Clonal evolution in relapsed NPM1-mutated acute myeloid leukemia.

Area of Science:

• Hematology
• Genetics
• Cancer Biology

Background:

• Mutations in the nucleophosmin 1 (NPM1) gene are a key event in acute myeloid leukemia (AML) pathogenesis.
• Understanding clonal evolution in relapsed NPM1-mutated (NPM1mut) AML is crucial for treatment strategies.

Purpose of the Study:

• To investigate the role of clonal evolution in NPM1mut AML relapse.
• To identify genomic alterations acquired during relapse in NPM1mut AML.

Main Methods:

• Genome-wide single-nucleotide polymorphism array profiling to detect copy number alterations (CNAs) and uniparental disomies (UPDs).
• Comprehensive gene mutation screening in paired diagnostic and relapse bone marrow/peripheral blood samples from 53 NPM1mut AML patients.

Main Results:

• Genomic complexity significantly increased at relapse, with 55% of patients showing alterations compared to 25% at diagnosis.
• Recurrent acquired aberrations at relapse included deletions in tumor suppressor genes (e.g., ETV6, TP53, WT1) and homozygous FLT3 mutations via UPD13q.
• DNMT3A mutations demonstrated high stability (97%), and their persistence after NPM1mut loss suggested they may precede NPM1 mutations in AML pathogenesis.

Conclusions:

• Clonal evolution leads to increased genomic complexity in relapsed NPM1mut AML.
• Acquired genetic alterations at relapse provide potential therapeutic targets.
• Shared genetic aberrations between diagnosis and relapse samples indicate common ancestral clones, highlighting the importance of tracking clonal dynamics.