Abstract
Adenosine is an immunosuppressive factor that limits anti-tumor immunity through the suppression of multiple immune subsets including T cells via activation of the adenosine A
2A
receptor (A
...2A
R). Using both murine and human chimeric antigen receptor (CAR) T cells, here we show that targeting A
2A
R with a clinically relevant CRISPR/Cas9 strategy significantly enhances their in vivo efficacy, leading to improved survival of mice. Effects evoked by CRISPR/Cas9 mediated gene deletion of A
2A
R are superior to shRNA mediated knockdown or pharmacological blockade of A
2A
R. Mechanistically, human A
2A
R-edited CAR T cells are significantly resistant to adenosine-mediated transcriptional changes, resulting in enhanced production of cytokines including IFNγ and TNF, and increased expression of JAK-STAT signaling pathway associated genes. A
2A
R deficient CAR T cells are well tolerated and do not induce overt pathologies in mice, supporting the use of CRISPR/Cas9 to target A
2A
R for the improvement of CAR T cell function in the clinic.
Cancer cells exploit the expression of the programmed death-1 (PD-1) ligand 1 (PD-L1) to subvert T-cell-mediated immunosurveillance. The success of therapies that disrupt PD-L1-mediated tumour ...tolerance has highlighted the need to understand the molecular regulation of PD-L1 expression. Here we identify the uncharacterized protein CMTM6 as a critical regulator of PD-L1 in a broad range of cancer cells, by using a genome-wide CRISPR-Cas9 screen. CMTM6 is a ubiquitously expressed protein that binds PD-L1 and maintains its cell surface expression. CMTM6 is not required for PD-L1 maturation but co-localizes with PD-L1 at the plasma membrane and in recycling endosomes, where it prevents PD-L1 from being targeted for lysosome-mediated degradation. Using a quantitative approach to profile the entire plasma membrane proteome, we find that CMTM6 displays specificity for PD-L1. Notably, CMTM6 depletion decreases PD-L1 without compromising cell surface expression of MHC class I. CMTM6 depletion, via the reduction of PD-L1, significantly alleviates the suppression of tumour-specific T cell activity in vitro and in vivo. These findings provide insights into the biology of PD-L1 regulation, identify a previously unrecognized master regulator of this critical immune checkpoint and highlight a potential therapeutic target to overcome immune evasion by tumour cells.
The presence of tumour-infiltrating lymphocytes (TILs) is associated with favourable outcomes in patients with breast cancer as well as in those with other solid tumours. T cells make up a ...considerable proportion of TILs and current evidence suggests that CD8
T cells are a crucial determinant of favourable clinical outcomes. Studies involving tumour material from numerous solid tumour types, including breast cancer, demonstrate that the CD8
TILs include a subpopulation of tissue-resident memory T (T
) cells. This subpopulation has features consistent with those of T
cells, which have been described as having a role in peripheral immune surveillance and viral immunity in both humans and mice. Patients with early-stage triple-negative breast cancers harbouring greater numbers of T
cells have a substantially improved prognosis and longer overall survival. Furthermore, patients with advanced-stage breast cancers with higher levels of T
cells have increased response rates to anti-PD-1 antibodies. These findings have motivated efforts to explore whether CD8
T
cells include tumour-specific T cells, their functional responses to cognate antigens and their role in responses to immune checkpoint inhibition. In this Review, we focus on the clinical significance of CD8
T
cells and the potential ways that these cells can be targeted to improve the success of immunotherapeutic approaches in patients with breast cancer, as well as in those with other solid tumour types.
