High-Affinity GD2-Specific CAR T Cells Induce Fatal Encephalitis in a Preclinical Neuroblastoma Model

• Published in: Cancer immunology research 2018-01, Vol.6 (1), p.36-46
• Main Authors: Richman, Sarah A, Nunez-Cruz, Selene, Moghimi, Babak, Li, Lucy Z, Gershenson, Zachary T, Mourelatos, Zissimos, Barrett, David M, Grupp, Stephan A, Milone, Michael C
• Format: Article
• Language: English
• Subjects: Animals; CD3 Complex - genetics; Cell Line, Tumor; Cell Proliferation; Cytotoxicity, Immunologic; Disease Models, Animal; Encephalitis - diagnosis; Encephalitis - etiology; Gangliosides - immunology; Gangliosides - metabolism; Gene Order; Genetic Vectors - genetics; Humans; Immunotherapy, Adoptive - adverse effects; Immunotherapy, Adoptive - methods; Mice; Neuroblastoma - complications; Neuroblastoma - immunology; Neuroblastoma - therapy; Receptors, Antigen, T-Cell - genetics; Receptors, Antigen, T-Cell - metabolism; Receptors, Chimeric Antigen - genetics; Receptors, Chimeric Antigen - metabolism; Single-Chain Antibodies - genetics; Single-Chain Antibodies - immunology; T-Lymphocytes - immunology; T-Lymphocytes - metabolism; Tumor Necrosis Factor Receptor Superfamily, Member 9 - genetics; Tumor Necrosis Factor Receptor Superfamily, Member 9 - metabolism; Xenograft Model Antitumor Assays
• ISSN: 2326-6066; 2326-6074
• DOI: 10.1158/2326-6066.CIR-17-0211

The GD2 ganglioside, which is abundant on the surface of neuroblastoma cells, is targeted by an FDA-approved therapeutic monoclonal antibody and is an attractive tumor-associated antigen for cellular immunotherapy. Chimeric antigen receptor (CAR)-modified T cells can have potent antitumor activity in B-cell malignancies, and trials to harness this cytolytic activity toward GD2 in neuroblastoma are under way. In an effort to enhance the antitumor activity of CAR T cells that target GD2, we generated variant CAR constructs predicted to improve the stability and the affinity of the GD2-binding, 14G2a-based, single-chain variable fragment (scFv) of the CAR and compared their properties We included the E101K mutation of GD2 scFv (GD2-E101K) that has enhanced antitumor activity against a GD2 human neuroblastoma xenograft However, this enhanced antitumor efficacy was concomitantly associated with lethal central nervous system (CNS) toxicity comprised of extensive CAR T-cell infiltration and proliferation within the brain and neuronal destruction. The encephalitis was localized to the cerebellum and basal regions of the brain that display low amounts of GD2. Our results highlight the challenges associated with target antigens that exhibit shared expression on critical normal tissues. Despite the success of GD2-specific antibody therapies in the treatment of neuroblastoma, the fatal neurotoxicity of GD2-specific CAR T-cell therapy observed in our studies suggests that GD2 may be a difficult target antigen for CAR T-cell therapy without additional strategies that can control CAR T-cell function within the CNS. .