The initial crizotinib clinical trial in ALK positive pediatric cancers showed strong anti-tumor activity in patients harboring ALK fusions in inflammatory myofibroblastic tumors (IMTs) and anaplastic large cell lymphomas (ALCLs), but less impressive results in neuroblastoma patients, which express mutated variants of full-length ALK26. This evidence concerns the gene ALK and anaplastic large cell lymphoma.