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Cancer cells frequently display defects in their antigen-processing pathway and thereby evade CD8 T cell immunity. We described a novel category of cancer antigens, named TEIPP, that emerge on cancers with functional loss of the peptide pump TAP. TEIPPs are non-mutated neoantigens despite their 'self' origin by virtue of their absence on normal tissues. Here, we describe the development of a synthetic long peptide (SLP) vaccine for the most immunogenic TEIPP antigen identified thus far, derived from the TAP-independent LRPAP1 signal sequence. LRPAP1 21-30 -specific CD8 T cells were present in blood of all tested healthy donors as well as patients with non-small cell lung adenocarcinoma. SLPs with natural flanking, however, failed to be cross-presented by monocyte-derived dendritic cells. Since the C-terminus of LRPAP1 21-30 is an unconventional and weakly binding serine (S), we investigated if replacement of this anchor would result in efficient cross-presentation. Exchange into a valine (V) resulted in higher HLA-A2 binding affinity and enhanced T cell stimulation. Importantly, CD8 T cells isolated using the V-variant were able to bind tetramers with the natural S-variant and respond to TAP-deficient cancer cells. A functional screen with an array of N-terminal and C-terminal extended SLPs pointed at the 24-mer V-SLP, elongated at the N-terminus, as most optimal vaccine candidate. This SLP was efficiently cross-presented and consistently induced a strong polyclonal LRPAP1 21-30 -specific CD8 T cells from the endogenous T cell repertoire. Thus, we designed a TEIPP SLP vaccine from the LRPAP1 signal sequence ready for validation in clinical trials., (© 2021. The Author(s).)

Background: Disturbed cognitive function is associated with several causes of mortality; however, the association between cognitive function and the risk of cancer death has not been extensively investigated yet. We aimed to evaluate the association of cognitive function with the risk of cancer death and all-cause mortality in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) and Leiden 85-plus Study. Additionally, a systematic review and meta-analysis of longitudinal studies were conducted to evaluate the association of cognitive function and risk of cancer death., Methods: Risk of cancer death and all-cause mortality were reported using hazard ratios (HRs) with 95% confidence interval (CI) in tertiles of cognitive function of PROSPER and Leiden85-Plus Study. Additionally, PubMed, Embase, Web of Science, Cochrane, PsycINFO, Academic Search Premier, CINHAL, and Emcare were searched up to November 1st, 2020 to perform a systematic review and meta-analysis. The relative risks (RRs) with 95%CI of cancer death per each standard deviation lower performance in cognitive measurements were calculated., Results: Participants of PROSPER had 1.65-fold (95%CI 1.11-2.47) greater risk of cancer death (P for trend = 0.016) and 1.85-fold (95%CI 1.46-2.34) higher risk of all-cause mortality (P for trend<0.001), in multivariable models. Results of the Leiden-85 Plus Study showed that subjects with MMSE score below 24 had a lower chance of cancer death (HR 0.79, 95%CI 0.36-1.70, P for trend = 0.820) but had 2.18-fold (95%CI 1.57-3.02) higher risk of all-cause mortality compared to the reference group (P for trend<0.001). Besides, the results of systematic review and meta-analysis showed that per each standard deviation lower performance in cognitive function, individuals were at a 10% higher chance of cancer death (RR 1.10, 95%CI 1.00-1.20, P-value = 0.044)., Conclusions: Lower cognitive function performance is associated with a marginally increased risk of cancer death, in line with a significantly greater risk of all-cause mortality., Competing Interests: The authors have declared that no competing interests exist.

