[Results of following up patients with chronic myeloid leukemia and a deep molecular response without tyrosine kinase inhibitor therapy]

A prospective study of the monitoring of patients with chronic myeloid leukemia upon withdrawal of tyrosine kinase inhibitor therapy

Introduction. The advent of tyrosine kinase inhibitors (TKIs) in clinical practice drastically improved prognosis in patients with chronic myeloid leukaemia (CML). Adverse events of the TKI therapy and its high financial burden warrant the trend to gradually abandon this treatment.

Aim. To assess the results of CML patient monitoring after the withdrawal of TKI therapy.

Patients and methods. This prospective study included 98 chronic phase CML patients satisfying the criteria: any receiving of TKI therapy for ≥3 years; deep molecular response (DMR, BCR-ABL ≤ 0.01 % IS) during ≥ 2 years. The withdrawal was followed by quantitative BCR-ABL estimation performed monthly for the first 6 months of the survey, bimonthly for 1 year and every 3 months from the second year onwards. Therapy was resumed at a loss of major molecular response (MMR, BCR-ABL ≥ 0.1 % IS).

Results. The MMR loss upon the TKI withdrawal was observed in 48 (49 %) patients. Survival without MMR loss was 52 % past 24 months since withdrawal, with a median of 35 months (23–52). The duration of therapy, MR and the MR depth at the time of withdrawal significantly correlated with a conserved post-therapy MMR. Gender, age, a Sokal risk group, type and line of TKI therapy at withdrawal, and imatinib resistance in history were not observed to significantly impact molecular relapse-free remission. MMR was recovered in all 48 patients with TKI therapy resumed in molecular relapse. In 65 % of the patients, adverse therapy events observed during treatment completely resolved by 6 months of post-therapy monitoring. Musculoskeletal pain (withdrawal syndrome, WS) was reported in 42 % patients in the post-therapeutic period, which did not lead to TKI resumption. The WS development correlated with an elder age and longer therapy prior to withdrawal.

Conclusion. Molecular relapse-free survival in CML patients with treatment-free remission (TFR) is comparable to other published evidence. Monitoring safety during TFR is attested by the lack of disease progression and MMR recovery upon TKI resumption in all patients.

[Successful use of long-term follow-up in patients with chronic myeloid leukemia with a deep molecular response at reduced doses of 2nd generation tyrosine kinase inhibitors: clinical cases and literature review]

Therapy with tyrosine kinase inhibitors (TKI) allows to achieve a deep molecular response in 6070% of patients with chronic myeloid leukemia (CML). According to the current guidelines CML patients receive a long-term treatment with TKI in standard dose. The frequently observed adverse effects (AE) of TKI therapy are mostly dose-dependent. A new treatment approach with TKI use in reduced dose is desirable for the CML patients with existing AE or with a high risk of AE occurrence. We report the two cases of successful long-term treatment of CML patients with reduced doses of second generation TKIs. The aim of the TKI dose reduction was to reduce the clinical manifestations of drug toxicities and to prevent the AE.