BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Compared with CML patients with typical BCR::ABL (P210), patients with the a3 type had a better response to imatinib.[18] In 2019, Xue et al[19] identified 40 patients (1.7%) with rare BCR::ABL1 transcripts from a cohort of 2331 patients with CML, including 7 with e14a3 and 2 with e13a3.