Results from a multicenter phase 2 clinical trial showed that metformin could yield objective PSA responses and induce disease stabilization for chemotherapy-naive CRPC.27 We found that combinatorial treatment of metformin and bicalutamide can additively repress the growth of prostate cancer.26 In this research, we demonstrated that metformin is capable of inhibiting enzalutamide-induced EMT in prostate cancer cells via repressing TGF-β1/STAT3 axis. Here, TGFB1 is linked to prostate cancer.