Differential cytokine architecture in patients treated with CART19 versus CART22.

Cytokine release syndrome (CRS) is a life-threatening toxicity of chimeric antigen receptor T-cell therapy (CART) for B-cell acute lymphoblastic leukemia (B-ALL). Lower rates of severe CRS have been reported in patients treated with CD22-directed CART (CART22) compared with those treated with CD19-directed CART (CART19). More than 1,000 serum proteins were measured using a proximity extension assay on 40 patients treated with CART19 or CART22 and cytokines were compared. Single-cell (single-cell RNA-sequencing (scRNAseq)) was used to identify cellular and transcriptional differences between patients treated with CART19 and CART22. CART19-blast and CART22-blast interactions at the immune synapse (IS) were modeled in vitro. We identified interleukin-10 (IL-10) as a critical endogenous modulator of CRS and demonstrated that previous treatment with CART is associated with increased serum IL-10 in the setting of subsequent relapse. Mechanistically, IL-10 induced higher interferon gamma expression and SOCS3 upregulation in both CART19 and CART22 cells. IL-10 differentially impacted the CART IS, prolonging the CART19 but shortening the CART22 IS. Using scRNAseq we demonstrated upregulation of SOCS3 in CART22 patient CD4 T-cells, potentially suppressing trans-IL-6 signaling. These findings reveal IL-10 as a potent CRS-mitigating factor and support IL-10 enhancement strategies to improve the safety of CART.