Evaluating the benefits of metformin during treatment of metastatic prostate cancer with androgen deprivation therapy

For men with newly diagnosed metastatic prostate cancer who will be treated with androgen deprivation. This world-first study evaluates the benefits of a common diabetes drug, metformin, in helping men undergoing androgen deprivation therapy.

Patients with metastatic prostate cancer are usually treated with androgen deprivation therapy. 

Although successful in the short term, the cancer eventually progresses.  It is thought that the side effects of androgen deprivation such as obesity and high levels of insulin contribute towards treatment resistance.  Metformin is the most commonly used diabetic medication in the world.  It lowers insulin and helps patients lose weight.  The purpose of this study is to evaluate whether metformin will help delay treatment resistance.

This is a multicentre, prospective, randomised, controlled pilot study. Patients are being recruited through the Princess Alexandra Hospital in Brisbane, Gold Coast University Hospital in Southport, and Epworth Healthcare Centre in Melbourne.

Inclusion Criteria

  • Metastatic prostate adenocarcinoma defined by radiological diagnosis (TNM staging), PSA ≥20 in the presence of tissue diagnosis or abnormal prostate examination, PSA recurrence post surgery or radiotherapy
  • No prior chemotherapy for prostate cancer
  • Not on insulin control medications [Insulin, oral hypoglycaemic agents, systemic corticosteroid, atypical antipsychotic drugs]
  • Adequate renal and liver function as per defined biochemical criteria
  • Life expectancy greater than 6 months

Exclusion Criteria

  • Known brain metastasis
  • Malignant disease other than prostate cancer at the time of enrolment, apart from completely treated non-melanomatous skin malignancy
  • Prior chemotherapy for prostate cancer
  • Prior primary radiotherapy within 6 weeks
  • Previously treated with ketoconazole for greater than 7 days
  • Prior systemic treatment with an azole drug within 4 weeks
  • Prior antiandrogen treatment within 6 weeks
  • History of lactic acidosis
  • History of pituitary or adrenal dysfunction
  • Cardiac (heart failure NYHA class II or greater, acute myocardial infarct, unstable angina, arterial-thromboembolic event within past 6 months) or respiratory insufficiency (active pulmonary embolism, severe chronic obstructive pulmonary disease), severe liver failure (cirrhosis with a Child-Pugh level of B or greater), severe infection that is likely to increase the risk of lactic acidosis
  • History of pituitary or adrenal dysfunction

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.

For more information please contact Dr Yang Sun, Principal Investigator GCUH (