• Histological diagnosis of a high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancer.

• Have platinum-resistant disease:

‣ Participants who have only had 1 line of platinum-based therapy must have received at least 4 cycles of a platinum-containing regimen.

⁃ Participants who have received 2 to 4 lines of platinum-based therapy must have progressed on or within 6 months after the last dose of platinum.

• Willingness to undergo a pretreatment biopsy. Note: Tissue from a fresh pretreatment biopsy is preferred, however an archival sample is acceptable as long as the sample is no older than 5 years.

• Received at least 1 and no more than 4 prior lines of systemic therapy following the initial diagnosis, after which single-agent therapy is considered an appropriate next therapeutic option.

• Must have received bevacizumab unless there was a contraindication for its use.

• If the tumor tests positive for FRα, participants must have received mirvetuximab soravtansine unless there is an exception for its use on medical grounds.