Palliative treatment standards for head and neck squamous cell carcinoma : Survey of clinical routine in German-speaking countries

BACKGROUND

The EXTREME (Erbitux in First-Line Treatment of Recurrent and Metastatic Head and Neck Squamous Cell Carcinoma) protocol is generally considered the gold standard in palliative first-line treatment. However, there is some disagreement about its effectivity, toxicity, and applicability in daily clinical routine. The purpose of this cross-sectional survey was to describe the palliative treatment offered in German-speaking countries.

METHODS

From November 2013 to July 2014, 204 departments of otorhinolaryngology (ORL) in Germany, Austria, and the German-speaking parts of Switzerland were contacted and invited to take part in a web-based survey on the treatment of HNSCC.

RESULTS

In all, 62 of 204 treatment centers (30.4 %) participated in the survey. Of these, 58 departments offered palliative systemic therapy to their patients; 19 of 58 (32.8 %) treated patients undergoing palliative chemotherapy in their own ORL departments, while 40 of 58 (69 %) upheld a cooperation with medical oncologists in the same hospital and 24 of 58 (41.4 %) with medical oncologic practices. Many of these treatment centers offered multiple locations for treatment. Of the 58 departments, 56 provided an institutional standard for first-line palliative treatment, 13 for second-line, and two for third-line treatment. In 42 of 58 departments the EXTREME protocol was the institutional standard of care for first-line treatment. Moreover, 12 of 58 departments mentioned an individual protocol and two of 58 the inclusion in clinical trials as their local standard. The assessment of patients who could be treated with the first-line standard ranged from 0 to 95 % with a mean of 44.5 %.

CONCLUSION

Palliative systemic therapy seems to be well standardized for first-line treatment, whereas there is little standardization in second- and third-line treatments. A large variation was found regarding the estimate of the applicability of the institutional standard. Reasons for this could be the physicians' individual experience as well as the varying assessment regarding the toxicity of palliative systemic therapy.

[Immunotherapeutic studies of head and neck tumors : Highlights of the 2016 ASCO Annual Meeting]

Immunotherapeutic drugs in the form of novel immune checkpoint inhibitors have had a significant impact on and revival of the treatment standards for head and neck tumors. Recently, at the annual meeting of the American Society of Clinical Oncology (ASCO) several innovative immunotherapies in head and neck cancer were presented, which might lead to a paradigm shift in the palliative as well as curative setting in the near future.The most common approaches are antibodies targeting the programmed cell death 1 (PD-1) axis. These therapies seem to be effective in a significant proportion of patients (independent of human papillomavirus) and show an extended duration of response.In a phase III trial for palliative second-line therapy, the PD-1 antibody nivolumab demonstrated a significant improvement in survival in patients with head and neck squamous cell carcinoma (HNSCC) who were experiencing disease progression after platinum-based therapy; therefore, the Food and Drug Administration gave it a breakthrough therapy designation.Further clinical trials focusing on first-line palliative treatment (compared with the EXTREME protocol) as well as neoadjuvant therapies using immune checkpoint-inhibitors are ongoing. However, valid testing systems (e. g., PD-L1 testing) as well as reliable predictive markers for patient selection are necessary to avoid increasing public health costs and to protect patients from potentially serious adverse events.

Response Evaluation in Head and Neck Oncology: Definition and Prediction

Curative treatment of head and neck squamous cell carcinoma includes surgery and/or (chemo)radiation, whereas in the palliative setting, chemotherapy and/or immunotherapy represent(s) the standard approach. With regard to quality control, methods for determining treatment response are sorely needed. For surgical therapy, histopathology is the standard quality control. Established criteria for high-risk patients include resection margins of the primary tumor and extracapsular extension of lymph node metastases. After definitive chemoradiation, treatment response is generally evaluated by tomographic imaging combined with endoscopy including re-biopsy of the tumor region. Single-cycle induction chemotherapy may be used to determine the radiosensitivity of tumors, helping to define surgical and nonsurgical treatment options. Innovative approaches with implications for prognosis include the analysis of immune infiltrates, liquid biopsy, molecular characterization (proteomics, genomics), molecular and functional imaging (PET-CT, PET-MRI), as well as advanced imaging data analysis (radio[geno]mics/texture analysis). Human papilloma virus, as a prognostically relevant parameter, is currently being investigated for de-escalation strategies. With regard to the extended personalization of oncologic therapy, markers predicting treatment response are desirable and seem to be important, also from a socioeconomic perspective.

