3F8 is an antibody that attaches to neuroblastoma cells and helps focus a patient’s own immune system — especially white blood cells — to attack neuroblastoma cells. Conventional 3F8 is made from mouse cells. Humanized 3F8 (Hu3F8) is made to be more like the human immune system than a mouse’s immune system, so it may be associated with fewer side effects in patients than standard mouse-derived 3F8.
GM-CSF is a protein that increases the number of white blood cells and may make them better able to kill cancer cells. GM-CSF has been shown to make mouse 3F8 more effective against neuroblastoma, and it is believed to make Hu3F8 more effective as well. The purpose of this study is to find the highest dose of Hu3F8 that can be given safely with GM-CSF in patients with neuroblastoma that has persisted or returned despite prior treatment.