[Treatment strategy for infants with acute lymphoblastic leukemia]

Acute lymphoblastic leukemia (ALL) in infants under 1 is a rare and dismal disease. It is associated with a unique and specific biology, and 80% of cases harbor a KMT2A (MLL) gene rearrangement (KMT2A-r). In contrast to ALL in older children, with a survival rate of 80% or more, the prognosis of infant ALL is very poor, at 40%. In addition, the unique pharmacodynamics exhibited by infants has historically led to independent therapeutic development either in the U.S., Europe, or Japan. To improve the prognosis of infant ALL, it is necessary to uncover a supplementary novel effective agent to be used in combination with the existing conventional multi-agent chemotherapy. Because of the rarity of the disease, this could be only established by an international study, for which the consensus has already been established through discussions between the U.S., Europe, and Japan. Additionally, severe late effects in survivors are also problematic. Establishing novel treatment strategies to reduce relapse rates, treatment-related toxicities, and critical late effects is strongly encouraged in near future.