α-Gal Nanoparticles in CNS Trauma: II. Immunomodulation Following Spinal Cord Injury (SCI) Improves Functional Outcomes

BACKGROUND

Previous investigations have shown that local application of nanoparticles presenting the carbohydrate moiety galactose-α-1,3-galactose (α-gal epitopes) enhance wound healing by activating the complement system and recruiting pro-healing macrophages to the injury site. Our companion in vitro paper suggest α-gal epitopes can similarly recruit and polarize human microglia toward a pro-healing phenotype. In this continuation study, we investigate the in vivo implications of α-gal nanoparticle administration directly to the injured spinal cord.

METHODS

α-Gal knock-out (KO) mice subjected to spinal cord crush were injected either with saline (control) or with α-gal nanoparticles immediately following injury. Animals were assessed longitudinally with neurobehavioral and histological endpoints.

RESULTS

Mice injected with α-gal nanoparticles showed increased recruitment of anti-inflammatory macrophages to the injection site in conjunction with increased production of anti-inflammatory markers and a reduction in apoptosis. Further, the treated group showed increased axonal infiltration into the lesion, a reduction in reactive astrocyte populations and increased angiogenesis. These results translated into improved sensorimotor metrics versus the control group.

CONCLUSIONS

Application of α-gal nanoparticles after spinal cord injury (SCI) induces a pro-healing inflammatory response resulting in neuroprotection, improved axonal ingrowth into the lesion and enhanced sensorimotor recovery. The data shows α-gal nanoparticles may be a promising avenue for further study in CNS trauma.

Emerging antibody-based therapies for Huntington's disease: current status and perspectives for future development

INTRODUCTION

Being an inherited neurodegenerative disease with an identifiable genetic defect, Huntington's disease (HD) is a suitable candidate for early intervention, possibly even in the pre-symptomatic stage. Our recent advances in elucidating the pathogenesis of HD have revealed a series of novel potential therapeutic targets, among which immunotherapies are actively pursued in preclinical experiments.

AREAS COVERED

This review focuses on the potential of antibody-based treatments targeting various epitopes (of mutant huntingtin as well as phosphorylated tau) that are currently evaluated in vitro and in animal experiments. The references used in this review were retrieved from the PubMed database, searching for immunotherapies in HD, and clinical trial registries were reviewed for molecules already evaluated in clinical trials.

EXPERT OPINION

Antibody-based therapies have raised considerable interest in a series of neurodegenerative diseases characterized by deposition of aggregated of aberrantly folded proteins, HD included. Intrabodies and nanobodies can interact with mutant huntingtin inside the nervous cells. However, the conflicting results obtained with some of these intrabodies highlight the need for proper choice of epitopes and for developing animal models more closely mimicking human disease. Approval of these strategies will require a considerable financial and logistic effort on behalf of healthcare systems.

Using imlifidase to elucidate the characteristics and importance of anti-GBM antibodies produced after start of treatment

BACKGROUND

Autoantibodies are common in glomerulonephritis, but the clinical benefit of rapid elimination has not been determined, even in anti-glomerular basement membrane (GBM) disease. Even less is known about the importance of autoantibody characteristics, including epitope specificity and immunoglobulin G (IgG) subclass distribution. We aimed to address this by characterizing the autoantibody profile in anti-GBM patients: we utilized samples from the GOOD-IDES-01 (treating GOODpasture's disease with Imunoglobulin G Degrading Enzyme of Streptococcus pyogenous) (ClinicalTrials.gov identifier: NCT03157037) trial , where imlifidase, which cleaves all IgG in vivo within hours, was given to 15 anti-GBM patients.

METHODS

In the GOOD-IDES-01 trial, plasmapheresis was (re)started if anti-GBM antibodies rebounded. Serum samples were collected prospectively for 6 months and analyzed for anti-GBM epitope specificity using recombinant constructs of the EA and EB epitopes, IgG subclass using monoclonal antibodies, and anti-neutrophil cytoplasmic antibodies (ANCA). The results were correlated with clinical data.

RESULTS

Patients with a rebound (n = 10) tended to have lower eGFR at 6 months (11 vs 34 mL/min/1.73 m2, P = .055), and patients with dialysis at 6 months had a higher EB/EA ratio at rebound (0.8 vs 0.5, P = .047). Moreover, two patients demonstrated increasing epitope restriction and several patients displayed a shift in subclass distribution at rebound. Six patients were double positive for ANCA. ANCA rebound was seen in 50% of patients; only one patient remained ANCA positive at 6 months.

CONCLUSIONS

In this study, rebound of anti-GBM antibodies, especially if directed against the EB epitope, was associated with a worse outcome. This supports the notion that all means should be used to eliminate anti-GBM antibodies. In this study ANCA was removed early and long-term by imlifidase and cyclophosphamide.

