The invention relates to a CDC25A phosphatase inhibitor for use in the treatment of drug resistant cancer or for use in the prevention of tumor relapse in a patient suffering or having suffered from cancer.rnIn a preferred embodiment, the drug resistant cancer according to the invention is associated with a mutated FLT3-ITD such as Acute Myeloid Leukemia (AML).rnAutors demonstrate that inhibiting CDC25A reduces proliferation and induces monocytic differentiation of FLT3-ITD-positive AML cells in vitro and in vivo, and they argue for a central function of this phosphatase in the hematopoieticrndifferentiation arrest of these cells.rn