Gilteritinib response in acute myeloid leukemia harboring a rare FLT3 juxtamembrane domain mutation with subsequent...

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• FMS-like tyrosine kinase 3 (FLT3) mutations are key drivers in acute myeloid leukemia (AML).
• The clinical impact of rare, non-canonical FLT3 juxtamembrane domain (JMD) mutations is not well understood.
• Standard chemotherapy can be ineffective for certain AML subtypes, necessitating novel therapeutic strategies.

Purpose of the Study:

• To investigate the therapeutic significance of a rare FLT3-JMD missense mutation (V579A) in acute monocytic leukemia.
• To evaluate the efficacy of FLT3 inhibition in a patient with relapsed AML harboring a rare FLT3 mutation.
• To explore mechanisms of resistance and clonal evolution in relapsed AML.

Main Methods:

• Targeted next-generation sequencing for comprehensive genomic profiling.
• Administration of gilteritinib, a type I FLT3 inhibitor, as salvage therapy.
• Longitudinal genomic analysis to track clonal dynamics and identify resistance mechanisms.

Main Results:

• A patient with acute monocytic leukemia and a rare FLT3 V579A mutation experienced early relapse after standard chemotherapy.
• Salvage therapy with gilteritinib induced rapid hematologic remission, enabling stem cell transplantation.
• Relapse post-transplantation was associated with the emergence of TP53-mutated clones, indicating a shift away from FLT3 dependence.

Conclusions:

• Rare FLT3-JMD point mutations in AML may confer sensitivity to FLT3 inhibitors, even without canonical mutations.
• Clonal evolution and the emergence of TP53 mutations can lead to resistance against FLT3-targeted therapies.
• Extended molecular profiling and longitudinal assessment are crucial for identifying therapeutic targets and resistance mechanisms in relapsed AML.