Advances in chimeric antigen receptor immunotherapy for neuroblastoma

Neuroblastoma (NBL) is the most common extracranial pediatric solid tumor and has heterogeneous biology and behavior. Patients with high-risk disease have poor prognosis despite complex multimodal therapy; therefore, novel curative approaches are needed. Immunotherapy is a novel therapeutic approach that harnesses the inherent activity of the immune system to control and eliminate malignant cells. One form of immunotherapy uses chimeric antigen receptors (CAR) to target tumor-associated antigens. CARs are derived from the antigen-binding domain of a monoclonal antibody (MAb) coupled with the intracellular signaling portion of the T cell receptor. CARs can combine the specificity and effectiveness of MAbs with the active bio-distribution, direct cytotoxicity, and long-term persistence of T cells. NBL provides an attractive target for CAR immunotherapy as many of its tumor-associated antigens are not expressed at significant levels on normal tissues, thus decreasing potential treatment related toxicity. Two previous clinical trials utilizing L1-cell adhesion molecule (L1-CAM) and disialoganglioside (GD2) specific CARs (GD2-CAR) have demonstrated safety and anti-tumor efficacy in heavily pretreated relapsed/refractory neuroblastoma patients. Based on these promising results and on improved techniques that can further potentiate CAR therapies, two clinical trials are currently investigating the use of GD2-CARs in children with NBL. Several approaches may further enhance anti-tumor activity and persistence of CAR modified cells, and if these can be safely translated into the clinic, CAR-based immunotherapy could become a viable adjunct or potential alternative to conventional treatment options for patients with NBL.