Project description:Chronic viral infections are characterized by a state of CD8 T cell dysfunction termed exhaustion. A better understanding of the mechanisms that regulate CD8 T cell responses during chronic infection is required to improve immunotherapies that restore function in exhausted CD8 T cells. Here we identify a novel population of virus-specific CD8 T cells with a T follicular helper (Tfh)-like signature in mice chronically infected with lymphocytic choriomeningitis virus (LCMV). These Tfh-like CD8 T cells expressed the programmed cell death-1 (PD-1) inhibitory receptor but at the same time also expressed co-stimulatory molecules and had a gene signature that was related to CD8 T cell memory precursor cells and hematopoietic stem cells (HSC). These Tfh-like CD8 T cells acted as stem cells during chronic infection undergoing self-renewal and also differentiating into the terminally exhausted CD8 T cells that were present in both lymphoid and non-lymphoid tissues. The Tfh-like CD8 T cells were found only in lymphoid tissues and resided predominantly in the T cell zones along with naïve CD8 T cells. Interestingly, the proliferative burst after PD-1 blockade came almost exclusively from this Tfh-like CD8 T cell subset. Importantly, the transcription factor TCF1 played a cell intrinsic and essential role in the generation of Tfh-like CD8 T cells. Taken together, our study identifies Tfh-like CD8 T cells as the critical subset for maintaining the pool of virus-specific CD8 T cells during chronic infection and as the cells that proliferate after PD-1 blockade. These findings provide a better understanding of T cell exhaustion and have implications towards optimizing PD-1 directed immunotherapy. 8 samples isolated from CD8 T-cells in LCMV clone 13 GK1.5 infected mice (2 naïve, 3 CXCR5+Tim3-, 3 CXCR5-Tim3+) cells were analyzed
Project description:TGFb signaling is a major pathway associated with poor clinical outcome in patients with
advanced metastatic cancers and non-response to immune checkpoint blockade, particularly in the immune-excluded tumor phenotype. While previous pre-clinical studies demonstrated that converting tumors from an excluded to an inflamed phenotype and curative anti-tumor immunity require attenuation of both PD-L1 and TGFb signaling, the underlying cellular mechanisms remain unclear. Recent studies suggest that stem cell-like CD8 T cells (TSCL) can differentiate into non-exhausted CD8 T effector cells that drive durable anti-tumor immunity. Here, we show that TGFb and PD-L1 restrain TSCL expansion as well as replacement of progenitor exhausted and dysfunctional CD8 T cells with non-exhausted IFNghi CD8 T effector cells in the tumor microenvironment (TME). Blockade of TGFb and PD-L1 generated IFNghi CD8 T effector cells with enhanced motility, enabling both their accumulation in the TME and increased interaction with other cell types. Ensuing IFNg signaling markedly transformed myeloid, stromal, and tumor niches to yield a broadly immune-supportive ecosystem. Blocking IFNg completely abolished the effect of anti-PD-L1/ TGFb combination therapy. Our data suggest that TGFb works in concert with PD-L1 to prevent TSCL expansion and replacement of exhausted CD8 T cells with fresh CD8
T effector cells, thereby maintaining the CD8 T cell compartment in a dysfunctional state.
Project description:Blockade of programmed death-1 (PD-1) reinvigorates exhausted CD8+ T cells, resulting in tumor regression in cancer patients. Recently, reinvigoration of exhausted CD8+ T cells following PD-1 blockade was shown to be CD28-dependent in mouse models. Herein, we examined the role of CD28 in anti-PD-1-induced human T-cell reinvigoration using tumor-infiltrating CD8+ T cells (CD8+ TILs) obtained from non-small cell lung cancer patients. Single cell analysis demonstrated a distinct expression pattern of CD28 between mouse and human CD8+ TILs. Furthermore, we found that human CD28+CD8+, but not CD28–CD8+ TILs, responded to PD-1 blockade irrespective of B7/CD28 blockade, indicating that CD28 co-stimulation in human CD8+ TILs is dispensable for PD-1 blockade-induced reinvigoration, and loss of CD28 expression rather serve as a marker of anti-PD-1-unresponsive CD8+ TILs. Transcriptionally and phenotypically, PD-1 blockade-unresponsive human CD28–PD-1+CD8+ TILs exhibited characteristics of terminally exhausted CD8+ T cells with low TCF1 expression. Notably, CD28–PD-1+CD8+ TILs had preserved machinery to respond to IL-15, and IL-15 treatment enhanced proliferation of CD28–PD-1+CD8+ TILs as well as CD28+PD-1+CD8+ TILs. Taken together, we demonstrate loss of CD28 expression as a marker of PD-1 blockade-unresponsive human CD8+ TILs with TCF1– signature and provide mechanistic insights into combining IL-15 with anti-PD-1.
