Mo-Rez in First- Line (1L) Maintenance Treatment of Non- Homologous Recombination Deficient Ovarian Cancer (HRd OC) [BEHOLD-Ovarian03]

NCT07694427 | Not Yet Recruiting Phase 3 DMC FDA Drug

• 5 other identifiers: 2240372025-523365-13-00ENGOT-ov105GOG-3135APGOT-OV20
• Study Type: interventional
• Target: 720
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study specifically aims to evaluate how well mocertatug rezetecan (Mo-Rez) alone or in combination with bevacizumab works in treating ovarian cancer compared to bevacizumab alone or active observation (AO). The study also assesses whether Mo-Rez is safe and tolerated well by participants in comparison to bevacizumab alone OR AO and will help provide a better understanding of the main side effects of the drugs.

Conditions

Ovarian Neoplasms

Keywords

Ovarian Cancer; Mocertatug rezetecan; Mo-Rez; GSK5733584; Bevacizumab; Active Observation; BEHOLD-Ovarian03

Outcome Measures

Primary Outcomes (1)

• Progression Free Survival (PFS)

  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

  Up to approximately 34 months

Secondary Outcomes (15)

• Overall Survival (OS)

  Up to approximately 72 months

• PFS by investigator assessment

  Up to approximately 72 months

• Time to first subsequent therapy (TFST)

  Up to approximately 72 months

• Time to second subsequent therapy (TSST)

  Up to approximately 72 months

• Time from randomization to objective progression on first subsequent anticancer therapy or death from any cause (PFS2)

  Up to approximately 72 months

Study Arms (2)

Mocertatug rezetecan +/- Bevacizumab

EXPERIMENTAL

Drug: Mocertatug rezetecan; Drug: Bevacizumab

Active Observation +/- Bevacizumab

ACTIVE COMPARATOR

Drug: Bevacizumab

Interventions

Mocertatug rezetecan DRUG

Mocertatug rezetecan will be administered

Mocertatug rezetecan +/- Bevacizumab

Bevacizumab DRUG

Bevacizumab will be administered

Active Observation +/- Bevacizumab; Mocertatug rezetecan +/- Bevacizumab

Eligibility Criteria

• Age: 18 Years+
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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 newly diagnosed Stage III/IV (2014 FIGO staging) \[Berek, 2021\] epithelial ovarian, primary peritoneal or fallopian tube cancer with a histologically confirmed diagnosis of high grade serous, high grade endometrioid, clear cell carcinoma, carcinosarcoma or mixed histology.
• Has Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1) response determined by investigator after the completion of first-line treatment must be Complete response (CR), Partial response (PR), No evidence of disease (NED), or Stable disease (SD).
• Is able to commence C1D1 of study treatment within 9 weeks of the final dose of front-line therapy. Final dose of front-line therapy is defined as the last day that platinum-based chemotherapy with/without bevacizumab was given. Participants may continue bevacizumab dosing if specified cycles of bevacizumab post-chemotherapy are administered prior to randomization.
• If planning to receive bevacizumab: Has received at least specified number of cycles of bevacizumab per label and local approval in combination front-line chemotherapy
• Has provided a sample sufficient for Homologous repair deficiency (HRD) testing (if local testing is not available), and the results available prior to date of randomization.
• Tumor specimen should be obtained from the most recent procedure and from a site not previously irradiated. If a suitable archival sample is not available, a fresh tumor tissue sample must be obtained during Screening. Fine needle aspirates, bone marrow samples, bone specimens, or cell blocks are not acceptable. Additional details regarding acceptable biopsy collections and processing can be found in the Laboratory Manual and other laboratory documentation. Tumor sample may also be used for other biomarker testing.
• 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), preferably with low user dependency, as described in Protocol, 30 days prior to 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., non-compliance, 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., a positive result or an indeterminate 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 provided in Protocol

You may not qualify if:

• Participants are excluded from the study if any of the following criteria apply:
• Has Ovarian cancer (OC) with germline or somatic pathogenic/likely pathogenic Breast cancer gene (BRCA)1/2 mutation or evidence of homologous repair deficiency as per local or central test.
• 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.
• First-line Poly adenosine diphosphate-ribosylation (ADP) ribose polymerase inhibitor(s) (PARPi) for maintenance is a treatment option for participants, as determined by the Principal 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 prior to the 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, endocrinopathy managed with replacement therapy, Grade 2 neuropathy, or 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 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 clinically significant wound healing complications or incompletely healed wounds.
• Has a history or evidence of Gastrointestinal (GI) perforation, tracheoesophageal fistula, or any Grade 4 fistula; participants with GI fistula, visceral fistula, or abdominal abscess within 6 months prior to the date of C1D1; has osteonecrosis of the jaw.
• Has evidence of recto-sigmoid involvement by pelvic examination or bowel involvement on Computed tomography (CT) scan or clinical symptoms of bowel obstruction.
• Has clinically significant bleeding symptoms, significant bleeding tendency, or bleeding tumors within 30 days prior to the date of C1D1.
• Has congenital bleeding diathesis, acquired coagulopathy, recent pulmonary hemorrhage/hemoptysis (\>2.5 mL of red blood or a half teaspoon) within the last 3 months prior to the date of C1D1.

Sponsors & Collaborators

• GlaxoSmithKline: lead
• ENGOT, GOG, APGOT: collaborator

MeSH Terms

Conditions

Ovarian Neoplasms

Interventions

Bevacizumab

Condition Hierarchy (Ancestors)

Endocrine Gland Neoplasms; Neoplasms by Site; Neoplasms; Ovarian Diseases; Adnexal Diseases; Genital Diseases, Female; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Genital Neoplasms, Female; Urogenital Neoplasms; Genital Diseases; Endocrine System Diseases; Gonadal Disorders

Intervention Hierarchy (Ancestors)

Antibodies, Monoclonal, Humanized; Antibodies, Monoclonal; Antibodies; Immunoglobulins; Immunoproteins; Blood Proteins; Proteins; Amino Acids, Peptides, and Proteins; Serum Globulins; Globulins

Central Study Contacts

US GSK Clinical Trials Call Center

CONTACT

877-379-3718; GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Center

CONTACT

+44 (0) 20 89904466; GSKClinicalSupportHD@gsk.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 1, 2026
• First Posted: July 10, 2026
• Study Start (Estimated): October 9, 2026
• Primary Completion (Estimated): September 6, 2029
• Study Completion (Estimated): November 8, 2032
• Last Updated: July 15, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR
• 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.