Neoplasms, EndometrialPhase 3NCT07684599
A Study to Investigate Mocertatug Rezetecan as Maintenance Treatment for Participants With MMRp Endometrial Cancer (BEHOLD-Endometrial02)
A Phase 3 study testing Mocertatug rezetecan, Dostarlimab and Pembrolizumab in people with Neoplasms, Endometrial, run by GlaxoSmithKline at 12 sites in 3 countries.
Trial summary
The purpose of this study is to see how well mocertatug rezetecan (Mo-Rez) in combination with physician's choice of immunotherapy (dostarlimab or pembrolizumab) works as maintenance therapy in participants with advanced or recurrent endometrial cancer (EC) compared with the physician's choice of immunotherapy… Read more about this study
- Who is it for?
- Ages 18 years and older, women only
- Conditions the study is for
- Neoplasms, Endometrial
- What is being tested?
- Mocertatug rezetecan, Dostarlimab and Pembrolizumab
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 610 participants
- Where
- 12 sitesin 3 countries
- Study dates
- 24 Sep 2026to 18 Sep 2031
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- Women only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Is at least 18 years of age and the legal age of consent in the jurisdiction in which the study is taking place at the time of signing the Informed consent form (ICF).
- Has received 6 cycles of first-line therapy (i.e. induction therapy), consisting of platinum-based doublet chemotherapy (e.g., carboplatin/paclitaxel) with immune checkpoint inhibition as part of standard of care (either pembrolizumab or dostarlimab) or via trial Run-In (dostarlimab). Receipt of only 4 cycles of chemotherapy is permitted if chemotherapy was discontinued due to toxicity, provided that the participant received at least 12 weeks of immune checkpoint inhibitor therapy during the induction period.
- Is able to commence C1D1 of study treatment within 3 - 9 weeks of the final dose of first-line therapy.
- Is deemed suitable to continue with maintenance therapy with immune checkpoint inhibition (dostarlimab or pembrolizumab).
- Demonstrates no clinical or radiographic progression of disease per investigator after the final dose of induction therapy. Final dose is defined as the last day that either platinum chemotherapy, taxane chemotherapy or immune checkpoint inhibition was given within the last cycle of induction therapy
- Has histologically confirmed endometrial carcinoma including but not limited to endometrioid, serous, clear cell and endometrial carcinosarcoma. Mixed epithelial carcinomas are permitted.
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- Meets one of the following criteria:
- Has newly diagnosed stage III disease [2023 International Federation of Gynecology and Obstetrics (FIGO) staging] with measurable residual disease >1 cm after primary debulking surgery (incomplete cytoreduction).
- Has newly diagnosed stage III disease (2023 FIGO staging) that is not suitable for primary debulking surgery with measurable disease.
- Has newly diagnosed stage IV disease (2023 FIGO staging) and any residual disease status (measurable or non-measurable) following debulking surgery. Participants not suitable for primary debulking surgery are also permitted.
- Has recurrent disease and is naïve to systemic anticancer therapy and any disease status (measurable or non-measurable).
- Has recurrent disease after receiving prior neo-adjuvant/adjuvant systemic anticancer therapy and had a recurrence >12 months after last dose of neo-adjuvant/adjuvant treatment. Participants with any disease status (measurable or non-measurable) are permitted.
- Has a tumor demonstrating either Mismatch Repair proficient (MMRp) or Microsatellite stable (MSS).
- Has provided a Formalin fixed, paraffin embedded (FFPE) tumor tissue sample sufficient for the central assessment of B7 homolog 4 protein (B7-H4) expression and MMR (if local MMRp/MSS test result(s) not available), with the result of B7-H4 expression testing available prior to date of randomization.
- Is willing to use adequate contraception. Contraceptive use should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
- Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
Who cannot join
- Mesenchymal tumors of the uterus (uterine sarcomas) and neuroendocrine uterine cancer.