Impact of Decalcification, Cold Ischemia, and Deglycosylation on Performance of Programmed Cell Death Ligand-1 Antibodies With Different Binding Epitopes: Comparison of 7 Clones

Programmed cell death ligand-1 (PD-L1) expression levels in patients' tumors have demonstrated clinical utility across many cancer types and are used to determine treatment eligibility. Several independently developed PD-L1 immunohistochemical (IHC) predictive assays are commercially available and have demonstrated different levels of staining between assays, generating interest in understanding the similarities and differences between assays. Previously, we identified epitopes in the internal and external domains of PD-L1, bound by antibodies in routine clinical use (SP263, SP142, 22C3, and 28-8). Variance in performance of assays utilizing these antibodies, observed following exposure to preanalytical factors such as decalcification, cold ischemia, and duration of fixation, encouraged additional investigation of antibody-binding sites, to understand whether binding site structures/conformations contribute to differential PD-L1 IHC assay staining. We proceeded to further investigate the epitopes on PD-L1 bound by these antibodies, alongside the major clones utilized in laboratory-developed tests (E1L3N, QR1, and 73-10). Characterization of QR1 and 73-10 clones demonstrated that both bind the PD-L1 C-terminal internal domain, similar to SP263/SP142. Our results also demonstrate that under suboptimal decalcification or fixation conditions, the performance of internal domain antibodies is less detrimentally affected than that of external domain antibodies 22C3/28-8. Furthermore, we show that the binding sites of external domain antibodies are susceptible to deglycosylation and conformational structural changes, which directly result in IHC staining reduction or loss. The binding sites of internal domain antibodies were unaffected by deglycosylation or conformational structural change. This study demonstrates that the location and conformation of binding sites, recognized by antibodies employed in PD-L1 diagnostic assays, differ significantly and exhibit differing degrees of robustness. These findings should reinforce the need for vigilance when performing clinical testing with different PD-L1 IHC assays, particularly in the control of cold ischemia and the selection of fixation and decalcification conditions.

Tissue Age Affects Antigenicity and Scoring for the 22C3 Immunohistochemistry Companion Diagnostic Test

Programmed death-ligand 1 (PD-L1) antibody 22C3 is the approved companion diagnostic immunohistochemistry test for treatment with pembrolizumab and cemiplimab in multiple cancer types. The 22C3 and 28-8 antibodies target the extracellular domain (ECD) of PD-L1, which is known to contain N-glycosylation sites. We hypothesize that antigenicity could be affected by the degradation of the glycan part of the epitope and thus change the scoring of the assay over time. Here, we test samples over time and assess the effects of time and deglycosylation on PD-L1 signal by comparing an antibody with an ECD antigen to an antibody with an intracellular domain (ICD) antigen. Ten whole-tissue sections of non-small-cell lung cancer (NSCLC) from 2018 were selected for testing. Fresh-cut serial sections for each case were stained on DAKO Link48 for 22C3 according to the label. In parallel, a previously described laboratory-developed test using E1L3N (an ICD antibody) was performed on the Leica BondRX. Tumor proportion scores for 22C3 and E1L3N were read by a pathologist and compared to the previous clinical diagnoses. To determine the effect using a quantitative approach, a tissue microarray (TMA) cohort with 90 NSCLC cases was similarly assessed. Finally, to determine whether the possible effect of epitope glycosylation, antibodies were tested before and after enzymatic deglycosylation of specimens. We found that 6 of 7 archival positive samples showed a significant reduction in positive staining with 22C3 compared to the original diagnostic sample assessed 3 years earlier. In an older archival TMA cohort, a quantitative significant difference in signal intensity was noted when staining with 22C3 was compared to E1L3N. This loss of signal was not noted in the fresh cell line TMA consistent with a time-dependent degradation of staining. Finally, quantitative assessment of the fresh TMA showed a significant loss of signal after a deglycosylation procedure when stained with 22C3, which was not seen when stained with E1L3N. We believe that these data show that the glycan part of the 22C3 epitope is not stable over time, and that this issue should be considered when assessing archival tissue for diagnostic or research purposes.

Anti-citrullinated protein antibodies as biomarkers in rheumatoid arthritis

INTRODUCTION

The serological biomarker anti-citrullinated protein antibodies (ACPAs) may have several functions but is especially important for the diagnosis of rheumatoid arthritis (RA) along with clinical symptoms.

AREAS COVERED

This review provides an overview of ACPAs, which are useful in RA diagnostics and may improve our understanding of disease etiology. PubMed was searched with combinations of words related to antibodies recognizing epitopes containing the post-translationally modified amino acid citrulline in combination with rheumatoid arthritis; cyclic citrullinated peptide, CCP, anti-CCP, anti-citrullinated protein antibodies, ACPA, citrullination, peptide/protein arginine deiminase, PAD, filaggrin, vimentin, keratin, collagen, perinuclear factor, EBNA1, EBNA2, and others. From this search, we made a qualitative extract of publications relevant to the discovery, characterization, and clinical use of these antibodies in relation to RA. We highlight significant findings and identify areas for improvement.

