Asciminib Use Highlighting Underlying Moyamoya Disease: A Case Report.

We highlight here a case of Moyamoya disease (MMD) developed after treatment for chronic myeloid leukemia (CML). Moyamoya, a term meaning "a hazy puff of smoke" in Japanese, denotes a chronic occlusive cerebrovascular condition involving bilateral stenosis or closure of the terminal part of the internal carotid arteries (ICAs) and the proximal sections of the anterior cerebral arteries (ACAs) and middle cerebral arteries (MCAs) resulting in the development of abnormal vascular collaterals. A 40-year-old African-American female with a past medical history of CML presented to the oncology clinic with expressive aphasia. Of note, she was diagnosed with CML eight years ago and was previously treated with dasatinib and nilotinib with only partial remission. She tested positive for the T315I mutation and was initiated on asciminib therapy about a month before her symptoms surfaced. Asciminib, an allosteric inhibitor targeting breakpoint cluster region-abelson murine leukemia 1 (BCR-ABL1) kinase activity, has gained approval for treating patients diagnosed with chronic-phase CML who have not responded to two prior lines of therapy or for those carrying the T315I mutation. During admission, the patient underwent brain magnetic resonance imaging (MRI) and a computed tomography (CT) angiogram of the head showed moderate to severe narrowing at the origins of the bilateral MCA and ACA, concerning Moyamoya syndrome. Although not classically associated with asciminib therapy, we report here a patient with CML who developed expressive aphasia one month after starting the medication. Due to the high index of suspicion, asciminib was discontinued, and the patient was referred for bone marrow transplant evaluation and concurrently started on cytarabine + peginterferon. The patient had improvement in her symptoms of aphasia after the drug was discontinued and returned to her baseline functional status.  No cardiovascular side effects associated with the use of asciminib are currently reported in the literature. However, we have described a case of such an occurrence. Therefore, extra caution should be taken in prescribing asciminib in patients with risk factors or a prior history of stroke.