Genomics and precision medicine in pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most frequent malignant disease in the pediatric population, accounting for about 25% of childhood cancers. Drastic therapeutic improvements have been made for pediatric ALL since the early 1960s, marking the most successful treatment paradigm in pediatric oncology. The clinical success derived from refined risk-adapted therapy based on presenting features, cytogenetics and minimal residual disease, prevention of central nervous system relapse, and improvement of supportive care measures. With contemporary therapies, survival of children with ALL now exceeds 90%. However, ALL represents one of leading causes of cancer-related death, as 15%-20% of patients continue to relapse and outcomes post-relapse remain poor. Since the early 2000s, large-scale genomic studies of ALL, greatly facilitated by the advent of next generation sequencing (NGS), have enabled the development of a novel taxonomy for ALL in the molecular era. The access to NGS technologies identifies novel ALL subsets characterized by “driver” oncogenic alterations, previously cryptic on conventional karyotyping methods. With genomic characterization, the group of formerly unclassified B-lineage ALL reduces from 25% to a marginal 5% of ALL. The revised molecular classification of ALL confers prognostic significance and describes the predilection of unfavorable ALL subtypes with increasing age, partially elucidating the worst outcome of adolescents and young adults with ALL. Large-scale genomic analysis also reveals inherited alterations predisposing to ALL occurrence or to different drugs’ sensitivities. Most importantly, the genomic portrait of ALL uncovers novel therapeutic vulnerabilities, paving the way towards precision medicine opportunities in ALL