A Study of MK-5684 in People With Certain Solid Tumors (MK-5684-015/OMAHA-015)

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Cohort A:

• Has a diagnosis of hormone receptor positive/Human Epidermal Growth FactorReceptor 2 negative (HR+/HER2-) invasive breast carcinoma that is eitherlocally advanced disease not amenable to resection with curative intent (hereincalled unresectable) or metastatic disease not treatable with curative intent.

• Has experienced disease progression on or after at least 1 priorendocrine-based therapy in the metastatic setting and received either, 1 lineof an approved protocol-specified combination endocrine-based therapy, or 2 ormore lines of protocol-specified endocrine-based therapy in the metastaticsetting

• Cohort B:

• Has histologically confirmed high-grade epithelial (including high-grade serousor predominantly serous, high-grade endometrioid, malignant mixed Mülleriantumors [carcinosarcoma], or clear cell) ovarian, fallopian tube, or primaryperitoneal carcinoma.

• Has received between 4 to 8 cycles of platinum-based doublet chemotherapy inthird-line (3L) setting for ovarian cancer.

• Cohort C:

• Histologically confirmed diagnosis of primary advanced or recurrent low-gradeendometrioid carcinoma (eg, Federation of Gynecology and Obstetrics [FIGO]Grade 1/2, or well/moderately differentiated).

• Treatment naïve or has received up to 1 prior line of platinum-based therapy ineither the advanced/metastatic OR adjuvant/neoadjuvant setting.

• All Cohorts :

• Participants who have AEs due to previous anticancer therapies must haverecovered to ≤Grade 1 or baseline.

• Human immunodeficiency virus (HIV)-infected participants must have wellcontrolled HIV on antiretroviral therapy.

• Participants who are Hepatitis B surface antigen positive are eligible if theyhave received Hepatitis B virus (HBV) antiviral therapy for at least 4 weeksand have undetectable HBV viral load.

• Participants with a history of Hepatitis C virus (HCV) infection are eligibleif HCV viral load is undetectable.

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Cohort A:

• Breast cancer amenable to treatment with curative intent.

• Has advanced/metastatic, symptomatic visceral spread at risk of rapidlyevolving into life-threatening complications, such as lymphangitic lungmetastases, radiographic evidence of intratumoral cavitation orinvasion/infiltration of a major blood vessel, bone marrow replacement,carcinomatous meningitis, significant symptomatic liver metastases, symptomaticpericardial effusion, symptomatic peritoneal carcinomatosis, or the need toachieve rapid symptom control.

• Cohort B:

• Has nonepithelial cancers (germ cell tumors and sex cord-stromal tumors),borderline tumors (low malignant potential), mucinous, seromucinous that ispredominantly mucinous, malignant Brenner's tumor, low-grade serous, low-gradeendometrioid, and undifferentiated carcinoma.

• Has platinum-resistant ovarian cancer (defined as disease that has progressedper radiographic imaging within 180 days after the last dose of first-line [1L]platinum-based therapy) or platinum-refractory ovarian cancer (defined asdisease that has progressed per radiographic imaging while receiving or within 28 days of the last dose of 1L platinum based therapy).

• Is a candidate for curative-intent surgery or curative-intent radiotherapy forovarian cancer.

• Cohort C:

• Has high-grade (FIGO Grade 3 or poorly differentiated) endometrioid carcinomaand nonendometrioid histologies of any type (including serous, clear cell,mixed, carcinosarcoma), and neuroendocrine tumors are not eligible. Uterinemesenchymal tumors such as an endometrial stromal sarcoma, leiomyosarcoma, orother types of pure sarcomas, and adenosarcomas are not eligible.

• Is a candidate for curative-intent surgery or curative-intent radiotherapy.

• All Cohorts:

• Has confirmed or suspected adrenal metastases.

• Has known difficulty in tolerating oral medications, unable to swallow orallyadministered medication, or conditions which would impair absorption of oralmedications.

• Has any prior history or current condition of adrenal insufficiency.

• HIV-infected participants with a history of Kaposi's sarcoma and/orMulticentric Castleman's Disease.

• Has received a live or live-attenuated vaccine within 30 days before the firstdose of study intervention. Administration of killed vaccines is allowed.

• Has a known additional malignancy that is progressing or has required activetreatment within the past 3 years.

• Has known active central nervous system metastases and/or carcinomatousmeningitis.

• Has a history of stem cell/solid organ transplant.

• Has not adequately recovered from major surgery or has ongoing surgicalcomplications.