ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Furthermore, Cortes et al showed that Ph+ ALL patients with E255 V/K at baseline achieved a worse response to ponatinib than chronic-phase chronic myeloid leukemia patients with the same mutation.[5] All the above data suggested that ponatinib, which is an active pan-inhibitor of BCR-ABL, including the T315I mutation, might not be effective for Ph+ ALL patients with E255 V/K mutation-based resistance.