EXPERT OPINION

ACPAs have high diagnostic sensitivity and specificity for RA and recognize citrullinated epitopes from several proteins. The best-performing single epitope originates from Epstein-Barr Virus nuclear antigen 2 and contains a central Cit-Gly motif, which is recognized by ACPAS when located in a flexible peptide structure. In addition, ACPAs may also have prognostic value, especially in relation to early treatment, although ACPAs' main function is to aid in the diagnosis of RA.

Unlocking the potential of agonist antibodies for treating cancer using antibody engineering

Agonist antibodies that target immune checkpoints, such as those in the tumor necrosis factor receptor (TNFR) superfamily, are an important class of emerging therapeutics due to their ability to regulate immune cell activity, especially for treating cancer. Despite their potential, to date, they have shown limited clinical utility and further antibody optimization is urgently needed to improve their therapeutic potential. Here, we discuss key antibody engineering approaches for improving the activity of antibody agonists by optimizing their valency, specificity for different receptors (e.g., bispecific antibodies) and epitopes (e.g., biepitopic or biparatopic antibodies), and Fc affinity for Fcγ receptors (FcγRs). These powerful approaches are being used to develop the next generation of cancer immunotherapeutics with improved efficacy and safety.

Mosaic RBD nanoparticles protect against challenge by diverse sarbecoviruses in animal models

To combat future severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and spillovers of SARS-like betacoronaviruses (sarbecoviruses) threatening global health, we designed mosaic nanoparticles that present randomly arranged sarbecovirus spike receptor-binding domains (RBDs) to elicit antibodies against epitopes that are conserved and relatively occluded rather than variable, immunodominant, and exposed. We compared immune responses elicited by mosaic-8 (SARS-CoV-2 and seven animal sarbecoviruses) and homotypic (only SARS-CoV-2) RBD nanoparticles in mice and macaques and observed stronger responses elicited by mosaic-8 to mismatched (not on nanoparticles) strains, including SARS-CoV and animal sarbecoviruses. Mosaic-8 immunization showed equivalent neutralization of SARS-CoV-2 variants, including Omicrons, and protected from SARS-CoV-2 and SARS-CoV challenges, whereas homotypic SARS-CoV-2 immunization protected only from SARS-CoV-2 challenge. Epitope mapping demonstrated increased targeting of conserved epitopes after mosaic-8 immunization. Together, these results suggest that mosaic-8 RBD nanoparticles could protect against SARS-CoV-2 variants and future sarbecovirus spillovers.

Modulation of CD22 Protein Expression in Childhood Leukemia by Pervasive Splicing Aberrations: Implications for CD22-Directed Immunotherapies

Downregulation of surface epitopes causes postimmunotherapy relapses in B-lymphoblastic leukemia (B-ALL). Here we demonstrate that mRNA encoding CD22 undergoes aberrant splicing in B-ALL. We describe the plasma membrane-bound CD22 Δex5-6 splice isoform, which is resistant to chimeric antigen receptor (CAR) T cells targeting the third immunoglobulin-like domain of CD22. We also describe splice variants skipping the AUG-containing exon 2 and failing to produce any identifiable protein, thereby defining an event that is rate limiting for epitope presentation. Indeed, forcing exon 2 skipping with morpholino oligonucleotides reduced CD22 protein expression and conferred resistance to the CD22-directed antibody-drug conjugate inotuzumab ozogamicin in vitro. Furthermore, among inotuzumab-treated pediatric patients with B-ALL, we identified one nonresponder in whose leukemic blasts Δex2 isoforms comprised the majority of CD22 transcripts. In a second patient, a sharp reduction in CD22 protein levels during relapse was driven entirely by increased CD22 exon 2 skipping. Thus, dysregulated CD22 splicing is a major mechanism of epitope downregulation and ensuing resistance to immunotherapy.

SIGNIFICANCE

The mechanism(s) underlying downregulation of surface CD22 following CD22-directed immunotherapy remains underexplored. Our biochemical and correlative studies demonstrate that in B-ALL, CD22 expression levels are controlled by inclusion/skipping of CD22 exon 2. Thus, aberrant splicing of CD22 is an important driver/biomarker of de novo and acquired resistance to CD22-directed immunotherapies. See related commentary by Bourcier and Abdel-Wahab, p. 87. This article is highlighted in the In This Issue feature, p. 85.

The nine lives of epitope-based antibody patents

Epitope-based antibody claims have emerged to become one of the most important claim species in antibody patents. At the same time, they are heavily disputed. This article strives to give an overview about the as is situation both in Europe and the United States.