[Immunotherapy for HNSCC : Quo vadis?]

BACKGROUND

Immunotherapy remains a hot topic with an endless stream of new upcoming clinical trials. The results of studies to date are promising for second-line palliative treatment of head and neck squamous cell carcinoma (HNSCC). The next step is testing these strategies in randomized trials for first-line and curative treatment in an adjuvant, neoadjuvant, and primarily nonsurgical setting. So far, established biomarkers have not proven reliable enough to predict response rates precisely.

OBJECTIVES

On occasion of the annual meeting of the American Society of Clinical Oncology (ASCO), we aimed to invesitage the future of immunotherapies.

METHODS

We collected the most promising upcoming studies alongside current research in the field of biomarkers with a  view to interesting new immunotherapeutic strategies.

RESULTS

The search for appropriate biomarkers in particular seems to be a central research objective in the short term. There is a broad range of new agents that will be tested in clinical trials as well as the combination of immunotherapy with chemo- and chemoradiotherapy or other immune-modulating drugs.

CONCLUSION

The real challenge will be to find the most fitting therapy for each patient out of a large panel of available regimens. Therefore, it is most important to find a set of reliable biomarkers that together could predict treatment response.

Dendritic Cells Guide Islet Autoimmunity through a Restricted and Uniquely Processed Peptidome Presented by High-Risk HLA-DR

Identifying T cell epitopes of islet autoantigens is important for understanding type 1 diabetes (T1D) immunopathogenesis and to design immune monitoring and intervention strategies in relationship to disease progression. Naturally processed T cell epitopes have been discovered by elution from HLA-DR4 of pulsed B lymphocytes. The designated professional APC directing immune responses is the dendritic cell (DC). To identify naturally processed epitopes, monocyte-derived DC were pulsed with preproinsulin (PPI), glutamic acid decarboxylase (65-kDa isoform; GAD65), and insulinoma-associated Ag-2 (IA-2), and peptides were eluted of HLA-DR3 and -DR4, which are associated with highest risk for T1D development. Proteome analysis confirmed uptake and processing of islet Ags by DC. PPI peptides generated by DC differed from those processed by B lymphocytes; PPI signal-sequence peptides were eluted from HLA-DR4 and -DR3/4 that proved completely identical to a primary target epitope of diabetogenic HLA-A2-restricted CD8 T cells. HLA-DR4 binding was confirmed. GAD65 peptides, eluted from HLA-DR3 and -DR4, encompassed two core regions overlapping the two most immunodominant and frequently studied CD4 T cell targets. GAD65 peptides bound to HLA-DR3. Strikingly, the IA-2 ligandome of HLA-DR was exclusively generated from the extracellular part of IA-2, whereas most previous immune studies have focused on intracellular IA-2 epitopes. The newly identified IA-2 peptides bound to HLA-DR3 and -DR4. Differential T cell responses were detected against the newly identified IA-2 epitopes in blood from T1D patients. The core regions to which DC may draw attention from autoreactive T cells are largely distinct and more restricted than are those of B cells. GAD65 peptides presented by DC focus on highly immunogenic T cell targets, whereas HLA-DR-binding peptides derived from IA-2 are distinct from the target regions of IA-2 autoantibodies.

