Asciminib remained superior vs bosutinib in late-line CML-CP after nearly 4 years of follow-up in ASCEMBL.

The efficacy of and disease control afforded by tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia in chronic phase (CML-CP) have led to increased longevity and thus the continued pursuit of alternative therapies that are efficacious and maximize tolerability. The 24- and 96-week analyses from ASCEMBL demonstrated superior efficacy, safety, and tolerability of asciminib when compared with bosutinib in later-line therapy, thereby meeting the primary and key secondary objectives. With nearly 4 years of follow-up, data from ASCEMBL continued to demonstrate the superior efficacy, safety, and tolerability of asciminib over bosutinib. At week 156, the major molecular response (MMR) rates remained higher with asciminib (33.8%) than with bosutinib (10.5%); the difference in MMR rates between arms, after adjusting for baseline major cytogenetic response, was 23.2% (95% confidence interval, 13.14-33.18; 2-sided P < .001). Asciminib continued to cause fewer grade ≥3 adverse events (AEs; 59.6% vs 68.4%) and fewer AEs that led to treatment discontinuation (8.3% vs 27.6%) than bosutinib. This updated analysis also includes patients who switched to asciminib because of a lack of efficacy with bosutinib. Two of the 25 patients who switched achieved MMR by the end of study, suggesting that earlier incorporation of asciminib, before other TKIs, may improve responses, albeit modestly. These long-term results further solidify asciminib as the therapy of choice for patients with CML-CP who were previously treated with ≥2 previous TKIs. This trial was registered at clinicaltrials.gov as #NCT03106779.