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RecruitingNCT07286331Updated Nov 3, 2026

A Study to Investigate Mocertatug Rezetecan Compared With Chemotherapy in Participants With Endometrial Cancer After Platinum-based Chemotherapy and Immunotherapy (BEHOLD-Endometrial01)

A Phase 3 interventional study of Mocertatug rezetecan and Paclitaxel in Neoplasms, Endometrial, sponsored by GlaxoSmithKline. Recruiting at 56 sites in 10 countries. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-03.

Sponsored by GlaxoSmithKline · Phase 3, Interventional, and Treatment

From the registry’s dates

  • Started Jun 2026; still recruiting 5 months later.
Updated Nov 3, 2026First sites in 4 new countries28 sites addedGo to Updates ↓
Phase
Phase 3
Study type
Interventional
Enrollment
600
Allocation
Randomized
Ages
18 Years and older
Sex
Female
01

Study summary

This study specifically aims to evaluate how well mocertatug rezetecan (Mo-Rez) works in treating Endometrial Cancer (EC) compared to standard of care. The study also assesses whether Mo-Rez is safe and tolerated well by participants in comparison to standard of care and will help provide a better understanding of the main side effects of the drugs.

02

Conditions studied

  • Neoplasms, Endometrial

Keywords

  • Endometrial Cancer
  • Mocertatug rezetecan
  • Mo-Rez
  • GSK5733584
  • Paclitaxel
  • Doxorubicin
  • Antibody-drug conjugate
  • BEHOLD-Endometrial01
03

In context

Endometrial Neoplasms

1,425 studies on the registry are indexed under Endometrial Neoplasms; 473 are open to participants now.

This study's planned enrollment of 600 is above the median of 71 across 1,026 interventional studies indexed under Endometrial Neoplasms.

Browse Endometrial Neoplasms studies →

Lead sponsor

GlaxoSmithKline is the lead sponsor of 3,650 studies on the registry; 118 are open to participants now.

Of its 264 completed or terminated interventional studies of FDA-regulated products, 241 (91%) have results posted.

Browse GlaxoSmithKline studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
Female
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

Participants are eligible to be included in the study only if all of the following criteria apply:

  • 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 form (ICF).
  • Has confirmed endometrial carcinoma including but not limited to endometroid, serous, clear cell, and endometrial carcinosarcoma. Mixed epithelial carcinomas are permitted.

  • Has undergone at least 1 and no more than 2 lines of prior systemic treatment for EC. Up to 3 lines of prior systemic treatment are acceptable if one line was administered in the /neo-adjuvant setting. The definition of is as follows:

    • Adjuvant ± neo-adjuvant therapy counts as one line of treatment.
    • Maintenance therapy is considered part of the preceding line and does not count as an independent line.
    • Switching to another agent within the same class due to toxicity (without disease progression) is considered part of the same line of therapy.
    • Unplanned addition or switching to a new anti-cancer therapy in a different class is considered a separate line of therapy.
    • Hormonal therapy is NOT counted as a separate line.
  • Must have progressed on or after prior platinum-based chemotherapy and have received anti- Programmed cell death 1 () /anti- Programmed cell death ligand 1 (PD-L1) therapy, either separately or in combination. Participants deemed unsuitable for a prior PD-1/PD-L1 inhibitor therapy ( such as immunodeficiency, disease that required systemic treatment) as determined by the investigator or treating physician are eligible.

  • Participants must have a platinum-free interval of less than 12 months if they previously received platinum-based therapy solely in the adjuvant setting. The platinum-free interval is defined as the date of the last dose of platinum-based chemotherapy to the date of disease progression.

