Cellular phenotypes correlated with immune effector cell-associated neurotoxicity syndrome severity in CD19 CAR T cell therapy

Abstract

CD19-directed chimeric antigen receptor (CAR) T cell therapy has emerged as a transformative treatment for patients with relapsed or refractory B cell malignancies. Since gaining FDA approval in 2017, CAR T cell therapy has become increasingly implemented in both pediatric and adult populations. Despite its remarkable efficacy, treatment-related toxicities remain common, most notably cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS). While CRS is often mitigated through IL-6 pathway blockade, the underlying mechanisms driving ICANS remain incompletely understood.In this thesis, I leverage high-dimensional mass cytometry to characterize immune phenotypic heterogeneity across multiple stages of CD19 CAR T cell therapy. As ICANS is thought to arise from dysregulated cellular phenotypes, I hypothesize that cellular phenotypes present before and during therapy reflect underlying inflammatory programs that drive toxicity. By resolving these phenotypes at high dimensionality, I aim to identify cellular states that both inform mechanisms of ICANS pathogenesis and serve as predictive biomarkers. First, I define differences in T cell composition within leukapheresis samples and corresponding infusion products generated at distinct institutions, evaluating how patient age and manufacturing practices contribute to phenotypic variability. I then assess whether pre-infusion cellular features serve as predictive biomarkers of severe ICANS. Finally, I conduct longitudinal immune profiling of adult patients with diffuse large B cell lymphoma undergoing CD19 CAR T cell therapy, integrating cellular and cytokine data to identify dynamic immune shifts associated with severe ICANS compared to patients without severe ICANS to define the temporal immune dynamics that precede and accompany toxicity and gain insight into mechanisms driving ICANS. Collectively, this work provides a systems-level framework linking pre-infusion immune composition and post-infusion immune dynamics to neurotoxicity risk in CAR T cell therapy.