Immunotherapy With Apitopes Blocks the Immune Response to TSH Receptor in HLA-DR Transgenic Mice

We have combined major histocompatibility complex-binding assays with immunization and tolerance induction experiments in HLA-DR3 transgenic mice to design apitopes (antigen-processing independent epitopes) derived from thyrotropin receptor (TSHR) for treatment of patients with Graves' disease (GD). A challenge model was created by using an adenovirus-expressing part of the extracellular domain of the thyrotropin receptor (TSHR289). This model was used to test whether current drug treatments for GD would have an impact on effective antigen-specific immunotherapy using the apitope approach. Furthermore, selected peptides were assessed for their antigenicity using peripheral blood mononuclear cell samples from patients with GD. A mixture of two immunodominant apitopes was sufficient to suppress both the T-cell and antibody response to TSHR when administered in soluble form to HLA-DR transgenic mice. Tolerance induction was not disrupted by current drug treatments. These results demonstrate that antigen-specific immunotherapy with apitopes from TSHR is a suitable approach for treatment of GD.

Bivalent mucosal peptide vaccines administered using the LCP carrier system stimulate protective immune responses against Streptococcus pyogenes infection

Despite the broad knowledge about the pathogenicity of Streptococcus pyogenes there is still a controversy about the correlate of protection in GAS infections. We aimed in further improving the immune responses stimulated against GAS comparing different vaccine formulations including bis-(3',5')-cyclic dimeric adenosine monophosphate (c-di-AMP) and BPPCysMPEG, a derivative of the macrophage-activating lipopeptide (MALP-2), as adjuvants, respectively, to be administered with and without the universal T helper cell epitope P25 along with the optimized B cell epitope J14 of the M protein and B and T cell epitopes of SfbI. Lipopeptide based nano carrier systems (LCP) were used for efficient antigen delivery across the mucosal barrier. The stimulated immune responses were efficient in protecting mice against a respiratory challenge with a lethal dose of a heterologous S. pyogenes strain. Moreover, combination of the LCP based peptide vaccine with c-di-AMP allowed reduction of antigen dose at the same time maintaining vaccine efficacy.

Identificaiton of Novel Immunogenic Human Papillomavirus Type 16 E7-Specific Epitopes Restricted to HLA-A*33;03 for Cervical Cancer Immunotherapy

PURPOSE

To identify new immunogenic HLA-A*33;03-restricted epitopes from the human papillomavirus (HPV) 16 E7 protein for immunotherapy against cervical cancer.

MATERIALS AND METHODS

We synthesized fourteen overlapping 15-amino acid peptides and measured intracellular interferon-γ (IFN-γ) production in PBMC and CD8+ cytotoxic T lymphocytes (CTLs) after sensitization with these peptides using flow cytometry and ELISpot assay. The immunogenicity of epitopes was verified using a ⁵¹Cr release assay with SNU1299 cells.

RESULTS

Among the fourteen 15-amino acid peptides, E7₄₉₋₆₃ (RAHYNIVTFCCKCDS) demonstrated the highest IFN-γ production from peripheral blood mononuclear cells (PBMCs), and CD8+ CTLs sensitized with E7₄₉₋₆₃ showed higher cytotoxic effect against SNU1299 cells than did CD8+ CTLs sensitized with other peptides or a negative control group. Thirteen 9- or 10-amino acid overlapping peptides spanning E7₄₉₋₆₃, E7₅₀₋₅₉ (AHYNIVTFCC), and E7₅₂₋₆₁ (YNIVTFCCKC) induced significantly higher IFN-γ production and cytotoxic effects against SNU1299 cells than the other peptides and negative controls, and the cytotoxicity of E7₅₀₋₅₉- and E7₅₂₋₆₁-sensitized PBMCs was induced via the cytolytic effect of CD8+ CTLs.

CONCLUSION

We identified E7₅₀₋₅₉ and E7₅₂₋₆₁ as novel HPV 16 E7 epitopes for HLA-A*33;03. CD8+ CTL sensitized with these peptides result in an antitumor effect against cervical cancer cells. These epitopes could be useful for immune monitoring and immunotherapy for cervical cancer and HPV 16-related diseases including anal cancer and oropharyngeal cancer.

Vaccine manufacturing and technology: from biotechnological platforms to syntethic epitopes, current viepoint

THE PURPOSES

The Purposes: the review take into account short history of vaccination practice and development of vaccine technology.

