A Study to Investigate Mocertatug Rezetecan Compared With Standard of Care in Participants With Platinum-resistant Ovarian Cancer (BEHOLD-Ovarian01)

NCT07286266 | Not Yet Recruiting Phase 3 DMC FDA Drug

• 2 other identifiers: 2240312025-523361-25-00
• Study Type: interventional
• Target: 450
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study specifically aims to evaluate how well mocertatug rezetecan (Mo-Rez) works in treating ovarian cancer compared to standard treatments. The study also assesses whether Mo-Rez is safe and tolerated well by participants compared to standard treatments and aims to provide a better understanding of the main side effects of the drug.

Conditions

Ovarian Neoplasms

Keywords

Platinum-resistant Ovarian Cancer; Mocertatug rezetecan; Mo-Rez; GSK5733584; Paclitaxel; Pembrolizumab; Bevacizumab; Pegylated liposomal doxorubicin (PLD); Topotecan; Gemcitabine; Antibody-drug conjugate; BEHOLD-Ovarian01

Outcome Measures

Primary Outcomes (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) 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 212 weeks

• Overall Survival (OS)

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

  Up to approximately 212 weeks

Secondary Outcomes (18)

• PFS by investigator assessment

  Up to approximately 212 weeks

• Objective response rate (ORR) by BICR

  Up to approximately 212 weeks

• Duration of Response (DOR) by BICR

  Up to approximately 212 weeks

• ORR by investigator assessment

  Up to approximately 212 weeks

• DOR by investigator assessment

  Up to approximately 212 weeks

Study Arms (2)

Mocertatug rezetecan

EXPERIMENTAL

Participants will receive Mocertatug rezetecan

Drug: Mocertatug rezetecan

Standard of care

ACTIVE COMPARATOR

Participants will receive standard of care chemotherapy (Paclitaxel or Pembrolizumab + paclitaxel ± bevacizumab or PLD or Topotecan or Gemcitabine) as per investigator's choice

Drug: Paclitaxel; Drug: Pegylated liposomal doxorubicin (PLD); Drug: Topotecan; Drug: Gemcitabine; Drug: Pembrolizumab; Drug: Bevacizumab

Interventions

Paclitaxel DRUG

Paclitaxel will be administered

Standard of care

Pegylated liposomal doxorubicin (PLD) DRUG

PLD will be administered

Standard of care

Topotecan DRUG

Topotecan will be administered

Standard of care

Gemcitabine DRUG

Gemcitabine will be administered

Standard of care

Mocertatug rezetecan DRUG

Mocertatug rezetecan will be administered

Mocertatug rezetecan

Pembrolizumab DRUG

Pembrolizumab will be administered

Standard of care

Bevacizumab DRUG

Bevacizumab will be administered

Standard of care

Eligibility Criteria

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

You may qualify if:

• 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 epithelial ovarian cancer, inclusive of primary peritoneal or fallopian-tube cancer with a histologically confirmed diagnosis of high grade serous, high grade endometrioid, or clear cell carcinoma, or carcinosarcoma that is resistant to platinum-based therapy.
• Platinum-resistance is defined as follows:
• Participants who have only had 1 line of platinum-based therapy must have received at least 4 cycles of platinum therapy, must have had a response (CR, PR, stable disease) and then progressed from \>3 months to ≤6 months after the last dose of platinum therapy.
• Participants who have received \>1 line of platinum therapy must have progressed on or ≤6 months after the date of the last dose of platinum therapy.
• Has received at least 1 but no more than 4 prior lines of systemic anti-cancer therapy. Prior lines of therapy are defined as follows:
• Adjuvant ± neoadjuvant are considered one line of therapy.
• Maintenance therapy (e.g., bevacizumab, \[poly adenosine diphosphate-ribosylation (ADP) ribose polymerase inhibitor (PARPi)\] will be considered as part of the preceding line of therapy (i.e., not counted independently).
• Therapy changed to another agent in the same class due to toxicity in the absence of progression will be considered as part of the same line of therapy (i.e., not counted independently).
• Unplanned addition or switching to a new drug in a different class is considered a separate line of therapy.
• Hormonal therapy will be counted as a separate line of therapy unless it was given as maintenance.
• Must have received prior treatment with the following therapies unless they have a contraindication per label or institutional guidelines as described below:
• Mirvetuximab soravtansine (MIRV),.
• The tumor demonstrates positive folate receptor alpha FRα expression (≥ 75% of viable tumor cells with moderate (2+) and/or strong (3+) membrane staining) per a test compliant to local regulation, AND
• Does not have a documented contraindication per label or local institutional guidelines, including but not limited to chronic corneal disorders, history of corneal transplantation, or active ocular conditions requiring ongoing treatment/monitoring, such as uncontrolled glaucoma, active diabetic retinopathy with macular edema, macular degeneration, presence of papilledema, monocular vision, peripheral neuropathy, interstitial lung disease, or hypersensitivity. AND

