Toll-like receptor agonists: Current status and future perspective on their utility as adjuvants in improving antic ancer vaccination strategies

Toll-like receptor (TLR) agonists possess remarkable properties, particularly with regard to dendritic cell activation, promoting Th1-type cytokine production and optimizing cytotoxic T-cell responses. Preclinical and clinical studies conducted to date show that TLR agonists can improve currently applied anticancer vaccination protocols. Although these have resulted in the US FDA approval of three TLR agonists for use in humans, their abundant application encounters limitations, principally due to dose-limiting toxicity evoking from systemic cytokine production. Here, using selected examples of clinical studies, we provide a concise review regarding the knowledge acquired thus far on the adjuvant use of TLR agonists as cancer vaccine components. We also provide evidence on the exploitation of a novel TLR agonist, prothymosin-α, which enhances the efficacy of tumor-reactive effectors without causing severe adverse effects. © 2013 Future Medicine Ltd

Daily variation in circulating cytokines and acute-phase proteins correlates with clinical and laboratory indices in community-acquired pneumonia

Our objective was to investigate the initial levels of circulating proinflammatory cytokines, such as interleukin 1β (IL-1β), interleukin 6 (IL-6, and tumour necrosis factor alpha (TNF-α), of certain acute-phase proteins, such as C-reactive protein (CRP), fibrinogen (FBN) and albumin, and of the glycoprotein fibronectin at presentation and their daily variation during the clinical course of community-acquired pneumonia (CAP) in relation to clinical and laboratory indices of infection. Thirty otherwise healthy hospitalized patients aged 48 ± 3 years (mean ± SEM) and with bacteriologically confirmed CAP were studied prospectively. IL-1β and IL-6 were found to be 15-fold higher on admission (122 ± 9 pg mL-1 and 60 ± 4 pg mL-1 respectively), whereas TNF-α was three-fold higher (102 ± 5 pg mL-1) than those of controls, all of them showing a decline towards normal. Initial CRP levels were increased 90-fold (416 ± 1 mg L-1), whereas fibronectin levels were reduced (242 ± 9 mg dL-1). The presence of parapneumonic effusion was associated with a higher TNF-α serum level (127 ± 7 vs. 86 ± 4 pg mL-1, P = 0.0002), a more rapid daily decline in TNF-α (-7.2 ± 0.7 vs. -3.8 ± 0.5 pg mL-1 day-1, P = 0.0005), a slower rate of decline in CRP (-42.8 ± 3.0 vs. -54.6 ± 3.0 mg L-1 day-1, P = 0.02) and a slower rate of increase in FBN (5.9 ± 1.0 vs. 11.7 ± 1.0 mg dL-1 day-1), P = 0.001]. Furthermore, daily progression of serum levels of-cytokines and acute-phase proteins correlated strongly with pyrexia, erythrocyte sedimentation rate (ESR), neutrophil count, alveolar-arterial oxygen difference and radiographic resolution, clinically manifested by improvement in the patients' condition

Combined treatment with Bevacizumab and standard chemotherapy restores abnormal immune parameters in advanced colorectal cancer patients