Project description:An improved understanding of the anti-tumor CD8+ T cell response after checkpoint blockade would enable more informed and effective therapeutic strategies. Here we examined the dynamics of the effector response of CD8+ tumor-infiltrating lymphocytes (TILs) after checkpoint blockade therapy. Bulk and single-cell RNA profiles of CD8+ TILs after combined Tim-3+PD-1 blockade in preclinical models revealed significant changes in the transcriptional profile of PD-1? TILs. These cells could be divided into subsets bearing characterstics of naive-, effector-, and memory-precursor-like cells. Effector- and memory-precursor-like TILs contained tumor-antigen-specific cells, exhibited proliferative and effector capacity, and expanded in response to different checkpoint blockade therapies across different tumor models. The memory-precursor-like subset shared features with CD8+ T cells associated with response to checkpoint blockade in patients and was compromised in the absence of Tcf7. Expression of Tcf7 was requisite for the efficacy of diverse immunotherapies, highlighting the importance of this transcriptional regulator in the development of effective CD8+ T cell responses upon immunotherapy.
Project description:The gut microbiota is related to the antitumour efficacy of immune checkpoint blockade, but the mechanism(s) of action have not been fully elucidated. Here, we show that a novel Ruminococcaceae strain (designated YB328) isolated from the faeces of patients who responded to programmed cell death 1 (PD-1) blockade primes/activates tumour-specific CD8+ T cells through stimulation/maturation of CD103+CD11b- conventional dendritic cells (cDCs) which migrate from the gut to the tumour microenvironment (TME). YB328 administration improved the antitumour efficacy of PD-1 blockade even when it was added to faecal transplantation from non-responder patients in animal models. YB328 promoted the IRF8-driven differentiation of CD103+CD11b- cDCs expressing multiple Toll-like receptors, which received additional stimulation/maturation signals from other bacteria, and the accumulation of these DCs in tumour lesions. These CD103+CD11b- cDCs prolonged engagement with cognate antigen-specific CD8+ T cells, which induced the activation of CD8+ T cells specific for diverse tumour antigens and fostered PD-1 expression through NFATc1 nuclear translocation, thereby leading to an increase in PD-1+CD8+ T cells harbouring a broader T-cell receptor repertoire in the TME. We propose that the gut microbiota augments antitumour immunity by accelerating the differentiation/maturation and migration of DCs to increase CD8+ T cells responding to diverse tumour antigens.