Discovery of a Selective Islet Peptidome Presented by the Highest-Risk HLA-DQ8trans Molecule

HLA-DQ2/8 heterozygous individuals are at far greater risk for type 1 diabetes (T1D) development by expressing HLA-DQ8trans on antigen-presenting cells compared with HLA-DQ2 or -DQ8 homozygous individuals. Dendritic cells (DC) initiate and shape adaptive immune responses by presenting HLA-epitope complexes to naïve T cells. To dissect the role of HLA-DQ8trans in presenting natural islet epitopes, we analyzed the islet peptidome of HLA-DQ2, -DQ8, and -DQ2/8 by pulsing DC with preproinsulin (PPI), IA-2, and GAD65. Quality and quantity of islet epitopes presented by HLA-DQ2/8 differed from -DQ2 or -DQ8. We identified two PPI epitopes solely processed and presented by HLA-DQ2/8 DC: an HLA-DQ8trans-binding signal-sequence epitope previously identified as CD8 T-cell epitope and a second epitope that we previously identified as CD4 T-cell epitope with increased binding to HLA-DQ8trans upon posttranslational modification. IA-2 epitopes retrieved from HLA-DQ2/8 and -DQ8 DC bound to HLA-DQ8cis/trans. No GAD65 epitopes were eluted from HLA-DQ. T-cell responses were detected against the novel islet epitopes in blood from patients with T1D but scantly detected in healthy donor subjects. We report the first PPI and IA-2 natural epitopes presented by highest-risk HLA-DQ8trans. The selective processing and presentation of HLA-DQ8trans-binding islet epitopes provides insight in the mechanism of excessive genetic risk imposed by HLA-DQ2/8 heterozygosity and may assist immune monitoring of disease progression and therapeutic intervention as well as provide therapeutic targets for immunotherapy in subjects at risk for T1D.

Life or death by NFκB, Losartan promotes survival in dy2J/dy2J mouse of MDC1A

Inflammation and fibrosis are well-defined mechanisms involved in the pathogenesis of the incurable Laminin α2-deficient congenital muscular dystrophy (MDC1A), while apoptosis mechanism is barely discussed. Our previous study showed treatment with Losartan, an angiotensin II type I receptor antagonist, improved muscle strength and reduced fibrosis through transforming growth factor beta (TGF-β) and mitogen-activated protein kinases (MAPK) signaling inhibition in the dy^2J/dy^2J mouse model of MDC1A. Here we show for the first time that Losartan treatment up-regulates and shifts the nuclear factor kappa B (NFκB) signaling pathway to favor survival versus apoptosis/damage in this animal model. Losartan treatment was associated with significantly increased serum tumor necrosis factor alpha (TNF-α) level, p65 nuclei accumulation, and decreased muscle IκB-β protein level, indicating NFκB activation. Moreover, NFκB anti-apoptotic target genes TNF receptor-associated factor 1 (TRAF1), TNF receptor-associated factor 2 (TRAF2), cellular inhibitor of apoptosis (cIAP2), and Ferritin heavy chain (FTH1) were increased following Losartan treatment. Losartan induced protein expression toward a pro-survival profile as BCL-2 expression levels were increased and Caspase-3 expression levels were decreased. Muscle apoptosis reduction was further confirmed using terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) assay. Thus, along with TGF-β and MAPK signaling, NFκB serves as an important regulatory pathway which following Losartan treatment promotes survival in the dy^2J/dy^2J mouse model of MDC1A.

[Molecular approaches to systemic therapy of adenoid cystic carcinoma of the head and neck area]

The adenoid cystic carcinoma (ACC) is a neurotropic salivary gland tumor with a high blood-borne metastasis tendency. The treatment of choice for localized disease consists of radical surgical resection and, depending on resection status, adjuvant radiotherapy. Due to the high recurrence rate with limited local therapeutic options and frequent occurrence of distant metastases, one is confronted inevitably with the search for an adequate systemic therapy. ACC shows little response to a variety of chemotherapeutic agents, partial or complete remissions are extremely rare. Beside classical chemotherapies, immunotherapeutics and targeted therapies with more favorable side effect profiles were tested in trials, but due to the small number of patients, a definitive statement on the effectiveness can be hardly made. This results in the need for prospective multicenter studies that allow clear recommendations for systemic therapy of the tumor. The present paper gives an overview of the sub-cellular and genetic characteristics of ACC, which represent possible targets for systemic therapies and have partly already been included in running clinical trials.

