ABCB1 and chronic myelogenous leukemia, BCR-ABL1 positive: However, a previous meta-analysis showed that neither ABCB1 c.2677G>T(A) nor c.3435C>T was a risk factor for poor clinical response of imatinib treatment in Asian CML patients, whereas c.1236C>T was a risk factor in Asian but not Caucasian CML patients (Zu et al., 2014; Zheng et al., 2015).