- Has a malignancy (except disease under study) that has progressed or required active treatment within 36 months prior to date of randomization except for basal cell or squamous cell carcinomas of the skin or in-situ carcinomas.
- Any evidence of current Interstitial lung disease (ILD) or pneumonitis or a prior history of ILD or non-infectious pneumonitis.
- Has experienced 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 (Stevens-Johnson syndrome [SJS], Toxic Epidermal Necrolysis [TEN], or Drug Reaction with Eosinophilia and Systemic Symptoms [DRESS] syndrome, or myocarditis of any grade.
- Has ongoing adverse reaction(s) from prior therapy that has(have) not recovered to ≤ Grade 1 or to the baseline status preceding prior therapy, excluding alopecia, hearing loss, vitiligo, endocrinopathy managed with replacement therapy, and Grade 2 neuropathy, or adverse reactions that the investigator, with the agreement of the sponsor, considers to be not clinically relevant for the tolerability of study intervention in the current clinical study.
- Has had any major surgery within 28 days prior to date of C1D1 or received focal radiotherapy within 21 days prior to date of C1D1.
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- Has received treatment with an investigational agent within 30 days prior to C1D1.
- Has received prior therapy with topoisomerase I inhibitors (e.g. irinotecan or topotecan) or Antibody-Drug Conjugate (ADC)with a topoisomerase I inhibitor warhead, B7-H4 targeted therapy, or immune checkpoint inhibitor.
- Has received treatment with inhibitors of P-glycoprotein (P-gp) or Breast cancer resistant protein (BCRP), or OATP1B1/1B3 transporterswithin 7 days prior to the date of C1D1. Inducers of P-gp should be discontinued for at least 14 days prior to the date of C1D1.
- Has received any transfusion of blood products (including platelets or red blood cells) or administration of colony-stimulating factors (including Granulocyte-Colony Stimulating Factor [G-CSF], Granulocyte-Macrophage Colony-Stimulating Factor [GM-CSF], or recombinant erythropoietin) within 14 days prior to C1D1.
- Has an Alanine aminotransferase (ALT) value >2.5 × Upper limit of normal (ULN) or for participants with documented liver metastases/tumor infiltration has an ALT value >5 × ULN.
- Has a total bilirubin value >1.5 × ULN.
- Has cirrhosis or current unstable liver or biliary disease per investigator assessment defined by the presence of ascites, encephalopathy, coagulopathy, hypoalbuminemia, esophageal/gastric varices, or persistent jaundice. Participants who exhibit these signs or symptoms as a result of the malignancy under investigation and whose conditions are deemed adequately controlled by the investigator may be eligible for inclusion.
- Has Corrected QT interval (QTc) >470 milliseconds (msec).
- Has a history of symptomatic pericarditis of any cause within 6 months prior to screening or evidence of cardiac abnormalities within 12 months prior to screening such as serious, uncontrolled cardiac arrhythmia or clinically significant ECG abnormalities.
- Has any active renal condition (e.g., infection, requirement for dialysis, or any other significant renal condition that could affect the participant's safety).
Trial locations and contacts
12 sites in 3 countries. Contact the study team or a site near you to ask about taking part.
