The purpose of this study is to evaluate the efficacy and safety of avapritinib in relapsed or refractory pediatric core binding factor acute myeloid leukemia with KIT mutation.

This is a multicenter, single-arm, prospective, and intervention trial. About 30% of core binding factor acute myeloid leukemia (CBF-AML) patients still relapse under current treatment. Some studies have found that KIT mutations, especially the D816V mutation, may predict relapse and decrease overall survival (OS) in CBF-AML. Avapritinib has been approved for the treatment of gastrointestinal stromal tumors with KIT or PDGFRA mutations. Avapritinib was also effective for the treatment of minimal residual disease in acute myeloid leukemia with t (8;21) and KIT mutation failing to immunotherapy after allogeneic hematopoietic stem cell transplantation in a single-center, retrospective report. 11 centers from China carry out the AVACBFKIT regimen including Avapritinib, hypomethylating agents and low dose chemotherapy for the treatment of relapsed or refractory pediatric CBF-AML with KIT mutation. The main focus of this study is to evaluate the efficacy and safety of avapritinib in the regimen.

Inclusion Criteria:

1. Gender unlimited;
2. Under 18 years;
3. Diagnosis of acute myeloid leukemia (according to the 2022 WHO classification).
4. Presence of t(8;21)/RUNX1::RUNX1T1 or inv(16)/t(16;16)/CBFβ::MYH11;
5. KIT mutation;
6. Refractory AML: AML patients who do not achieve CR or CRi after induction therapy;
7. Relapsed AML: patients who achieved remission after consolidation therapy or transplantation, FISH confirmed that the fusion gene turned positive, or extramedullary leukemia infiltration;
8. No active infections;
9. Liver function: Tbil ≤2×ULN, ALT/AST ≤3×ULN, creatinine clearance ≥50ml/min;
10. ECOG score <2;
11. Expected survival time >12 weeks;
12. Participants must have the ability to understand and be willing to participate in this study and must sign an informed consent form.

Exclusion Criteria:

1. Have received prior treatment with avapritinib;
2. Receiving other targeted therapies for AML at the same time, such as dasatinib, sorafenib, gilteritinib, venetoclax, etc;
3. Presence of active uncontrolled infection (including bacterial, fungal, or viral infection);
4. Present of significant underlying organ diseases: such as myocardial infarction, chronic heart failure, decompensated liver or kidney dysfunction；
5. With other malignancies requiring treatment；
6. Already enrolled in another interventional clinical study；
7. The researchers determined that the individual is not suitable to participate in this trial.