Abstract CT-04: A phase II study of neoadjuvant metformin in prostatic carcinoma

Abstract

Abstract Background: Metformin is an inhibitor of the complex 1 in the respiratory chain, and is widely used in diabetes due to its effect on reducing insulin resistance. It has also been recently described to have effects via AMPK on inhibiting the mTOR kinase. Significant preclinical and epidemiological studies suggest its role in chemoprevention. These actions provide significant rationale to evaluate its utility in prostate cancer. We conducted a phase II single centre study of neoadjuvant metformin in localised prostate cancer. Methods: Men were required to have histologically confirmed prostate cancer involving at least 20% of at least 1 unfragmented biopsy core. Exclusion criteria included patients who on initial assessment are found to be on treatment with any drug used for the treatment of any form of diabetes, or patients that begin treatment for any form of diabetes during the course of the study. Pts were treated with up to 500mg tid of metformin. The primary objectives were to demonstrate safety and tolerability of neoadjuvant metformin administration in men with prostate cancer and to document changes in phospho-AKT signalling indices. Results: 24 patients were enrolled with 22 evaluable; median age was 64 yrs (range, 45-70 yrs). Baseline characteristics included median PSA 6 ng/mL (range, 3.22-36.11ng/mL). Median duration of drug treatment was 41 days (range 18-81). No grade 3 adverse events were reported, all patients underwent subsequent radical prostatectomy with adverse effects related to metformin. Significant pre-and post changes were noted in serum IGF1 (p=0.02), fasting glucose (p=0.03), BMI (p<0.01) and waist/hip ratio (p<0.01). There was a trend for a PSA reduction (p=0.08). There were no correlations between any metabolic, morphometric or cancer-related serum indices. Conclusions: Neoadjuvant metformin is well tolerated prior to radical prostatectomy. Data to date indicates promising effects on metabolic parameters, tissue results will be presented including proliferation indices and signaling pathway assessments. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr CT-04. doi:1538-7445.AM2012-CT-04