Assessment of Transitioning from High-Potency to Low-Potency Inhibitors in Chronic Myeloid Leukemia (CML) Patients: The Downgrading-Impact (D-IMPACT) Project

Background: Since the advent of imatinib, more potent next-generation tyrosine kinase inhibitors (TKIs) and asciminib have expanded therapeutic options for chronic myeloid leukemia (CML). Treatment-free remission (TFR) is an important goal in CML management, but only ~30% of patients can achieve it, leaving many on lifelong therapy. TKIs are usually used in escalating order of potency, but in patients ineligible for or failing TFR, "downgrading" to safer, lower-potency agents may be advantageous. Methods: We analyzed this strategy in 157 patients across 29 Italian CML Campus centres. Data were collected via e-forms in July 2024. Prognostic scores at diagnosis did not influence downgrading. Results: The most downgraded TKIs were nilotinib (47%) and dasatinib (37%). Imatinib was the most frequent target agent (69.7%), followed by nilotinib and bosutinib. The majority underwent downgrading during first-line therapy and most after prior dose de-escalation. Adverse events were the leading reason for downgrading (79%). Notably, in 52.6% of cases, molecular responses improved afterwards. Twenty-one patients subsequently attempted TFR, with 17 (81%) remaining treatment-free at a median follow-up of 22 months. Conclusions: These results show that, beyond the known role of de-escalation, downgrading represents a new, feasible approach to maintaining long-term control, limiting toxicity and costs, and favouring TFR.