Project description:Immunotherapy has opened hitherto unknown possibilities to treat cancer. Whereas some cancer types (e.g. melanoma) can be efficiently treated, others lack measurable positive effects (e.g. PDAC). Moreover, stratification of responders/non-responders is only possible in some cancer types (e.g. melanoma). Hepatocellular carcinoma (HCC) has a dismal prognosis, limited treatment options and survival benefit, and represents a potential cancer entity for successful immunotherapy. Here, we investigated NASH-triggered HCC in the context PD-1-targeted immunotherapy. Using flow cytometry, single cell RNA sequencing, immunohistochemistry and mass spectrometric analyses, we found a progressive increase of CD8+PD-1+ effector T-cells with a unique profile of exhaustion and activation markers rising with murine and human NASH severity. Notably, late-stage HCC treatment with PD-1-targeted immunotherapy enhanced hepatic carcinogenesis in mice. Dissecting potential mechanisms of action during tumor-initiation and -progression we analyzed the effects of PD-1-targeted immunotherapy at HCC initiation. PD-1-targeted immunotherapy induced a pro-tumorigenic environment, enhanced necro-inflammation and increased NAFLD-activation score (NAS), leading to increased liver cancer incidence, tumor number and nodule size. In contrast, anti-CD8 or anti-CD8/anti-NK1.1 treatment reduced NAS and abrogated the development of liver cancer, thus identifying CD8+PD-1+ T-cells as drivers of liver cancer in NASH-triggered HCC. Increased apoptotic signaling, STAT3 phosphorylation and hepatic proliferation were detected in intra-tumoral liver tissue upon PD-1-targeted immunotherapy. In line, PD-1-/- mice challenged with a NASH diet displayed early onset of hepatocarcinogenesis, corroborating the pro-tumorigenic role of absent or reduced PD-1. Mechanistically PD-1-targeted immunotherapy mainly affected hepatic abundance of CD8+PD-1+ T-cells, instead of altering the quality of Tox+CXCR6+ expressing CD8+PD-1+TNF+CD39+Gzmb+ T-cells found in NASH livers, leading to an aggressive, pro-tumorigenic liver environment. Single-cell mapping of human NASH-, borderline NASH- or unaffected livers corroborated our preclinical NASH results. Moreover, in human NASH livers a correlation of hepatic CD8+, PD-1+, TNF+ T-cells with fibrosis and NASH severity was observed. Accordingly, HCC patients with NASH etiology display a sharp increase in intra- and peri-tumoral CD8+ PD-1+ T-cells. In a cohort of 65 patients recruited across 6 centers in Germany and Austria, patients with NAFLD/NASH-driven HCC responded worse to PD-1-targeted immunotherapy by Nivolumab or Pembrolizumab compared to non-NAFLD patients. This resulted in significant reduced overall survival, in trends of faster disease progression and reduced progression free survival. Histological analysis of livers derived from HCC patients treated with PD-1-targeted immunotherapy displayed high levels of intra and peri-tumoral CD8+ PD-1+ T-cells and Ki67+ hepatocytes. Taken together, these data indicate that PD-1-targeted immunotherapy induces immune-related adverse effects in NAFLD/NASH-driven HCC through CD8+PD-1+ T-cells. Our data call for stratification of HCC patients subjected to PD-1-targeted immunotherapy, with NAFLD being a negative predictor.
Project description:Upon chronic antigen exposure, CD8+ T cells become exhausted acquiring a dysfunctional state correlated with the inability to control infection or tumor. In contrast to exhausted T cells, stem-like CD8+ T progenitors maintain the ability to promote and sustain effective immunity. Adenovirus (Ad) vectored vaccines encoding tumor neoantigens have been shown to eradicate large tumors when combined with anti-Programmed cell death protein 1 (αPD-1) in murine models, however the mechanisms and translational potential have not yet been elucidated. Here, we show that gorilla Ad vaccine targeting tumor neoepitopes enhance responses to αPD-1 therapy, by improving immunogenicity and anti-tumor efficacy. Single cell RNA-seq demonstrated that the combination of Ad vaccine and αPD-1 increased the number of murine polyfunctional neoantigen specific CD8+ T cells over αPD-1 monotherapy, with an accumulation of Tcf1+ stem-like progenitors in draining lymph nodes and effector CD8+T cells in tumors. Combined TCR sequencing analysis highlighted a broader spectrum of neoantigen specific CD8+ T cells upon vaccination compared to αPD-1 monotherapy. The translational relevance of these data is supported by results obtained in the first 12 patients with metastatic deficient mismatch repair (dMMR) tumors vaccinated with an Ad vaccine encoding shared neoantigens. Expansion and diversification of TCRs was observed in post-treatment biopsies of patients with clinical response, as well as an increase in tumor infiltrating T cells with an effector memory signature. These findings indicate a promising mechanism to overcome resistance to PD-1 blockade, by promoting immunogenicity and broadening the spectrum and magnitude of neoantigen-specific T cells infiltrating tumors.