Long-term treatment-free remission in patients with chronic myeloid leukemia after second-line nilotinib: ENESTop 5-year update.

The ENESTop study evaluated treatment-free remission (TFR) in patients with chronic myeloid leukemia (CML) in chronic phase who had received ≥3 years of tyrosine kinase inhibitor therapy and achieved sustained deep molecular response only after switching from imatinib to nilotinib. After 1-year nilotinib consolidation, 126 patients attempted TFR. At 48 weeks (primary analysis), 57.9% (73/126) were in TFR. In the present analysis at 5 years, 42.9% (54/126) were in TFR. Since the 48-week analysis, among patients who left the TFR phase, 58% (11/19) did not have a loss of molecular response and discontinued for other reasons. Of the 59 patients who reinitiated nilotinib upon loss of major molecular response (MMR) or confirmed loss of MR4, 98.3% regained MMR, 94.9% regained MR4, and 93.2% regained MR4.5. Overall adverse event rates decreased over the 5 years of TFR. In patients reinitiating nilotinib, there was a cumulative increase in cardiovascular events with longer nilotinib exposure. No disease progression or CML-related deaths were reported. Overall, these results confirm the durability and safety of TFR for patients receiving second-line nilotinib. Cardiovascular risk should be carefully managed, particularly when reinitiating treatment after TFR.