Fenretinide is a synthetic derivative of retinoic acid that has a broad-spectrum of cytotoxic activity against primary tumor cells, cell lines, and/or xenografts of various cancers (including neuroblastoma). Fenretinide (4-hydroxy(phenyl)retinamide; 4-HPR) is a synthetic derivative of retinoic acid, fenretinide can bind to retinoic acid receptor (RAR) and retinoid X receptor (RXR) at concentrations necessary to induce cell death.