12 sites in 3 countries
Japan9 sites, 9 recruiting
- Recruiting
GSK Investigational Site
Fukuoka, 812-8582
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Fukushima, 960-1295
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Hokkaido, 060-8648
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Ibaraki, 305-8576
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Miyagi, 980-8574
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Numakunai, 028-3695
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Osaka, 569-8686
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Saitama, 350-1298
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Tokyo, 135-8550
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
Canada2 sites, 2 recruiting
- Recruiting
GSK Investigational Site
Montreal, Quebec, H4A 0B1
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
- Recruiting
GSK Investigational Site
Toronto, Ontario, M5G 1X6
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
South Korea1 site, 1 recruiting
- Recruiting
GSK Investigational Site
Daegu, 700-712
US GSK Clinical Trials Call Center, 877-379-3718, GSKClinicalSupportHD@gsk.com
EU GSK Clinical Trials Call Centre, +44 (0) 20 8990 4466, GSKClinicalSupportHD@gsk.com
About this study
Official title: A Randomized, Open-label, Multicenter, Phase 3 Study to Investigate Mocertatug Rezetecan in Combination With Immune Checkpoint Inhibition for Maintenance Treatment of Participants With Mismatch Repair Proficient (MMRp) Endometrial Cancer
The purpose of this study is to see how well mocertatug rezetecan (Mo-Rez) in combination with physician's choice of immunotherapy (dostarlimab or pembrolizumab) works as maintenance therapy in participants with advanced or recurrent endometrial cancer (EC) compared with the physician's choice of immunotherapy (dostarlimab or pembrolizumab) alone, which represents the current standard of care. The study will also assess whether the drug combination is safe and tolerated well by participants compared to standard of care and will help us better understand its impact on Health-Related Quality of Life of participants.
- Conditions
- Neoplasms, Endometrial
- Being tested
- Mocertatug rezetecan, Dostarlimab, Pembrolizumab
- Keywords
- Mocertatug rezetecan, Mo-Rez, GSK5733584, Dostarlimab, Pembrolizumab, Endometrial Cancer, Antibody-Drug Conjugate, BEHOLD-Endometrial02
- Medical subject headings
- Endometrial Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Mocertatug rezetecanDrug
Mocertatug rezetecan will be administered
DostarlimabDrug
Dostarlimab will be administered
PembrolizumabDrug
Pembrolizumab will be administered
| Study group | Role | What they receive |
|---|---|---|
| Mocertatug rezetecan plus physician's choice of immunotherapy (dostarlimab or pembrolizumab) | Experimental | Participants will receive Mocertatug rezetecan along with physician's choice of immunotherapy (Dostarlimab or Pembrolizumab) Receives: Drug: Mocertatug rezetecan; Drug: Dostarlimab; Drug: Pembrolizumab |
| Physician's choice of immunotherapy (dostarlimab or pembrolizumab) | Active comparator | Participants will receive physician's choice of immunotherapy (Dostarlimab or Pembrolizumab alone) Receives: Drug: Dostarlimab; Drug: Pembrolizumab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Progression free survival (PFS) by BICR assessment
PFS is defined as the time from the date of randomization to the date of first documented Progressive Disease (PD) per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1) by Blinded independent central review (BICR) assessment or death from any cause, whichever occurs first
Measured: Up to approximately 143 weeks
Secondary outcomes (19)
Overall Survival (OS)
OS is defined as the time from the date of randomization to the date of death due to any cause
Measured: Up to approximately 260 weeks
PFS by investigator assessment
PFS is defined as the time from the date of randomization to the date of first documented PD per RECIST 1.1 by investigator assessment or death from any cause, whichever occurs first
Measured: Up to approximately 143 weeks
Objective response rate (ORR) by investigator assessment
ORR is defined as the percentage of participants with best overall response of either complete response (CR) or partial response (PR) per RECIST 1.1 by investigator assessment
Measured: Up to approximately 260 weeks
ORR by BICR assessment
ORR is defined as the percentage of participants with best overall response of either CR or PR per RECIST 1.1 by BICR assessment
