Asciminib monotherapy in patients with chronic myeloid leukemia in chronic phase without BCR::ABL1 treated with at least 2 prior TKIs: Phase 1 final results.

Asciminib is the first approved BCR::ABL1 inhibitor that Specifically Targets the ABL Myristoyl Pocket (STAMP). The present final analysis of the phase 1, open-label, nonrandomized trial (NCT02081378) assessed the long-term safety, tolerability, and antileukemic activity of asciminib in 115 patients with chronic myeloid leukemia in chronic phase without the BCR::ABL1 mutation who received asciminib 10-200 mg twice daily (BID) or 80-200 mg once daily (cutoff: March 14, 2023). Median exposure duration was 5.9 (range, 0-8.4) years; 60.9% of patients continued receiving asciminib through post-trial access. Grade ≥3 adverse events (AEs) occurred in 88 patients (76.5%). AEs led to treatment discontinuation, dose adjustment/interruption, or additional therapy in 15 (13.0%), 74 (64.3%), and 106 (92.2%) patients, respectively. Most first-ever AEs, particularly hematologic AEs, presented within the first year and no new safety signals emerged. Of 56 patients who achieved major molecular response, 50 maintained the response by cutoff; the Kaplan-Meier-estimated probability of maintaining this response for ≥432 weeks ( ≈ 8.3 years) was 88% (95% confidence interval, 78.2-97.0%). The recommended dose for expansion was determined at 40 mg BID. With up to 8.4 years of treatment, asciminib continued to demonstrate long-term safety and efficacy in this population.