The Use of Crizotinib Neutralizes Differences in Event-Free Survival in Paediatric Patients with Different Morphologic Subtypes of ALK-positive Anaplastic Large Cell Lymphoma

Introduction: ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) is a rare T-cell lymphoma that constitutes 10-20% of paediatric non-Hodgkin lymphoma cases.It is characterized by translocations involving the ALK gene.ALK+ ALCL is traditionally subdivided into common and non-common subtypes.5-year overall survival rate is around 80%, however, relapse probability during the first 5 years after diagnosis is approximately 30%.Patients with non-common morphologic subtype demonstrated lower progression-free survival and higher risk of treatment failure in earlier studies.Since that, new treatment strategies including targeted therapy have been developed.This study aims to analyze overall survival (OS) and event-free survival (EFS) in paediatric patients with ALK+ ALCL treated with tyrosine kinase receptor inhibitor crizotinib depending on morphologic subtype. Methodology:We retrospectively analyzed tissue samples and medical records of 45 children diagnosed with ALK+ ALCL at a single tertiary care center in 2016-2023 and treated with crizotinib in addition to standard chemotherapy regimen in case of non-common morphologic subtype.Progression, relapse and death were considered to be events.3-year OS and EFS were calculated.