A Study of Mocertatug Rezetecan in Combination With Anti-cancer Therapies for Advanced Solid Tumors (BEHOLD-2)

May 19, 2026 updated by: GlaxoSmithKline

A Phase 1/2 Randomized Multi-Cohort Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Clinical Activity of Mocertatug Rezetecan in Combination With Anti-Cancer Agents in Participants With Advanced Solid Tumors

Advanced solid tumors are cancers that have spread to other parts of the body. While many treatments exist, most people become resistant to them, and the cancer returns. Researchers are developing new treatments that combine different medicines for those who do not respond to single medicine. This study is looking at how safe and tolerable Mocertatug Rezetecan (Mo-Rez) is, how the body handles it, and how well it works when used with other cancer medicines. The study will include participants with advanced solid tumors who have either not responded to standard treatments or cannot tolerate them or have no available effective treatment.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

305

Phase

  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Argentina
      • Buenos Aires, Argentina, C1181ACH
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ventura Simonovich
      • Buenos Aires, Argentina, C1280AEB
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Karina Vera
      • CABA, Argentina, C1187
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Gabriela Cinat
      • Viedma, Argentina, R8500ACE
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Rubén Kowalyszyn
  • Australia
    • New South Wales
      • Liverpool, New South Wales, Australia, 2170
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Kate Wilkinson
      • Wollongong, New South Wales, Australia, 2500
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Udit Nindra
  • Belgium
      • Brussels, Belgium, 1200
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Jean Francois Baurain
      • Ghent, Belgium, 9000
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Sylvie Rottey
        • Contact:
        • Contact:
      • Leuven, Belgium, 3000
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Toon van Gorp
        • Contact:
        • Contact:
      • Liège, Belgium, 4000
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Christine Gennigens
  • Brazil
      • Barretos, Brazil, 14784-400
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ana Suellen Carneiro
      • Goiânia, Brazil, 74605-070
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ruffo de Freitas Júnior
      • Natal, Brazil, 59075-740
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Andrea Juliana Pereira Santana Gomes
      • Porto Alegre, Brazil, 90020-090
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Katsuki Tiscoski
        • Contact:
        • Contact:
      • São Paulo, Brazil, 01246-000
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Maria Del Pilar Diz
      • Vitória, Brazil, 29043-260
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • GLAUCIO BERTOLLO
  • Canada
    • British Columbia
      • Vancouver, British Columbia, Canada, V5Z 4E6
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Yvette Drew
    • Ontario
      • Toronto, Ontario, Canada, M5G 2M9
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Stephanie Lheureux
    • Quebec
      • Montreal, Quebec, Canada, H4A 3J1
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Xing Zeng
      • Montreal, Quebec, Canada, H2X 0A9
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Principal Investigator:
          • Diane Provencher
        • Contact:
  • Denmark
      • Copenhagen, Denmark, 2100
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Kristoffer Rohrberg
        • Contact:
        • Contact:
      • Herlev, Denmark
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Rikke Eefsen
  • Finland
      • Helsinki, Finland, 00029
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Katriina Jalkanen
      • Tampere, Finland, 33520
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Annika Auranen
  • France
      • Lyon, France, 69373
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Isabelle Ray Coquard
      • Marseille, France, 13273
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Renaud Sabatier
        • Contact:
        • Contact:
      • Montpellier, France, 34298
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Diego Tosi
        • Contact:
        • Contact:
      • Pierre-Bénite, France, 69495
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Benoit YOU
        • Contact:
        • Contact:
      • Villejuif, France, 94805
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Yohann Loriot
        • Contact:
        • Contact:
  • Germany
      • Leipzig, Germany, 04103
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Gertraud Stocker
      • Mainz, Germany, 55131
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Alexander Desuki
      • München, Germany, 81377
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Lena Weiss
  • Greece
      • Athens, Greece, 11528
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Michalis Liontos
        • Contact:
        • Contact:
      • Athens, Greece, 12462
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Amanda Psyrri
      • Pylaia Thessaloniki, Greece, 570 01
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Sofia Baka
      • Thessaloniki, Greece, 55236
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Eleni Fountzila
  • Italy
      • Milan, Italy, 20141
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Giuseppe Curigliano
      • Naples, Italy, 80131
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Adriano Gravina
        • Contact:
        • Contact:
      • Roma, Italy, 00168
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Vanda Salutari
        • Contact:
        • Contact:
  • Japan
      • Chiba, Japan, 277-8577
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Shigehiro Koganemaru
      • Fukuoka, Japan, 811-1395
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Kazuya Ariyoshi
      • Tokyo, Japan, 104-0045
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Noboru Yamamoto
        • Contact:
        • Contact:
      • Tokyo, Japan, 135-8550
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Shigehisa Kitano
        • Contact:
        • Contact:
  • Mexico
      • DF, Mexico, 14080
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Fidel David Huitzil-Melendez
      • Monterrey, Mexico, 66260
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Raul Alejandro Andrade Moreno
  • Netherlands
      • Amsterdam, Netherlands, 1066 CX
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Tim Schutte
      • Amsterdam, Netherlands, 1081 HV
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Catharina W. Menke - van der Houven van Oordt
        • Contact:
        • Contact:
      • Rotterdam, Netherlands, 3015 GD
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Sander Bins
  • Norway
      • Oslo, Norway, 0379
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Kristina Lindemann
  • Panama
      • Panama City, Panama
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Omar Castillo-Fernandez
      • Punta Pacifica Panama City Panama, Panama
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ignacio Veliz
  • Poland
      • Bialystok, Poland, 15-027
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Beata Maćkowiak-Matejczyk
      • Józefów, Poland, 05-410
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Rafal Stec
      • Warsaw, Poland, 01-748
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Maciej Studziński
  • South Korea
      • Seoul, South Korea, 05505
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Jeong-Yeol Park
      • Seoul, South Korea, 135-710
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Yooyoung Lee
      • Seoul, South Korea, 120-752
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Jung-Yun Lee
  • Spain
      • A Coruña, Spain, 15006
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • María Quindos Varela
      • Barcelona, Spain, 08035
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Roberta Mazzeo
      • Barcelona, Spain, 08036
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Lydia Gaba
        • Contact:
        • Contact:
      • Barcelona, Spain, 08023
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Tatiana Hernandez
        • Contact:
        • Contact:
      • Madrid, Spain, 28041
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Luis Manso Sánchez
      • Madrid, Spain, 28050
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ramón Yarza
      • Madrid, Spain, 28033
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Raúl Márquez Vázquez
      • Málaga, Spain, 29010
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Javier García Corbacho
      • Valencia, Spain, 46009
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ignacio Romero Noguera
      • Zaragoza, Spain, 50009
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • EUGENIA ORTEGA
  • Sweden
      • Stockholm, Sweden, 17164
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Lisa Liu Burstrom
  • Turkey (Türkiye)
      • Ankara, Turkey (Türkiye), 06590
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Yuksel Urun
        • Contact:
        • Contact:
      • Ankara, Turkey (Türkiye), 6170
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ozturk Ates
      • Istanbul, Turkey (Türkiye), 34010
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Fatih Selcukbiricik
  • United Kingdom
      • Glasgow, United Kingdom, G12 0YN
        • Withdrawn
        • GSK Investigational Site
      • London, United Kingdom, NW1 2BU
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Michael Flynn
  • United States
    • California
      • La Jolla, California, United States, 92093
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Ramez Eskander
    • New York
      • Rochester, New York, United States, 55905-0001
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Grace Choong
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Angeles Secord
        • Contact:
        • Contact:
    • Ohio
      • Columbus, Ohio, United States, 43210
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • John Hays
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participants must be 18 years of age inclusive or older, at the time of signing the informed consent, or the legal age of consent in the jurisdiction in which the study is taking place.
  • Participant capable of giving signed informed consent including compliance with the requirements and restrictions listed in the Informed consent form (ICF) and in this protocol.