Islet-specific CTL cloned from a type 1 diabetes patient cause beta-cell destruction after engraftment into HLA-A2 transgenic NOD/scid/IL2RG null mice

Despite increasing evidence that autoreactive CD8 T-cells are involved in both the initiation of type 1 diabetes (T1D) and the destruction of beta-cells, direct evidence for their destructive role in-vivo is lacking. To address a destructive role for autoreactive CD8 T-cells in human disease, we assessed the pathogenicity of a CD8 T-cell clone derived from a T1D donor and specific for an HLA-A2-restricted epitope of islet-specific glucose-6-phosphatase catalytic-subunit related protein (IGRP). HLA-A2/IGRP tetramer staining revealed a higher frequency of IGRP-specific CD8 T-cells in the peripheral blood of recent onset human individuals than of healthy donors. IGRP_265–273-specific CD8 T-cells that were cloned from the peripheral blood of a recent onset T1D individual were shown to secrete IFNγ and Granzyme B after antigen-specific activation and lyse HLA-A2-expressing murine islets in-vitro. Lytic capacity was also demonstrated in-vivo by specific killing of peptide-pulsed target cells. Using the HLA-A2 NOD-scid IL2rγ^null mouse model, HLA-A2-restricted IGRP-specific CD8 T-cells induced a destructive insulitis. Together, this is the first evidence that human HLA-restricted autoreactive CD8 T-cells target HLA-expressing beta-cells in-vivo, demonstrating the translational value of humanized mice to study mechanisms of disease and therapeutic intervention strategies.

Tolerogenic dendritic cells impede priming of naïve CD8⁺ T cells and deplete memory CD8⁺ T cells

Type 1 diabetes is a T-cell-mediated autoimmune disease in which autoreactive CD8(+) T cells destroy the insulin-producing pancreatic beta cells. Vitamin D3 and dexamethasone-modulated dendritic cells (Combi-DCs) loaded with islet antigens inducing islet-specific regulatory CD4(+) T cells may offer a tissue-specific intervention therapy. The effect of Combi-DCs on CD8(+) T cells, however, remains unknown. To investigate the interaction of CD8(+) T cells with Combi-DCs presenting epitopes on HLA class I, naive, and memory CD8(+) T cells were co-cultured with DCs and proliferation and function of peptide-specific T cells were analyzed. Antigen-loaded Combi-DCs were unable to prime naïve CD8(+) T cells to proliferate, although a proportion of T cells converted to a memory phenotype. Moreover, expansion of CD8(+) T cells that had been primed by mature monocyte-derived DCs (moDCs) was curtailed by Combi-DCs in co-cultures. Combi-DCs expanded memory T cells once, but CD8(+) T-cell numbers collapsed by subsequent re-stimulation with Combi-DCs. Our data point that (re)activation of CD8(+) T cells by antigen-pulsed Combi-DCs does not promote, but rather deteriorates, CD8(+) T-cell immunity. Yet, Combi-DCs pulsed with CD8(+) T-cell epitopes also act as targets of cytotoxicity, which is undesirable for survival of Combi-DCs infused into patients in therapeutic immune intervention strategies.

[New aspects in the therapy of recurrence and metastasis of head and neck cancer: highlights from the 2012 ASCO meeting]

The majority of patients with a squamous cell carcinoma of the head and neck region (HNSCC) initially present in a locally advanced stage of the disease. Despite aggressive protocols in first-line treatment, some of these patients develop locoregional recurrences or metastases and are, in particular, extraordinarily challenging for the multidisciplinary treatment team. Therefore, among resectability and prior therapy, age, performance status and individual expectations of the patient have to be taken into account. Apart from surgical options like salvage surgery, chemotherapy and target therapy as well as reirradiation are possible treatment concepts. Unfortunately, most treatment options offer only little to no survival benefit.

