Study to Evaluate INCB123667 Versus Investigator's Choice of Chemotherapy in Participants With Platinum-Resistant Ovarian Cancer With Cyclin E1 Overexpression

Inclusion Criteria:

* Histological diagnosis of 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 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.
* Archival FFPE tumor tissue block or slides from a specimen no older than 5 years must be available. If not available, participant must be willing to undergo a pretreatment tumor biopsy.
* Received at least 1 and no more than 4 prior lines of systemic therapy following the initial diagnosis, after which single-agent chemotherapy is considered an appropriate next therapeutic option.
* Should have received prior treatment with bevacizumab unless there was a contraindication for its use.
* Should have received prior treatment with mirvetuximab soravtansine if the tumor is positive for FRα, unless there is an exception for its use on medical grounds.
* Measurable disease per RECIST v1.1.

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, defined as progression on or within 3 months after the last dose of first line platinum-containing therapy.
* Clinically significant or uncontrolled cardiac disease within 6 months before the first dose of study treatment.
* Known active CNS metastases and/or carcinomatous meningitis.
* Known additional malignancy that is progressing or requires active treatment, or history of other malignancy within 3 years before the first dose of study treatment.
* Clinically significant gastrointestinal abnormalities.

Other protocol-defined Inclusion/Exclusion Criteria may apply.