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

The study is being done to see if a small daily dose of naltrexone (LDN, 3 mg pill) can help reduce tiredness (fatigue) in men with prostate cancer. All men in this study are being treated with hormone therapy (also called androgen deprivation therapy, or ADT). Some may also be taking newer hormone medicines such as apalutamide, daralutamide, enzalutamide, or abiraterone.

The purpose of this study is to learn if low dose naltrexone can safely improve energy and reduce fatigue in men receiving these treatments. Primary Objectives 1. Characterize mitochondrial bioenergetics, inflammation and oxidative stress after ADT and the remediating effects of LDN. 2. Assess the impact of low-dose naltrexone (LDN) on Cancer-related fatigue as measured by the FACIT-F questionnaire. Secondary Objectives 1. Evaluate quality of life (QOL) measures \[Functional Assessment of Cancer Therapy-Prostate (FACT-P) on subjects receiving LDN. 2. Evaluate safety and tolerability of LDN.

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.