A study to investigate GSK5733584 compared with chemotherapy in participants with platinum-resistant ovarian cancer (BEHOLD-Ovarian01)

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, 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 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 3 prior lines of systemic anti-cancer therapy, and for whom single-agent therapy is appropriate as the next line of treatment. Participants who received mirvetuximab soravtansine as prior therapy are permitted to have received up to 4 prior lines. Prior lines of therapy are defined as follows:

Hormonal therapy will be counted as a separate line of therapy unless it was given as maintenance.

• Has received prior treatment with Mirvetuximab soravtansine (MIRV), bevacizumab and/or PARPi if the participant was considered a candidate for this treatment and the treatment is locally available.
• Has at least one Target lesion (TL) per RECIST 1.1, as determined by the investigator. Measurable lesions that have been previously irradiated and have been shown to be progressing following irradiation may be considered as TLs.
• 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.
• Is eligible to receive 1 of the standard of care interventions if randomized to physician’s choice arm. Participants not selected to receive taxane as physician’s choice regimen must have previously received taxane-based treatment in the platinum-resistant setting or be intolerant to taxane-based treatment.
• A female participant is eligible to participate if they are not pregnant or breastfeeding, and one of the following conditions applies:

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.

• Is capable of giving signed informed consent, including compliance with the requirements and restrictions listed in the ICF and in the study protocol.
• Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Has adequate organ function

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 or 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.
• 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 treatment with strong or moderate inhibitor of Cytochrome P450 3A4 (CYP3A4) or Cytochrome P450 2D6 (CYP2D6), strong or moderate inducer of CYP3A4, inhibitor of P-glycoprotein (P-gp) or Breast cancer resistant protein (BCRP), or inducer of P-gp within 14 days prior to date of C1D1 or anticipates their use during study participation and up to 30 days after the last dose of study intervention administration.
• Use of drugs known to prolong the QT interval or potentially cause torsades de pointes; or need to continue these medications during the study and up to 30 days after the last dose of study intervention.
• 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.
• For participants receiving PLD only: Has baseline Left ventricular ejection fraction (LVEF) <50% or lower than institutional lower limits of normal.