Measured: Up to approximately 260 weeks
Duration of Response (DOR) by investigator assessment
DOR is defined as the time from the date of first documented objective response (CR or PR) to the date of first documented PD per RECIST 1.1 by investigator assessment or death from any cause, whichever comes first
Measured: Up to approximately 260 weeks
DOR by BICR assessment
DOR is defined as the time from the date of first documented objective response (CR or PR) to the date of first documented PD per RECIST 1.1 by BICR assessment or death from any cause, whichever comes first
Measured: Up to approximately 260 weeks
Progression Free Survival on subsequent line of therapy (PFS2)
PFS2 is defined as the time from the date of randomization to the date of first documented investigator-assessed clinical or radiographical progression following the first subsequent anticancer therapy and after the progression event used for PFS, or death from any cause, whichever occurs first
Measured: Up to approximately 260 weeks
Time to first subsequent therapy or death (TFST)
TFST is defined as the time from the date of randomization to the date of initiation of subsequent therapy or death from any cause, whichever occurs first
Measured: Up to approximately 260 weeks
Time to second subsequent therapy (TSST)
TSST is defined as the time from the date of randomization to the date of initiation of second subsequent therapy or death from any cause, whichever occurs first
Measured: Up to approximately 260 weeks
Serum pharmacokinetic (PK) concentration of Mo-Rez (conjugated antibody and payload)
Measured: Up to approximately 260 weeks
Number of participants with Antidrug antibody (ADA) or Neutralizing Antibody (NAb) against Mo-Rez
Measured: Up to approximately 260 weeks
Titers of ADA against Mo-Rez
Measured: Up to approximately 260 weeks
Number of participants with Treatment-emergent adverse event (TEAEs), Adverse event of special interest (AESIs), Immune-mediated adverse event (imAEs) and Treatment-emergent serious adverse event (TESAEs)
Measured: Up to approximately 260 weeks
Number of participants with TEAEs leading to dose modifications or study intervention discontinuation
Measured: Up to approximately 260 weeks
Number of participants with changes in vital signs, laboratory tests (hematology and clinical chemistry), and Electrocardiogram (ECG)
Measured: Up to approximately 260 weeks
Change from baseline in European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) score
The EORTC QLQ-C30 includes 30-item questionnaire for evaluating the health-related quality of life (HRQoL) of participants participating in cancer clinical studies. Participants responses on these items are averaged and then transformed to scores ranging from 0 to 100. For items related to function and global health status, a higher score indicates better functioning or a better overall state of health, while, for symptom-related items, a higher score denotes more severe symptoms.
Measured: Up to approximately 260 weeks
Change from baseline in EORTC QLQ- Endometrial Cancer Module (EN24) score
The EORTC QLQ-EN24 includes a 24-item questionnaire for evaluating endometrial cancer-specific symptoms and concerns in participants of cancer clinical studies. Participants responses are averaged and then transformed to a score ranging from 0 to 100. For functional and global health items, a higher score indicates better functioning or a better overall state of health, while for symptom items, a higher score indicates more severe symptoms.
Measured: Up to approximately 260 weeks
Time to deterioration (TTD) of EORTC QLQ-EN24
TTD is defined as the time from date of randomization to the first confirmed clinically meaningful deterioration on any of the domains of EORTC QLQ-EN24: lymphoedema, urological symptoms, gastrointestinal symptoms, and pain in back and pelvis
Measured: Up to approximately 260 weeks
TTD of EORTC QLQ-C30
TTD is defined as the time from date of randomization to the first confirmed clinically meaningful deterioration on any of the domains of EORTC QLQ-C30: physical functioning, role functioning, and Global Health Status (GHS) /Quality of Life (QoL)
Measured: Up to approximately 260 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Jul 2026
- Study start24 Sep 2026
- Primary completion23 Jul 2029 (estimated)
- Study completion18 Sep 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Neoplasms, EndometrialStudies of the same condition, open and under way.
