EBF1-PDGFRΒFusion in Paediatric Acute Lymphoblastic Leukaemia (ALL): Genetic Profile and Clinical Implications

Incorporating cytogenetics into risk stratification for the treatment of childhood ALL has contributed to increased survival rates. However 25% patients, the B-other subgroup, do not have any of the known major chromosomal abnormalities. Within this group, BCR-ABL1-like cases show a similar gene expression profile to those with BCR-ABL1fusion and share the same high risk of relapse. BCR-ABL1-like cases are genetically heterogeneous and some harbour tyrosine kinase activating gene fusions e.g. EBF1-PDGFRB. Recent reports suggest patients with EBF1-PDGFRBALL who are refractory to conventional therapy respond to the tyrosine kinase inhibitor (TKI), imatinib. Here we present 14 patients treated on ALL97 (n=3), UKALL2003 (n=10) or UKALL2011 (n=1) who were EBF1-PDGFRBpositive including 1 patient treated with imatinib.