Successful Treatment-Free Remission After Ponatinib Discontinuation in Pretreated Patients with Chronic Myeloid Leukemia in Chronic Phase

Introduction: The discontinuation of third-generation BCR::ABL1 tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia in chronic phase (CML-CP) is not well understood. We aim to evaluate treatment-free remission in patients with CML-CP who discontinue ponatinib.

Methods: We retrospectively reviewed 361 patients who attempted TKI discontinuation between November 2005 and February 2024 and identified those receiving ponatinib at the time of discontinuation. Molecular relapse-free survival (MRFS) was calculated from the time of ponatinib discontinuation to the date of loss of major molecular response (MMR) or last follow-up.

Results: Eleven patients discontinued ponatinib. Before ponatinib discontinuation, patients were on TKI therapy for a median of 146.6 months and on ponatinib for a median of 67.5 months. The median number of TKIs prior to starting ponatinib was 2 (range, 1-3). The median durations of sustained MR4 and MR4.5 before ponatinib discontinuation were 32.8 and 29.4 months, respectively. After a median follow-up of 60.3 months, the 60-month MRFS rate was 53%. Five patients lost MMR; their median MR4.5 duration was 5 months before ponatinib discontinuation.

Conclusion: Ponatinib discontinuation is feasible in patients with CML-CP failing prior TKIs. Patients who achieve sustained MR4.5 for at least 2 years have the highest likelihood of remaining in treatment-free remission following ponatinib discontinuation.