Molecular monitoring of T-cell kinetics and migration in severe neurotoxicity after real-world CD19-specific chimeric antigen receptor T cell therapy

Abstract

CD19-specific chimeric antigen receptor (CD19-CAR)-T cell therapies mediate durable responses in late-stage B-cell malignancies, but can be complicated by a potentially severe immune effector cell-associated neurotoxicity syndrome (ICANS). Despite broad efforts, the precise mechanisms of ICANS are not entirely known, and resistance to current ICANSdirected therapies (especially corticosteroids) has been observed. Recent data suggest that inflammatory cytokines and/or targeting of cerebral CD19-expressing pericytes can disrupt the blood-brain barrier and facilitate influx of immune cells, including CAR-T cells. However, specific tools for CD19-CAR-T cell analysis within often minute samples of cerebrospinal fluid (CSF) are not broadly available. Here, we applied our recently developed digital-PCR assays to monitor CD19-CAR-T cell kinetics in CSF and blood in real-world patients with neurotoxicity. Consistently, we observed a CAR-T cell enrichment within CSF in ICANS patients with further progressive accumulation despite intense corticosteroid-containing immuno-chemotherapies in a subset of patients with prolonged and therapy-resistant grade 3-4 neurotoxicity. We used next-generation T-cell receptor-β sequencing to assess the repertoire of treatment-refractory cells. Longitudinal analysis revealed a profound skewing of the T-cell receptor repertoire, which at least partly reflected selective expansion of infused Tcell clones. Interestingly, a major fraction of eventually dominating hyperexpanded T-cell clones were of non-CAR-T cell derivation. These findings hint to a role of therapy-refractory T-cell clones in severe ICANS development and prompt future systematic research to determine if CAR-T cells may serve as ‘door openers’ and to further characterize both CARpositive and non-CAR-T cells to interrogate the transcriptional signature of these possibly pathologic T cells.

Early Use of Corticosteroids following CAR T-Cell Therapy Correlates with Reduced Risk of High-Grade CRS without Negative Impact on Neurotoxicity or Treatment Outcome

“…Moreover, recently proposed predictive scores for CRS and ICANS, integrating laboratory and clinical data, might be used to find optimal prophylactic and/or early corticosteroid regimens in order to prevent high-grade CRS and ICANS [25,41,42]. Finally, recent data on the underlying mechanisms of CAR T-mediated neurotoxicity have suggested that CAR Tcells may allow other cytotoxic T-cells across the blood-brain barrier and that corticosteroids only insufficiently antagonize this T-cell infiltration [43]. Further translational research is needed to provide mechanistic insights and uncover novel therapeutic strategies for more effective prevention and management of ICANS.…”

Gene Targets of CAR-T Cell Therapy for Glioblastoma

“…ICANS is another common complication of CAR-T therapy [ 120 , 121 ]. However, the pathogenesis of ICANS is still unclear [ 122 ]. The possible cause is the increase in inflammatory cytokines and activation of endothelial cells, increasing vascular permeability and disrupting BBB, resulting in many cytokines and chemokines entering the CNS, thus causing injury [ 123 ].…”