This study firstly confirmed the in vitro anti-leukemic activity of coumarin derivatives DBH2 in not only the K562 cells, but the bone marrow cells from SCL-tTA-BCR/ABL transgenic model mice and CML patients, and in contrast to the IC50 of coumarin derivatives reported in other cancer cells, these compounds inhibited the proliferation of CML cells much more effectively. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.