  • Participants with pathologically confirmed advanced solid tumor specific for study Module (key local diagnostic molecular and/or immunophenotyping testing results/tumor cell phenotype results for confirmed diagnosis should be provided) with no more than 4 lines of prior systemic therapies. Please note:

    1. Adjuvant +/- neoadjuvant considered one line of therapy
    2. Maintenance therapy will be considered as part of the preceding line of therapy (i.e., not counted independently)
    3. Unplanned addition or switching to a new drug in a different class is considered a separate line of therapy. If an agent in a regimen is switched to another agent in the same class due to toxicity or intolerance (e.g. hypersensitivity reaction) this is considered part of the same line (i.e. not counted independently).
  • Requirements for tumor tissue samples: Archival or fresh tumor tissue is required for retrospective central assessment of B7H4 expression by immunohistochemistry (IHC) and other biomarker analysis. The archival tumor tissue should be from the most recent procedure (ideally obtained after the last anti-cancer treatment). If an archival tissue is not available a new biopsy should be performed, and the newly obtained tissue provided.
  • Participants have at least one target lesion as assessed per RECIST 1.1. A target lesion is defined as a measurable lesion that has not undergone locoregional treatment such as irradiation or that has unequivocal progression following locoregional treatment, with the longest diameter of ≥ 10 millimeter (mm) at Baseline (for lymph node lesions, the short axis should be ≥ 15 mm).
  • Participants have a life expectancy of at least 12 weeks per investigator assessment based on disease burden and extent of supportive care needed.

