It was later observed that the response to treatment in patients with neuroblastoma was improved when GM-CSF, IL-2, and the biologic disease modifier isotretinoin (13-cis-retinoic acid, a retinoid derivative of vitamin A) are combined with anti-GD2 mAbs (73, 85, 86) to enhance ADCC (68). This evidence concerns the gene IL2 and neuroblastoma.