Beyond Midostaurin: Role of Avapritinib in Managing Systemic Mastocytosis

Abstract

We present a case of an adult male who presented with pancytopenia accompanied by symptomatic anemia, necessitating chronic transfusions. He was diagnosed with systemic mastocytosis with an associated hematologic neoplasm. Following an inadequate response to midostaurin therapy, the patient was initiated on the newly approved avapritinib. The patient showed significant improvements in all three blood cell lines; however, he developed leg edema, blepharedema, and gum bleeding on this medication. This case underscores the intricacies of managing a patient with advanced systemic mastocytosis, the emerging role of highly selective KIT inhibition in its treatment, and the practical management of adverse medication effects.

Keywords: molecular target therapies; systemic mastocytosis; systemic mastocytosis with an associated clonal hematological non-mast cell lineage disease (sh-ahnmd); targeted therapeutics; tyrosine kinase receptor inhibitors.

Figure 1. H&E sections showing clustered spindle-shaped mast cells

Figure 2. Neoplastic mast cells showing CD117 reactivity

Figure 3. Neoplastic mast cells showing CD25 reactivity