Physicians can safely discontinue imatinib in patients with chronic myeloid leukemia (CML) who have achieved a sustained deep molecular response, according to updated results from a study published in the Journal of Clinical Oncology.1

Tyrosine kinase inhibitor (TKI) therapy induces deep molecular responses in most patients with CML in chronic phase, and those patients have a low risk of progression and a high rate of long-term survival. Several discontinuation clinical trials demonstrate that patients with sustained deep molecular responses can safety discontinue TKI treatment and achieve treatment-free remission.

Researchers designed the STIM1 trial (Evaluation of the Persistence of the Complete Molecular Remission After Stopping Imatinib Chronic Myeloid Leukemia; ClinicalTrials.gov Identifier: NCT00478985) to evaluate the impact of imatinib discontinuation in patients who have had undetectable minimal residual disease for at least 2 years. Preliminary results demonstrated that nearly 40% of patients maintained a molecular remission following treatment discontinuation despite persistent low levels of leukemic cells.

After a median follow-up of 77 months after imatinib discontinuation, investigators found that molecular recurrence-free survival was 43% (95% CI, 33-52) at 6 months and 38% (95% CI, 29-47) at 60 months among the 100 patients evaluated.

Sixty-one patients lost undetectable minimal residual disease after a median of 2.5 months and 1 patient with undetectable minimal residual disease died at 10 months post-treatment discontinuation.

Investigators restarted imatinib treatment in 57 of those 61 patients with molecular recurrence, and 55 achieved a second deep molecular response within a median of 4 months.

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No patients with CML in chronic phase experienced progression to accelerated or blast phase.

Imatinib treatment duration longer than 54 months and a low or intermediate Sokal risk score were associated with a lower risk of molecular recurrence.                        

Reference

  1. Etienne G, Guilhot J, Rea D, et al. Long-Term follow-up of the French Stop Imatinib (STIM1) study in patients with chronic myeloid leukemia. J Clin Oncol. 2016 Oct 3. doi: 10.1200/JCO.2016.68.2914 [Epub ahead of print]