Key PointsQuestionIs it feasible to collect prospective clinical safety and activity data for the use of compassionate or off-label innovative anticancer medicines at a multicenter, national level?FindingsThis cohort study included information collected from 366 children, adolescents, and young adults treated with 55 compassionate or off-label innovative drugs as part of the SACHA (Securing Access to Innovative Therapies for Children, Adolescents, and Young Adults with Cancer Used Outside Clinical Trials)-France study. Pharmacovigilance monitoring confirmed significant adverse drug reactions in one-third of them; 25% of the patients achieved at least a partial response.MeaningThese results confirm the feasibility of this prospective real-word study.