You may not qualify if:

• Has primary platinum-refractory Ovarian Cancer (OC), defined as disease that did not respond to or has progressed within \<3 months of the final dose of first line platinum containing chemotherapy.
• Has a malignancy (except disease under study) that has progressed or required active treatment within 36 months prior to date of randomization, except for basal cell or squamous cell carcinomas of the skin, 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 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 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 date of C1D1 are not excluded from participation.
• Has any evidence of current 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 e.g., alopecia, hearing loss, vitiligo, endocrinopathy managed with replacement therapy, and 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, including requirements for the Follow-up Period of the study.
• For participants selected to receive the pembrolizumab-containing regimen as the intended physician's choice only: Has experienced any of the following with prior immunotherapy-any immune-mediated adverse event (imAE) ≥ Grade 3, immune-mediated severe neurologic events of any grade (e.g., myasthenic syndrome/myasthenia gravis, encephalitis, Guillain-Barré Syndrome, or transverse myelitis), exfoliative dermatitis of any grade (Stevens-Johnson Syndrome \[SJS\], Toxic Epidermal Necrolysis \[TEN\], or drug reaction with eosinophilia and systemic symptoms \[DRESS\] syndrome), or myocarditis of any grade
• For participants selected to receive bevacizumab as part of the pembrolizumab + paclitaxel ± bevacizumab intended physician's choice regimen only: Has a history of vascular disorders (uncontrolled hypertension, arterial thromboembolic events), fistula, gastro-intestinal disorders (rectosigmoid involvement, bowel obstruction), delayed wound healing, bleeding diathesis (hemoptysis, epistaxis, pulmonary hemorrhage, acquired coagulopathy), nephrotic syndrome or significant proteinuria, or osteonecrosis of the jaw, or hypersensitivity.
• Has had any major surgery within 28 days prior to date of C1D1 or received focal radiotherapy within 21 days prior to date of C1D1.
• Has received treatment with an investigational agent within 30 days prior to date of C1D1.
• Has received treatment with any cytotoxic chemotherapy drugs or other anti-tumor drugs (including endocrine therapy, molecular targeted therapy, immunotherapy, biotherapy, or investigational agent) within 30 days or 5 half-lives, whichever is shorter, prior to date of C1D1; or need to continue these drugs during study participation.
• Has ever received prior therapy with topoisomerase I inhibitors (e.g., topotecan) or ADC with a topo1i payload, or B7-H4 targeted therapy.
• Has received any live vaccine within 30 days prior to date of C1D1.
• Has received any transfusion of blood products (including platelets or red blood cells) or administration of colony-stimulating factors (including Granulocyte colony stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor, or recombinant erythropoietin) within 14 days prior to date of C1D1.

Sponsors & Collaborators

• GlaxoSmithKline: lead
• GOG Foundation: collaborator
• European Network of Gynaecological Oncological Trial Groups (ENGOT): collaborator
• Asia-Pacific Gynecologic Oncology Trials Group: collaborator

MeSH Terms

Conditions

Ovarian Neoplasms

Interventions

Paclitaxel; liposomal doxorubicin; Topotecan; Gemcitabine; pembrolizumab; 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)

Taxoids; Cyclodecanes; Cycloparaffins; Hydrocarbons, Alicyclic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals; Diterpenes; Terpenes; Camptothecin; Alkaloids; Heterocyclic Compounds; Deoxycytidine; Cytidine; Pyrimidine Nucleosides; Pyrimidines; Heterocyclic Compounds, 1-Ring; 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: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: The independent central reviewer assessing primary outcome data will be masked (blinded) from participants treatment assignment.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 12, 2025
• First Posted: December 16, 2025
• Study Start (Estimated): June 24, 2026
• Primary Completion (Estimated): August 21, 2030
• Study Completion (Estimated): August 21, 2030
• Last Updated: May 27, 2026

Record last verified: 2026-05

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.