Gilteritinib hemifumarate is primarily used in the treatment of relapsed or refractory acute myeloid leukemia (AML) with a FLT3 mutation. It functions as a FLT3 inhibitor, targeting and blocking the activity of the FLT3 receptor tyrosine kinase, which is often mutated in AML patients. This inhibition helps to slow down or stop the growth of cancer cells. It is administered orally, allowing for convenient outpatient treatment. The drug is particularly beneficial for patients who have not responded well to other therapies, offering a targeted approach to managing the disease. Clinical trials have demonstrated its efficacy in improving survival rates and inducing remission in a significant proportion of patients with FLT3-mutated AML. Regular monitoring of patients is essential to manage potential side effects, which may include liver function abnormalities, muscle pain, and fatigue. Overall, it represents a significant advancement in the targeted therapy of AML, providing hope for patients with this challenging condition.