METHODS

In the review we include data from several monographs about manufacturing of vaccines published by authors from such companies as Merck & Co; Sanofi Pasteur; Dynavax Europe/Rhein Biotech GmbH; Latham Biopharm Group; Aridis Pharmaceuticals LLC; Genentech; Amgen; Shamir Biologics LLC; Biopharm Services US; Novartis Pharma AG, аnd several research centers: Laboratory of Bacterial Polysaccharides, Center for Biologics Evaluation and Research; Purdue University, West Lafayette, IN, US; Department of Pharmaceutical Chemistry, Univ. Of Kansas; Max Planck Institute for dynamics of Complex Technical Systems; Fraunhofer USA Center for Molecular Biotechnology; US Dep. of Agriculture Animal and Plant Health Inspection Service, etc.

RESULTS

In historic literature there are data about inoculation practices in antique China, Persia, India, Byzantium, native Americans, some African population. In modern immunology since the end of XIX century the vaccines were produced at the in vivo platforms - in animals (rabbits, mice, cows). Since 1931 due to E. Goodpasture' elaboration most virus vaccines were and are produced at the in ovo platform. In 1949 J.F. Enders elaborated large-scale polio virus production in the primary culture of monkey kidney cells in vitro. Up to day primary culture of chiken embrio fibroblasts are used to large-scale production of vaccine viruses of measles, mumps, rabies. Since 2000-th in Western countries most part of virus vaccines were began to produced via a cultivation in continuous tumor cell lines. The last technology is the most low cost for large-scale production of vaccines. We review several new biotechnological platforms for the production of the recombinant protein or virus-like particles as subunit vaccines: plant system, algae, mushrooms, insect cells, etc.

CONCLUSION

Beside of good purpose of vaccination - prophylactic of several infectious deseases, doctors must take into account possibility of inter-species transmission of unknown pathogens (retroviruses, prions, etc) from biotechnological platforms - animals, cell cultures - into human population, and don't ignore L.A. Zilber' theory of virus' etiology of cancer diseases.

Tumor neoantigens: building a framework for personalized cancer immunotherapy

It is now well established that the immune system can recognize developing cancers and that therapeutic manipulation of immunity can induce tumor regression. The capacity to manifest remarkably durable responses in some patients has been ascribed in part to T cells that can (a) kill tumor cells directly, (b) orchestrate diverse antitumor immune responses, (c) manifest long-lasting memory, and (d) display remarkable specificity for tumor-derived proteins. This specificity stems from fundamental differences between cancer cells and their normal counterparts in that the former develop protein-altering mutations and undergo epigenetic and genetic alterations, resulting in aberrant protein expression. These events can result in formation of tumor antigens. The identification of mutated and aberrantly expressed self-tumor antigens has historically been time consuming and laborious. While mutant antigens are usually expressed in a tumor-specific manner, aberrantly expressed antigens are often shared between cancers and, therefore, in the past, have been the major focus of therapeutic cancer vaccines. However, advances in next-generation sequencing and epitope prediction now permit the rapid identification of mutant tumor neoantigens. This review focuses on a discussion of mutant tumor neoantigens and their use in personalizing cancer immunotherapies.

Immune modulations during chemoimmunotherapy & novel vaccine strategies--in metastatic melanoma and non small-cell lung cancer

