A Study of Dostarlimab in Combination With Carboplatin-paclitaxel in Japanese Participants With Primary Advanced or Recurrent Endometrial Cancer (RUBY-J)

A Phase 2, Multicenter, Open-label, Single Arm Study of Dostarlimab Plus Carboplatin-paclitaxel Followed by Dostarlimab Monotherapy in Japanese Patients With Primary Advanced or Recurrent Endometrial Cancer (RUBY-J)

The goal of this clinical trial is to understand the effectiveness of dostarlimab and carboplatin-paclitaxel followed by dostarlimab monotherapy in participants with endometrial cancer

Study Overview

• Status: Active, not recruiting
• Conditions: Carcinoma
• Intervention / Treatment: Biological: Dostarlimab; Drug: Carboplatin; Drug: Paclitaxel

• Study Type: Interventional
• Enrollment (Actual): 41
• Phase: Phase 2

Contacts and Locations

Study Locations

• Japan
  • Aichi, Japan, 464-8681
    • GSK Investigational Site
  • Chiba, Japan, 260-8717
    • GSK Investigational Site
  • Ehime, Japan, 791-0280
    • GSK Investigational Site
  • Fukuoka, Japan, 811-1395
    • GSK Investigational Site
  • Fukuoka, Japan, 830-0011
    • GSK Investigational Site
  • Gunma, Japan, 373-8550
    • GSK Investigational Site
  • Hokkaido, Japan, 060-8648
    • GSK Investigational Site
  • Hyogo, Japan, 673-8558
    • GSK Investigational Site
  • Ibaraki, Japan, 305-8576
    • GSK Investigational Site
  • Iwate, Japan, 028-3695
    • GSK Investigational Site
  • Kanagawa, Japan, 259-1193
    • GSK Investigational Site
  • Okayama, Japan, 700-8558
    • GSK Investigational Site
  • Osaka, Japan, 569-8686
    • GSK Investigational Site
  • Osaka, Japan, 541-8567
    • GSK Investigational Site
  • Saitama, Japan, 350-1298
    • GSK Investigational Site
  • Shizuoka, Japan, 411-8777
    • GSK Investigational Site
  • Tochigi, Japan, 329-0498
    • GSK Investigational Site
  • Tokyo, Japan, 160-8582
    • GSK Investigational Site
  • Tokyo, Japan, 104-0045
    • GSK Investigational Site
  • Tokyo, Japan, 135-8550
    • GSK Investigational Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Participant has histologically or cytologically proven endometrial cancer with recurrent or advanced disease.
2. Participant has molecular subtype of defective mismatch repair/microsatellite instability high (dMMR/MSI-H) or mismatch repair proficient/microsatellite stable (MMRp/MSS) determined.
3. Participant must have primary Stage III or Stage IV disease or first recurrent endometrial cancer with a low potential for cure by radiation therapy or surgery alone or in combination, and presence of at least one measurable lesion per RECIST 1.1 based on Investigator's assessment.
4. Participant is not pregnant or breastfeeding and agrees to use a highly effective contraceptive method during the study period if a woman of childbearing potential (WOCBP).
5. Participant has an Eastern Cooperative Oncology Group Performance status (ECOG PS) of 0 or 1.
6. Participant has adequate organ function, as assessed by hematologic, renal, hepatic and coagulation parameters.

Exclusion Criteria:

1. Participant has a concomitant malignancy, or participant has a prior non-endometrial invasive malignancy who has been disease-free for <3 years or who received any active treatment in the last 3 years for that malignancy. Non-melanoma skin cancer is allowed.
2. Participant has any medical history of interstitial lung disease or pneumonitis.
3. Participant has cirrhosis or current unstable liver or biliary disease.
4. Participant has known uncontrolled central nervous system metastases, carcinomatosis meningitis, or both.
5. Participant has a diagnosis of immunodeficiency.
6. Participant has received prior therapy with an anti- Programmed death protein 1 (PD-1), anti- Programmed death ligand 1 (PD-L1), anti- Programmed death ligand 2 (PD-L2), or anti- Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) agent.
7. Participant has not recovered adequately from AEs.
8. Participant has received prior anticancer therapy (chemotherapy, targeted therapies, hormonal therapy, radiotherapy, or immunotherapy) within 21 days or <5 times the half-life of the most recent therapy prior to the first dose of study intervention, whichever is shorter.
9. Participant has received any live vaccine within 30 days of the first dose of study intervention. Vaccination against coronavirus disease 2019 (COVID-19) using vaccines that are authorized via the appropriate regulatory mechanisms are not exclusionary.
10. Participant has HBsAg positive, or HCV RNA positive.
11. Participant is known HIV infection.
12. Participant is currently participating and receiving study intervention or has participated in a study of an investigational agent and received study intervention or used an investigational device within 4 weeks of the first dose of treatment.
13. Participant with contraindication to carboplatin and paclitaxel.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Dostarlimab- Carboplatin-Paclitaxel followed by Dostarlimab Monotherapy

