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A Randomized Phase 3 Trial of Metformin in Patients Initiating Androgen Deprivation Therapy as Prevention and
Bernhard J Eigl1, Arun Elangovan2, Sunita Ghosh3
1Department of Medical Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.
Purpose:
We investigated whether metformin decreases metabolic syndrome (MS) risk in patients with prostate cancer (PCa) receiving androgen deprivation therapy (ADT).
Materials And Methods:
In this phase 3, multicenter, double-blind, randomized controlled trial, normoglycemic patients with PCa planned for at least 9 months of ADT were randomized 2:1 to receive metformin 850 mg or placebo twice daily orally for 18 months. The primary objective was to compare proportions of MS at 18 months between the study arms.
Results:
Between July 2018 and November 2023, 166 patients were randomized. The trial closed prematurely on November 24, 2023, because of drug supply cessation and the planned enrollment numbers (n = 300) were not met. A total of 90 (metformin) and 45 patients (placebo) were analyzed in the final analysis. The median follow-up was 24 months (IQR: 19.5-36 months). Proportions of MS between metformin and placebo arms were 38/90 (42%) vs 26/45 (58%) at baseline (P = .09) and 40/73 (55%) vs 23/34 (68%) at 18 months (P = .2). Significant reductions in mean (SD) body weight occurred with metformin at 9 (-0.9 [4] vs +1.8 [3.8] kg; P < .001) and 12 months (-0.33 [3.9] vs +1.8 [3.9] kg; P = .004). Mean (SD) hemoglobin A1c was lowered with metformin at 9% (-0.02% [0.23%] vs +0.08% [0.26%]; P = .02) and 12 months (+0.03% [0.27%] vs +0.08% [0.27%]; P = .03). Significantly smaller increments in mean (SD) waist circumferences were noted with metformin at 9 (+0.8 [4.3] vs +2.9 [5.7] cm; P = .03), 12 (+1.9 [5.1] vs +3.3 [6] cm; P = .15), and 18 months (+1.8 [3.8] vs +3.8 [6.1] cm; P = .03).
Conclusions:
Metformin did not reduce the risk of MS in patients with PCa on ADT. However, significant improvements in body weight, waist circumference, and hemoglobin A1c suggest a potential role for metformin in reducing ADT-related complications.
Insights
Metformin did not reduce metabolic syndrome risk in prostate cancer patients on androgen deprivation therapy. However, it showed benefits in weight, waist circumference, and HbA1c, potentially mitigating treatment side effects.
Area of Science:
- Oncology
- Endocrinology
- Metabolic Health
Background:
- Androgen deprivation therapy (ADT) for prostate cancer (PCa) is associated with increased metabolic syndrome (MS) risk.
- Metformin, a common diabetes drug, is being investigated for its potential to mitigate ADT-related metabolic complications.
Purpose of the Study:
- To evaluate the efficacy of metformin in reducing the risk of metabolic syndrome (MS) in patients with prostate cancer (PCa) undergoing androgen deprivation therapy (ADT).
Main Methods:
- A phase 3, multicenter, double-blind, randomized controlled trial involving normoglycemic PCa patients receiving ADT.
- Participants were randomized to receive metformin (850 mg BID) or placebo for 18 months.
- The primary endpoint was the proportion of patients developing MS at 18 months.
Main Results:
- The trial was prematurely closed due to drug supply issues, with 90 patients in the metformin arm and 45 in the placebo arm analyzed.
- Metformin did not significantly reduce the proportion of MS at 18 months (55% vs. 68%, P = .2).
- Significant reductions in body weight, waist circumference, and HbA1c were observed in the metformin group compared to placebo.
Conclusions:
- Metformin did not decrease the risk of metabolic syndrome in PCa patients on ADT.
- Despite not meeting the primary endpoint, metformin demonstrated potential benefits in managing ADT-associated weight gain, central obesity, and glycemic control.
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