- More trials run by GlaxoSmithKlineThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 610 participants (estimated)
Sponsor and investigators
- Lead sponsor
- GlaxoSmithKline
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- ENGOT, GOG, APGOT
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07684599
- Sponsor's protocol ID
- 224039
- Other IDs
- 2025-523363-37-00, ENGOT-en33, GOG-3130, APGOT-EN5, 2025
- Status last verified
- Oct 2026
- First submitted
- 29 Jun 2026
- Last updated
- 3 Nov 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: 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
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Randomized, Open-label, Multicenter, Phase 3 Study to Investigate Mocertatug Rezetecan in Combination With Immune Checkpoint Inhibition for Maintenance Treatment of Participants With Mismatch Repair Proficient (MMRp) Endometrial Cancer
- ClinicalTrials.gov ID
- NCT07684599
- Acronym / sponsor ID
- 224039
- Conditions
- Neoplasms, Endometrial
- Keywords
- Mocertatug rezetecan, Mo-Rez, GSK5733584, Dostarlimab, Pembrolizumab, Endometrial Cancer, Antibody-Drug Conjugate, BEHOLD-Endometrial02
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 610 participants (estimated)
- Lead sponsor
- GlaxoSmithKlineIndustry (pharma, biotech, devices)
- Collaborators
- ENGOT, GOG, APGOT
- Study start
- 24 Sep 2026 (actual)
- Primary completion
- 23 Jul 2029 (estimated)
- Study completion
- 18 Sep 2031 (estimated)
- First posted
- 6 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to see how well mocertatug rezetecan (Mo-Rez) in combination with physician's choice of immunotherapy (dostarlimab or pembrolizumab) works as maintenance therapy in participants with advanced or recurrent endometrial cancer (EC) compared with the physician's choice of immunotherapy (dostarlimab or pembrolizumab) alone, which represents the current standard of care. The study will also assess whether the drug combination is safe and tolerated well by participants compared to standard of care and will help us better understand its impact on Health-Related Quality of Life of participants.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Mocertatug rezetecan plus physician's choice of immunotherapy (dostarlimab or pembrolizumab) | Experimental | Drug: Mocertatug rezetecan, Drug: Dostarlimab, Drug: PembrolizumabParticipants will receive Mocertatug rezetecan along with physician's choice of immunotherapy (Dostarlimab or Pembrolizumab) |
| Physician's choice of immunotherapy (dostarlimab or pembrolizumab) | Active comparator | Drug: Dostarlimab, Drug: PembrolizumabParticipants will receive physician's choice of immunotherapy (Dostarlimab or Pembrolizumab alone) |
Who may qualify
- Ages
- 18 years and older
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (16 listed)
- Is at least 18 years of age and the legal age of consent in the jurisdiction in which the study is taking place at the time of signing the Informed consent form (ICF).
- Has received 6 cycles of first-line therapy (i.e. induction therapy), consisting of platinum-based doublet chemotherapy (e.g., carboplatin/paclitaxel) with immune checkpoint inhibition as part of standard of care (either pembrolizumab or dostarlimab) or via trial Run-In (dostarlimab). Receipt of only 4 cycles of chemotherapy is permitted if chemotherapy was discontinued due to toxicity, provided that the participant received at least 12 weeks of immune checkpoint inhibitor therapy during the induction period.
- Is able to commence C1D1 of study treatment within 3 - 9 weeks of the final dose of first-line therapy.
- Is deemed suitable to continue with maintenance therapy with immune checkpoint inhibition (dostarlimab or pembrolizumab).
- Demonstrates no clinical or radiographic progression of disease per investigator after the final dose of induction therapy. Final dose is defined as the last day that either platinum chemotherapy, taxane chemotherapy or immune checkpoint inhibition was given within the last cycle of induction therapy
Key exclusion criteria (16 listed)
- Mesenchymal tumors of the uterus (uterine sarcomas) and neuroendocrine uterine cancer.
- Has a malignancy (except disease under study) that has progressed or required active treatment within 36 months prior to date of randomization except for basal cell or squamous cell carcinomas of the skin or in-situ carcinomas.
- Any evidence of current Interstitial lung disease (ILD) or pneumonitis or a prior history of ILD or non-infectious pneumonitis.
- Has experienced 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 (Stevens-Johnson syndrome [SJS], Toxic Epidermal Necrolysis [TEN], or Drug Reaction with Eosinophilia and Systemic Symptoms [DRESS] syndrome, or myocarditis of any grade.