Biological: Dostarlimab; Dostarlimab is administered via intravenous (IV) infusion at a dose of 500 milligram (mg) for first 6 cycles (each cycle is of 21 days) followed by 1,000 mg from cycle 7 (each cycle is of 42 days); Drug: Carboplatin; Carboplatin is administered IV at a dose of Area under the concentration time curve (AUC) 5 milligram*millilitre/ minute (mg•mL/min) for cycles 1 to 6 (each cycle is of 21 days); Drug: Paclitaxel; Paclitaxel is administered IV at a dose of 175 milligram per meter square (mg/m2) for cycles 1 to 6 (each cycle is of 21 days)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Durable response rate for 12 months (DRR12) assessed by Blinded independent central review (BICR)	DRR12 is defined as the proportion of participants with Complete Response (CR) or Partial Response (PR) lasting greater than or equal to (≥) 12 months, per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1)	Approximately 18 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
DRR12 per RECIST 1.1, assessed by investigator		Approximately 18 months
Progression-free survival (PFS) per RECIST 1.1, assessed by BICR and investigator	PFS is defined as the time from the date of first dose to the earlier date of assessment of progression or death by any cause	Up to approximately 3 years
Overall survival (OS)	OS is defined as time from first dose of study intervention to death from any cause	Up to approximately 3 years
Overall response rate (ORR) per RECIST 1.1 assessed by BICR	ORR is achieving a best overall response (BOR) of CR or PR. BOR is defined as the best confirmed response [CR > PR > Stable disease (SD) > Progressive Disease (PD) > Not evaluable (NE)] from treatment start date until disease progression, death or initiation of next line of therapy, whichever is earlier	Up to approximately 3 years
ORR per RECIST 1.1 assessed by investigator		Up to approximately 3 years
Disease control rate (DCR) per RECIST 1.1 assessed by BICR	Achieving a BOR of CR, PR, or SD, defined as the best confirmed response (CR > PR > SD) from treatment start date until disease progression, death or initiation of next line of therapy, whichever is earlier	Up to approximately 3 years
DCR per RECIST 1.1 assessed by investigator		Up to approximately 3 years
Duration of response (DOR) per RECIST 1.1 assessed by BICR	DOR is defined as the time from the date of first documented objective response to the date of first documented PD or death, whichever comes first	Up to approximately 3 years
DOR per RECIST 1.1 assessed by investigator		Up to approximately 3 years
Maximum concentration (Cmax) for dostarlimab		Up to 67 weeks
Minimum concentration (Cmin) for dostarlimab		Up to 67 weeks
Number of participants with adverse events (AEs), Immune-related adverse events (irAEs), and serious adverse events (SAEs) by severity		Up to approximately 3 years
Number of participants AEs, irAEs, and SAEs leading to dose modifications such as dose delay or study intervention discontinuation		Up to approximately 3 years
Number of participants with AEs leading to death		Up to approximately 3 years

Collaborators and Investigators

• Sponsor: GlaxoSmithKline

Study record dates

Study Major Dates

• Study Start (Actual): May 7, 2024
• Primary Completion (Estimated): July 15, 2026
• Study Completion (Estimated): August 31, 2027

Study Registration Dates

• First Submitted: March 12, 2024
• First Submitted That Met QC Criteria: March 12, 2024
• First Posted (Actual): March 19, 2024

Study Record Updates

• Last Update Posted (Actual): July 25, 2025
• Last Update Submitted That Met QC Criteria: July 24, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Carboplatin; Paclitaxel; Endometrial cancer; Dostarlimab
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Uterine Diseases; Genital Diseases, Female; Genital Neoplasms, Female; Uterine Neoplasms; Endometrial Neoplasms; Antineoplastic Agents; Molecular Mechanisms of Pharmacological Action; Tubulin Modulators; Antimitotic Agents; Mitosis Modulators; Antineoplastic Agents, Phytogenic; Dostarlimab; Carboplatin; Paclitaxel
• Other Study ID Numbers: 221968

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Qualified researchers may request access to anonymized individual patient-level data (IPD) and related study documents of the eligible studies via the Data Sharing Portal. Details on GSK's data sharing criteria can be found at: https://www.gsk.com/en-gb/innovation/trials/data-transparency/
• IPD Sharing Time Frame: Anonymized IPD will be made available within 6 months of publication of primary, key secondary and safety results for studies in product with approved indication(s) or terminated asset(s) across all indications.
• IPD Sharing Access Criteria: Anonymized IPD is shared with researchers whose proposals are approved by an Independent Review Panel and after a Data Sharing Agreement is in place. Access is provided for an initial period of 12 months but an extension may be granted, when justified, for up to 6 months.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No