This Phase 3 study will be conducted in different countries around the world with up to about 688 participants.

The purpose of this study is to evaluate how well Rina-S works against ovarian cancer in combination with or without bevacizumab and how it compares to an investigator's choice of platinum-based chemotherapy with or without bevacizumab.

Participants will receive either:

• Rina-S monotherapy (by itself),
• Rina-S plus bevacizumab,
• investigator's choice chemotherapy (by itself) (standard of care), or
• investigator's choice chemotherapy plus bevacizumab (standard of care).

No participants will be given placebo. Participants will participate in 1 of 2 arms.

The treatment duration will be different for every participant. If a participant's cancer stays the same or gets better, and there are not any serious problems, participants can keep getting study treatment for as long as the study is open.

Participants will be asked to attend 1 to 3 visits at the study clinic for each cycle (duration of cycle is 3 or 4 weeks, depending on medication received). During visits, there will be various tests (such as blood draws) and procedures (such as recording of heart activity and imaging) to monitor whether the study treatment is safe and effective.

The overall study duration (including screening, treatment, and follow-up) will be different for every participant.

This is a global, open-label, randomized, Phase 3 study of Rina-S ± bevacizumab versus investigator's choice (IC) ± bevacizumab as second-line (2L) treatment in participants with recurrent platinum-sensitive ovarian cancer (PSOC).

Key Inclusion Criteria:

• Participant must have histologically confirmed high-grade serous or endometrioid epithelial ovarian cancer (EOC), including primary peritoneal or fallopian tube cancer.
• Participant must have documented recurrence or progression after first-line (1L) platinum-based chemotherapy regimen (carboplatin + paclitaxel ≥ 4 cycles) with or without bevacizumab and have platinum-sensitive disease defined as radiographic progression at least 6 months (ie, >183 days) after their last dose administration of platinum-based therapy.
• Prior poly (ADP-ribose) polymerase inhibitor(s) (PARPi) maintenance therapy (alone or in combination with bevacizumab) is required for participants with breast cancer susceptibility gene (BRCA 1- and BRCA 2)-mutated (germline or somatic) or homologous recombination deficiency (HRD)-positive disease.
• Participants must have measurable disease per RECIST v1.1 by investigator at baseline.
• All participants must provide a tumor specimen.
• Participants must have Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at baseline.

Key Exclusion Criteria:

• Participants with clear cell, mucinous, or sarcomatous histology, mixed tumors containing any of the above histologies, or low-grade/borderline ovarian tumors.
• Participant has received previous therapy with other anti-angiogenetic agents different from bevacizumab or biosimilar.
• Participant has received prior therapy with an antibody-drug conjugate (ADC) containing a topoisomerase-1 inhibitor.
• Participant has received prior therapy with an ADC targeting folate receptor alpha (FRα).

Note: Other protocol-defined Inclusion and Exclusion criteria may apply.