# FLT3-ITD (internal tandem duplication)

Source: https://onco.cc/biomarkers/flt3-itd/  
OnCo record `flt3-itd` (Biomarker). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

FLT3-ITD is a duplicated stretch of the FLT3 receptor gene found in about a quarter of acute myeloid leukaemias; it makes relapse more likely and is treated with midostaurin, quizartinib or gilteritinib.

## Summary

Internal tandem duplications in the juxtamembrane domain are detected by PCR fragment analysis (the LeukoStrat CDx FLT3 Mutation Assay reports ITD and the TKD mutations D835 and I836) or by sequencing; the allelic ratio once used in ELN risk stratification was dropped in ELN 2022. Midostaurin (Rydapt) is labelled for newly diagnosed FLT3 mutation-positive AML with induction and consolidation chemotherapy; quizartinib (Vanflyta, 2023) specifically for FLT3-ITD-positive newly diagnosed AML including maintenance; gilteritinib (Xospata) for relapsed or refractory AML with a FLT3 mutation. All three name an FDA-approved test, and the LeukoStrat assay is the companion diagnostic for each.

## Fields

- Kind: Biomarker
- Last checked: 2026-09-23
- Also known as: FLT3-ITD; FLT3 ITD; FLT3 internal tandem duplication; FLT3-ITD positive; FLT3-ITD allelic ratio; ITD-positive AML
- Tags: biomarker; flt3

## Sources

- VANFLYTA prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=29cdbcfe-497d-4e78-bb7b-2d4acafe8e86
- RYDAPT prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=11fa3fc9-6776-49a6-b1c1-653f627c3e58

## Connected records

- biomarkers: [CD33 expression (CD33-positive)](https://onco.cc/biomarkers/cd33-expression/), [FLT3-TKD (D835 and I836 tyrosine kinase domain mutations)](https://onco.cc/biomarkers/flt3-tkd/), [NPM1 mutation](https://onco.cc/biomarkers/npm1-mutation/)
- cancers: [Acute myeloid leukaemia](https://onco.cc/cancers/aml/), [FLT3-mutated acute myeloid leukaemia](https://onco.cc/cancers/aml-flt3/)
- drugs: [Gilteritinib](https://onco.cc/drugs/gilteritinib/), [Midostaurin](https://onco.cc/drugs/midostaurin/), [Quizartinib](https://onco.cc/drugs/quizartinib/)
- terms: [FLT3-ITD allelic ratio](https://onco.cc/terms/flt3-itd-allelic-ratio/)
- targets: [FLT3](https://onco.cc/targets/flt3/)

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JSON: https://onco.cc/api/v1/entities/flt3-itd.json