Hematology Xagena

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Philadelphia-like acute lymphoblastic leukemia is associated with minimal residual disease persistence and poor outcome. GIMEMA LAL1913

Early recognition of Ph-like acute lymphoblastic leukemia cases could impact on the management and outcome of this subset of B-lineage ALL.

To assess the prognostic value of the Ph-like status in a pediatric-inspired, minimal residual disease (MRD)-driven trial, researchers have screened 88 B-lineage ALL cases negative for the major fusion genes ( BCR-ABL1, ETV6-RUNX1, TCF3-PBX1 and KTM2Ar ) enrolled in the GIMEMA LAL1913 front-line protocol for adult BCR/ABL1-negative ALL.

The screening, performed using the BCR/ABL1-like predictor, has identified 28 Ph-like cases ( 31.8% ), characterized by CRLF2 overexpression ( 35.7% ), JAK/STAT pathway mutations ( 33.3% ), IKZF1 ( 63.6% ), BTG1 ( 50% ) and EBF1 ( 27.3% ) deletions, and rearrangements targeting tyrosine kinases or CRLF2 ( 40% ).

The correlation with outcome highlighted that:

i) the complete remission ( CR ) rate was significantly lower in Ph-like compared to non-Ph-like cases ( 74.1% vs 91.5%, p=0.044 );

ii) at time point 2 ( TP2 ), decisional for transplant allocation, 52.9% of Ph-like cases vs 20% of non-Ph-like were MRD-positive ( p=0.025 );

iii) the Ph-like profile was the only parameter associated with a higher risk of being MRD-positive at TP2 ( p=0.014 );

iv) at 24 months, Ph-like patients had a significantly inferior event-free and disease-free survival compared to non-Ph-like patients ( 33.5% vs 66.2%, p=0.005 and 45.5% vs 72.3%, p=0.062, respectively ).

This study has shown that Ph-like patients have a lower complete remission rate, event-free survival ( EFS ) and disease-free survival ( DFS ), as well as a greater minimal residual disease persistence also in a pediatric-oriented and MRD-driven adult ALL protocol, thus reinforcing that the early recognition of Ph-like ALL patients at diagnosis is crucial to refine risk-stratification and to optimize therapeutic strategies. ( Xagena )

Chiaretti S et al, Haematologica 2021; 106 :1559-1568