This study will evaluate the safety and efficacy of INCB123667 in Participants With Platinum-Resistant Ovarian Cancer (PROC) With Cyclin E1 Overexpression.

Inclusion Criteria:

• 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.

Exclusion Criteria:

• Have endometrioid, clear cell, mucinous, or sarcomatous histology, mixed tumors containing any of these histologies, or low-grade/borderline ovarian cancer.
• Have primary platinum-refractory disease: either did not respond (CR or PR) to first-line platinum-containing therapy or progressed on or within 3 months after the last dose of the first line platinum-containing therapy.
• The tumor tests positive for FRα but the participant has not received mirvetuximab soravtansine for any reason other than medical contraindication.
• Clinically significant or uncontrolled cardiac disease within 6 months before the first dose of study drug.
• Known active CNS metastases and/or carcinomatous meningitis.
• Known additional malignancy that is progressing or requires active treatment.

Other protocol-defined Inclusion/Exclusion Criteria may apply.

Incyte shares data with qualified external researchers after a research proposal is submitted. These requests are reviewed and approved by a review panel on the basis of scientific merit. All data provided is anonymized to respect the privacy of patients who have participated in the trial in line with applicable laws and regulations. The trial data availability is according to the criteria and process described on https://www.incyte.com/our-company/compliance-and-transparency

Data will be shared after the primary publication or 2 years after the study has ended for market authorized products and indications.

Data from eligible studies will be shared with qualified researchers according to the criteria and process described in the Data Sharing section of the www.incyteclinicaltrials.com website. For approved requests, the researchers will be granted access to anonymized data under the terms of a data sharing agreement.