This thesis describes the treatment of metastatic melanoma (MM) and non small-cell lung cancer (NSCLC) from an immunotherapeutic approach. The purpose of the first part of the thesis was to assess how treatment with Temozolomide (TMZ) chemotherapy affects the immune system in patients with metastatic MM. Our results showed that the number of T lymphocytes was significantly reduced after 3 treatment cycles. Furthermore, the induced lymphopenia was positive correlated to achievement of clinical benefit. We demonstrated that the proportion of CD4+ and Treg lymphocytes decreased whereas the CD8+ T cells increased. In particular, we demonstrated that mature CD8+ T cells increased during treatment. Analyses of peripheral blood before and after treatment showed that T cell responses against common viral epitopes were conserved despite chemotherapy. Surprisingly, we found a significant increase in T cell responses against well-known MM tumour specific antigens. Overall, we have verified that TMZ in addition to being an alkylating and cytotoxic chemotherapy, also possess immune modulatory effect in MM patients treated with standard dosage of TMZ. In the second part of the thesis we examined how treatment with Interferon alfa-2b and Interleukin 2 (IFNα/IL2) affects the immune system. We demonstrated a significant induced lymphocytosis during treatment. Furthermore, we showed that the percentage increase in lymphocytes was positively correlated to clinical outcome. Moreover, we have seen that IFNα/IL2 leads to significant increase in NK and Treg cells in both patients with and without clincal effect. In general, T cell responses against common viral epitopes and well-known melanoma tumour specific antigens were low. Furthermore, the study confirmed that elevated LDH is negatively correlated with both treatment response and median overall survival. Overall, we have characterized changes of immune cells and correlated them with clinical efficacy during the couse of IFNα/IL2 used in standard dosage. In the third part we investigated if vaccination with a peptide derived from IDO was feasible in patients with metastatic NSCLC. This "First in Man" trial was safe and showed modest side effects only. Since IDO was expressed in NSCLC tissues it was found to be a relevant target. One patient achieved significant regression of liver metastases (confirmed partial response) and another 6/15 patients achieved prolonged disease stabilization. Furthermore, median overall survival was 25.9 months demonstrating a better survival in vaccinated compared to non-vaccinated comparable NSCLC patients. The presence of IDO specific CD8+ T cells were detected by IFNy Elispot. In patients with clinical effect of the vaccine IDO-specific CD8+ T cells at pre-treatment was significanctly increased. Moreover, low-frequent IDO positive tetramer CD8+ T cells were detected and led to effective killing of an IDO+ HLA-A2 positive cancer cell line (SW480) in 1 patient. Moreover, flow cytometry was performed and in general no significant changes in CD8+ and CD4+ T cells were seen, although patients with clinical response showed a trend towards increased mature CD8+ T cells during treatment. In addition, we found lower levels of Tregs as well as an increased level of NK cells after 6 vaccinations. Elevated Kyn/Trp ratio is suggested to mirror IDO activity. In 8/11 patients the level after the 6th vaccine was stable compared to baseline. No differences between patients with clinical benefit (4/5) and patients with progressive disease (4/6) were demonstrated. Two patients had an increase in Kyn/Trp ration meanwhile demonstrating a high expression of IDO. In 2 patients with clinical response long-term stabilization of Kyn/Trp was observed. Overall, the vaccine was well tolerated with no adverse toxicity. Median overall survival was 25.9 months with long term disease stabilization achieved in 47% of the treated patients. Based on the promising clinical results achieved in the vaccine trial for NSCLC patients, we launched a new clinical trial for MM patients (ongoing patient recruitment) in June 2012. In order to enhance the immune response the vaccine comprises IDO plus Survivin peptide as well as the adjuvants Montanide, Aldara and GM-CSF. Finally, the vaccine is given in combination with TMZ. Patients are evaluated every 3rd month with PET-CT scan. Preliminary clinical data from the first 7/30 evaluable patients are presented. Two patients demonstrated a patial response with 57% and 45% tumour regression lasting for 10 months and 6+ months respectively, corresponding to a preliminary objective response rate of 29%. The vaccine has been manageable and without significant side effects.

A multivalent and cross-protective vaccine strategy against arenaviruses associated with human disease

Arenaviruses are the causative pathogens of severe hemorrhagic fever and aseptic meningitis in humans, for which no licensed vaccines are currently available. Pathogen heterogeneity within the Arenaviridae family poses a significant challenge for vaccine development. The main hypothesis we tested in the present study was whether it is possible to design a universal vaccine strategy capable of inducing simultaneous HLA-restricted CD8⁺ T cell responses against 7 pathogenic arenaviruses (including the lymphocytic choriomeningitis, Lassa, Guanarito, Junin, Machupo, Sabia, and Whitewater Arroyo viruses), either through the identification of widely conserved epitopes, or by the identification of a collection of epitopes derived from multiple arenavirus species. By inoculating HLA transgenic mice with a panel of recombinant vaccinia viruses (rVACVs) expressing the different arenavirus proteins, we identified 10 HLA-A02 and 10 HLA-A03-restricted epitopes that are naturally processed in human antigen-presenting cells. For some of these epitopes we were able to demonstrate cross-reactive CD8⁺ T cell responses, further increasing the coverage afforded by the epitope set against each different arenavirus species. Importantly, we showed that immunization of HLA transgenic mice with an epitope cocktail generated simultaneous CD8⁺ T cell responses against all 7 arenaviruses, and protected mice against challenge with rVACVs expressing either Old or New World arenavirus glycoproteins. In conclusion, the set of identified epitopes allows broad, non-ethnically biased coverage of all 7 viral species targeted by our studies.

Arenaviruses cause significant morbidity and mortality worldwide and are also regarded as a potential bioterrorist threat. CD8⁺ T cells restricted by class I MHC molecules clearly play a protective role in murine models of arenavirus infection, yet little is known about the epitopes recognized in the context of human class I MHC (HLA). Here, we defined 20 CD8⁺ T cell epitopes restricted by HLA class I molecules, derived from 7 different species of arenaviruses associated with human disease. To accomplish this task, we utilized epitope predictions, in vitro HLA binding assays, and HLA transgenic mice inoculated with recombinant vaccinia viruses (rVACV) expressing arenavirus antigens. Because our analysis targeted two of the most common HLA types worldwide, we project that the CD8⁺ T cell epitope set provides broad coverage against diverse ethnic groups within the human population. Furthermore, we show that immunization with a cocktail of these epitopes protects HLA transgenic mice from challenge with rVACV expressing antigens from different arenavirus species. Our findings suggest that a cell-mediated vaccine strategy might be able to protect against infection mediated by multiple arenavirus species.

