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Table 1 Objectives

From: Metformin and longevity (METAL): a window of opportunity study investigating the biological effects of metformin in localised prostate cancer

Objectives Endpoints
Primary endpoints  
 To determine the biological effect of metformin on markers of the FASN/AMPK pathway in prostate tissue by comparison of pre and post-treatment samples. Assessment of the difference in expression levels of markers of the FASN/AMPK pathway pre and post treatment between the placebo and metformin arms.
Secondary endpoints  
 To evaluate the biological effect of metformin on markers of proliferation in prostate tissue by comparison of pre and post-treatment samples. Assessment of the difference in expression levels of indicators of proliferation (ki67 and Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)) pre and post treatment between the placebo and metformin arms.
 To evaluate differences in FASN/AMPK-associated markers in benign and malignant prostate tissue. Assessment of the difference in expression levels of markers of the FASN/AMPK pathway and indicators of proliferation between benign and malignant prostate tissue in the placebo and metformin arms.
 To measure metformin levels in prostate tissue. Assessment of the difference in metformin levels in baseline and post-treatment prostate tissue.
 To determine safety of metformin in this non-diabetic patient cohort. Assessment of adverse events and laboratory evaluations.
 To determine surgical toxicity. Assessment of surgical-specific toxicities: time between biopsy and surgery, peri-operative bleeding, infection, rectal injury and length of hospital stay.
Exploratory Objectives and Endpoints  
 To evaluate the effects of metformin on functional imaging of the prostate. Difference in 18F Choline PET/MRI between baseline and post-treatment (prior to prostatectomy) in a separate non-randomised cohort of five patients with MRI positive disease receiving metformin.