Metformin for Rising PSA Remote Trial

Men with an isolated PSA recurrence after local therapy are an ideal population for the evaluation of novel therapies given the minimal disease burden, generally indolent natural history, and patients' preference to avoid the adverse effects of androgen deprivation therapy. Metformin has shown anti-prostate cancer activity in preclinical models and cohort studies. Metformin, a biguanide oral antihyperglycemic agent, abrogates hyperinsulinemia in individuals with and without diabetes and has shown promising anti-prostate cancer activity in preclinical models, epidemiologic studies, and retrospective cohorts. Several epidemiologic/retrospective studies have shown that metformin has a positive impact on overall survival among men with prostate cancer. These nonclinical and clinical studies have led to calls for prospective studies of metformin in patients with prostate cancer. This is a pilot telemedicine study of metformin in patients with a rising PSA ("biochemical recurrence") after definitive local therapy for prostate cancer. The current study is supported by the following rationale: * A large proportion of clinical trials close prematurely due to poor accrual. * Geographic inaccessibility is a barrier to clinical trial participation. * Metformin is a safe and inexpensive medication that has demonstrated anti-prostate cancer activity in nonclinical and epidemiologic studies. Importantly, metformin has been shown to be safe in non-diabetic patients (e.g., patients with polycystic ovary disease) and does not cause hypoglycemia. * Use of novel technologies may facilitate clinical trial accrual and minimize the burden of participation for patients. Ultimately, these approaches may also decrease the cost of drug development and increase the pace of progress. In the absence of prohibitive toxicities or disease progression (defined in 4.4), patients may continue treatment for the 6-month study period. This study will include a baseline visit for study enrollment at Mount Sinai. The remainder of the visits will be telemedicine visits conducted using secure video conferencing.