How I Treat Philadelphia Chromosome-like Acute Lymphoblastic Leukemia in Children, Adolescents, and Young Adults

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) represents a high-risk B-lineage ALL subtype characterized by adverse clinical features and poor relapse-free survival despite risk-adapted multi-agent chemotherapy regimens. The advent of next-generation sequencing has unraveled the diversity of kinase-activating genetic drivers in Ph-like ALL that are potentially amenable to 'personalized' molecularly-targeted therapies. Based upon robust preclinical data and promising case series of clinical activity of tyrosine kinase inhibitor (TKI)-based treatment in adults and children with relevant genetic Ph-like ALL subtypes, several clinical trials have investigated the efficacy of JAK- or ABL-directed TKIs in CRLF2/JAK pathway-mutant or ABL-class Ph-like ALL, respectively. Final results of these trials are pending, and standard-of-care therapeutic approaches for patients with Ph-like ALL have yet to be defined. In this How I Treat perspective, we review recent literature to guide current evidence-based treatment recommendations via illustrative clinical vignettes of children, adolescents, and young adults with newly-diagnosed or relapsed/refractory Ph-like ALL, and we further highlight open and soon-to-open trials investigating immunotherapy and TKIs specifically for this high-risk patient population.