Inclusion criteria of participants under arm Module 1 (Mo-Rez +Dostarlimab) Endometrial Cancer Part 1A:

a. Participants with histologically documented, advanced (metastatic and/or unresectable) or recurrent endometrial cancer who have failed in adequate standard treatments, do not have effective standard treatment or are intolerant to standard of care, and who are not candidates for further curative external radiotherapy or brachytherapy.

Inclusion criteria of participants under arm Module 1 (Mo-Rez +Dostarlimab) Endometrial Cancer Part 1B:

  1. Diagnosis of endometrial cancer with confirmed mismatch repair proficient (MMRp) or microsatellites stable (MSS) tumor status by local test.
  2. Participants who have progressed on or are intolerant to at least 1 line of standard prior systemic therapy (including neoadjuvant or adjuvant as prior line), and who are not candidates for curative external radiotherapy or brachytherapy. Maintenance therapy will be considered part of the preceding line of therapy (i.e, not counted independently).

Inclusion criteria of participants under arm Module 2 (Mo-Rez +/- Bevacizumab) Ovarian Cancer Part 2A:

a. Participants with histologically or cytologically confirmed advanced epithelial ovarian cancer/fallopian tube/peritoneal cancer (any epithelial histology - mucinous, clear cell, carcinosarcoma, high/low grade serous, endometrioid) who have failed in adequate standard treatments, do not have effective standard treatment or are intolerant to standard of care.

Inclusion criteria of participants under arm Module 2 (GSK5733584 +/- Bevacizumab) Ovarian Cancer Part 2B:

  1. Participants whose advanced ovarian cancer/fallopian tube/peritoneal cancer has relapsed more than 6 months from the last dose of platinum before enrollment, i.e., platinum sensitive.

  2. Participants who have progressed on or are intolerant to at least 1 line of standard prior lines of chemotherapy and are not candidates for second cytoreductive surgery.

    • Participants willing to use adequate contraception.

Female participants:

A female participant is eligible to participate if she is not pregnant or breastfeeding, and one of the following conditions applies:

  • Is a Woman of non-childbearing potential (WONCBP) OR
  • Is a Woman of childbearing potential (WOCBP) and using a contraceptive method that is highly effective.

  • A WOCBP must have a negative highly sensitive pregnancy test (urine or serum as required by local regulations) within 24 hours before the first dose of study intervention

    • Has an ECOG performance status of 0 to 1.
    • Participants with normal organ and bone marrow function.

Exclusion Criteria:

  • Has a second malignancy (except disease under study) that has progressed or required active treatment within the past 24 months except for basal cell or squamous cell carcinomas of the skin or in-situ carcinomas [e.g., breast, cervix, bladder] that have been resected with no evidence of metastatic disease.
  • Has had any major surgery within 28 days prior to enrolment.
  • Has any history of prior allogenic or autologous bone marrow transplant or other solid organ transplant.
  • Has known sensitivity to study intervention components, Mo-Rez (antibody-drug conjugate, antibody, free cytotoxin GSK5757810A) and combination partner, or its excipients or other allergy that, in the opinion of the investigator, contraindicates participation in the study.

  • Has any following cardiological examination abnormality:

    1. history in prior year of clinically significant or uncontrolled cardiac disease, acute myocardial infarction, NYHA Class III or IV congestive heart failure or clinically significant arrhythmia not controlled by standard of care therapy.
    2. Corrected QT Interval (QTcF) >450 millisecond (msec) or QTcF >480 msec for participants with bundle branch block
  • Has untreated brain or CNS metastases or brain/CNS metastases rapidly progressing requiring urgent medical intervention.
  • Any evidence of current interstitial lung disease (ILD) or pneumonitis or a prior history of ILD or non-infectious pneumonitis.
  • Has a history of autoimmune disease that has required systemic treatments in the 2 years prior to screening (i.e., with use of disease modifying agents, corticosteroids, or immunosuppressive drugs). Replacement therapy is not considered a form of systemic therapy (e.g., thyroid hormone for autoimmune thyroiditis or insulin is not exclusionary).
  • Clinically significant bleeding symptoms, significant bleeding tendency, or bleeding tumors within 1 month prior to the first dose of study treatment.
  • Serious or poorly controlled hypertension, including history of hypertensive crisis, hypertensive encephalopathy; adjustment of antihypertensive medications due to poor blood pressure control within 2 weeks prior to the first dose of study treatment;
  • Has any active renal condition (e.g., infection, requirement for dialysis, or any other active significant renal condition or dehydrated condition that could affect the participant's safety). Note: renal obstruction successfully managed by stenting is permitted.
  • Has any serious and/or unstable medical condition (such as clinical symptoms of intestinal obstruction) or psychiatric disorder or other condition(s) (including laboratory assessment abnormalities) that could interfere with the participant's safety, obtainment of informed consent, or compliance to the study procedures.
  • Participants with known history of Human immunodeficiency virus (HIV).

