Conditions: Prostate Cancer
Keywords: castration-resistant prostate cancer insulin levels metformin
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 21
Healthy volunteers: no

Brief summary:
Metformin is a medication that is prescribed for people with diabetes to help the body respond better to its own insulin and decrease sugar production by the liver. This helps control the body's blood sugar level and is approved by the Food and Drug Administration (FDA) for the treatment of diabetes. Participant's in this research study will already be receiving androgen deprivation therapy (ADT) for prostate cancer. ADT is considered standard of care for prostate cancer. Changes in the participant's metabolism, including changes in insulin and blood sugar levels, are often seen as a result of this type of hormone therapy. Some studies have shown a relationship between insulin and prostate cancer. These studies have suggested that insulin may signal tumor cells to grow. Other studies suggest that people receiving metformin treatment for diabetes may enjoy better outcomes from their prostate cancer then other similar patients who are not treated with metformin.

Detailed description:
* Each treatment cycle lasts 4 weeks (28 days). Participants will take metformin twice a day for all 28 days (except for the first 7 days of the first cycle when they will take it just once daily.)
* The following procedures will be done on Day 1 of treatment cycles 1, 2, 4, 7 and 10: medical history review, performance status, physical exam, blood tests.
* If the participant's first computed tomography (CT) or bone scan at the time of screening showed evidence of cancer, CT and bone scans will be repeated on Day 1 of treatment cycles 4, 7 and 10.
* Participants will be in this research study for about 12 months.

Arms:
arm 1: This is the only arm of this phase 2 open label study

Interventions: intervention 1: Metformin
Intervention descriptions: intervention 1: Taken orally twice daily each 28-day cycle, for 12 cycles

Protocol document: