UP-NEXT: This phase III study is evaluating the effectiveness of targeted therapy (upifitamab rilsodotin), compared to placebo, in people with recurrent, platinum-sensitive high-grade serous ovarian cancer, including fallopian tube and primary peritoneal cancer, expressing high levels of NaPi2bA Phase 3, Randomized, Double-blind, Placebo-controlled, Multicenter Study of Upifitamab Rilsodotin (XMT-1536) as Post-Platinum Maintenance Therapy for Participants With Recurrent, Platinum-Sensitive, Ovarian Cancer (UP-NEXT)

Inclusion

1. Participant must have a histological diagnosis of high grade serous ovarian cancer, which includes fallopian tube and primary peritoneal cancer, that is metastatic or recurrent.
2. Participant must have platinum-sensitive recurrent disease, defined as having achieved either a partial or complete response to 4 or more cycles in their penultimate platinum- containing regimen and their disease progressing more than 6 months after completion of the last dose of platinum containing therapy in the penultimate regimen.

3. Participant must have had 4 to 8 cycles of platinum-based chemotherapy in 2nd to 4th line setting in their most recent treatment regimen as defined below:

   1. Platinum-based chemotherapy regimens allowed immediately preceding enrollment to the study: carboplatin or cisplatin ±: paclitaxel, docetaxel, pegylated liposomal doxorubicin or gemcitabine.
   2. Participant must receive first study treatment infusion between 4 and 12 weeks after completing final dose of platinum in the most recent platinum-based regimen.
4. Participant must have had as their best response to last line of treatment one of the following: No Evidence of Disease (NED); Complete Response (CR); Partial Response (PR); OR Stable Disease (SD)
5. Participants with NED, CR, or PR as their best response to most recent line of treatment and who have not received treatment with a prior PARP inhibitor must have definitive BRCA1 and BRCA2 testing results that demonstrate no evidence of a deleterious BRCA1 or BRCA2 mutation. Somatic BRCA mutation testing is required for participants who are classified as not having a deleterious mutation by germline testing alone.
6. Participant must provide either a tumor tissue block or fresh cut slides for measurement of NaPi2b expression by a central laboratory. If sufficient archival tumor tissue is not available, then a tumor tissue block or slides must be obtained from a fresh biopsy and provided to the central laboratory. Confirmation of a NaPi2b-H/positive tumor by the central laboratory is required prior to randomization.