Azacitidine and Quizartinib for the Treatment of Myelodysplastic Syndrome or Myelodysplastic/Myeloproliferative Neoplasm With FLT3 or CBL Mutations

This phase I/II trial studies the side effects and best dose of quizartinib when given with azacitidine and to see how well they work in treating patients with myelodysplastic syndrome or myelodysplastic/myeloproliferative neoplasm with FLT3 or CBL mutations. Chemotherapy drugs, such as azacitidine, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Quizartinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Giving azacitidine and quizartinib may help to control myelodysplastic syndrome or myelodysplastic/myeloproliferative neoplasm.

Inclusion Criteria: 1. Age ≥ 18 years as MDS is a very rare disease in the pediatric setting. 2. Diagnosis of MDS or MDS/MPN including CMML according to WHO. 3. For hypomethylating agent naïve patients: int-2 or higher by IPSS or \>5% bone marrow blasts if MDS or dysplastic CMML (WBC \/= 13x109/L) CMML or MDS/MPN, or those with dysplastic CMML with high-risk molecular features (mutations in ASXL1, TP53 or more than 3 mutations) are also eligible independently of IPSS risk score or bone marrow blast percentage. 4. For patients with prior hypomethylating agent therapy: no response after 6 cycles of azacitidine, decitabine, guadecitabine or ASTX727 or relapse or progression after any number of cycles. 5. Detectable FLT3-ITD mutation in bone marrow and/or peripheral blood, or presence of CBL exon 8 or 9 deletions or point mutations. 6. Serum creatinine \