# Case Report: Refractory systemic nmastocytosis with AML1::ETO+ acute myeloid leukemia driven by rare KIT mutation: remarkable therapeutic efficacy of avapritinib

## TL;DR

This case report describes two children with a rare form of leukemia and mastocytosis who responded remarkably well to avapritinib after failing other treatments.

## Contribution

The paper reports novel KIT exon11 mutations in systemic mastocytosis with AML1::ETO+ AML and demonstrates the efficacy of avapritinib in refractory cases.

## Key findings

- Two pediatric patients with novel KIT exon11 mutations developed refractory systemic mastocytosis and AML1::ETO+ AML.
- Avapritinib treatment led to significant clinical responses in these previously untreatable cases.
- Allogeneic stem cell transplantation failed to control disease progression in both patients.

## Abstract

This article describes two pediatric SM with AML1::ETO+ AML patients induced by novel KIT exon11 mutations not previously documented in medical literature. Both patients underwent allogeneic hematopoietic stem cell transplantation, but subsequently developed refractory disease progression unresponsive to multiple salvage regiments. Strikingly, avapritinib intervention achieved unprecedented clinical responses in these complex cases.