INTRODUCTION
The development of imatinib and now newer tyrosine kinase inhibitors (TKIs) has revolutionized the overall survival of patients with CML. However, toxicity and treatment-resistance can result in premature discontinuation of therapy. Asciminib, a novel TKI, may have fewer off-target effects. It also bypasses the mechanism of resistance to first-line TKIs by binding to a different site on the BCR-ABL fusion protein. In our institution, three patients have been initiated on asciminib thus far. We present their cases, with a focus on quality of life.
CASE PRESENTATIONS
(1) A 76-year-old male with a history of diffuse vascular disease experienced off-target effects on multiple TKIs (i.e. intolerable nausea on imatinib, pleural effusion on dasatinib, complete heart block on nilotinib), so he was switched to asciminib. He has been tolerating asciminib well over five months and continues to see significant log reduction in BCR-ABL transcripts. (2) A 71-year-old male with a history of multiple complicated gastrointestinal infections never achieved major molecular remission on imatinib and was unable to tolerate dasatinib or bosutinib due to severe nausea and vomiting. He was switched to asciminib, which he has been tolerating well for one year, and has achieved complete hematologic response. (3) A 73-year-old male with a history of chronic kidney disease experienced kidney injury thought to be due to imatinib and was switched to bosutinib. His BCRABL transcripts rose on bosutinib, so patient was started on asciminib, which he has been tolerating well.
DISCUSSION
In this series of patients in their 70s with multiple underlying comorbidities, the unifying theme is that of intolerance to first-line TKIs due to toxicity (cardiac, pulmonary, gastrointestinal, and renal). Existing data suggests that asciminib results in less toxicity than other first-line TKIs, and this is evident in our patients. More importantly, the combination of efficacy and tolerability gives these patients the opportunity to proceed with life-prolonging therapy, even for those who face treatment resistance with other agents.
CONCLUSIONS
For CML patients who have failed at least two lines of treatment, whether it is due to disease progression or intolerable toxicity, asciminib is an effective alternative. Further study may result in its promotion to first-line therapy for this disease.