Pilot of Osanetant to Reduce Severity of Hot Flashes in Men With Adenocarcinoma of the Prostate

Inclusion Criteria: * Ability of participant OR Legally Authorized Representative (LAR) to understand this study, and participant or LAR willingness to sign a written informed consent * Males ≥ 18 years * Histologic diagnosis of prostate cancer (PCa) * Undergoing active treatment with ADT within ≥ 30 days prior to randomization * Using either an gonadotropin releasing hormone (GNRH) agonist with a planned duration covering the 8 weeks of the study or are status post bilateral orchiectomy, * Have a castrate level of testosterone (≤ 50 ng/dL) at enrollment * Have moderate-to-severe hot flashes defined as * Seven (7) or more hot flashes per day * Total hot flash severity (HFS: total number of hot flashes for 1 week multiplied by the average severity/week) ≥ 100 * Adequate organ function, defined as follows: Result Date * Leukocytes \> 1.5K/UL * Absolute Neutrophil Count (ANC) \>1.5K/UL NOTE: Patients with established diagnosis of benign neutropenia are eligible to participate with ANC between 1000-1500 if in the opinion of treating physician the trial treatment does not pose excessive risk of infection to the patient. * Platelets \>100K/UL * Hemoglobin ≥ 9 g/dL * Serum creatinine ≤ 1.5 x upper limit of normal (ULN) or calculated creatinine clearance ≥ 50 mL/min using the Cockcroft-Gault equation * Serum creatinine ≤ 1.5 x upper limit of normal (ULN) or calculated creatinine clearance ≥ 50 mL/min using the Cockcroft-Gault equation * Total bilirubin ≤ 1.5 x ULN OR direct bilirubin ≤ 1 x ULN * Aspartate aminotransferase and alanine aminotransferase ≤ 1.5 x ULN * Women of child-bearing potential and men with partners of childbearing potential must agree to practice sexual abstinence or to use the forms of contraception listed in Child-Bearing Potential/Pregnancy section for the duration of study participation and for 30 days following completion of therapy. Exclusion Criteria: * Concurrent invasive malignancy or invasive malignancy within 2 years except for chronic lymphocytic leukemia/small lymphocytic lymphoma on surveillance, suspected or proven clinical stage 1 (cT1) renal cell carcinoma on active surveillance, or the following malignancies treated with curative intent via surgical resection: carcinoma in situ of the cervix, ductal carcinoma in situ of the breast, low-grade non-muscle-invasive urothelial carcinoma, non-melanoma skin cancer. * Simultaneously enrolled in any therapeutic clinical trial * Current or anticipating use of other pharmacologic anti-neoplastic (including hormonal), or investigational agents while participating in this study. Concurrent treatment with radiotherapy is permitted. * Diagnosed with a psychiatric illness or is in a social situation that would limit compliance with study requirements * Has a known allergic reaction to any excipient contained in the study drug formulation * Active Grade 3 (per the NCI CTCAE, Version 5.0) or higher viral, bacterial, or fungal infection within 2 weeks prior to the first dose of study treatment. * Participants using the following medications within 2 weeks prior to first dosing (or within 5 times the half-life of that medication, whichever is longer) will be excluded from the study: * Inhibitors of CYP3A4 (including but not limited to macrolide antibiotics, HIV protease inhibitor, azole antifungal drugs, cyclosporine, calcium channel inhibitor, cimetidine) * Inducers of CYP3A4 (including but not limited to rifampicin, carbamazepine, efavirenz, bosentan, modafinil, St. John's Wort), Medications with narrow therapeutic index that are metabolized CYP3A4 and/or CYP2D6 are not allowed from screening until up to 5 half-lives after last dose of Osanetant is administered.