[The treatment development for T cell acute lymphoblastic leukemia in children, adolescents, and young adults]

T-cell acute lymphoblastic leukemia (T-ALL) accounts for 10%-15% of pediatric ALL, and its frequency increases during the adolescent and young adult (AYA) periods. The improvements in pediatric T-ALL outcomes have been achieved through the treatment intensification strategies addressing the cranial radiotherapy omission issue. Furthermore, pediatric-inspired regimens have been adopted for AYA patients with T-ALL, improving outcomes. In Japan, the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) ALL-T11/JALSG T-ALL-211-U trial has been conducted for newly diagnosed patients with T-ALL aged <25 years and has been shown to have excellent outcomes. While early T cell precursor ALL is not an obvious poor prognostic factor in recent treatment strategies for pediatric T-ALL, the minimal residual disease (MRD) has been recognized as the most reliable prognostic indicator. Therefore, MRD is now widely used in T-ALL clinical trials for risk stratification and stem cell transplantation indications. Further progress in the novel therapeutic approaches can potentially improve the outcomes of pediatric and AYA patients with T-ALL.