Immunomodulatory drugs (IMiDs) are effective treatments for patients with multiple myeloma. IMiDs have pleotropic effects including targeting the myeloma cells directly, and improving the ...anti-myeloma immune response. In the absence of myeloma cells, lenalidomide and pomalidomide induce CD4
T cell secretion of IL-2 and indirect activation of Natural Killer (NK) cells. In the context of T cell receptor ligation, IMiDs enhance T cell proliferation, cytokine release and Th1 responses, both
and
. Furthermore, combination treatment of IMiDs and myeloma-targeting monoclonal antibodies eg. daratumumab (anti-CD38) and elotuzumab (anti-SLAMF7), checkpoint inhibitors, or bispecific T cell engagers showed synergistic effects, mainly via enhanced T and NK cell dependent cellular toxicity and T cell proliferation. Conversely, the corticosteroid dexamethasone can impair the immune modulatory effects of IMiDs, indicating that careful choice of myeloma drugs in combination with IMiDs is key for the best anti-myeloma therapeutic efficacy. This review presents an overview of the role for T cells in the overall anti-myeloma effects of immunomodulatory drugs.
Mucosal‐associated invariant T (MAIT) cells represent up to 10% of circulating human T cells. They are usually defined using combinations of non‐lineage‐specific (surrogate) markers such as ...anti‐TRAV1‐2, CD161, IL‐18Rα and CD26. The development of MR1‐Ag tetramers now permits the specific identification of MAIT cells based on T‐cell receptor specificity. Here, we compare these approaches for identifying MAIT cells and show that surrogate markers are not always accurate in identifying these cells, particularly the CD4+ fraction. Moreover, while all MAIT cell subsets produced comparable levels of IFNγ, TNF and IL‐17A, the CD4+ population produced more IL‐2 than the other subsets. In a human ontogeny study, we show that the frequencies of most MR1 tetramer+ MAIT cells, with the exception of CD4+ MAIT cells, increased from birth to about 25 years of age and declined thereafter. We also demonstrate a positive association between the frequency of MAIT cells and other unconventional T cells including Natural Killer T (NKT) cells and Vδ2+ γδ T cells. Accordingly, this study demonstrates that MAIT cells are phenotypically and functionally diverse, that surrogate markers may not reliably identify all of these cells, and that their numbers are regulated in an age‐dependent manner and correlate with NKT and Vδ2+ γδ T cells.
This study uses MR1 tetramers to enumerate and phenotypically characterize human blood MAIT cells, and subsets thereof based on CD4 and CD8 expression. Furthermore MR1 tetramers are compared to the commonly used mAb‐based MAIT cell identification techniques.
The presence of tumor-infiltrating lymphocytes in triple-negative breast cancers is correlated with improved outcomes. Ras/MAPK pathway activation is associated with significantly lower levels of ...tumor-infiltrating lymphocytes in triple-negative breast cancers and while MEK inhibition can promote recruitment of tumor-infiltrating lymphocytes to the tumor, here we show that MEK inhibition adversely affects early onset T-cell effector function. We show that α-4-1BB and α-OX-40 T-cell agonist antibodies can rescue the adverse effects of MEK inhibition on T cells in both mouse and human T cells, which results in augmented anti-tumor effects in vivo. This effect is dependent upon increased downstream p38/JNK pathway activation. Taken together, our data suggest that although Ras/MAPK pathway inhibition can increase tumor immunogenicity, the negative impact on T-cell activity is functionally important. This undesirable impact is effectively prevented by combination with T-cell immune agonist immunotherapies resulting in superior therapeutic efficacy.MEK inhibition in breast cancer is associated with increased tumour infiltrating lymphocytes (TILs), however, MAPK activity is required for T cells function. Here the authors show that TILs activity following MEK inhibition can be enhanced by agonist immunotherapy resulting in synergic therapeutic effects.
