Collaborative clinical research on acute lymphoblastic leukemia between pediatric and adult hematologists

Abstract

I present a summary of the application of pediatric protocols for the treatment of adult patients with acute lymphoblastic leukemia (ALL) in the Japan Adult Leukemia Study Group (JALSG), including the process leading to collaborative clinical research with the Japanese Pediatric Leukemia Study Group (JPLSG) and the steps taken to initiate collaborative studies. Historically, the 5-year survival rate for adult ALL has remained low at 30–40%. In response, we incorporated high-dose methotrexate into adult-type ALL treatment for patients aged 25 years and older, increasing the 5-year overall survival (OS) rate to 64%. Patients younger than 25 years were treated with a pediatric high-risk ALL regimen, achieving a 5-year OS rate of 73% (ALL202). Subsequently, in the ALL213 study, a pediatric-type protocol was adopted, resulting in a 3-year OS rate of 69.3% among patients with Philadelphia chromosome-negative B-cell ALL. Among patients with T-cell acute lymphoblastic leukemia younger than 25 years, collaborative research with the JPLSG yielded a 3-year OS rate of 93.4% in the 15–24-year age group. Subsequent clinical studies were planned as a fully integrated collaboration between JALSG and JPLSG; the first JPLSG–JALSG Joint ALL meeting was held in June 2017. Despite differences in perspective between pediatric and adult hematologists, both groups prioritized safer and more effective treatment for patients with ALL. This shared commitment has facilitated the progress from protocol development to clinical trial initiation. The ongoing ALL-B19 and ALL-T19 trials have passed the midpoint and remain on track.