Asciminib (Scemblix): A third-line treatment option for chronic myeloid leukemia in chronic phase with or without T315I mutation

To review the pharmacology, efficacy, safety, dosing and administration, and place in therapy of asciminib, an oral tyrosine kinase inhibitor (TKI) used as a third-line treatment option for Philadelphia chromosome-positive chronic myeloid leukemia (CML) in chronic phase.CML is a rare cancer caused by a chromosomal translocation that forms a fusion of the BCR and ABL1 genes on chromosomes 22 and 9. Until recently, patients for whom first-line treatment options failed were treated with TKIs that bind to the adenosine triphosphate-binding site on BCR-ABL1. However, because of similar mechanisms of action, there continues to be an unmet need in patients for whom at least 2 TKIs have failed or those with a T315I mutation unable to tolerate ponatinib. In October 2021, the Food and Drug Administration approved asciminib (Scemblix), the first TKI specifically targeting the ABL1 myristoyl pocket (STAMP) via allosteric binding, as a third-line option for patients with chronic-phase (CP)-CML. Asciminib received accelerated approval due to meeting its primary endpoint at week 24, demonstrating a major molecular response rate of 25.5% for patients on asciminib compared to 13.2% for those receiving bosutinib. In addition, patients on asciminib achieved a higher rate of complete cytogenetic response at 40.8% compared to a rate of 24.2% for bosutinib. Clinicians prescribing asciminib should monitor for increased levels of pancreatic enzymes, hypertension, cardiovascular toxicity including ischemic and thromboembolic conditions, and decreased numbers of neutrophils and platelets, as these may require treatment interruption, dose reduction, or treatment discontinuation.Asciminib is a unique targeted TKI that provides clinicians with an additional third-line and beyond treatment option for adults with CP-CML regardless of mutation status as well as a second TKI treatment option for patients harboring a T315I mutation.