Context: The fusion gene BCR-ABL1 is present in at least the fourth part of B-cell acute lymphoblastic leukemia adult cases. Patients with this fusion gene are candidates to tyrosine kinase inhibitors treatment, and the response to this therapy can be measure by quantification of BCR-ABL1 transcripts. Some patients relapse because the presence of mutations in the tyrosine kinase domain of BCR-ABL1.
Case report: This is a report of a patient with BCR-ABL1 who initially achieved molecular response with imatinib therapy, relapsing after fifteen months. The treatment was changed to dasatinib, but the patient doesn't achieve molecular response. Retrospectively, we analyzed the tyrosine kinase domain of BCR-ABL1 and we found three mutations (E459K, E255K and V299L).
Conclusions: We conclude that gain of mutations during treatment with TKIs has strong impact in the progress of disease, being relevant the detection of BCR-ABL1 mutations in relapsed patients or in case of BCR-ABL1 persistence.