    • If PD-L1/PD-1 inhibitor therapy was administered with platinum-based treatment, participant is eligible regardless of whether the Platinum-free interval (PFI) exceeds 12 months.
    • Participants with disease who underwent treatment including gynecological surgery followed by a platinum-based regimen, or those deemed intolerant to platinum-based therapy, are eligible regardless of whether the PFI exceeds 12 months.
  • Has provided a Formalin-fixed, paraffin-embedded (FFPE) tumor tissue sample sufficient for the central assessment of B7 homolog 4 protein (B7-H4) expression, with the result of B7-H4 expression testing available prior to date of randomization.
  • Has ≥1 Target Lesion per 1.1 by BICR eligibility review of screening scans.
  • Is willing to use adequate . Contraceptive use should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

  • A female participant is eligible to participate if she is not pregnant or breastfeeding, and 1 of the following conditions applies:

    • Is a Participant of non- (PONCBP) OR
    • Is a Participant of childbearing potential (POCBP) and using a contraceptive method that is highly effective (with a failure rate of \<1% per year), with low user dependency, 30 days prior to Cycle 1 Day 1 (C1D1) and during the study intervention period and for at least 8 months after the last dose of study intervention and agrees not to donate eggs (ova, oocytes) for the purpose of reproduction during this period. The investigator should evaluate the potential for contraceptive method failure (e.g., noncompliance, recently initiated) in relationship to the first dose of study intervention.

  • A POCBP 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

    • If a urine test cannot be confirmed as negative (e.g., an ambiguous result), a serum pregnancy test is required. In such cases, the participant must be excluded from participation if the serum pregnancy result is positive.
    • Additional requirements for pregnancy testing during and after study intervention are described in protocol.
    • The investigator is responsible for review of medical history, menstrual history, and recent sexual activity to decrease the risk for inclusion of a participant with an early undetected pregnancy.
  • Is capable of giving signed informed consent including compliance with the requirements and restrictions listed in the ICF and in the protocol.
  • Has an (ECOG) performance status of 0 or 1.
  • Has adequate organ function.

Exclusion criteria

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

  • Mesenchymal tumors of the uterus (uterine sarcomas) and neuroendocrine uterine cancer.
  • Has a (except disease under study) that has progressed or required active treatment within the past 36 months prior to date of randomization 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 disease, or that is otherwise considered cured by the investigator.
  • Has any history of prior allogenic or bone marrow transplant or other solid organ transplant.
  • Has known sensitivity to study intervention components or or other allergy that, in the opinion of the investigator or medical monitor, contraindicates participation in the study.
  • Has untreated brain or Central nervous system (CNS) metastases or brain/ that have progressed (e.g., evidence of new or enlarging brain metastasis or new neurologic symptoms attributable to brain/CNS metastases). Participants with previously treated and clinically stable brain/CNS metastases and who have completed all therapy for ≥14 days before date of C1D1 are not excluded from participation.
  • Has any evidence of current Interstitial lung disease (ILD) or pneumonitis or a prior history of ILD or non-infectious pneumonitis.
  • 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 and endocrinopathy managed with replacement therapy, or that the investigator, with the agreement of the sponsor, considers to be stable or not for the tolerability of study intervention in the current clinical study.
  • Has any serious and/or unstable medical condition (including infection) or any serious and/or unstable psychiatric disorder or other condition(s) (including laboratory assessment abnormalities) that could interfere with the participant's safety, obtainment of , or compliance to the study procedures.
  • Has had any major surgery within 28 days prior to date of C1D1 or history of local radiotherapy within 21 days prior to C1D1.
  • Has received treatment with an agent within 30 days prior to C1D1.
  • Has received prior therapy with Topo1i (e.g. irinotecan or topotecan) or ADC with a Topo1i payload, or B7-H4 targeted therapy.
  • Has received treatment with any cytotoxic chemotherapy drugs or other antitumor drugs (including endocrine therapy, molecular targeted therapy, immunotherapy, biotherapy and investigational drug) within 30 days or 5 half-lives, whichever is shorter, prior to C1D1; or need to continue these drugs during the study.
  • Has received any within 30 days prior to C1D1.Note: mRNA and adenoviral-based Coronavirus disease 2019 (COVID-19) vaccines are considered non-live.
  • Has received treatment with inhibitors of P-glycoprotein (P-gp), Breast cancer resistant protein (BCRP), or OATP1B1/1B3 transporters within 7 days prior to first dose of study drug. P-gp inducers should be discontinued for at least 14 days before the start of the study drug.
  • Has received any transfusion of blood products (including 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 a known (HIV) infection AND meets at least 1 of the following criteria:

