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

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.

Inclusion Criteria: * 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 * It is available in the enrolment country. A regimen is considered available if it is approved and reimbursed (covered by national healthcare or private insurance) in the participating country. * Bevacizumab, unless the participant has a documented contraindication per label or local institutional guidelines. Contraindications include but are not limited to vascular disorders (uncontrolled hypertension, arterial thromboembolic events), fistula, gastro-intestinal disorders (rectosigmoid involvement, bowel obstruction), delayed wound healing, bleeding diathesis (haemoptysis, epistaxis, pulmonary haemorrhage, acquired coagulopathy), nephrotic syndrome or significant proteinuria, or osteonecrosis of the jaw, or hypersensitivity * PARPi, in participants with known or suspected deleterious germline or somatic BRCA mutations and who achieved a complete or partial response to platinum-based chemotherapy must have been treated with a poly ADP-ribose polymerase PARPi as maintenance treatment, if a PARPi is available in the enrolment country, unless the participants is not eligible for treatment with PARPi. A regimen is considered available if it is approved and reimbursed (covered by national healthcare or private insurance) in the participating country. * 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 of sufficient quantity and quality for the central assessment of B7 homolog 4 protein (B7-H4) expression, with B7-H4 expression result available prior to date of randomization. AND * FR alpha expression * In countries where mirvetuximab is available, an FR alpha expression result from a test compliant with local regulation or by central testing is required to determine eligibility. * In countries where mirvetuximab is unavailable, an FFPE tumor tissue sample confirmed to be of sufficient quantity and quality must be provided. The FR alpha expression result is not required prior to randomisation or to determine eligibility. AND * PD-L1 expression, where a result from a local test is NOT available, an FFPE tumor tissue sample confirmed to be of sufficient quantity and quality must be provided. The PD-L1 expression result is not required prior to randomisation or to determine eligibility. * Is eligible to receive 1 of the standard of care interventions if randomized to physician's choice arm. * 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 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 \