Given the importance of drug transporters in CML treatment, we evaluated the possible association of ABCB1, ABCG2, SLC22A1, and SLC22A5 genetic variants with disease prognosis (TKI response rates, number of TKIs required, and mutational state). The gene discussed is ABCB1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.