Clinical and Biological Correlates of Neurotoxicity Associated with CAR T-cell Therapy in Patients with B-cell Acute Lymphoblastic Leukemia

CD19-specific chimeric antigen receptor (CAR) T-cell therapy is highly effective against relapsed or refractory acute lymphoblastic leukemia (ALL), but is hindered by neurotoxicity. In 53 adult patients with ALL, we found a significant association of severe neurotoxicity with high pretreatment disease burden, higher peak CAR T-cell expansion, and early and higher elevations of proinflammatory cytokines in blood. Patients with severe neurotoxicity had evidence of blood-cerebrospinal fluid (CSF) barrier disruption correlating with neurotoxicity grade without association with CSF white blood cell count or CAR T-cell quantity in CSF. Proinflammatory cytokines were enriched in CSF during severe neurotoxicity with disproportionately high levels of IL6, IL8, MCP1, and IP10, suggesting central nervous system-specific production. Seizures, seizure-like activity, myoclonus, and neuroimaging characteristics suggested excitatory neurotoxicity, and we found elevated levels of endogenous excitatory agonists in CSF during neurotoxicity.<b>Significance:</b> We detail the neurologic symptoms and blood, CSF, and neuroimaging correlates of neurotoxicity associated with CD19 CAR T cells and identify neurotoxicity risk factors. Our findings implicate cellular components other than T cells and suggest novel links between systemic inflammation and characteristic neurotoxicity symptoms. <i>Cancer Discov; 8(8); 958-71. ©2018 AACR.</i><i>This article is highlighted in the In This Issue feature, p. 899</i>.