A Study to Investigate Mocertatug Rezetecan With Bevacizumab Compared With Platinum Doublet With Bevacizumab in Participants With Platinum-sensitive Ovarian Cancer (BEHOLD-Ovarian02)

This study specifically aims to evaluate how well mocertatug rezetecan (Mo-Rez) in combination with bevacizumab works in treating platinum-sensitive ovarian cancer compared to standard treatments by checking whether it makes cancers smaller or disappear completely and if it helps participants live longer. The study also assesses whether Mo-Rez in combination with bevacizumab is safe and tolerated well by participants compared to standard treatments and aims to provide a better understanding of the main side effects of Mo-Rez.

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, primary peritoneal, or fallopian-tube cancer with a histologically confirmed diagnosis of high grade serous, high grade endometrioid, clear cell carcinoma, or carcinosarcoma. * Has recurrent or progressive disease after completion of at least 1 and a maximum of 2 previous lines of systemic anticancer therapy. Recurrent or progressive disease should be determined based on radiographic assessment according to RECIST 1.1 per investigator and/or clinical assessment of disease progression by investigator. Prior lines of therapy are defined as follows: * Adjuvant ± neoadjuvant is considered one line of therapy. * Maintenance therapy (e.g., bevacizumab, Poly 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 (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. * Has platinum-sensitive disease and is suitable for platinum doublet chemotherapy with bevacizumab for the treatment of recurrent disease. Platinum sensitive disease is defined as recurrent or progressive disease \>6 months after last dose of platinum-based chemotherapy. * Has documented results of local testing (compliant to local regulations) for tumor and/or germline Breast Cancer Gene (BRCA1 and BRCA2) mutation. Participants with a known tumor or germline deleterious BRCA1 or BRCA2 mutation must have previously received PARPi maintenance therapy, alone or in combination with bevacizumab, if the participant was considered a candidate for this treatment and the treatment is locally available. * 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 the date of randomization. * 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 they are 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 \