Reducing AD-like pathology in 3xTg-AD mouse model by DNA epitope vaccine - a novel immunotherapeutic strategy

BACKGROUND

The development of a safe and effective AD vaccine requires a delicate balance between providing an adequate anti-Abeta antibody response sufficient to provide therapeutic benefit, while eliminating an adverse T cell-mediated proinflammatory autoimmune response. To achieve this goal we have designed a prototype chemokine-based DNA epitope vaccine expressing a fusion protein that consists of 3 copies of the self-B cell epitope of Abeta(42) (Abeta(1-11)) , a non-self T helper cell epitope (PADRE), and macrophage-derived chemokine (MDC/CCL22) as a molecular adjuvant to promote a strong anti-inflammatory Th2 phenotype.

METHODS AND FINDINGS

We generated pMDC-3Abeta(1-11)-PADRE construct and immunized 3xTg-AD mouse model starting at age of 3-4 months old. We demonstrated that prophylactic immunizations with the DNA epitope vaccine generated a robust Th2 immune response that induced high titers of anti-Abeta antibody, which in turn inhibited accumulation of Abeta pathology in the brains of older mice. Importantly, vaccination reduced glial activation and prevented the development of behavioral deficits in aged animals without increasing the incidence of microhemorrhages.

CONCLUSIONS

Data from this transitional pre-clinical study suggest that our DNA epitope vaccine could be used as a safe and effective strategy for AD therapy. Future safety and immunology studies in large animals with the goal to achieve effective humoral immunity without adverse effects should help to translate this study to human clinical trials.

PEDF-derived synthetic peptides exhibit antitumor activity in an orthotopic model of human osteosarcoma

Pigment epithelium-derived factor (PEDF) is one of the most potent inhibitors of angiogenesis, and has recently been demonstrated to have an important multifunctional role in tumor growth, invasion, and metastasis. However, relatively little is known of mechanisms through which PEDF exerts its antitumor activity. Therefore, with the aim of identifying potential functional epitopes specifically against osteosarcoma, we evaluated the bioactivity of four 25-mer synthetic PEDF-derived peptides (termed StVOrth-1, -2 -3, and -4) against a human osteosarcoma cell line, SaOS-2. We found that StVOrth-2 (residues 78-102) predominantly inhibited tumor cell proliferation, while StVOrth-3 (residues 90-114) markedly increased cellular adhesion to collagen type-1, with StVOrth-4 (residues 387-411) demonstrating most significant inhibition of Matrigel invasion. Furthermore, we show that StVOrth-1 (residues 40-64), -2 and -3 induce osteoblastic differentiation, evidenced by increased mineralized nodule formation. Interestingly, although no peptide inhibited angiogenesis in the tube formation assay, StVOrth-3 and -4 markedly suppressed VEGF expression. We further tested the activity of StVOrth-2 and StVOrth-3 in vivo, in an orthotopic model of osteosarcoma and found that both peptides significantly inhibited primary tumor growth and the development of pulmonary metastases. Together these results provide greater insight into the potential mechanisms through which PEDF exerts its antitumor function. Furthermore, this raises the possibility of developing short PEDF fragments as lead compounds for the treatment of osteosarcoma.

Novel engineered trastuzumab conformational epitopes demonstrate in vitro and in vivo antitumor properties against HER-2/neu

Trastuzumab is a growth-inhibitory humanized Ab targeting the oncogenic protein HER-2/neu. Although trastuzumab is approved for treatment of advanced breast cancer, a number of concerns exist with passive immunotherapy. Treatment is expensive and has a limited duration of action, necessitating repeated administrations of the mAb. Active immunotherapy with conformational B cell epitopes affords the possibility of generating an enduring immune response, eliciting protein-reactive high-affinity anti-peptide Abs. The three-dimensional structure of human HER-2 in complex with trastuzumab reveals that the Ag-binding region of HER-2 spans residues 563-626 that comprises an extensive disulfide-bonding pattern. To delineate the binding region of HER-2, we have designed four synthetic peptides with different levels of conformational flexibility. Chimeric peptides incorporating the measles virus fusion "promiscuous" T cell epitope via a four-residue linker sequence were synthesized, purified, and characterized. All conformational peptides were recognized by trastuzumab and prevented the function of trastuzumab inhibiting tumor cell proliferation, with 563-598 and 597-626 showing greater reactivity. All epitopes were immunogenic in FVB/N mice with Abs against 597-626 and 613-626 recognizing HER-2. The 597-626 epitope was immunogenic in outbred rabbits eliciting Abs which recognized HER-2, competed with trastuzumab for the same epitope, inhibited proliferation of HER-2-expressing breast cancer cells in vitro and caused their Ab-dependent cell-mediated cytotoxicity. Moreover, immunization with the 597-626 epitope significantly reduced tumor burden in transgenic BALB-neuT mice. These results suggest the peptide B cell immunogen is appropriate as a vaccine for HER-2-overexpressing cancers because the resulting Abs show analogous biological properties to trastuzumab.

