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Metformin in chemotherapy-naive castration-resistant prostate cancer: a multicenter phase 2 trial (SAKK 08/09)


Rothermundt, Christian; Hayoz, Stefanie; Templeton, Arnoud J; Winterhalder, Ralph; Strebel, Räto T; Bärtschi, Daniela; Pollak, Michael; Lui, Lillianne; Endt, Kathrin; Schiess, Ralph; Rüschoff, Jan H; Cathomas, Richard; Gillessen, Silke (2014). Metformin in chemotherapy-naive castration-resistant prostate cancer: a multicenter phase 2 trial (SAKK 08/09). European Urology, 66(3):468-474.

Abstract

BACKGROUND There is evidence linking metformin to improved prostate cancer (PCa)-related outcomes. OBJECTIVE To evaluate treatment with metformin in patients with castration-resistant PCa (CRPC) and the effect of the treatment on progression-free survival (PFS) and PSA doubling time (PSA DT). DESIGN, SETTING, AND PARTICIPANTS Forty-four men with progressive metastatic CRPC from 10 Swiss centers were included in this single-arm phase 2 trial between December 2010 and December 2011. INTERVENTION Patients received metformin 1000 mg twice daily until disease progression. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The primary end point was the absence of disease progression at 12 wk. Simon two-stage optimal design was applied. With a 5% significance level and 90% power, 44 patients were required to test PFS at 12 wk ≤ 15% (H0) compared with ≥ 35% (H1). RESULTS AND LIMITATIONS Thirty-six percent of patients were progression-free at 12 wk, 9.1% were progression-free at 24 wk, and in two patients a confirmed ≥ 50% prostate-specific antigen (PSA) decline was demonstrated. In 23 patients (52.3%) we observed a prolongation of PSA DT after starting metformin. The homeostatic model assessment index fell by 26% from baseline to 12 wk, indicating an improvement in insulin sensitivity. There was a significant change in insulin-like growth factor-1 and insulin-like growth factor binding protein 3 from baseline to 12 wk. Sample size and lack of a control arm are the limitations of this trial; analyses are therefore exploratory. CONCLUSIONS Treatment with metformin is safe in nondiabetic patients, and it yields objective PSA responses and may induce disease stabilization. The activity of metformin in PCa, along with its low cost, favorable toxicity profile, and positive effect on metabolic parameters, suggests that further investigation of metformin as therapy for patients with PCa is of interest. PATIENT SUMMARY In this trial we assessed the use of the diabetes mellitus drug metformin in patients with advanced prostate cancer. We found disease stabilization and prolongation of prostate-specific antigen doubling time in some patients as well as effects on metabolic parameters. TRIAL REGISTRATION This study is registered with ClinicalTrials.gov with the identifier NCT01243385. PREVIOUS PRESENTATION The study was presented at ESMO 2012 (abstract 1460).

Abstract

BACKGROUND There is evidence linking metformin to improved prostate cancer (PCa)-related outcomes. OBJECTIVE To evaluate treatment with metformin in patients with castration-resistant PCa (CRPC) and the effect of the treatment on progression-free survival (PFS) and PSA doubling time (PSA DT). DESIGN, SETTING, AND PARTICIPANTS Forty-four men with progressive metastatic CRPC from 10 Swiss centers were included in this single-arm phase 2 trial between December 2010 and December 2011. INTERVENTION Patients received metformin 1000 mg twice daily until disease progression. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The primary end point was the absence of disease progression at 12 wk. Simon two-stage optimal design was applied. With a 5% significance level and 90% power, 44 patients were required to test PFS at 12 wk ≤ 15% (H0) compared with ≥ 35% (H1). RESULTS AND LIMITATIONS Thirty-six percent of patients were progression-free at 12 wk, 9.1% were progression-free at 24 wk, and in two patients a confirmed ≥ 50% prostate-specific antigen (PSA) decline was demonstrated. In 23 patients (52.3%) we observed a prolongation of PSA DT after starting metformin. The homeostatic model assessment index fell by 26% from baseline to 12 wk, indicating an improvement in insulin sensitivity. There was a significant change in insulin-like growth factor-1 and insulin-like growth factor binding protein 3 from baseline to 12 wk. Sample size and lack of a control arm are the limitations of this trial; analyses are therefore exploratory. CONCLUSIONS Treatment with metformin is safe in nondiabetic patients, and it yields objective PSA responses and may induce disease stabilization. The activity of metformin in PCa, along with its low cost, favorable toxicity profile, and positive effect on metabolic parameters, suggests that further investigation of metformin as therapy for patients with PCa is of interest. PATIENT SUMMARY In this trial we assessed the use of the diabetes mellitus drug metformin in patients with advanced prostate cancer. We found disease stabilization and prolongation of prostate-specific antigen doubling time in some patients as well as effects on metabolic parameters. TRIAL REGISTRATION This study is registered with ClinicalTrials.gov with the identifier NCT01243385. PREVIOUS PRESENTATION The study was presented at ESMO 2012 (abstract 1460).

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Institute of Pathology and Molecular Pathology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:September 2014
Deposited On:28 Dec 2018 07:59
Last Modified:28 Dec 2018 08:02
Publisher:Elsevier
ISSN:0302-2838
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.eururo.2013.12.057
PubMed ID:24412228

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