# Differentiation Syndrome in Acute Myeloid Leukemia: Molecular Mechanisms, Clinical Spectrum, and Emerging Therapeutic Paradigms

## TL;DR

This paper reviews how differentiation therapy is transforming AML treatment, focusing on new drugs and managing side effects like differentiation syndrome.

## Contribution

The paper provides a synthesis of emerging differentiation-inducing therapies and their clinical outcomes in non-APL AML.

## Key findings

- IDH1/2 inhibitors show high response rates in AML with differentiation syndrome in 10–19% of cases.
- Menin inhibitors achieve significant response rates in KMT2A-rearranged or NPM1-mutated AML with manageable toxicity.
- FLT3 inhibitors improve survival in FLT3-mutated AML but face resistance challenges.

## Abstract

Acute myeloid leukemia (AML) is characterized by differentiation arrest, driving blast proliferation, and abnormal blood formation. While differentiation therapy revolutionized acute promyelocytic leukemia (APL) with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), its extension into non-APL AML has been limited until recent targeted agents. This narrative review synthesizes preclinical and clinical evidence into differentiation-inducing therapy, with a focus on IDH1/2, FLT3 and menin inhibitors. Following SANRA guidelines, we searched PubMed (2010–September 2025) for clinical trials and key preclinical studies, with particular attention to the molecular mechanism of differentiation induction, clinical efficacy, and the management of differentiation syndrome (DS). IDH1/2 inhibitors (ivosidenib, enasidenib, olutasidenib) yield overall response rates (ORRs) of 30–94% in AML with DS in 10–19%. Menin inhibitors (revumenib, ziftomenib, enzomenib, bleximenib) achieve ORRs of 33–88% in KMT2A-rearranged or NPM1-mutated AML, with DS in 10–25% and QT prolongation as key toxicities. FLT3 inhibitors (gilteritinib, quizartinib) improve survival in FLT3-mutated AML with DS in 1–5%. Resistance mutations limit durability and combinations enhance efficacy. Differentiation therapy represents a paradigm shift towards non-cytotoxic AML management. Improved recognition of DS and rational combination approaches will be essential to maximize the therapeutic benefit. Future research should address mechanisms of resistance and biomarkers to achieve cures beyond APL.