Chronic myeloid leukaemia (CML) is a myeloproliferative neoplasm characterised by the presence of the BCR::ABL1 fusion transcript. Despite the effectiveness of tyrosine kinase inhibitors (TKIs), factors such as treatment adherence, intolerance, and resistance significantly influence therapeutic outcomes. The assessment of local cohorts enables a better understanding of disease progression, treatment patterns, and prognostic implications in specific populations.

To describe the clinical and laboratory characteristics, therapeutic patterns, and outcomes of a retrospective cohort of CML patients followed at a referral centre between 2006 and 2024.

This was a retrospective observational study involving 176 patients with confirmed CML by cytogenetics or RT-qPCR. Clinical, haematological, and molecular data were analysed, including disease phase, TKI use, treatment adherence, intolerance, and cause of death.

Most patients were male (57.1%) and lived in the state capital (51%), with a median age of 45.9 years. At diagnosis, 86% were in the chronic phase. Marked leucocytosis (median: 181,500/mm3) and elevated LDH (median: 1,049 U/L) were observed. Prognostic scores showed a median EUTOS of 60 and ELTS of 1.28. Molecular response improved progressively: baseline BCR::ABL1 was 92%, dropping to 0.02% at the last follow-up, consistent with major molecular response in most patients. While 44.9% remained on first-line imatinib, 55.1% required second-line therapy, predominantly nilotinib (64%). Of those, 26.8% progressed to a third-line regimen, including ponatinib in selected cases. Treatment adherence was documented in 90 patients, with 92.2% considered adherent. Clinically documented intolerance occurred in 11.1% of patients. Eleven deaths were recorded, 81.8% due to disease progression.

The cohort reflects demographic and clinical features, with diagnosis predominantly in young to middle-aged adults and in the chronic phase. The high rate of molecular response supports TKI efficacy. However, over half of the patients required treatment escalation, highlighting the importance of close monitoring. Adherence appeared high but may be overestimated due to reliance on medical records. Although the intolerance rate was low, it significantly impacted treatment strategies. Disease progression remained the leading cause of mortality, underlining the relevance of therapeutic resistance.

This analysis confirms the therapeutic success of TKIs in CML management, though emphasises the ongoing challenge of resistance and the need for TKI change therapy. The high adherence and molecular response rates reflect favourable outcomes in most patients, reinforcing the importance of long-term follow- up and personalised approaches to treatment optimisation.