4-1BB enhancement of CAR T function requires NF-κB and TRAFs

Abstract

Chimeric antigen receptors (CARs) have an antigen-binding domain fused to transmembrane, costimulatory, and CD3ζ domains. Two CARs with regulatory approval include a CD28 or 4-1BB costimulatory domain. While both CARs achieve similar clinical outcomes, biologic differences have become apparent but not completely understood. Therefore, in this study we aimed to identify mechanistic differences between 4-1BB and CD28 costimulation that contribute to the biologic differences between the 2 CARs and could be exploited to enhance CAR T cell function. Using CD19-targeted CAR T cells with 4-1BB we determined that enhancement of T cell function is driven by NF-κB. Comparison to CAR T cells with CD28 also revealed that 4-1BB is associated with more antiapoptotic proteins and dependence on persistence for B cell killing. While TNF receptor-associated factor 2 (TRAF2) has been presupposed to be required for 4-1BB costimulation in CAR T cells, we determined that TRAF1 and TRAF3 are also critical. We observed that TRAFs impacted CAR T viability and proliferation, as well as cytotoxicity and/or cytokines, in part by regulating NF-κB. Our study demonstrates how 4-1BB costimulation in CAR T cells impacts antitumor eradication and clinical outcomes and has implications for enhanced CAR design.

CD137 ligand feedback upregulates PD‐L1 expression on lung cancer via T cell production of IFN‐γ

“…43 CD137 signaling can enhance T cell function and is also dependent on other TNF-receptor associated factors (TRAFs) that associate TNFRs with NF-κB and on stress kinase signaling pathways. 34,35 In vivo, there were also reports showing a strong IFN-γ production when CD137 signaling was stimulated by using a CD137 agonist. 44,45 CD137L provides a CD28-independent signal resulting in cell division, and delivered systemically increases CD8 + T cell expansion in comparison to CD4 + T cell expansion.…”

“…Anti‐CD137 mAb stimulates CD8 + T cells to produce IFN‐γ . CD137 signaling can enhance T cell function and is also dependent on other TNF‐receptor associated factors (TRAFs) that associate TNFRs with NF‐κB and on stress kinase signaling pathways . In vivo, there were also reports showing a strong IFN‐γ production when CD137 signaling was stimulated by using a CD137 agonist .…”

“…An effective antitumor immune response demands collaboration between CD8 + and CD4 + T lymphocytes, and CD8 + cytotoxic T lymphocytes (CTL) play a central part in antitumor immunity through the production of IFN-γ, TNF, and granzyme B following ligation of their T cell receptors (TCRs). 34,35 It has been clearly established that IFN can regulate the PD-L1 expression in cancer cells and is the mechanism by which carcinoma cells elude being killed by immune cells. In contrast, the other cytokines and molecular pathways that regulate PD-L1 expression have not been well identified.…”

Concomitant PIK3CD and TNFRSF9 deficiencies cause chronic active Epstein-Barr virus infection of T cells

“…Furthermore, targeting CD137 with agonistic antibodies also demonstrated potent effects on antitumoral and viral responses (Chester et al, 2018). Chimeric antigen receptor (CAR) T cell therapy using CARs containing the intracytoplasmic domain of CD137 was also shown to be the most efficient to sustained CAR T cell responses (Li et al, 2018).…”

Allogeneic haematopoietic cell transplantation after CAR T‐cell therapy: safe, effective and contentious

“…The difference in study population and CAR T constructs makes the cross‐study comparison difficult. It has been shown that CAR T constructs based on the 4‐1BB (CD137) costimulatory molecule led to longer persistence of CAR T cells compared to CD28 (Li et al , ). One could speculate that given the shorter persistence of CD28‐based CAR T cells, allo‐HCT might be necessary to maintain remission, but a randomized study is needed to validate this hypothesis.…”