- Has ongoing adverse reaction(s) from prior therapy that has(have) not recovered to ≤ Grade 1 or to the baseline status preceding prior therapy, excluding alopecia, hearing loss, vitiligo, endocrinopathy managed with replacement therapy, and Grade 2 neuropathy, or adverse reactions that the investigator, with the agreement of the sponsor, considers to be not clinically relevant for the tolerability of study intervention in the current clinical study.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Mocertatug rezetecanMocertatug rezetecan will be administered | Drug | Mocertatug rezetecan plus physician's choice of immunotherapy (dostarlimab or pembrolizumab) |
| DostarlimabDostarlimab will be administered | Drug | Mocertatug rezetecan plus physician's choice of immunotherapy (dostarlimab or pembrolizumab), Physician's choice of immunotherapy (dostarlimab or pembrolizumab) |
| PembrolizumabPembrolizumab will be administered | Drug | Mocertatug rezetecan plus physician's choice of immunotherapy (dostarlimab or pembrolizumab), Physician's choice of immunotherapy (dostarlimab or pembrolizumab) |
Primary outcome
Progression free survival (PFS) by BICR assessment
Time frame: Up to approximately 143 weeks
PFS is defined as the time from the date of randomization to the date of first documented Progressive Disease (PD) per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1) by Blinded independent central review (BICR) assessment or death from any cause, whichever occurs first
19 secondary outcomes
Overall Survival (OS)
Time frame: Up to approximately 260 weeks
PFS by investigator assessment
Time frame: Up to approximately 143 weeks
Objective response rate (ORR) by investigator assessment
Time frame: Up to approximately 260 weeks
ORR by BICR assessment
Time frame: Up to approximately 260 weeks
Duration of Response (DOR) by investigator assessment
Time frame: Up to approximately 260 weeks
DOR by BICR assessment
Time frame: Up to approximately 260 weeks
Progression Free Survival on subsequent line of therapy (PFS2)
Time frame: Up to approximately 260 weeks
Time to first subsequent therapy or death (TFST)
Time frame: Up to approximately 260 weeks
Time to second subsequent therapy (TSST)
Time frame: Up to approximately 260 weeks
Serum pharmacokinetic (PK) concentration of Mo-Rez (conjugated antibody and payload)
Time frame: Up to approximately 260 weeks
Number of participants with Antidrug antibody (ADA) or Neutralizing Antibody (NAb) against Mo-Rez
Time frame: Up to approximately 260 weeks
Titers of ADA against Mo-Rez
Time frame: Up to approximately 260 weeks
Number of participants with Treatment-emergent adverse event (TEAEs), Adverse event of special interest (AESIs), Immune-mediated adverse event (imAEs) and Treatment-emergent serious adverse event (TESAEs)
Time frame: Up to approximately 260 weeks
Number of participants with TEAEs leading to dose modifications or study intervention discontinuation
Time frame: Up to approximately 260 weeks
Number of participants with changes in vital signs, laboratory tests (hematology and clinical chemistry), and Electrocardiogram (ECG)
Time frame: Up to approximately 260 weeks
Change from baseline in European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) score
Time frame: Up to approximately 260 weeks
Change from baseline in EORTC QLQ- Endometrial Cancer Module (EN24) score
Time frame: Up to approximately 260 weeks
Time to deterioration (TTD) of EORTC QLQ-EN24
Time frame: Up to approximately 260 weeks
TTD of EORTC QLQ-C30
Time frame: Up to approximately 260 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Nov 2026.
- Individual participant dataSharing planned: Yes. 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
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
12 sites in 3 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Mocertatug rezetecan, Dostarlimab and Pembrolizumab in people with Neoplasms, Endometrial, run by GlaxoSmithKline at 12 sites in 3 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 16 inclusion and 16 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 12 sites in Japan, Canada, South Korea. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact US GSK Clinical Trials Call Center (877-379-3718, GSKClinicalSupportHD@gsk.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Progression free survival (PFS) by BICR assessment (time frame: Up to approximately 143 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Nov 2026.