Neuroblastoma is a common pediatric extracranial solid tumor, that arises in the developing sympathetic nervous system. Chimeric antigen receptor (CAR) T-cell therapy has demonstrated promising clinical responses, yet its effectiveness in neuroblastoma benefits only a subset of patients. We evaluated the immunosuppressive secretome of neuroblastoma tumoroids that attenuate CAR T-cells function and efficacy. Secreted proteins were collected from tumoroids and identified by shotgun MS.