Imatinib-induced severe hematological toxicity: Prolonged myelosuppression resulting from extraordinary sensitivity in an old age

Abstract

The advent of tyrosine kinase inhibitors (TKIs) has profoundly changed the therapeutic landscape of chronic myeloid leukemia (CML) in the chronic phase (CML-CP). Imatinib is the first-generation, and the first and as yet the most widely used TKI, and the recommended dose is 400 mg/day for treating CML-CP. Most patients tolerate this treatment well, and prolonged hematological toxicities have rarely been reported. In this manuscript, we report a newly diagnosed CML-CP patient who developed prolonged myelosuppression (lasting for more than three months) following only one week of imatinib at 400 mg/day as the solitary treatment. Imatinib was discontinued, and pancytopenia persisted, with a continuous decrease in hemoglobulin levels. After restoration of autologous hematopoiesis, reintroduction of imatinib at 100 mg/day resulted in recurrent myelosuppression, and subsequent treatment with imatinib at 50 mg/day achieved good hematological homeostasis. We hypothesized that extraordinary sensitivity resulted in severe and prolonged myelosuppression.