ABSTRACT
INTRODUCTION: The T315I mutation in patients with chronic myeloid leukemia (CML) has been associated with therapeutic resistance and an unfavourable prognosis. AIM: To study the frequency of T315I mutation in patients with CML, BCR-ABL (+), their clinical characteristics, disease evolution, and median survival. PATIENTS AND METHODS: We studied 75 patients with CML and BCR-ABL1 (+). T315I mutation was detected by digital droplet PCR and BCR-ABL1 was analyzed by RT-PCR. A comparative analysis was performed by sex, age, disease phase, risk group, treatment, molecular response (MR), and median survival in T315I (+) and T315I (-) patients. RESULTS: T315I mutation was detected in 11 patients (14.7%). No significant difference was found in the phase, risk group, and first-line therapy. A significantly higher proportion of T315I (+) did not achieve MR >3.5 log: 8 (72.7%) vs. 22 (34.4%) (p=0.023). The lowest mean BCR-ABL1 levels were significantly higher in the CML T315I (+) group compared to the CML T315I (-) group: 12.1±6.0 vs. 3.77±1.28 (p=0.009). The median survival of T315I (+) patients was significantly shorter: 73 months vs. 175 months (p<0.0001, CI 95%). CONCLUSIONS: Our data confirm the world experience on the frequency of T315I mutation, including the unfavourable evolution, resistance to TKI treatment and short survival. ddPCR is a highly sensitive method for early detection of genetic mutations which gives the chance for effective treatment.
Subject(s)
Leukemia, Myelogenous, Chronic, BCR-ABL Positive , Protein Kinase Inhibitors , Drug Resistance, Neoplasm/genetics , Fusion Proteins, bcr-abl/genetics , Humans , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics , Mutation , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic useABSTRACT
Chronic myeloid leukemia (CML) arises from the fusion of the BCR and the ABL1 genes. The BCR gene (chromosome 22q11.2) and the ABL1 gene (chromosome 9q34) fuse together due to reciprocal chromosome translocation forming the Philadelphia chromosome (Ph). This fusion gene codes tyrosine kinase which accelerates the cell division and reduces DNA repair. Imatinib mesylate is a selective inhibitor of this tyrosine kinase. It is the first-line treatment for CML-patients. However, it became clear that Philadelphia-positive (Ph+) cells could evolve to elude inhibition due to point mutations within the BCR-ABL kinase domain. To date more than 40 mutations have been identified and their early detection is important for clinical treatment. With the development of the new tyrosine kinase inhibitors (TKIs), associated with these mutations, the resistance problem seems to diminish, as some of the new drugs are less prone to resistance. The aim of this review is to focus on the diff erent mutations leading to resistance.
