A Real-World Evidence-Based Study of Long-Term Tyrosine Kinase Inhibitors Dose Reduction or Discontinuation in Patients with Chronic Myeloid Leukaemia

The therapeutic approach to chronic myeloid leukaemia (CML) has changed in recent years. As a result, a high percentage of current patients in the chronic phase of the disease almost have an average life expectancy. Treatment also aims to achieve a stable deep molecular response (DMR) that might allow dose reduction or even treatment discontinuation. These strategies are often used in authentic practices to reduce adverse events, yet their impact on treatment-free remission (TFR) is a controversial debate. In some studies, it has been observed that as many as half of patients can achieve TFR after the discontinuation of TKI treatment. If TFR was more widespread and globally achievable, the perspective on toxicity could be changed. We retrospectively analysed 80 CML patients treated with tyrosine kinase inhibitor (TKI) at a tertiary hospital between 2002 and 2022. From them, 71 patients were treated with low doses of TKI, and 25 were eventually discontinued, 9 of them being discontinued without a previous dose reduction. Regarding patients treated with low doses, only 11 of them had molecular recurrence (15.4%), and the average molecular recurrence free survival (MRFS) was 24.6 months. The MRFS outcome was not affected by any of the variables examined, including gender, Sokal risk scores, prior treatment with interferon or hydroxycarbamide, age at the time of CML diagnosis, the initiation of low-dose therapy and the mean duration of TKI therapy. After TKI discontinuation, all but four patients maintained MMR, with a median follow-up of 29.2 months. In our study, TFR was estimated at 38.9 months (95% CI 4.1-73.9). This study indicates that low-dose treatment and/or TKI discontinuation is a salient, safe alternative to be considered for patients who may suffer adverse events (AEs), which hinder the adherence of TKI and/or deteriorate their life quality. Together with the published literature, it shows that it appears safe to administer reduced doses to patients with CML in the chronic phase. The discontinuation of TKI therapy once a DMR has been reached is one of the goals for these patients. The patient should be assessed globally, and the most appropriate strategy for management should be considered. Future studies are needed to ensure that this approach is included in clinical practice because of the benefits for certain patients and the increased efficiency for the healthcare system.