Aiming to improve the safety of CAR T cells, Tan et al. designed a membrane-bound form of an scFv derived from a human anti-IL-6 antibody linked to the hinge and transmembrane domains of the CD8α peptide (mbaIL6). T cells transduced with a single construct encoding mbaIL6 and an anti-CD19 CAR bound IL-6 and neutralized its function in vitro, and expression of mbaIL6 did not affect CAR T cells’ proliferation or cytotoxicity against CD19 target cells. In NSG mice bearing CD19+ tumors, CAR T cells with or without mbaIL6 exerted a strong antitumor effect, however, only the mbaIL6-expressing CAR T cells lowered human IL-6 levels.
Contributed by Anna Scherer
ABSTRACT: Infusion of T lymphocytes expressing chimeric antigen receptors (CARs) can produce extraordinary antitumor activity in patients with leukemia, lymphoma, and myeloma. The signaling mechanisms activating T cells and provoking tumor cell killing also trigger cytokine secretion and macrophage activation, leading to cytokine release syndrome (CRS). CRS is a serious side effect of CAR-T cells, and proinflammatory interleukin-6 (IL-6) is central to its pathogenesis. To endow T cells with anti-CRS activity, we designed a nonsignaling membrane-bound IL-6 receptor (mbaIL6) constituted by a single chain variable fragment derived from an anti-IL-6 antibody linked to a transmembrane anchoring peptide. We found that mbaIL6 expressed on the surface of T cells could rapidly remove IL-6 from the culture supernatant. IL-6 removal was proportional to the number of mbaIL6+ cells, increased with T-cell proliferation, and neutralized IL-6 signaling and function. A construct encoding for mbaIL6 and an anti-CD19-41BB-CD3zeta CAR allowed simultaneous expression of both receptors. T cells with mbaIL6 and CAR neutralized macrophage-derived IL-6 while exerting powerful antitumor activity. Cytotoxicity and proliferation were identical to those of cells expressing CAR alone in vitro, and CAR-T cells were effective in xenograft models regardless of mbaIL6 expression. Levels of human IL-6 in mice, however, were greatly reduced if T cells expressed both receptors instead of CAR alone. Thus, CAR-T cells with on-board capacity to extinguish IL-6 represent a new approach to prevent CRS and suppress its severity without affecting the antitumor potential of CAR-T cells.
Author Info: (1) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (2) Department of Pediatrics, Yong Loo Lin School of Medicine, National
Author Info: (1) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (2) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (3) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