Exclusion criteria of participants under arm Module 1 (Mo-Rez +Dostarlimab) Endometrial Cancer:

  1. Has mesenchymal tumor of the uterus (uterine sarcoma).
  2. Has experienced symptomatic pericarditis of any etiology within 6 months of study treatment or any of the following with prior immunotherapy: any imAE ≥ Grade 3, immune-mediated severe neurologic events of any-grade (e.g., myasthenic syndrome/myasthenia gravis, encephalitis Guillain-Barré Syndrome, or transverse myelitis), exfoliative dermatitis of any grade (SJS, TEN, or DRESS syndrome), or myocarditis of any grade.

Exclusion criteria of participants under arm Module 2 (Mo-Rez +/-Bevacizumab) Ovarian Cancer:

  1. Participants with wound healing complications or incompletely healed wounds.
  2. Participants with history or evidence of gastrointestinal perforation, tracheoesophageal fistula, or any grade 4 fistula; participants with gastrointestinal fistula, visceral fistula, or abdominal abscess within 6 months prior to the first dose, participants with history of osteonecrosis of the jaw.
  3. Participants who have evidence of recto-sigmoid involvement by pelvic examination or bowel involvement on CT scan or clinical symptoms of bowel obstruction.
  4. Participants with congenital bleeding diathesis, acquired coagulopathy, recent pulmonary haemorrhage/ haemoptysis (> 2.5 mL of red blood or ½ teaspoon) within the last 3 months. Participants receiving treatment for thromboembolism are permitted as long as they have been on a stable dose of anticoagulation for at least 1 month.
  5. Participant has history of congestive heart failure (CHF) or baseline LVEF <50% or institutional lower limits of normal.

  6. Participant with history of nephrotic syndrome or grade 3 proteinuria. Participants has proteinuria as demonstrated by urine dipstick for proteinuria ≥2 (participants discovered to have ≥2 proteinuria on dipstick at baseline should undergo 24-hour urine collection and must demonstrate ≤1 g of protein in 24 hours to be eligible).

