Recently, the use of metformin has been combined with tyrosine kinase inhibitors (imatinib, sorafenib), and it has been effective in improving responses in cases of not only chronic myeloid leukemia but also myeloid leukemia with mutations in FLT3/ITD [28, 29]. Here, FLT3 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.