Low Dose Naltrexone (LDN) for Management of Fatigue in Prostate Cancer Patients on Androgen Deprivation Therapy (ADT)

Inclusion Criteria * Histologically or cytologically confirmed biochemical recurrence and on ADT for at least 3 months. Metastatic castrate-sensitive and castrate-resistant prostate cancer on ADT with or without novel hormonal therapy like apalutamide, darolutamide, enzalutamide and abiraterone. * Initiation of hormonal ablative therapy within 3 months of registration. * ECOG performance status \<3. * Patients must have normal organ and marrow function as defined below: * leukocytes \>3,000/μL * absolute neutrophil count \>1,500/μL * platelets \>100,000/μL * total bilirubin within normal institutional limits * AST(SGOT)/ALT(SGPT) \<2.5 X institutional upper limit of normal * creatinine ≤2.5.0 * left ventricular ejection fraction \>45% * FACIT-F score \< 43 on screening * Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria * Prior chemotherapy received in the last three months. * Patients currently on PARP inhibitors. * Currently taking or have taken within 10 days of enrollment. * Patients may not be receiving any other investigational agents. * History of allergic reactions attributed to compounds of similar chemical or biologic composition to Naltrexone or other agents used in the study. * History of other malignancies other than nonmelanoma skin cancer, unless in complete remission and off therapy for that disease for at least 5 years. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, history of congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Any Patient with acute hepatitis and liver failure are excluded.