Background Bevacizumab, a monoclonal antibody (mAb) targeting vascular endothelial growth factor (VEGF), has produced promising results when combined with chemotherapy in the treatment of advanced colorectal cancer (CRC). The aim of the present study was to define the immunological profile of metastatic CRC patients at baseline and following chemotherapy with either irinotecan/5- fluorouracil/leucovorin (IFL) alone or IFL in combination with.bevacizumab (B-IFL). Methods Peripheral blood mononuclear cells (PBMCs) obtained from healthy donors (HD) (n=20) and patients (n=40) were tested for T-cell proliferation in the autologous mixed lymphocyte reaction (auto-MLR), and cytokine production following stimulation with anti-CD3 mAb. Results,PBMCs obtained from CRC patients prior to treatment exhibited lower auto-MLR responses and low production of IL-2, IFN-γ, IL-12 and IL-18 cytokines, whereas IL-4 and IL-10 cytokines were increased as compared to HD (p<0.001, for all parameters) following in vitro stimulation with anti-CD3 mAb. During treatment, and in particular in week 12 of evaluation, IL-2 (p <0.001 for both IFL and B-IFL groups), IFN-γ (p<0.001 for IFL and p=0.001 for B-IFL), IL-12 (p<0.001 for both IFL and B-IFL) and IL-18 (p<0.001 for both IFL and B-IFL) production, as well as auto-MLR responses increased (p< 0.001 for both IFL and B-IFL), whereas IL-4 (p<0.001 for IFL and p=0.001 for B-IFL) and IL-10 [p<0.001 for IFL and p=0.067 (non-significant) for B-IFL] production decreased over baseline in the two treatment groups, yet their respective values never reached those of HD. Moreover, IL-2, IFN-γ production, and auto-MLR were higher in the B-IFL over the IFL treatment group (p<0.001, p<0.04, p<0.001, respectively). Conclusion Our study demonstrates that the abnormal immune parameters observed inmetastatic CRC patients at presentation can substantially improve during treatment with either IFL or B-IFL. The immune parameters examined can provide a sensitive and valuable tool for monitoring immune function in CRC patients, and could be applied as surrogate markers predicting treatment-related outcome. © Springer Science+Business Media, LLC 2010

Induction of tumor-specific T lymphocyte responses in vivo by prothymosin α

We have recently reported that administration of Pro Tα to DBA/2 mice before the inoculation of syngeneic L1210 leukemic cells prolonged the survival of these animals by (a) inducing tumoricidal peritoneal macrophages, (b) enhancing natural killer (NK) and inducing lymphokine-activated killer (LAK) activities in splenocytes and (c) inducing the production of interleukin-2 and tumor necrosis factor α [Papanastasiou et al. (1992) Cancer Immunol Immunother 35:145; Baxevanis et al. (1994) Cancer Immunol Immunother 38:281]. In this report we demonstrate that Pro T α, when administered simultaneously with L1210 tumor cells, is capable of generating in DBA/2 animals tumorspecific CD8+ cytotoxic T lymphocytes (CTL). The Pro T α-induced CD8+ CTL lysed their syngeneic L1210 targets in a major histocompatibility complex (MHC)-restricted fashion since monoclonal antibodies (mAb) against the H-2Kd allelic product could inhibit the cytotoxic response. Mice receiving only Pro T α developed non-MHC-restricted cytotoxic activity (NK, and LAK activities) whereas those receiving Pro T α and L1210 tumor cells developed both MHC-restricted (CTL) and non-MHC-restricted cytotoxic activities and survived longer. The Pro T α-induced CD8+ CTL activity was regulated by Pro T α-induced L1210-specific syngeneic CD4+ cells. This was shown in two different ways: first, CD8+-cell-mediated cytotoxic responses against L1210 targets were associated with L1210-specific and MHC-restricted proliferative responses of syngeneic CD4+ cells and, second, CD4+ cells from mice that had received both Pro T α and L1210 tumor cells could enhance in vitro the otherwise weak, MHC-restricted and L1210-specific cytotoxicity of syngeneic CD8+ cells from mice that had received only L1210 cells. Our data suggest that Pro T α is capable of inducing nonspecific, as well as tumor-specific CTL responses in vivo. This is of importance since Pro T α may prove to be useful in clinical protocols aimed at cancer immunotherapy. © 1995 Springer-Verlag

2nd Symposium on Advances in Cancer Immunology and Immunotherapy, December 15–17, 2016, Athens, Greece

This is the 2nd Symposium of a series organized annually. It aims to integrate tumor immunology basic research with results from most recent clinical trials based on the use of anti-cancer agents targeting immune system components. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature

Natural CD8+ T-cell responses against MHC class I epitopes of the HER-2/neu oncoprotein in patients with epithelial tumors

