Prolonged indolent clinical course in a high-risk chronic phase-CML patient without cytogenetic or molecular response: a case challenging established response paradigms

Chronic-phase chronic myeloid leukemia (CP-CML) is currently treated with tyrosine kinase inhibitors (TKIs), and the early achievement of cytogenetic and molecular milestones is strongly associated with improved clinical outcomes. Here, we describe the case of a 55-year-old woman diagnosed with CP-CML in 2002 who received sequential TKI therapy for more than 20 years. Despite continuous treatment, she never achieved a complete cytogenetic response (CCyR) or a major molecular response (MMR), and the BCR::ABL1 IS transcript levels remained above 10% for most of the disease course. At diagnosis, she presented with high-risk features, including p190 BCR::ABL1 transcript expression, and exhibited multiple mutations, but not driver ones, over time. Nevertheless, along with several TKIs treatments, she maintained a stable chronic-phase disease with sustained hematologic control and preserved a good quality of life throughout long-term follow-up. This case highlights the biological heterogeneity of CML, the timing and trajectory of BCR::ABL1-driven disease, the importance of patient-centered outcomes and the role of TKI therapy in maintaining durable hematologic remission and long-term disease control, even in the absence of optimal molecular milestones.