Metformin Prostate Cancer Adjuvant Trial

Prostate cancer patients who have received treatment with radiation therapy or surgery, who
have indicators of high-risk disease will be administered 750mg Metformin Extended Release
twice per day for a period of 9 months. Metformin is an FDA-approved drug that is prescribed
to treat high blood sugar levels in patients with Type 2 Diabetes. To track prostate cancer
response in study participants, investigators will obtain prostate specific antigen (PSA)
levels every three months for the duration of the trial.

Inclusion Criteria:

- Male > 18 years of age

- Biopsy confirmed adenocarcinoma of the prostate

- Able to swallow and retain oral medication

- Hemoglobin A1C <7.0%

- Able and willing to participate in the full 12 months of the study

- Able to understand instructions related to study procedures

- Able to read and write English

Exclusion Criteria:

- Metastatic Prostate Cancer

- Prostate Specific Antigen Doubling Time < 6 months

- Prior Chemotherapy, hormonal therapy, oral glucocorticoid therapy,
Gonadotropin-releasing hormone analogue therapy

- Current or previous use of 5α-reductase inhibitors, antiandrogen drugs, metformin,
oral or injectable diabetes drug

- Diagnosis of Type 1 Diabetes Mellitus

- Known hypersensitivity to metformin

- any condition associated with increased risk of metformin associated lactic acidosis

- participation in any investigational or marketed drug trial within 30 days prior to
screening or during study period

- any unstable, serious co-existing medical conditions including but not limited to
myocardial infarction, coronary bypass surgery, unstable angina, cardiac arrhythmias,
clinically evident congestive heart failure, or cerebrovascular accident within 6
months prior to screening

- history of megaloblastic anemia

- abnormal liver function test (total bilirubin, aspartate aminotransferase, alanine
aminotransferase, alkaline phosphatase or serum creatinine above upper limit of
normal)

- history of other malignancies, with the exception of adequately treated non-melanoma
skin cancer, stage 1 melanoma, non-muscle invasive bladder cancer, or other solid
tumors curatively treated with no evidence of disease for at least 5 years

- history or current evidence of substance abuse within 12 months of screening

- history of any illness (including psychiatric) that, in the opinion of the
investigator, might confound the results of the study or post an additional risk to
the subject