[The most important results on primary chemoradiation for head and neck squamous cell carcinoma: highlights from the 2012 ASCO meeting]

Primary concomitant and sequential chemoradiation is a commonly used therapeutic strategy for head and neck squamous cell carcinoma. At the annual meeting of the 2012 American Society of Clinical Oncology numerous trial results were presented. A selection of the most important trials will be summarized in this article. This year, several important results from phase III trials-including the long awaited comparison of sequential and concomitant chemoradiation-were demonstrated.

[New aspects of current therapeutic strategies in oropharyngeal carcinoma: highlights of the 2012 ASCO meeting]

Beside the surgical treatment of head and neck cancer, the concept of organ and function preserving therapy of locally advanced HNSCC (head and neck squamous cell carcinoma) especially of oropharyngeal origin is becoming increasingly important. The comparison of induction chemotherapy plus chemoradiation and primary concomitant chemoradiation has recently been the subject of randomized clinical trials. New combinations of different (chemo)radiation regimens and targeted therapies are also under investigation for HNSCC. Molecular markers predicting treatment efficacy as well as new potential targets are also being evaluated in several clinical trials. The good prognosis of HPV-associated HNSCC has sparked efforts to deintensify treatment to minimize therapy-related toxicities. The impact of specific therapies is growing due to the increasing incidence of young patients with HPV-positive carcinomas.

Current treatment options for recurrent/metastatic head and neck cancer: a post-ASCO 2011 update and review of last year's literature

The majority of patients with a squamous cell carcinoma of the head and neck present with locally advanced tumors. The first-line treatment of locally advanced tumor stages consists of a combined modality management. Despite these aggressive protocols, many patients develop locoregional recurrences or metastasis and place particularly high demands on the interdisciplinary treatment team. Treatment with a curative intent must be differentiated from a palliative one. In addition to prior treatment, resectability, age and performance status, patient wishes must be taken into consideration in treatment planning, especially considering that most therapies offer little to no overall survival benefit. Salvage surgery, chemo- and target therapies, and reirradiation are head and neck surgeon's and radiooncologist's weapons in the fight against these strong opponents. This review focuses on publications and meeting news from last year and reviews the current status of the clinical application of each treatment modality in recurrent or metastatic head and neck cancer.

Discovery of low-affinity preproinsulin epitopes and detection of autoreactive CD8 T-cells using combinatorial MHC multimers

Autoreactive cytotoxic CD8 T-cells (CTLs) play a key pathogenic role in the destruction of insulin-producing beta-cells resulting in type 1 diabetes. However, knowledge regarding their targets is limited, restricting the ability to monitor the course of the disease and immune interventions. In a multi-step discovery process to identify novel CTL epitopes in human preproinsulin (PPI), PPI was digested with purified human proteasomes, and resulting COOH-fragments aligned with algorithm-predicted HLA-binding peptides to yield nine potential HLA-A1, -A2, -A3 or -B7-restricted candidates. An UV-exchange method allowed the generation of a repertoire of multimers including low-affinity HLA-binding peptides. These were labeled with quantum dot-fluorochromes and encoded in a combinatorial fashion, allowing parallel and sensitive detection of specific, low-avidity T-cells. Significantly increased frequencies of T-cells against four novel PPI epitopes (PPI(4-13)/B7, PPI(29-38)/A2, PPI(76-84)/A3 and PPI(79-88)/A3) were detected in stored blood of patients with recent onset diabetes but not in controls. Changes in frequencies of circulating CD8 T-cells against these novel epitopes were detected in blood of islet graft recipients at different time points after transplantation, which correlated with clinical outcome. In conclusion, our novel strategy involving a sensitive multiplex detection technology and requiring minimal volumes of stored blood represents a major improvement in the direct ex-vivo characterization and enumeration of immune cells in the pathogenesis of type 1 diabetes.