    • Has documented evidence of plasma HIV-1 Ribonucleic acid (RNA) ≥50 c/mL within 3 months prior to or at screening. In the 3 to 12 months prior to screening, plasma HIV1 RNA levels consistently \<50 c/mL are required for enrollment; if multiple instances of plasma HIV-1 RNA values ≥50 c/mL occurred in the 3 to 12 months prior to screening, the participant is not eligible for enrollment unless, per the investigator's assessment, the elevations were neither persistent nor associated with antiretroviral resistance; OR
    • Has not had Cluster of differentiation (CD)4 cell counts measured in the past 12 months (i.e., at least 2 separate measurements taken a minimum of 28 days apart, 1 of which must be conducted at screening); OR
    • Has had any values ≤350 cells/mm3 in the past 12 months. OR
    • Has had 1 or more changes in their combination antiretroviral therapy regimen or has received an antiretroviral therapy regimen that is inconsistent with locally recommended guidelines during the 3 months prior to screening; OR
    • Has a history of HIV-associated non-Hodgkin lymphoma within 5 years prior to screening or a history of HIV-associated invasive cervical cancer; OR
    • Has received treatment with an HIV1 immunotherapeutic vaccine within 90 days prior to screening.
  • Has an (ALT) value >2.5× (ULN) and/or for participants documented liver metastases/tumor infiltration has an ALT value >5x ULN
  • Has a total value >1.5x 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.

  • Has documented presence of surface antigen (HBsAg) and/or Hepatitis B core antibody (HBcAb) at screening unless they meet both the following criteria:

    • Participants with chronic Hepatitis B virus (HBV) infection (HBsAg+) or positive HBcAb are required to be receiving effective antiviral therapy (i.e., with nucleos(t)ide analogs [Tenofovir or Entecavir]) for at least 14 days prior to C1D1 and are willing to continue for at least 6 months after treatment discontinuation or longer at the discretion of the treating hepatologist.
    • HBV Deoxyribonucleic acid (DNA) must be adequately suppressed, as per institutional or local guidelines, prior to initiation of study intervention.
  • Has a positive virus (HCV) antibody test result at screening or within 3 months prior to C1D1 unless HCV RNA is negative, indicating past resolved HCV infection, including participants who have undergone curative treatment.
  • Has a positive HCV RNA test result at screening or within 3 months prior to C1D1.
  • Has >470 milliseconds (msec)
  • Has a history within 12 months prior to screening of clinically significant or uncontrolled cardiac disease, acute myocardial infarction, Class III or IV congestive heart failure [NYHA 1994], or clinically significant arrhythmia not controlled by standard of care therapy.
  • Has (LVEF) \<50% or less than institutional lower limit of normal.
  • Has any active renal condition (e.g., infection, requirement for dialysis, or any other significant renal condition that could affect the participant's safety).
Terms in these criteria, in plain language(31)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Histologically or cytologically confirmed

The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).

Your pathology report is the document that shows this.

Adjuvant and neoadjuvant

Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.

Line of therapy

A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.

“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.

PD-1, PD-L1 and checkpoint inhibitors

PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.

PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.

Contraindication

A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.

Autoimmune disease

A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.

Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.

Metastases

Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.

RECIST

The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.

“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

ECOG performance status

A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.

0
Fully active, no restrictions.
1
Limited in strenuous activity, but walking and able to do light work, such as housework or office work.
2
Walking and able to look after yourself, but unable to work; up and about more than half of waking hours.
3
Able to look after yourself only in part; in bed or a chair more than half of waking hours.
4
Unable to look after yourself at all; in bed or a chair all day.

Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.

Cancer (malignancy)

Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.

Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.

Allogeneic and autologous transplant

Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.

Excipients

The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.

Brain metastases

Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).

Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Live vaccines

Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.

Platelets

Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.

HIV

The human immunodeficiency virus, which weakens the immune system.

Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.

CD4 count

The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

ULN (upper limit of normal)

The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.

“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.

Bilirubin

A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.

Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.

Hepatitis B tests

Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.

Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.

Hepatitis C tests

Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.

After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.

QT and QTc

On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.

The study may name a correction formula and a limit in milliseconds, often around 450–480.

NYHA class (heart failure)

The New York Heart Association’s four classes of how much heart failure limits physical activity.

I
No limits: ordinary activity causes no undue tiredness or breathlessness.
II
Slight limits: comfortable at rest, ordinary activity causes symptoms.
III
Marked limits: comfortable at rest, less than ordinary activity causes symptoms.
IV
Symptoms even at rest; any activity makes them worse.

Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.

LVEF (left ventricular ejection fraction)

The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.

05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Single (Outcomes assessor)
Enrollment
600 participants (estimated)

Study arms

  • Experimental
    Mocertatug rezetecan

    Participants will receive Mocertatug rezetecan

    Drug: Mocertatug rezetecan

  • Active comparator
    Standard of Care

    Participants will receive standard of care treatment (Paclitaxel or Doxorubicin) as per investigator's discretion

    Drug: Paclitaxel · Drug: Doxorubicin

Interventions

06

What researchers measure

Primary outcomes

  1. Objective response rate (ORR) by BICR

    ORR is defined as the percentage of participants with best overall confirmed response of either complete response (CR) or partial response (PR) per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1) by Blinded independent central review (BICR)

    Time frame: Up to approximately 97 weeks

  2. Progression Free Survival (PFS) by BICR

    PFS is defined as the time from the date of randomization to the date of first documented Progressive Disease (PD) or death from any cause, whichever occurs first per RECIST 1.1 by BICR assessment

    Time frame: Up to approximately 97 weeks

Secondary outcomes

  1. Overall Survival (OS)

    OS is defined as the time from the date of randomization to the date of death due to any cause

    Time frame: Up to approximately 156 weeks

  2. ORR by investigator assessment

    ORR is defined as the percentage of participants with best overall confirmed response of either CR or PR per RECIST 1.1 by investigator assessment

    Time frame: Up to approximately 156 weeks

  3. Duration of Response (DOR) by BICR

    DOR is defined as the time from the date of the first documented objective response (CR or PR) that is subsequently confirmed to the date of first documented PD or death due to any cause, whichever occurs first per RECIST 1.1 by BICR assessment

    Time frame: Up to approximately 156 weeks

  4. DOR by investigator assessment

    DOR is defined as the time from the date of first documented objective response (CR or PR) that is subsequently confirmed to the date of first documented PD or death due to any cause, whichever occurs first per RECIST 1.1 by investigator assessment

    Time frame: Up to approximately 156 weeks

  5. PFS by investigator assessment

    PFS is defined as the time from the date of randomization to the date of first documented PD or death due to any cause, whichever occurs first per RECIST 1.1 by investigator assessment

    Time frame: Up to approximately 156 weeks

  6. Number of participants with Treatment-emergent adverse event (TEAEs), Adverse event of special interest (AESIs) and Treatment-emergent serious adverse event (TESAEs)

    Time frame: Up to approximately 156 weeks

  7. Number of participants with TEAEs/AESIs/TESAEs leading to dose modifications or study intervention discontinuation

    Time frame: Up to approximately 156 weeks

  8. Number of participants with changes in vital signs, laboratory tests (hematology and clinical chemistry), and Electrocardiogram (ECG)

    Time frame: Up to approximately 156 weeks

  9. 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 endometrial cancer participants. These include functional scales, symptom scales, global health status scale, and single item scales. Scores are averaged and transformed to 0 to 100. Higher scores indicate greater functioning, better global health status, or more severe symptoms

    Time frame: Up to approximately 156 weeks

  10. Change from baseline in European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Endometrial Cancer Module 24 (EORTC QLQ-EN24)

    The EORTC QLQ-EN24 is a 24-item questionnaire designed as a supplement to the EORTC QLQ-C30 for evaluating quality of life of endometrial cancer participants. Scores are averaged and transformed to a 0 to 100 scale. Higher scores indicate more severe symptoms.

    Time frame: Up to approximately 156 weeks

  11. Time to deterioration (TTD) of EORTC QLQ-EN24

    TTD is defined as the time from date of randomization to the date of first confirmed clinically meaningful deterioration on any of the following domains: lymphedema, urological symptoms, gastrointestinal symptoms, and pain in back and pelvis domains

    Time frame: Up to approximately 156 weeks

  12. TTD of EORTC QLQ-C30

    TTD is defined as the time from date of randomization to the date of first confirmed clinically meaningful deterioration on any of the following domains: Physical Functioning, Role Functioning, and Global Health Status/QoL

    Time frame: Up to approximately 156 weeks

  13. Number of participants with severity and/or interference of symptomatic AEs as assessed by patient-reported outcome Common Terminology Criteria for Adverse Events (PRO-CTCAE)

    The PRO-CTCAE is a patient-reported outcome measure developed to evaluate symptomatic toxicities in participants in cancer clinical trials. The PRO-CTCAE includes an item library of 124 items representing 78 symptomatic toxicities drawn from the CTCAE.

    Time frame: Up to approximately 156 weeks

  14. Serum concentration of Mo-Rez (conjugated antibody and free payload)

    Time frame: Up to approximately 156 weeks

  15. Number of participants with Antidrug antibody (ADA) and Neutralizing Antibody (NAb) against Mo-Rez

    Time frame: Up to approximately 156 weeks

  16. Titers of ADA against Mo-Rez

    Time frame: Up to approximately 156 weeks

07

Study locations

56 of 56 sites recruiting
  • GSK Investigational Site
    Birmingham, Alabama 35226, United States
    Recruiting
  • GSK Investigational Site
    Omaha, Nebraska 68114-4108, United States
    Recruiting
  • GSK Investigational Site
    Sugar Land, Texas 77479-4308, United States
    Recruiting
  • GSK Investigational Site
    Charlottesville, Virginia 22908, United States
    Recruiting
  • GSK Investigational Site
    Florida, Buenos Aires B1602DQB, Argentina
    Recruiting
  • GSK Investigational Site
    Mendoza, MD 5500, Argentina
    Recruiting
  • GSK Investigational Site
    Buenos Aires, Argentina
    Recruiting
  • GSK Investigational Site
    Ciudad Autonoma de Buenos Aire, C1012AAR, Argentina
    Recruiting
  • GSK Investigational Site
    Ciudad Autonoma de Buenos Aire, C1426AGE, Argentina
    Recruiting
  • GSK Investigational Site
    Córdoba, 5000, Argentina
    Recruiting
  • GSK Investigational Site
    Rosario, S2000ORE, Argentina
    Recruiting
  • GSK Investigational Site
    Dubbo, New South Wales 2830, Australia
    Recruiting
  • GSK Investigational Site
    Auchenflower, Queensland 4066, Australia
    Recruiting
  • GSK Investigational Site
    Herston, Queensland 4006, Australia
    Recruiting
  • GSK Investigational Site
    São Luís, Maranhão 65060-645, Brazil
    Recruiting
  • GSK Investigational Site
    CuritibaPR, 80810-050, Brazil
    Recruiting
  • GSK Investigational Site
    Porto Alegre, 90035-000, Brazil
    Recruiting
  • GSK Investigational Site
    São Paulo, 01323-900, Brazil
    Recruiting
  • GSK Investigational Site
    São Paulo, 04537-080, Brazil
    Recruiting
  • GSK Investigational Site
    Vitória, 29043-260, Brazil
    Recruiting
  • GSK Investigational Site
    Toronto, Ontario M5G 1X6, Canada
    Recruiting
  • GSK Investigational Site
    Montreal, Quebec H2X 0C1, Canada
    Recruiting
  • GSK Investigational Site
    Montreal, Quebec H4A 3J1, Canada
    Recruiting
  • GSK Investigational Site
    Haifa, 31999, Israel
    Recruiting
  • GSK Investigational Site
    Haifa, 3436212, Israel
    Recruiting
  • GSK Investigational Site
    Kfar Saba, 44281, Israel
    Recruiting
  • GSK Investigational Site
    Aichi, 466-8560, Japan
    Recruiting
  • GSK Investigational Site
    Fukuoka, 830-0011, Japan
    Recruiting
  • GSK Investigational Site
    Hokkaido, 060-8648, Japan
    Recruiting
  • GSK Investigational Site
    Hyōgo, 673-8558, Japan
    Recruiting
  • GSK Investigational Site
    Kanagawa, 216-8511, Japan
    Recruiting
  • GSK Investigational Site
    Kanagawa, 241-8515, Japan
    Recruiting
  • GSK Investigational Site
    Kyoto, 612-8555, Japan
    Recruiting
  • GSK Investigational Site
    Mie, 514-8507, Japan
    Recruiting
  • GSK Investigational Site
    Numakunai, 028-3695, Japan
    Recruiting
  • GSK Investigational Site
    Okayama, 700-8558, Japan
    Recruiting
  • GSK Investigational Site
    Okinawa, 901-2725, Japan
    Recruiting
  • GSK Investigational Site
    Osaka, 565-0871, Japan
    Recruiting
  • GSK Investigational Site
    Saitama, 350-1298, Japan
    Recruiting
  • GSK Investigational Site
    Shizuoka, 411-8777, Japan
    Recruiting
  • GSK Investigational Site
    Tokyo, 135-8550, Japan
    Recruiting
  • GSK Investigational Site
    Tokyo, 160-8582, Japan
    Recruiting
  • GSK Investigational Site
    Panama City, Panama
    Recruiting
  • GSK Investigational Site
    Panama City, Panama
    Recruiting
  • GSK Investigational Site
    Panama City, Panama
    Recruiting
  • GSK Investigational Site
    Cheongju Chungcheongbuk-do, 28644, South Korea
    Recruiting
  • GSK Investigational Site
    Daegu, 41404, South Korea
    Recruiting
  • GSK Investigational Site
    Seongnam-si Gyeonggi-do, 13620, South Korea
    Recruiting
  • GSK Investigational Site
    Seoul, 03080, South Korea
    Recruiting
  • GSK Investigational Site
    Seoul, 03722, South Korea
    Recruiting
  • GSK Investigational Site
    Seoul, 05505, South Korea
    Recruiting
  • GSK Investigational Site
    Seoul, 06351, South Korea
    Recruiting
  • GSK Investigational Site
    Sutton, Surrey SM2 5PT, United Kingdom
    Recruiting
  • GSK Investigational Site
    Leicester, LE1 5WW, United Kingdom
    Recruiting
  • GSK Investigational Site
    London, NW1 2PG, United Kingdom
    Recruiting
  • GSK Investigational Site
    London, SW3 6JJ, United Kingdom
    Recruiting
08