A characteristic of mucosal-associated invariant T (MAIT) cells is the expression of TRAV1-2+ T cell receptors (TCRs) that are activated by riboflavin metabolite-based antigens (Ag) presented by the ...MHC-I related molecule, MR1. Whether the MR1-restricted T cell repertoire and associated Ag responsiveness extends beyond these cells remains unclear. Here, we describe MR1 autoreactivity and folate-derivative reactivity in a discrete subset of TRAV1-2+ MAIT cells. This recognition was attributable to CDR3β loop-mediated effects within a consensus TRAV1-2+ TCR-MR1-Ag footprint. Furthermore, we have demonstrated differential folate- and riboflavin-derivative reactivity by a diverse population of “atypical” TRAV1-2− MR1-restricted T cells. We have shown that TRAV1-2− T cells are phenotypically heterogeneous and largely distinct from TRAV1-2+ MAIT cells. A TRAV1-2− TCR docks more centrally on MR1, thereby adopting a markedly different molecular footprint to the TRAV1-2+ TCR. Accordingly, diversity within the MR1-restricted T cell repertoire leads to differing MR1-restricted Ag specificity.
•Identification of TRAV1-2− MR1 restricted T cells•Characterization of autoreactive and folate-derivative-reactive MAIT cells•Folate-derivative responsiveness and autoreactivity mediated by CDR3β hypervariability•Structure determination of a TRAV1-2− TCR-MR1-antigen complex
MAIT cells, defined by an invariant TRAV1-2+ TCR α-chain, respond to riboflavin-based metabolites presented by MR1. Rossjohn, Godfrey, and colleagues describe atypical TRAV1-2+ and TRAV1-2− MR1 restricted T cells that can be activated by riboflavin and folate derivatives, and provide a molecular basis underpinning their interactions.
Chimeric antigen receptors (CAR) are genetically engineered receptors that can recognise specific antigens and subsequently activate downstream signalling. Human T cells engineered to express a CAR, ...also known as CAR-T cells, can target a specific tumour antigen on the cell surface to mediate a cytotoxic response against the tumour. CAR-T cell therapy has achieved remarkable success in treating hematologic malignancies, but not in solid tumours. Currently, extensive research is being carried out to make CAR-T cells a therapy for solid tumours. To date, most of the research interest in the field has focused on cytotoxic T lymphocytes as the carrier of CAR products. However, in addition to T cells, the CAR design can be introduced in other immune cells, such as natural killer (NK)/NKT cells, γδ T cells, mucosal-associated invariant T (MAIT) cells, dendritic cells (DC), macrophages, regulatory T cells (Treg), B cells, etc. Some of the CAR-engineered immune cells, such as CAR- γδ T and CAR-NK/NK-T cells, are directly involved in the anti-tumour response, demonstrated in preclinical studies and/or clinical trials. CAR-Tregs showed promising therapeutic potential in treating autoimmune diseases. In particular, B cells engineered with chimeric receptors can be used as a platform for long-term delivery of therapeutic proteins, such as recombinant antibodies or protein replacement, in an antigen-specific manner. CAR technology is one of the most powerful engineering platforms in immunotherapy, especially for the treatment of cancers. In this review, we will discuss the recent application of the CAR design in non-CAR-T cells and future opportunities in immunotherapy.
The function of MR1-restricted mucosal-associated invariant T (MAIT) cells in tumor immunity is unclear. Here we show that MAIT cell-deficient mice have enhanced NK cell-dependent control of ...metastatic B16F10 tumor growth relative to control mice. Analyses of this interplay in human tumor samples reveal that high expression of a MAIT cell gene signature negatively impacts the prognostic significance of NK cells. Paradoxically, pre-pulsing tumors with MAIT cell antigens, or activating MAIT cells in vivo, enhances anti-tumor immunity in B16F10 and E0771 mouse tumor models, including in the context of established metastasis. These effects are associated with enhanced NK cell responses and increased expression of both IFN-γ-dependent and inflammatory genes in NK cells. Importantly, activated human MAIT cells also promote the function of NK cells isolated from patient tumor samples. Our results thus describe an activation-dependent, MAIT cell-mediated regulation of NK cells, and suggest a potential therapeutic avenue for cancer treatment.
PDF