Background: Pancreatic ductal adenocarcinoma (PDAC) is notoriously resistant to treatment including checkpoint-blockade immunotherapy. We hypothesized that a bimodal treatment approach consisting of dendritic cell (DC) vaccination to prime tumor-specific T cells, and a strategy to reprogram the desmoplastic tumor microenvironment (TME) would be needed to break tolerance to these pancreatic cancers. As a proof-of-concept, we investigated the efficacy of combined DC vaccination with CD40-agonistic antibodies in a poorly immunogenic murine model of PDAC. Based on the rationale that mesothelioma and pancreatic cancer share a number of tumor associated antigens, the DCs were loaded with either pancreatic or mesothelioma tumor lysates., Methods: Immune-competent mice with subcutaneously or orthotopically growing KrasG12D/+;Trp53R172H/+;Pdx-1-Cre (KPC) PDAC tumors were vaccinated with syngeneic bone marrow-derived DCs loaded with either pancreatic cancer (KPC) or mesothelioma (AE17) lysate and consequently treated with FGK45 (CD40 agonist). Tumor progression was monitored and immune responses in TME and lymphoid organs were analyzed using multicolor flow cytometry and NanoString analyzes., Results: Mesothelioma-lysate loaded DCs generated cross-reactive tumor-antigen-specific T-cell responses to pancreatic cancer and induced delayed tumor outgrowth when provided as prophylactic vaccine. In established disease, combination with stimulating CD40 antibody was necessary to improve survival, while anti-CD40 alone was ineffective. Extensive analysis of the TME showed that anti-CD40 monotherapy did improve CD8 +T cell infiltration, but these essential effector cells displayed hallmarks of exhaustion, including PD-1, TIM-3 and NKG2A. Combination therapy induced a strong change in tumor transcriptome and mitigated the expression of inhibitory markers on CD8 +T cells., Conclusion: These results demonstrate the potency of DC therapy in combination with CD40-stimulation for the treatment of pancreatic cancer and provide directions for near future clinical trials., Competing Interests: Competing interests: JA: Stock or other Ownership: Amphera. Consulting or Advisory Role: Eli-Lilly, MSD Oncology, Bristol-Myers Squibb, Roche Speakers Bureau: AstraZeneca, Takeda, Boehringer Ingelheim., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Vaccination of patients against neoantigens expressed in concurrent tumors, recurrent tumors, or tumors developing in individuals at risk of cancer is posing major challenges in terms of which antigens to target and is limited to patients expressing neoantigens in their tumors. Here, we describe a vaccination strategy against antigens that were induced in tumor cells by downregulation of the peptide transporter associated with antigen processing (TAP). Vaccination against TAP downregulation-induced antigens was more effective than vaccination against mutation-derived neoantigens, was devoid of measurable toxicity, and inhibited the growth of concurrent and future tumors in models of recurrence and premalignant disease. Human CD8 + T cells stimulated with TAP low dendritic cells elicited a polyclonal T-cell response that recognized tumor cells with experimentally reduced TAP expression. Vaccination against TAP downregulation-induced antigens overcomes the main limitations of vaccinating against mostly unique tumor-resident neoantigens and could represent a simpler vaccination strategy that will be applicable to most patients with cancer., (©2020 American Association for Cancer Research.)

Intracellular processing of antigens is crucial for the generation of T cell immunity towards cancers, since cleaved protein products are the molecular targets of these adaptive lymphocytes. The majority of antigenic peptides requires the TAP transporter to gain access to the peptide loading complex in the ER lumen where they bind MHC class I (MHC-I). This pivotal role of TAP in antigen processing makes the system vulnerable for modifications in cancer cells and indeed human cancers frequently silence this gene epigenetically. Interestingly, TAP-independent processing pathways then become apparent and partly restore MHC class I presentation with alternative peptides. In this review we discuss recent insights on how TAP-independent processing of immunogenic peptides occurs, and how these antigens can be exploited for cancer immunotherapy., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

T-cell based immunotherapies through checkpoint blockade or adoptive transfer are effective treatments for a wide range of cancers like melanomas and lung carcinomas that harbor a high mutational load. The HLA class I and class II (HLA-I and HLA-II) presented neoantigens arise from genetic mutations in the cancerous cells and are ideal non-self targets for the T cell-based treatments. Although some cancer patients responded with complete regression, many others are irresponsive to checkpoint blockade treatments, or relapse after initial success. One of the mechanisms by which tumors evade T cell recognition is by acquiring deficiencies in the HLA-I antigen-processing pathway, leading to downregulation of HLA-I molecules at the cell surface and thereby creating an 'invisible' tumor phenotype. Interestingly, an alternative antigen repertoire arises on these HLA-I low cancer cells. We refer to this alternative antigen repertoire as TEIPP: T cell epitopes associated with impaired peptide processing. TEIPP antigens are curious non-mutated peptides from housekeeping proteins that are not presented in homeostasis. In this review, for the first time we recapitulate all our published work on TEIPP antigens, including our recent understanding of the CD8 T cell repertoire. We are convinced that TEIPP-directed T cells will be valuable resources to target immune-edited tumors that have acquired resistance to checkpoint blockade therapy., (Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: T-cell mediated immunotherapy brought clinical success for many cancer patients. Nonetheless, downregulation of MHC class I antigen presentation, frequently occurring in solid cancers, limits the efficacy of these therapies. Unraveling the mechanisms underlying this type of immune escape is therefore of great importance. We here investigated the immunological effects of metabolic stress in cancer cells as a result of nutrient deprivation., Methods: TC1 and B16F10 tumor cell lines were cultured under oxygen- and glucose-deprivation conditions that mimicked the tumor microenvironment of solid tumors. Presentation of peptide antigens by MHC class I molecules was measured by flow cytometry and via activation of tumor-specific CD8 T cell clones. The proficiency of the IFNy-STAT1 pathway was investigated by Western blots on phosphorylated proteins, transfection of constitutive active STAT1 constructs and qPCR of downstream targets. Kinase inhibitors for PI3K were used to examine its role in IFNy receptor signal transduction., Results: Combination of oxygen- and glucose-deprivation resulted in decreased presentation of MHC class I antigens on cancer cells, even in the presence of the stimulatory cytokine IFNy. This unresponsiveness to IFNy was the result of failure to phosphorylate the signal transducer STAT1. Forced expression of constitutive active STAT1 fully rescued the MHC class I presentation. Furthermore, oxygen- and glucose-deprivation increased PI3K activity in tumor cells. Pharmacological inhibition of this pathway not only restored signal transduction through IFNy-STAT1 but also improved MHC class I presentation. Importantly, PI3K inhibitors also rendered tumor cells sensitive for recognition by CD8 T cells in culture conditions of metabolic stress., Conclusions: These data revealed a strong impact of metabolic stress on the presentation of tumor antigens by MHC class I and suggest that this type of tumor escape takes place at hypoxic areas even during times of active T cell immunity and IFNy release.

