Low Dose Naltrexone for Metastatic Melanoma, Castrate Resistant Prostate Cancer and Renal Cancer

Three types of solid tumors will be studied in this protocol: Melanoma, castrate resistant prostate cancer and kidney cancer. Systemic chemotherapy may weaken the immune system reducing the potential for response to LDN. Therefore, patients must either have not had previous chemotherapy or patients must not have received more than 1 prior chemotherapy regimen which must have been completed at least 6 months prior to LDN. Systemic chemotherapy has at best modest activity in melanoma, CRPC and renal cancer. * Melanoma will be evaluated since the responding patient at the Miriam Hospital had melanoma. Immunomodulatory agents such as ipilimumab have already demonstrated a survival advantage in melanoma. * Castrate Resistant Prostate Cancer (CRPC): It is common in CRPC for patients to have rising PSA after failure of androgen deprivation. These patients may be asymptomatic or minimally symptomatic and there is reluctance to initiate treatment with systemic chemotherapy with standard docetaxel since this agent has substantial toxicity and will impair quality of life. Waiting until symptomatic disease progression in patients with CRPC and rising PSA is a commonly utilized strategy. These patients are excellent candidates for a treatment with minimal toxicity such as LDA. The immunomodulatory agent Sipuleucel also improves survival in prostate cancer suggesting that an agent such as LDN could also be helpful. * Renal cancer will also be studied since this is a disease that has activity with immunomodulants such as IL-2 and interferon. Targeted therapies are generally used for renal cancer. Chemotherapy has minimal activity so most patients are chemotherapy-naive.