CHICAGO — Patients with chronic myeloid leukemia who have attained sustained deep molecular response with second-line nilotinib therapy can achieve treatment-free remission persisting nearly 3 years, according to updated results of the ENESTop study presented at the ASCO Annual Meeting.
“Treatment-free remission is a new treatment goal in patients with CML who achieve a sustained deep molecular response,” François-Xavier Mahon, MD, PhD, professor and senior house physician at University of Bordeaux in France, said during his presentation. “Together with previous results showing higher MR rates with a switch to second-line nilotinib [Tasigna, Novartis] vs. remaining on imatinib, these findings suggest that switching to nilotinib may enable more patients to reach eligibility for attempting and achieving treatment-free remission.”
The researchers originally enrolled 163 patients with Philadelphia chromosome-positive CML in the chronic phase who received tyrosine kinase inhibitor therapy for at least 3 years — including more than 4 weeks with imatinib, followed by 2 or more years of nilotinib — and achieved a deep molecular response of MR while receiving nilotinib. Researchers defined MR as BCR-ABL1 0.0032% on the International Scale.
Participants then entered a 1-year consolidation period, during which they received nilotinib. After this period, patients with no confirmed loss of MR could attempt treatment-free remission. The researchers restarted nilotinib in patients with loss of major molecular response or confirmed loss of MR.
Earlier results from the study showed, of patients who sustained a deep molecular response with second-line nilotinib, 57.9% remained in treatment-free remission at 48 weeks — meeting the study’s primary endpoint — and 53.2% remained in remission 96 weeks after stopping treatment.
Data cutoff for the current analysis occurred when all patients had completed at least 144 weeks of treatment-free remission, restarted nilotinib or discontinued the study.
Of 126 patients in treatment-free remission, 61 remained in remission at data cutoff, 58 restarted nilotinib — due to loss of major molecular response (n = 34) or loss of MR4 (n = 24) — and seven discontinued the study.
At 144 weeks, 48.4% (95% CI, 39.4-57.5) remained in treatment-free remission, and the treatment-free survival was 52% (95% CI, 42.9-60.4).
Only three patients experienced loss of response between the 96- and 144-week follow-up; 93% of patients who reinitiated nilotinib regained MR.
The overall rate for adverse events decreased as time increased during treatment-free remission. Researchers observed no reports of disease progression or deaths associated with CML. – by Jennifer Southall
Mahon FX, et al. Abstract 7003. Presented at: ASCO Annual Meeting; June 1-5, 2018; Chicago.
Disclosures: Mahon reports honoraria from Bristol-Myers Squibb, Novartis Pharma and Pfizer; advisory board roles with Ariad/Incyte, Bristol-Myers Squibb and Novartis Pharma; and research support from Novartis Pharma. Please see the abstract for all other authors’ relevant financial disclosures.