The intracellular peptide pump TAP feeds antigenic peptides for loading onto HLA class I molecules, and its down-modulation is a frequent immune evasion mechanism in human cancers. Two recent papers describe which 'hidden' antigens we might exploit to target these escaped cancer variants by CD8 T cells. These unTAPped peptides are now ready for clinical testing.

Cancer cells can evade immune surveillance through the expression of inhibitory ligands that bind their cognate receptors on immune effector cells. Expression of programmed death ligand 1 in tumor microenvironments is a major immune checkpoint for tumor-specific T cell responses as it binds to programmed cell death protein-1 on activated and dysfunctional T cells 1 . The activity of myeloid cells such as macrophages and neutrophils is likewise regulated by a balance between stimulatory and inhibitory signals. In particular, cell surface expression of the CD47 protein creates a 'don't eat me' signal on tumor cells by binding to SIRPα expressed on myeloid cells 2-5 . Using a haploid genetic screen, we here identify glutaminyl-peptide cyclotransferase-like protein (QPCTL) as a major component of the CD47-SIRPα checkpoint. Biochemical analysis demonstrates that QPCTL is critical for pyroglutamate formation on CD47 at the SIRPα binding site shortly after biosynthesis. Genetic and pharmacological interference with QPCTL activity enhances antibody-dependent cellular phagocytosis and cellular cytotoxicity of tumor cells. Furthermore, interference with QPCTL expression leads to a major increase in neutrophil-mediated killing of tumor cells in vivo. These data identify QPCTL as a novel target to interfere with the CD47 pathway and thereby augment antibody therapy of cancer.

Tumor-infiltrating CD8 T cells were found to frequently express the inhibitory receptor NKG2A, particularly in immune-reactive environments and after therapeutic cancer vaccination. High-dimensional cluster analysis demonstrated that NKG2A marks a unique immune effector subset preferentially co-expressing the tissue-resident CD103 molecule, but not immune checkpoint inhibitors. To examine whether NKG2A represented an adaptive resistance mechanism to cancer vaccination, we blocked the receptor with an antibody and knocked out its ligand Qa-1 b , the conserved ortholog of HLA-E, in four mouse tumor models. The impact of therapeutic vaccines was greatly potentiated by disruption of the NKG2A/Qa-1 b axis even in a PD-1 refractory mouse model. NKG2A blockade therapy operated through CD8 T cells, but not NK cells. These findings indicate that NKG2A-blocking antibodies might improve clinical responses to therapeutic cancer vaccines., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Most T cell-based immunotherapies of cancer depend on intact antigen presentation by HLA class I molecules (HLA-I). However, defects in the antigen-processing machinery can cause downregulation of HLA-I, rendering tumor cells resistant to CD8 + T cells. Previously, we demonstrated that a unique category of cancer antigens is selectively presented by tumor cells deficient for the peptide transporter TAP, enabling a specific attack of such tumors without causing immunopathology in mouse models. With a novel combinatorial screening approach, we now identify 16 antigens of this category in humans. These HLA-A*02:01 presented peptides do not derive from the mutanome of cancers, but are of "self" origin and therefore constitute universal neoantigens. Indeed, CD8 + T cells specific for the leader peptide of the ubiquitously expressed LRPAP1 protein recognized TAP-deficient, HLA-I low lymphomas, melanomas, and renal and colon carcinomas, but not healthy counterparts. In contrast to personalized mutanome-targeted therapies, these conserved neoantigens and their cognate receptors can be exploited for immune-escaped cancers across diverse histological origins., (© 2018 Marijt et al.)