    • Has an Alanine transaminase (ALT) value >2.5x Upper Limit of Normal (ULN) and for participants with documented liver metastases/tumor infiltration has an ALT value >5x ULN.
    • Has a total bilirubin value >1.5x ULN.
    • Has documented presence of HBsAg and/or HBcAb, or HBsAb (except for presence of HBsAb attributable to previous vaccination) at screening or within 3 months prior to the first dose of study intervention.
    • Has a positive HCV antibody test result at screening or within 3 months prior to the first dose of study intervention.
    • Has received prior therapy with topoisomerase-1 inhibitors or ADC with topoisomerase-1 inhibitor warhead, or B7H4 targeted therapy.
    • Has received treatment with any cytotoxic chemotherapy drugs or other anti-tumor drugs (including endocrine therapy, molecular targeted therapy, immunotherapy, biotherapy, and investigational drug) within 30 days or 5 half-lives, whichever is shorter of a medicinal product prior to the first dose of study drug; or need to continue these drugs during the study.
    • Use of inhibitors of P-gp, breast cancer resistance protein (BCRP) or OATP1B1/1B3 within 7 days prior to the first dose of study drug. P-gp inducers should be discontinued for at least 14 days before the start of the study.
    • Have received locoregional radiation therapy within 2 weeks prior to the first dose of study drug; more than 30% of bone marrow irradiation or wide-field radiation therapy within 4 weeks prior to the first dose of study treatment.
    • Has serious infections within 4 weeks prior to the first dose, including but not limited to infectious complications, bacteremia, severe pneumonia treated with intravenous antibiotics for ≥2 weeks.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Module 1 (Mo-Rez +Dostarlimab) Endometrial Cancer
Drug: Dostarlimab
Dostarlimab will be administered IV.
Drug: Mo-Rez
Mo-Rez will be administered intravenously (IV).
Experimental: Module 2 (Mo-Rez +/-Bevacizumab) Ovarian Cancer
Drug: Bevacizumab
Bevacizumab will be administered IV.
Drug: Mo-Rez
Mo-Rez will be administered intravenously (IV).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part A: Percentage of participants with dose limiting toxicities (DLTs)
Time Frame: Approximately 7 months
Approximately 7 months
Part B: Confirmed Objective Response Rate (ORR)
Time Frame: Up to approximately 37 months
ORR is defined as the percentage of participants with a best overall confirmed (BOR) of Partial Response (PR) or better per Response Evaluation Criteria in Solid Tumors (RECIST 1.1)
Up to approximately 37 months
Part A: Number of participants with adverse events (AEs), immune-mediated adverse events (imAEs), adverse events of special interest (AESI), serious adverse events (SAEs) by Severity
Time Frame: Up to approximately 22 months
Up to approximately 22 months
Part A: Number of participants with adverse events (AEs), immune-mediated adverse events (imAEs), adverse events of special interest (AESI), serious adverse events (SAEs) by Frequency
Time Frame: Up to approximately 22 months
Up to approximately 22 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part B: Number of participants with adverse events (AEs), immune-mediated adverse events (imAEs), adverse events of special interest (AESI), serious adverse events (SAEs) by Frequency
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Part B: Number of participants with adverse events (AEs), immune-mediated adverse events (imAEs), adverse events of special interest (AESI), serious adverse events (SAEs) by Severity
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Duration of response (DoR)
Time Frame: Up to approximately 37 months
DoR is defined as the time from date of first documented evidence of PR or better to the date of disease progression or death due to any cause.
Up to approximately 37 months
Parts A and B: Progression-free survival (PFS)
Time Frame: Up to approximately 37 months
PFS is defined as time from the date of randomization (Part B) / first dose of study intervention (Part A or B if single arm) to the date of disease progression according to investigator assessment or death due to any cause, whichever occurs first.
Up to approximately 37 months
Part B: Overall Survival (OS)
Time Frame: Up to approximately 37 months
OS is defined as the time from randomization (or date of first dose if single arm) to the date of death due to any cause.
Up to approximately 37 months
Parts A and B: Number of participants with Anti-drug antibodies (ADA)
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Number of participants with neutralizing antibody (nAb)
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Number of Participants with Clinically Significant Changes in Vital Signs, Laboratory parameters, and Electrocardiogram (ECG)
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Part A: Confirmed Objective Response Rate (ORR)
Time Frame: Up to approximately 22 months
ORR is defined as the percentage of participants with a best overall confirmed (BOR) of Partial Response (PR) or better per Response Evaluation Criteria in Solid Tumors (RECIST 1.1)
Up to approximately 22 months
Part B: Proportion of participants with CA-125 response
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Maximum observed concentration (Cmax) of Mo-Rez
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Time to reach Cmax (tmax) of Mo-Rez
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Trough concentration (Ctrough) of Mo-Rez
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Area under the concentration-time curve (AUC) of Mo-Rez
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Titers of ADA to Mo-Rez
Time Frame: Up to approximately 37 months
Up to approximately 37 months
Parts A and B: Change from Baseline in Eastern Cooperative Oncology Group Performance Scale (ECOG PS) score
Time Frame: Baseline and up to approximately 37 months
ECOG PS is used for measuring how the disease impacts a participant's daily living abilities. The grades for the scale range from 0 (fully active) to 5 (dead), with increasing severity.
Baseline and up to approximately 37 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

GlaxoSmithKline

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 4, 2025

Primary Completion (Estimated)

June 21, 2027

Study Completion (Estimated)

October 10, 2028

Study Registration Dates

First Submitted

January 22, 2025

First Submitted That Met QC Criteria

January 22, 2025

First Posted (Actual)

January 28, 2025

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 19, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 223559
  • 2024-517147-31-00 (Ctis: CTIS)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Study Sponsor will assess requests from qualified researchers for anonymized individual patient-level data and related study documents. Data sharing is subject to certain criteria, conditions, and exceptions. For further information, refer to https://www.gsk-studyregister.com/gsk-patient-level-data-sharing-july2025.pdf

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 asset(s) with development terminated 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

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Tumours, Gynecological

Clinical Trials on Dostarlimab

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Montenegro

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe