Neoplasms, EndometrialPhase 3NCT07286331
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 study testing Mocertatug rezetecan, Paclitaxel and Doxorubicin in people with Neoplasms, Endometrial, run by GlaxoSmithKline at 56 sites in 10 countries.
Trial 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… 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, Paclitaxel and Doxorubicin
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 600 participants
- Where
- 56 sitesin 10 countries
- Study dates
- 4 Jun 2026to 30 May 2029
- 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
- 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 Informed consent form (ICF).
- Has histologically 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 adjuvant/neo-adjuvant setting. The definition of prior lines of therapy 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.
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- 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 (PD-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 (contraindications such as immunodeficiency, autoimmune 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 metastatic 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 RECIST 1.1 by BICR eligibility review of screening scans.
- 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.
- 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-childbearing potential (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 Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
- Has adequate organ function.
Who cannot join
- 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 malignancy (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 metastatic disease, or that is otherwise considered cured by the investigator.
- Has any history of prior allogenic or autologous bone marrow transplant or other solid organ transplant.
- Has known sensitivity to study intervention components or excipients 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/CNS metastases 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 corticosteroid therapy for ≥14 days before date of C1D1 are not excluded from participation.
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- 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 clinically relevant 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 informed consent, 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 investigational 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 live vaccine 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 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 a known Human immunodeficiency virus (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 CD4 cell count 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 Alanine aminotransferase (ALT) value >2.5× Upper limit of normal (ULN) and/or for participants documented liver metastases/tumor infiltration has an ALT value >5x ULN
- Has a total bilirubin 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 Hepatitis B 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 Hepatitis C 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 QTc >470 milliseconds (msec)
- Has a history within 12 months prior to screening of clinically significant or uncontrolled cardiac disease, acute myocardial infarction, New York Heart Association Class III or IV congestive heart failure [NYHA 1994], or clinically significant arrhythmia not controlled by standard of care therapy.
- Has Left ventricular ejection fraction (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).
Trial locations and contacts
56 sites in 10 countries. Contact the study team or a site near you to ask about taking part.
56 sites in 10 countries
Japan16 sites, 16 recruiting
- Recruiting
GSK Investigational Site
Aichi, 466-8560
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
Fukuoka, 830-0011
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
Hyōgo, 673-8558
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
Kanagawa, 216-8511
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
Kanagawa, 241-8515
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
Kyoto, 612-8555
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
Mie, 514-8507
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
Okayama, 700-8558
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
Okinawa, 901-2725
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, 565-0871
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
Shizuoka, 411-8777
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
- Recruiting
GSK Investigational Site
Tokyo, 160-8582
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
Argentina7 sites, 7 recruiting
- Recruiting
GSK Investigational Site
Buenos Aires
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
Ciudad Autonoma de Buenos Aire, C1012AAR
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
Ciudad Autonoma de Buenos Aire, C1426AGE
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
Córdoba, 5000
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
Florida, Buenos Aires, B1602DQB
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
Mendoza, MD, 5500
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
Rosario, S2000ORE
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 Korea7 sites, 7 recruiting
- Recruiting
GSK Investigational Site
Cheongju Chungcheongbuk-do, 28644
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
Daegu, 41404
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
Seongnam-si Gyeonggi-do, 13620
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
Seoul, 03080
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
Seoul, 03722
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
Seoul, 05505
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
Seoul, 06351
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
Brazil6 sites, 6 recruiting
- Recruiting
GSK Investigational Site
CuritibaPR, 80810-050
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
Porto Alegre, 90035-000
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
São Luís, Maranhão, 65060-645
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
São Paulo, 01323-900
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
São Paulo, 04537-080
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
Vitória, 29043-260
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
United States4 sites, 4 recruiting
- Recruiting
GSK Investigational Site
Birmingham, Alabama, 35226
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
Charlottesville, Virginia, 22908
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
Omaha, Nebraska, 68114-4108
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
Sugar Land, Texas, 77479-4308
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
United Kingdom4 sites, 4 recruiting
- Recruiting
GSK Investigational Site
Leicester, LE1 5WW
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
London, NW1 2PG
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
London, SW3 6JJ
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
Sutton, Surrey, SM2 5PT
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
Australia3 sites, 3 recruiting
- Recruiting
GSK Investigational Site
Auchenflower, Queensland, 4066
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
Dubbo, New South Wales, 2830
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
Herston, Queensland, 4006
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
Canada3 sites, 3 recruiting
- Recruiting
GSK Investigational Site
Montreal, Quebec, H2X 0C1
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
Montreal, Quebec, H4A 3J1
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
Israel3 sites, 3 recruiting
- Recruiting
GSK Investigational Site
Haifa, 31999
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
Haifa, 3436212
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
Kfar Saba, 44281
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
Panama3 sites, 3 recruiting
- Recruiting
GSK Investigational Site
Panama City
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
Panama City
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
Panama City
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 Compared With Chemotherapy in Participants With Endometrial Cancer After Platinum-based Chemotherapy and Immunotherapy
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.
- Conditions
- Neoplasms, Endometrial
- Being tested
- Mocertatug rezetecan, Paclitaxel, Doxorubicin
- Keywords
- Endometrial Cancer, Mocertatug rezetecan, Mo-Rez, GSK5733584, Paclitaxel, Doxorubicin, Antibody-drug conjugate, BEHOLD-Endometrial01
- 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
PaclitaxelDrug
Paclitaxel will be administered
DoxorubicinDrug
Doxorubicin will be administered
| Study group | Role | What they receive |
|---|---|---|
| Mocertatug rezetecan | Experimental | Participants will receive Mocertatug rezetecan Receives: Drug: Mocertatug rezetecan |
| Standard of Care | Active comparator | Participants will receive standard of care treatment (Paclitaxel or Doxorubicin) as per investigator's discretion Receives: Drug: Paclitaxel; Drug: Doxorubicin |
What is being measured
The primary outcome is the main question the study is designed to answer.
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)
Measured: Up to approximately 97 weeks
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
Measured: Up to approximately 97 weeks
Secondary outcomes (16)
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 156 weeks
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
Measured: Up to approximately 156 weeks
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
Measured: Up to approximately 156 weeks
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
Measured: Up to approximately 156 weeks
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
Measured: Up to approximately 156 weeks
Number of participants with Treatment-emergent adverse event (TEAEs), Adverse event of special interest (AESIs) and Treatment-emergent serious adverse event (TESAEs)
Measured: Up to approximately 156 weeks
Number of participants with TEAEs/AESIs/TESAEs leading to dose modifications or study intervention discontinuation
Measured: Up to approximately 156 weeks
Number of participants with changes in vital signs, laboratory tests (hematology and clinical chemistry), and Electrocardiogram (ECG)
Measured: Up to approximately 156 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 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
Measured: Up to approximately 156 weeks
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.
Measured: Up to approximately 156 weeks
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
Measured: Up to approximately 156 weeks
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
Measured: Up to approximately 156 weeks
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.
Measured: Up to approximately 156 weeks
Serum concentration of Mo-Rez (conjugated antibody and free payload)
Measured: Up to approximately 156 weeks
Number of participants with Antidrug antibody (ADA) and Neutralizing Antibody (NAb) against Mo-Rez
Measured: Up to approximately 156 weeks
Titers of ADA against Mo-Rez
Measured: Up to approximately 156 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Dec 2025
- Study start4 Jun 2026
- Primary completion29 Feb 2028 (estimated)
- Study completion30 May 2029 (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
- 600 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
- NCT07286331
- Sponsor's protocol ID
- 224038
- Other IDs
- 2025-523362-25-00, ENGOT-en34, GOG-3131, APGOT-EN4, 2025
- Status last verified
- Oct 2026
- First submitted
- 12 Dec 2025
- 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 Compared With Chemotherapy in Participants With Endometrial Cancer After Platinum-based Chemotherapy and Immunotherapy
- ClinicalTrials.gov ID
- NCT07286331
- Acronym / sponsor ID
- 224038
- Conditions
- Neoplasms, Endometrial
- Keywords
- Endometrial Cancer, Mocertatug rezetecan, Mo-Rez, GSK5733584, Paclitaxel, Doxorubicin, Antibody-drug conjugate, BEHOLD-Endometrial01
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 600 participants (estimated)
- Lead sponsor
- GlaxoSmithKlineIndustry (pharma, biotech, devices)
- Collaborators
- ENGOT, GOG, APGOT
- Study start
- 4 Jun 2026 (actual)
- Primary completion
- 29 Feb 2028 (estimated)
- Study completion
- 30 May 2029 (estimated)
- First posted
- 16 Dec 2025 (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.
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.
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 | Experimental | Drug: Mocertatug rezetecanParticipants will receive Mocertatug rezetecan |
| Standard of Care | Active comparator | Drug: Paclitaxel, Drug: DoxorubicinParticipants will receive standard of care treatment (Paclitaxel or Doxorubicin) as per investigator's discretion |
Who may qualify
- Ages
- 18 years and older
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (26 listed)
- 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 Informed consent form (ICF).
- Has histologically 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 adjuvant/neo-adjuvant setting. The definition of prior lines of therapy is as follows:
- Must have progressed on or after prior platinum-based chemotherapy and have received anti- Programmed cell death 1 (PD-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 (contraindications such as immunodeficiency, autoimmune disease that required systemic treatment) as determined by the investigator or treating physician are eligible.
Key exclusion criteria (35 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 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 metastatic disease, or that is otherwise considered cured by the investigator.
- Has any history of prior allogenic or autologous bone marrow transplant or other solid organ transplant.
- Has known sensitivity to study intervention components or excipients 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/CNS metastases 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 corticosteroid therapy for ≥14 days before date of C1D1 are not excluded from participation.
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 |
| PaclitaxelPaclitaxel will be administered | Drug | Standard of Care |
| DoxorubicinDoxorubicin will be administered | Drug | Standard of Care |
Primary outcome
Objective response rate (ORR) by BICR
Time frame: Up to approximately 97 weeks
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)
Progression Free Survival (PFS) by BICR
Time frame: Up to approximately 97 weeks
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
16 secondary outcomes
Overall Survival (OS)
Time frame: Up to approximately 156 weeks
ORR by investigator assessment
Time frame: Up to approximately 156 weeks
Duration of Response (DOR) by BICR
Time frame: Up to approximately 156 weeks
DOR by investigator assessment
Time frame: Up to approximately 156 weeks
PFS by investigator assessment
Time frame: Up to approximately 156 weeks
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
Number of participants with TEAEs/AESIs/TESAEs leading to dose modifications or study intervention discontinuation
Time frame: Up to approximately 156 weeks
Number of participants with changes in vital signs, laboratory tests (hematology and clinical chemistry), and Electrocardiogram (ECG)
Time frame: Up to approximately 156 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 156 weeks
Change from baseline in European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Endometrial Cancer Module 24 (EORTC QLQ-EN24)
Time frame: Up to approximately 156 weeks
Time to deterioration (TTD) of EORTC QLQ-EN24
Time frame: Up to approximately 156 weeks
TTD of EORTC QLQ-C30
Time frame: Up to approximately 156 weeks
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)
Time frame: Up to approximately 156 weeks
Serum concentration of Mo-Rez (conjugated antibody and free payload)
Time frame: Up to approximately 156 weeks
Number of participants with Antidrug antibody (ADA) and Neutralizing Antibody (NAb) against Mo-Rez
Time frame: Up to approximately 156 weeks
Titers of ADA against Mo-Rez
Time frame: Up to approximately 156 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.
56 sites in 10 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Mocertatug rezetecan, Paclitaxel and Doxorubicin in people with Neoplasms, Endometrial, run by GlaxoSmithKline at 56 sites in 10 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 26 inclusion and 35 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 56 sites in Japan, Argentina, South Korea, Brazil, United States and 5 more countries. 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?
Objective response rate (ORR) by BICR (time frame: Up to approximately 97 weeks). The study lists 2 primary outcomes in all. 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.