This study investigates a new treatment, INCB123667, in participants with platinum-resistant ovarian cancer whose tumors exhibit high levels of a protein called Cyclin E1.

Approximately 160 participants will be enrolled based on the Cyclin E1 expression of their tumors, determined by a central immunohistochemistry (IHC) assay, into 1 of 3 cohorts. Before enrollment, all participants must provide biopsy tissue samples from before treatment (either freshly taken or archived biopsy samples) during the screening process. The degree of Cyclin E1 expression will be determined from these samples, and participants will be assigned to their cohort. The main study consists of 3 different sections: a screening phase of up to 28 days, a treatment period lasting as long as participants benefit from the treatment and do not meet criteria for treatment discontinuation, and a 30-day follow-up period. It is estimated that an individual will participate in the study for about 24 months. The investigational drug INCB123667 is new and not yet approved for marketing. The risks and potential side effects of taking INCB123667 are not fully known and may vary depending on the condition for which the patient is being treated. INCB123667 may offer a promising option for the treatment of advanced cancers by targeting cyclin-dependent kinase 2 (CDK2), a protein involved in cell division that is often overactive in certain tumors, such as ovarian cancer.

Inclusion Criteria:

- platinum-resistant, high-grade, serious epithelial carcinoma of the ovaries or fallopian tubes, or primary peritoneal carcinoma with increased production of Cyclin E1 (Cyclin E1 overexpression) 

- good physical performance status (ECOG performance status of 0 or 1) 

- documented disease progression during or after the last cancer therapy

Exclusion Criteria:

- tumors with a specific nature: attributable to endometrial tissue (endometriosis), clear cell, mucinous, or sarcomatoid, mixed tumors

- a platinum-refractory primary disease

- clinically significant (significant) or uncontrolled heart disease within 6 months prior to the first dose of the investigational drug