References and documents

Individual participant data

Plan to share: 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

Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report

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.

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.

Data sharing details ↗ · www.gsk-studyregister.com

No publications or documents are linked to this record.

09

Timeline

2 registry updates since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Started Jun 2026 (actual). Primary completion is estimated for Feb 2028, 20 months after the start.

Of 44 phase 3 interventional studies under Endometrial Neoplasms, half reached primary completion within 53 months of starting (the median), counting those still running; a quarter within 45 and three quarters within 126. This study's planned 20 months is below that.

How these figures are worked out, and which studies are left out of them.

Registered
Dec 12, 2025
First posted
Dec 16, 2025
StartActual
Jun 4, 2026
Primary completionEst.
Feb 29, 2028
CompletionEst.
May 30, 2029
Last update
Nov 3, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
Sites
28 sites added — first sites in Israel, South Korea, United Kingdom and United States
Show 28 added (7 South Korea, 5 Brazil, 4 United States, 4 United Kingdom, 3 Israel, 3 Japan, 2 Argentina)
  • GSK Investigational Site · Birmingham, United States
  • GSK Investigational Site · Omaha, United States
  • GSK Investigational Site · Florida, Argentina
  • GSK Investigational Site · São Luís, Brazil
  • GSK Investigational Site · CuritibaPR, Brazil
  • GSK Investigational Site · Porto Alegre, Brazil
  • GSK Investigational Site · São Paulo, Brazil
  • GSK Investigational Site · Vitória, Brazil
  • GSK Investigational Site · Kfar Saba, Israel
  • GSK Investigational Site · Aichi, Japan
  • GSK Investigational Site · Fukuoka, Japan
  • GSK Investigational Site · Shizuoka, Japan
  • GSK Investigational Site · Cheongju Chungcheongbuk-do, South Korea
  • GSK Investigational Site · Daegu, South Korea
  • GSK Investigational Site · Seoul, South Korea
  • GSK Investigational Site · Seoul, South Korea
  • GSK Investigational Site · Seoul, South Korea
  • GSK Investigational Site · Sutton, United Kingdom
  • GSK Investigational Site · Leicester, United Kingdom
  • GSK Investigational Site · London, United Kingdom
  • GSK Investigational Site · Sugar Land, United States
  • GSK Investigational Site · Charlottesville, United States
  • GSK Investigational Site · Córdoba, Argentina
  • GSK Investigational Site · Haifa, Israel
  • GSK Investigational Site · Haifa, Israel
  • GSK Investigational Site · Seongnam-si Gyeonggi-do, South Korea
  • GSK Investigational Site · Seoul, South Korea
  • GSK Investigational Site · London, United Kingdom
across 2 updates, Oct 2, 2026 – Nov 3, 2026
Site contacts
Changed at 3 sites. See the sites
Show 3 sites
  • GSK Investigational Site · São Paulo, BrazilContact person changed (no phone or email listed)
  • GSK Investigational Site · Seoul, South KoreaContact person changed (no phone or email listed)
  • GSK Investigational Site · London, United KingdomContact person changed (no phone or email listed)
across 2 updates, Oct 2, 2026 – Nov 3, 2026
Show all 2 updates
  1. Nov 3, 2026
    8 sites added
    Show 8 added (2 United States, 2 Israel, 2 South Korea, 1 Argentina, 1 United Kingdom)
    • GSK Investigational Site · Sugar Land, United States
    • GSK Investigational Site · Charlottesville, United States
    • GSK Investigational Site · Córdoba, Argentina
    • GSK Investigational Site · Haifa, Israel
    • GSK Investigational Site · Haifa, Israel
    • GSK Investigational Site · Seongnam-si Gyeonggi-do, South Korea
    • GSK Investigational Site · Seoul, South Korea
    • GSK Investigational Site · London, United Kingdom
    Site contacts Changed at 3 sites. See the sites
    Show 3 sites
    • GSK Investigational Site · São Paulo, BrazilContact person changed (no phone or email listed)
    • GSK Investigational Site · Seoul, South KoreaContact person changed (no phone or email listed)
    • GSK Investigational Site · London, United KingdomContact person changed (no phone or email listed)
    + 1 other change: verification date
  2. Oct 2, 2026
    20 sites added — first sites in Israel, South Korea, United Kingdom and United States
    Show 20 added (5 Brazil, 5 South Korea, 3 Japan, 3 United Kingdom, 2 United States, 1 Argentina, 1 Israel)
    • GSK Investigational Site · Birmingham, United States
    • GSK Investigational Site · Omaha, United States
    • GSK Investigational Site · Florida, Argentina
    • GSK Investigational Site · São Luís, Brazil
    • GSK Investigational Site · CuritibaPR, Brazil
    • GSK Investigational Site · Porto Alegre, Brazil
    • GSK Investigational Site · São Paulo, Brazil
    • GSK Investigational Site · Vitória, Brazil
    • GSK Investigational Site · Kfar Saba, Israel
    • GSK Investigational Site · Aichi, Japan
    • GSK Investigational Site · Fukuoka, Japan
    • GSK Investigational Site · Shizuoka, Japan
    • GSK Investigational Site · Cheongju Chungcheongbuk-do, South Korea
    • GSK Investigational Site · Daegu, South Korea
    • GSK Investigational Site · Seoul, South Korea
    • GSK Investigational Site · Seoul, South Korea
    • GSK Investigational Site · Seoul, South Korea
    • GSK Investigational Site · Sutton, United Kingdom
    • GSK Investigational Site · Leicester, United Kingdom
    • GSK Investigational Site · London, United Kingdom
    Site contacts Changed at 1 site. See the sites
    Show the site
    • GSK Investigational Site · São Paulo, BrazilContact person changed (no phone or email listed)
    + 1 other change: verification date

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT07286331
Lead sponsor
GlaxoSmithKline
Collaborators
ENGOT, GOG, APGOT
Responsible party
Sponsor
First posted
Dec 16, 2025
Start date
Jun 4, 2026
Primary completion
Feb 29, 2028 (estimated)
Completion
May 30, 2029 (estimated)
Last update
Nov 3, 2026

Study contacts

US GSK Clinical Trials Call Center
Contact
GSKClinicalSupportHD@gsk.com
877-379-3718
EU GSK Clinical Trials Call Center
Contact
GSKClinicalSupportHD@gsk.com
+44 (0) 20 89904466

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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Studies of the drug tested here: Mocertatug rezetecan

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