Chimeric antigen receptor T cells self-neutralizing IL6 storm

IL6 is one of the most elevated cytokines during chimeric antigen receptor (CAR) T cell cytokine release syndrome (CRS), and IL6R blockade by Tocilizumab has successfully relieved the most life-threatening aspects of CRS in patients. In addition, latest studies demonstrated the essential role of IL1 in driving CART induced neurotoxicity in mouse models. Here we present a clinical investigation (ChiCTR2000032124; ChiCTR2000031868) of anti-CD19 and anti-BCMA CART (41BBζ) secreting an anti-IL6 scFv and IL1 receptor antagonist (IL1RA) in treating patients with hematologic malignancy. Our results revealed that IL6 and IL1B were maintained at low levels without significant elevation during CRS, rendering Tocilizumab dispensable.


Fig: a The schematic illustration of CART-secreted anti-IL6 scFv and IL1RA in blocking IL6 and IL1 signalings during CRS of CART therapy. b The design of CAR construct and the sequences of aIL6 scFv and IL1RA. c Comparison of gene delivered expression of different scFv targeting IL6 or IL6R in blocking IL6 signaling and the scFv was consisting of variable regions derived from 1-Sarilumab, 2-Sirukumab, 3-Siltuximab or 4-Tocilizumab. Optimization of co-expressing IL1RA with aIL6 for inhibiting IL1 signaling. Construct 1 includes, from N-terminus to C-terminus, T2A linker, scFv derived from Sirukumab, P2A linker, and IL-1RA (T2A-Sir-P2A-IL1RA). Construct 2 contains, from N-terminus to C-terminus, T2A linker, scFv antibody, (G4S)3 linker, and IL1RA (T2A-Sir-(G4S)3-IL1RA). Construct 3 contains, from N-terminus to C-terminus, scFv antibody, (G4S)3 linker, IL1RA, and T2A linker (Sir-(G4S)3-IL1RA-T2A). Triplicate was included in the test. d Anti-tumor efficacy of anti-CD19 CART-aIL6/Fc (n = 8) and CART-Fc (n = 7) in Xenograft model and quantification of CART-secreted aIL6/Fc in D6 serum. The representative results of two independent experiments were presented. Student’s t-test was conducted, and * denotes statistical significance of P < 0.05. ns means no significance.

Moreover, treated patients did not show neurotoxicity during CRS and exhibited mild to moderate CRS. Notably, we observed high rate of complete response (CR) and significant CART expansion during treatment. In sum, we conclude that CART-secreting anti-IL6 scFv and IL1RA could self-neutralize IL6 storm and maintain low levels of IL1B during CART therapy to minimize IL6- and IL1-associated cytokine toxicity and neurotoxicity without impairing therapeutic efficacy.

Xue, L., Yi, Y., Xu, Q. et al. Chimeric antigen receptor T cells self-neutralizing IL6 storm in patients with hematologic malignancy. Cell Discov 7, 84 (2021).

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