Clinical features and chromosomal/genetic aberration in adult acute lymphoblastic leukemia in Japan: results of Fukuoka Blood & Marrow Transplant Group Studies ALL MRD 2002 and 2008.

Acute lymphoblastic leukemia (ALL) is a common neoplasm in children, but less frequent in adults. Since information on clinical features and genetics of adult ALL in Japan is limited, we analyzed 215 subjects aged 16-65 years with untreated ALL enrolled in the Fukuoka Blood & Marrow Transplant Group studies ALL MRD 2002 and 2008. The prevalence of ALL was bimodal, with the larger group aged 56-65 years. Immunophenotypic characterization showed B-lineage is more frequent than T-lineage ALL (78.6 vs 13.0%), with age-related differences. The proportion with BCR-ABL1 rearrangement increased progressively with age, up to 55.7% among subjects aged over 56-65 years. Rearrangements involving the KMT2A gene, ETV6-RUNX1, and TCF3-PBX1 were rare in this study cohort. The overall incidence of hyperdiploidy was only 1.7%, and there were no cases with hypodiploidy. Overall survival varied by age and cytogenetics. Older subjects and those with BCR-ABL1 tended to have inferior outcomes. In this epidemiological study of Japanese adult ALL, the majority of subjects had B-lineage ALL, the T-cell phenotype was most frequent in those aged 16-25, and BCR-ABL1 rearrangement was very common, with prevalence increasing with age. These types of adult ALL are potentially manageable with targeted therapies.