Tyrosine kinase domain mutations (TKDMs) plays an important role in prognosis of chronic myeloid leukemia (CML). The aim of the present study was to identify the TKDMs associated with imatinib mesylate (IM) drug resistant in CML, following European leukemia Net (ELN) guidelines. Direct sequencing analysis revealed point mutations in 69.44 % (50/72), compound/ polyclonal mutations in 11.11 % (8/72) and large deletions in 4.16 % (3/72) of IM non-responder CML patients. Additionally, we have identified low level mutations in 30.55 % of warning group patients through NGS analysis, that include singly occurring point mutations (5) and polyclonal (6) mutations with mutant allele frequency ranging from 1.1 % to 14.70 %. The low-level mutations detected through NGS in warning group patients
may be responsible for suboptimal response in our study. However, follow-up studies are important to understand the mechanism of clonal evolution. We also identified 5 novel mutations that had not been reported in public databases which expands the spectrum of known mutations in BCR::ABL1 fusion gene. Our study also highlighted the impact on patient outcomes following the implementation of ELN guidelines underscores the importance of adherence to standardized protocols in clinical practice.