Asciminib and pulsed ATRA as post-remission therapy in T315I mutated PML-RARA-positive blast crisis of chronic myeloid leukemia.

Promyelocytic blast crisis (BC) of CML is an extremely rare event, with only seven cases described as arising during therapy with TKIs. We present a 68-year-old male who developed promyelocytic blast crisis 12 months after CML diagnosis and start of Imatinib therapy, confirmed by the concomitant presence of the t(15;17) and t(9;22) translocations in the leukemic cells. Molecular remission for the PML-RARA clone was achieved with standard acute promyelocytic leukemia induction therapy with ATRA and idarubicin. However, BCR-ABL showed resistance to first-line Dasatinib and second-line Ponatinib, principally due to the presence of multiple mutations in ABL1 kinase domain, including T315I. Hematological and molecular response was achieved with Asciminib, a first‐in‐class STAMP (Specifically Targeting the ABL Myristoyl Pocket) inhibitor in combination with pulsed ATRA as post-remission strategy. Of the 7 cases of promyelocytic BC reported in the era of TKI therapy for CML, this is the first case effectively treated with Asciminib therapy.