the time from first documentation of CR or PR until the time of first documentation of PD as assessed by RECIST v.1.1, or death by any cause in the absence of progression, whichever occurs first.	Up to 5 years
Secondary	DOR in all the participants	DOR, defined as the time from first documentation of CR or PR until the time of first documentation of PD as assessed by RECIST v.1.1, or death by any cause in the absence of progression, whichever occurs first.	Up to 5 years
Secondary	Disease control rate (DCR) in PD-L1 positive participants	DCR, defined as the proportion of participants with a best overall response of CR, PR, or stable disease (SD), as assessed by RECIST v.1.1 criteria.	Up to 5 years
Secondary	DCR in all the participants	DCR, defined as the proportion of participants with a best overall response of CR, PR, or SD, as assessed by RECIST v.1.1 criteria.	Up to 5 years
Secondary	Maintenance progression-free survival (MPFS) in PD-L1 positive participants	MPFS, defined as the time from the date of the first maintenance period dose to the date of first documentation of progression or death by any cause in the absence of progression, whichever occurs first, as determined by the investigator. Progression will be assessed by RECIST v.1.1 criteria.	Up to 5 years
Secondary	MPFS in all the participants	MPFS, defined as the time from the date of the first maintenance period dose to the date of first documentation of progression or death by any cause in the absence of progression, whichever occurs first, as determined by the investigator. Progression will be assessed by RECIST v.1.1 criteria.	Up to 5 years
Secondary	Plasma concentration of dostarlimab in PD-L1 positive participants	Blood samples will be collected for pharmacokinetic analysis of dostarlimab.	Up to 5 years
Secondary	Plasma concentration of dostarlimab in all the participants	Blood samples will be collected for pharmacokinetic analysis of dostarlimab.	Up to 5 years
Secondary	Number of participants with positive antidrug antibodies (ADAs) against dostarlimab in PD-L1 positive participants	Serum samples will be collected for the analysis of the presence of ADAs using validated immunoassays.	Up to 5 years
Secondary	Number of participants with positive ADAs against dostarlimab in all the participants	Serum samples will be collected for the analysis of the presence of ADAs using validated immunoassays.	Up to 5 years
Secondary	Plasma concentration of niraparib in PD-L1 positive participants	Blood samples will be collected for pharmacokinetic analysis of niraparib.	Up to 5 years
Secondary	Plasma concentration of niraparib in all the participants	Blood samples will be collected for pharmacokinetic analysis of niraparib.	Up to 5 years