Critical role for TNF in the induction of human antigen-specific regulatory T cells by tolerogenic dendritic cells

TNF is a pleiotropic cytokine with differential effects on immune cells and diseases. Anti-TNF therapy was shown to be effective in rheumatoid arthritis but proved inefficient or even detrimental in other autoimmune diseases. We studied the role of TNF in the induction of Ag-specific regulatory T cells (Tregs) by tolerogenic vitamin D3-modulated human dendritic cells (VD3-DCs), which previously were shown to release high amounts of soluble TNF (sTNF) upon maturation with LPS. First, production of TNF by modulated VD3-DCs was analyzed upon maturation with LPS or CD40L with respect to both secreted (cleaved) TNF (sTNF) and expression of the membrane-bound (uncleaved) form of TNF (mTNF). Next, TNF antagonists were tested for their effect on induction of Ag-specific Tregs by modulated DCs and the subsequent functionality of these Tregs. VD3-DCs expressed greater amounts of mTNF than did control DCs (nontreated DCs), independent of the maturation protocol. Inhibition of TNF with anti-TNF Ab (blocking both sTNF and mTNF) during the priming of Tregs with VD3-DCs prevented generation of Tregs and their suppression of proliferation of CD4(+) T cells. In contrast, sTNF receptor II (sTNFRII), mainly blocking sTNF, did not change the suppressive capacity of Tregs. Blocking of TNFRII by anti-CD120b Ab during Treg induction similarly abrogated their subsequent suppressive function. These data point to a specific role for mTNF on VD3-DCs in the induction of Ag-specific Tregs. Interaction between mTNF and TNFRII instructs the induction of suppressive Tregs by VD3-DCs. Anti-TNF therapy may therefore act adversely in different patients or disease pathways.

Induction of Treg by monocyte-derived DC modulated by vitamin D3 or dexamethasone: differential role for PD-L1

Specific therapy with modulated DC may restore immunological tolerance, thereby obviating the need for chronic immunosuppression in transplantation or autoimmunity. In this study we compared the tolerizing capacity of dexamethasone (Dex)- and 1 alpha,25-dihydroxyvitamin D3 (VD3)-modulated DC. Treatment of monocytes with either VD3 or Dex resulted in DC with stable, semi-mature phenotypes compared with standard DC, with intermediate levels of co-stimulatory and MHC class II molecules, which remained unaltered after subsequent pro-inflammatory stimulation. IL-12p70 secretion was lost by VD3- and Dex-DC, whereas IL-10 secretion was unaffected. VD3-DC distinctly produced large amounts of TNF-alpha. Both VD3- and Dex-DC possessed the capacity to convert CD4 T cells into IL-10-secreting Treg potently suppressing the proliferation of responder T cells. However, only Treg induced by VD3-DC exhibited antigen specificity. VD3-, but not Dex-, DC expressed significant high levels of PD-L1 (programmed death-1 ligand), upon activation. Blockade of PD-L1 during priming redirected T cells to produce IFN-gamma instead of IL-10 and abolished acquisition of regulatory capacity. Our findings demonstrate that both VD3- and Dex-DC possess durable but differential tolerogenic features, acting via different mechanisms. Both are potentially useful to specifically down-regulate unwanted immune responses and induce immune tolerance. These modulated DC appear suitable as adjuvant in antigen-specific clinical vaccination intervention strategies.

