Molecular response in long-term monitoring of patients with chronic myelogenic leukemia (CML) on nilotinib therapy

Targeted therapy with tyrosine kinase inhibitors (TKIs) was introduced for the suppression of BCR-ABL fusion protein in chronic myelogenic leukemia (CML) more than 50 years ago. The introduction of TKI was an elegant way to gain control over the disease and opened a horizon to the development of new and safer drugs to better manage the disease progression in CML patients. Although Imatinib (the first TKI) was highly effective for the treatment of CML, the lack of response in some patients and the development of resistance led to the introduction of a second-generation TKI, like Nilotinib (Tasigna®). This study aimed to show the molecular response to Nilotinib after a long-term monitoring of CML patients. We analyzed the molecular response rate of twenty-seven CML patients admitted to the Hematology Ward. All of them were subjected to multiple control measurements of Philadelphia chromosome once in at least three months’ period between January 2017 and March 2020. All patients showed a remarkable decrease in the level of the fusion gene’s expression. The highest drop in the expression level was detected after the first dose admission. Some of the patients even reached an expression of BCR-ABL below the detection limit and it was maintained stably low during further examinations. In our patients with CML, Nilotinib resulted in prolonged and deep molecular response. The expression level of BCR-ABL fusion gene showed a substantial decrease immediately after Nilotinib treatment, revealed as early as the third month of therapy.