Cancers frequently evade immune-recognition by lowering peptide:MHC-I complexes on their cell surface. Limited peptide supply due to TAP-deficiency results in such MHC-I low immune-escape variants. Previously, we reported on a category of TAP-independent self-peptides, called TEIPP, with selective presentation by these tumors. Here we demonstrate that in contrast to T cells specific for conventional tumor antigens, TEIPP-directed T cells remain naïve in mice bearing immune-escaped tumors. This unaffected state was caused by low levels of MHC-I on the tumors and the failure to cross-present low levels of antigenic protein by host APCs. Importantly, increased levels of MHC-I, antigen or co-stimulation resulted in potent activation of TEIPP-specific T cells via direct presentation. Genetic knockdown by CRISPR/Cas9 technology of the relevant MHC-I allele in tumor cells indeed abrogated T cell activation. Vaccine-mediated priming of TEIPP-specific T cells induced efficient homing to MHC-I low tumors and subsequently protected mice against outgrowth of their MHC-I low tumor. Thus, our data open up the search of TEIPP-specific T cells in cancer patients to explore their application against MHC-I low tumor cells.

Immunotherapy with PD-1/PD-L1-blocking antibodies is clinically effective for several tumor types, but the mechanism is not fully understood. PD-L1 expression on tumor biopsies is generally regarded as an inclusion criterion for this cancer therapy. Here, we describe the PD-L1-blocking therapeutic responses of preclinical tumors in which PD-L1 expression was removed from cancer cells, but not from immune infiltrate. Lack of PD-L1 expression on malignant cells delayed tumor outgrowth in a CD8 + T cell-mediated fashion, showing the importance of this molecule in immune suppression. PD-L1 expression was evident on myeloid-infiltrating cells in the microenvironment of these tumors and targeting stromal PD-L1 with blocking antibody therapy had additional antitumor effect, demonstrating that PD-L1 on both malignant cells and immune cells is involved in the mechanism of immunotherapeutic antibodies. Importantly, comparable results were obtained with PD-1-blocking therapy. These findings have implications for inclusion of cancer patients in PD-1/PD-L1 blockade immunotherapies.

Glioblastomas (GBMs) rapidly become refractory to anti-VEGF therapies. We previously demonstrated that ectopic overexpression of angiopoietin-2 (Ang-2) compromises the benefits of anti-VEGF receptor (VEGFR) treatment in murine GBM models and that circulating Ang-2 levels in GBM patients rebound after an initial decrease following cediranib (a pan-VEGFR tyrosine kinase inhibitor) administration. Here we tested whether dual inhibition of VEGFR/Ang-2 could improve survival in two orthotopic models of GBM, Gl261 and U87. Dual therapy using cediranib and MEDI3617 (an anti-Ang-2-neutralizing antibody) improved survival over each therapy alone by delaying Gl261 growth and increasing U87 necrosis, effectively reducing viable tumor burden. Consistent with their vascular-modulating function, the dual therapies enhanced morphological normalization of vessels. Dual therapy also led to changes in tumor-associated macrophages (TAMs). Inhibition of TAM recruitment using an anti-colony-stimulating factor-1 antibody compromised the survival benefit of dual therapy. Thus, dual inhibition of VEGFR/Ang-2 prolongs survival in preclinical GBM models by reducing tumor burden, improving normalization, and altering TAMs. This approach may represent a potential therapeutic strategy to overcome the limitations of anti-VEGFR monotherapy in GBM patients by integrating the complementary effects of anti-Ang2 treatment on vessels and immune cells.

Resistance to docetaxel is a major clinical problem in advanced prostate cancer (PCa). Although glucocorticoids (GCs) are frequently used in combination with docetaxel, it is unclear to what extent GCs and their receptor, the glucocorticoid receptor (GR), contribute to the chemotherapy resistance. In this study, we aim to elucidate the role of the GR in docetaxel-resistant PCa in order to improve the current PCa therapies. GR expression was analyzed in a tissue microarray of primary PCa specimens from chemonaive and docetaxel-treated patients, and in cultured PCa cell lines with an acquired docetaxel resistance (PC3-DR, DU145-DR, and 22Rv1-DR). We found a robust overexpression of the GR in primary PCa from docetaxel-treated patients and enhanced GR levels in cultured docetaxel-resistant human PCa cells, indicating a key role of the GR in docetaxel resistance. The capability of the GR antagonists (RU-486 and cyproterone acetate) to revert docetaxel resistance was investigated and revealed significant resensitization of docetaxel-resistant PCa cells for docetaxel treatment in a dose- and time-dependent manner, in which a complete restoration of docetaxel sensitivity was achieved in both androgen receptor (AR)-negative and AR-positive cell lines. Mechanistically, we demonstrated down-regulation of Bcl-xL and Bcl-2 upon GR antagonism, thereby defining potential treatment targets. In conclusion, we describe the involvement of the GR in the acquisition of docetaxel resistance in human PCa. Therapeutic targeting of the GR effectively resensitizes docetaxel-resistant PCa cells. These findings warrant further investigation of the clinical utility of the GR antagonists in the management of patients with advanced and docetaxel-resistant PCa., (© 2016 The authors.)