Abstract 3269: Metformin to prevent metabolic syndrome associated with androgen deprivation therapy (ADT): Metabolic analysis from a placebo-controlled study of metformin in non-diabetic men initiating ADT for advanced prostate cancer (PCa)

Abstract

Abstract Background: ADT results in metabolic syndrome, characterized by hyperinsulinemia, insulin resistance and obesity. The hyperinsulinemia may result in ADT resistance; therefore preventing metabolic syndrome could have a therapeutic impact on PCa. Metformin decreases glucose & insulin by inhibiting hepatic gluconeogenesis. There is preclinical evidence for additional antineoplastic activity due to mTOR inhibition secondary to AMPK activation. Methods: We analyzed serum and PBMC from a recently completed clinical study of men with advanced PCa on ADT that were randomized 1:1 to metformin at 500mg TID or color matched placebo. Subjects serum insulin/glucose, metformin levels, weight and waist circumference (WC) was assessed at baseline, week 12 and 28. The primary endpoint of study was the metabolic consequences of metformin vs placebo cohort. Secondary endpoints were PSA response and PBMC analysis of downstream target of mTOR, phospho-S6 kinase. Results: There were 36 evaluable men. The mean age on study was 68.4. Mean weight, WC and insulin at baseline in metformin cohort was 187 lbs, 41.14 cm and 10.03 mIU/L respectively, and 177.65 lbs, 40.52 cm and 8.02 mIU/L in placebo cohort. An increase in mean weight, WC and insulin levels was seen in both cohorts. At week 12 and 28, no statistical difference in weight, WC and insulin was observe in either cohort. Four men randomized to metformin had undetectable serum drug levels despite drug-diary suggesting compliance; excluding them did not result in significant metabolic change. Assessing efficacy, 50% in metformin and 53.3% in placebo cohort achieved undetectable PSA at week 28; difference not statistically significant. PBMC analysis demonstrated variable down-regulation of phospho-S6 kinase in the metformin cohort. Conclusion: This study detected no impact of MET addition to ADT on the risk of metabolic syndrome and no additional anti-tumor effects. Control of hyperinsulinemia related to diabetes by MET does not necessarily imply MET has a similar action on hyperinsulinemia due to ADT. Citation Format: Devalingam Mahalingam, Salih Hanni, Christos Fountzilas, Joel Michalek, John Sarantopoulos, Sureshkumar Mulampurath Achuthan Pillai, John Kuhn, Michael Pollak, Ian Thompson. Metformin to prevent metabolic syndrome associated with androgen deprivation therapy (ADT): Metabolic analysis from a placebo-controlled study of metformin in non-diabetic men initiating ADT for advanced prostate cancer (PCa) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3269.