International Consensus Classification of acute lymphoblastic leukemia/lymphoma

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• The 2016 WHO classification for acute lymphoblastic leukemia (ALL) has been revised.
• Advances in molecular and cytogenetic analysis necessitate an updated classification system.

Purpose of the Study:

• To present the updated International Consensus Classification (ICC) for B-acute lymphoblastic leukemia (B-ALL) and T-acute lymphoblastic leukemia (T-ALL).
• To incorporate new entities and revisions based on recent clinical, cytogenetic, and molecular data.

Main Methods:

• Incorporation of whole transcriptome analysis and gene expression (GEX) clustering studies.
• Revision of B-ALL subclassification, including BCR::ABL1-positive and hypodiploid B-ALL.
• Updated T-ALL classification with BCL11B-activating rearrangements in early T-precursor (ETP) ALL.

Main Results:

• Defined nine new categories of B-ALL, including seven with gene rearrangements and two with specific gene mutations.
• Introduced four provisional B-ALL entities requiring GEX studies for definitive identification.
• Added eight new provisional entities to the T-ALL subclassification.

Conclusions:

• The enhanced specificity of the ICC classification allows for improved risk stratification.
• Optimized treatment plans for patients with ALL can be developed based on the new classification.
• Practical approaches for diagnostic technologies are discussed in relation to the new entities.