HER-2/neu is an immunogenic protein eliciting both humoral and cellular immune responses in patients with HER-2/neu-positive (+) tumors. Preexisting cytotoxic T lymphocyte (CTL) immunity to HER-2/neu has so far been mainly evaluated in terms of detection of CTL precursor (CTLp) frequencies to the immunogenic HLA-A2-binding nona-peptide 369-377 (HER-2(9369)). In the present study, we examined patients with HER-2/neu+ breast, ovarian, lung, colorectal, and prostate cancers for preexisting CTL immunity to four recently described HER-2/neu-derived and HLA-A2-restricted "cytotoxic" peptides and to a novel one spanning amino acids 777-785 also with HLA-A2-binding motif. We utilized enzyme-linked immunosorbent spot (ELISpot) assay, which allows a quantitative and functional assessment of T cells directed against specific peptides after only brief in vitro incubation. CTL reactivity was determined with an Interferon γ (IFN-γ) ELISpot assay detecting T cells at the single cell level secreting IFN-γ. CTLp were denned as peptide-specific precursors per 106 peripheral blood mononuclear cells (PBMCs). Patients' PBMCs with increased CTLp were also tested against autologous tumor targets and peptide-pulsed dendritic cells (DCs) in cytotoxicity assays. We also studied patients with HER-2/ neu-negative ( -) tumors and healthy individuals. Of the HER-2/neu+ patients examined, 31% had increased CTLp to HER-2(9952), 19% to HER-2(9665), 16% to HER-2(9689), and 12.5% HER-2(9 435), whereas only 2 of 32 patients (6%) responded to HER-2(9 777). The CTLp recognizing HER-2(9952) were extremely high in two patients with breast cancer, one with lung cancer, and one with prostate cancer. None of the HER-2/neu- patients or healthy donors exhibited increased CTLp to any of these peptides. Besides IFN-γ production, preexisting CTL immunity to all five HER-2/neu peptides was also shown in cytotoxicity assays where patients' PBMCs with increased CTLp specifically lysed autologous tumor targets and autologous peptide-pulsed DCs. Our results demonstrate for the first time that (1) preexisting immunity to peptides HER-2(9435), HER-2(9952), HER-2(9689), HER-2(9665), and HER-2(9777) is present in patients with HER-2/neu+ tumors of distinct histology, (2) HER-2(9777) is a naturally processed peptide expressed on the surface of HER-2/neu + tumors, as are the other four peptides, and (3) HER-2/neu + prostate tumor cells can be recognized and lysed by autologous HER-2 peptide-specific CTL. Our findings broaden the potential application of HER-2/neu-based immunotherapy

Identification and characterization of a BER-2/neu epitope as a potential target for cancer immunotherapy

Our aim is to develop peptide vaccines that stimulate tumor antigen-specific T-lymphocyte responses against frequently detected cancers. We describe herein a novel HLA-A*0201-restricted epitope, encompassing amino acids 828-836 (residues QIAKGMSYL), which is naturally presented by various HER-2/neu+ tumor cell lines. HER-2/neu(828-836), [HER-2(9 828)], possesses two anchor residues and stabilized HLA-A*0201 on T2 cells in a concentration-dependent Class I binding assay. This peptide was stable for 3.5 h in an off-kinetic assay. HER-2(9828) was found to be immunogenic in HLA-A*0201 transgenic (HHD) mice inducing peptide-specific and functionally potent CTL and long-lasting anti-tumor immunity. Most important, using HLA-A*0201 pentamer analysis we could detect increased ex vivo frequencies of CD8+ T-lymphocytes specifically recognizing HER-2(9828) in 8 out of 20 HLA-A*0201+ HER-2/neu+ breast cancer patients. Moreover, HER-2(9828)-specific human CTL recognized the tumor cell line SKOV3.A2 as well as the primary RS.A2.1.DR1 tumor cell line both expressing HER-2/neu and HLA-A*0201. Finally, therapeutic vaccination with HER-2(9828) in HHD mice was proven effective against established transplantable ALC.A2.1.HER tumors, inducing complete tumor regression in 50% of mice. Our data encourage further exploitation of HER-2(9828) as a promising candidate for peptide-based cancer vaccines. © 2009 Springer-Verlag