The nonpolymorphic MHC Qa-1b mediates CD8+ T cell surveillance of antigen-processing defects

The nonclassical major histocompatibility complex (MHC) Qa-1^b accommodates monomorphic leader peptides and functions as a ligand for germ line receptors CD94/NKG2, which are expressed by natural killer cells and CD8⁺ T cells. We here describe that the conserved peptides are replaced by a novel peptide repertoire of surprising diversity as a result of impairments in the antigen-processing pathway. This novel peptide repertoire represents immunogenic neoantigens for CD8⁺ T cells, as we found that these Qa-1^b–restricted T cells dominantly participated in the response to tumors with processing deficiencies. A surprisingly wide spectrum of target cells, irrespective of transformation status, MHC background, or type of processing deficiency, was recognized by this T cell subset, complying with the conserved nature of Qa-1^b. Target cell recognition depended on T cell receptor and Qa-1^b interaction, and immunization with identified peptide epitopes demonstrated in vivo priming of CD8⁺ T cells. Our data reveal that Qa-1^b, and most likely its human homologue human leukocyte antigen-E, is important for the defense against processing-deficient cells by displacing the monomorphic leader peptides, which relieves the inhibition through CD94/NKG2A on lymphocytes, and by presenting a novel repertoire of immunogenic peptides, which recruits a subset of cytotoxic CD8⁺ T cells.

TLR triggering on tolerogenic dendritic cells results in TLR2 up-regulation and a reduced proinflammatory immune program

Tolerogenic dendritic cells (TDC) offer a promising therapeutic potential to ameliorate autoimmune diseases. Reported to inhibit adaptive immune responses, little is known about their innate immunity receptor repertoire. In this study, we compared three types of human TDC (IL-10-DC, dexamethasone (DX)-DC, and 1,25(OH)(2)D(3)-DC) by their TLR expression and response to a set of TLR ligands. TDC are endowed with the same TLR set as standard monocyte-derived dendritic cells but respond differentially to the TLR stimuli Pam3CSK4, polyinosinic-polycytidylic acid, LPS, and flagellin. TDC expressed low or no IL-12-related cytokines and remarkably elevated IL-10 levels. Interestingly, only TDC up-regulated the expression of TLR2 upon stimulation. This boosted the tolerogenic potential of these cells, because IL-10 production was up-regulated in TLR2-stimulated, LPS-primed DX-DC, whereas IL-12 and TNF-alpha secretion remained low. When comparing the TDC subsets, DX-DC and 1,25(OH)(2)D(3)-DC up-regulated TLR2 irrespective of the TLR triggered, whereas in IL-10-DC this effect was only mediated by LPS. Likewise, DX-DC and 1,25(OH)(2)D(3)-DC exhibited impaired ability to mature, reduced allostimulatory properties, and hampered capacity to induce Th1 differentiation. Therefore, both DX-DC and 1,25(OH)(2)D(3)-DC display the strongest tolerogenic and anti-inflammatory features and might be most suitable tools for the treatment of autoimmune diseases.

Induction of protective CTL immunity against peptide transporter TAP-deficient tumors through dendritic cell vaccination

A large proportion of human cancers show deficiencies in the MHC class I antigen-processing machinery. Such defects render tumors resistant to immune eradication by tumoricidal CTLs. We recently identified a unique population of CTL that selectively targets tumor immune-escape variants through recognition of MHC-presented peptides, termed TEIPP (T cell epitopes associated with impaired peptide processing), expressed on cells lacking functional TAP-peptide transporters. Previously, we showed that vaccination with TEIPP peptides mediates protection against TAP-deficient tumors. Here, we further explored the concept of TEIPP-targeted therapy using a dendritic cell (DC)-based cellular vaccine. Impairment of TAP function in DC induced the presentation of endogenous TEIPP antigens by MHC class I molecules, and immunization with these DCs protected mice against the outgrowth of TAP-deficient lymphomas and fibrosarcomas. Immune analysis of vaccinated mice revealed strong TEIPP-specific CTL responses, and a crucial role for CD8(+) cells in tumor resistance. Finally, we show that TEIPP antigens could be successfully induced in wild-type DC by introducing the viral TAP inhibitor UL49.5. Our results imply that immune intervention strategies with TAP-inhibited DC could be developed for the treatment of antigen processing-deficient cancers in humans.