Identification of HLA-A2- or HLA-A24-restricted CTL epitopes possibly useful for glypican-3-specific immunotherapy of hepatocellular carcinoma

PURPOSE AND EXPERIMENTAL DESIGN

We previously reported that glypican-3 (GPC3) was overexpressed, specifically in hepatocellular carcinoma (HCC) and melanoma in humans, and it was useful as a novel tumor marker. We also reported that the preimmunization of BALB/c mice with dendritic cells pulsed with the H-2K(d)-restricted mouse GPC3(298-306) (EYILSLEEL) peptide prevented the growth of tumor-expressing mouse GPC3. Because of similarities in the peptide binding motifs between H-2K(d) and HLA-A24 (A*2402), the GPC3(298-306) peptide therefore seemed to be useful for the immunotherapy of HLA-A24+ patients with HCC and melanoma. In this report, we investigated whether the GPC3(298-306) peptide could induce GPC3-reactive CTLs from the peripheral blood mononuclear cells (PBMC) of HLA-A24 (A*2402)+ HCC patients. In addition, we used HLA-A2.1 (HHD) transgenic mice to identify the HLA-A2 (A*0201)-restricted GPC3 epitopes to expand the applications of GPC3-based immunotherapy to the HLA-A2+ HCC patients.

RESULTS

We found that the GPC3(144-152) (FVGEFFTDV) peptide could induce peptide-reactive CTLs in HLA-A2.1 (HHD) transgenic mice without inducing autoimmunity. In five out of eight HLA-A2+ GPC3+ HCC patients, the GPC3(144-152) peptide-reactive CTLs were generated from PBMCs by in vitro stimulation with the peptide and the GPC3(298-306) peptide-reactive CTLs were also generated from PBMCs in four of six HLA-A24+ GPC3+ HCC patients. The inoculation of these CTLs reduced the human HCC tumor mass implanted into nonobese diabetic/severe combined immunodeficiency mice.

CONCLUSION

Our study raises the possibility that these GPC3 peptides may therefore be applicable to cancer immunotherapy for a large number of HCC patients.

A double-blind clinical trial for treatment of Crohn's disease by oral administration of Alequel, a mixture of autologous colon-extracted proteins: a patient-tailored approach

OBJECTIVES

In this study, we evaluated the safety and efficacy of a personalized mode of treatment for Crohn's disease (CD) by oral administration of Alequel an extract of autologous colonic proteins.

METHODS

Thirty-one patients with moderate to severe CD were enrolled in a 27-wk randomized, double-blind, placebo-controlled trial. Patients were randomized to receive either a placebo or the study drug prepared from autologous colonic extract.

RESULTS

Oral administration of autologous colonic proteins resulted in clinical remission (58% vs 29%; 46.6% vs 26.6%, using an intention to treat analysis, p= NS), clinical response (67% vs 43%; 53.3% vs 40%, using an intention to treat analysis, p= NS) and improved quality of life (Inflammatory Bowel Disease Questionnaire score improvement 43%vs 12%) in the drug study group, compared to placebo group. No treatment-related adverse events were noted. Only in the study-drug-treated cohort who achieved clinical remission (DR), there was a decreased number of subject-specific, antigen-directed, IFNgamma spot-forming colonies. DR subjects had a lower initial C-reactive protein level than DNOR or placebo subjects, an increased percentage of peripheral blood nature killer T cells, and an increased CD4+/CD8+ T-cell ratio throughout the period of drug administration.

CONCLUSIONS

Oral administration of Alequel is a safe method for treatment of patients with moderate to severe CD, and its efficacy needs to be proven. Several markers may be applicable as surrogate markers for the clinical effect.

Rabies: epidemiological tendencies and control tools

Rabies encephalitis still generates 50,000 human deaths/year. It is due to neuron infection by lyssaviruses. Seven genotypes (GT) are currently distinguished within the Lyssavirus genus which segregate in two phylogroups (PG). This classification is constantly evolving due to isolation of new lyssaviruses within bat populations. Functional differences exist between GTs in term of neurotropism, pathogenesis, induction of apoptosis, immunogenicity, and their molecular basis are starting to be elucidated. Lyssavirus vectors are mammals, preferentially from the Carnivora and Chiroptera orders. Phylogenetic reconstruction strongly supports that lyssaviruses evolved in chiropters long before the emergence of carnivoran rabies which very likely occurred through host-switchings from bats to carnivores. If dog rabies control is possible by vaccination and population control, if oral vaccination demonstrated its potential to eliminate rabies from a terrestrial wildlife reservoir (fox in Western Europe), it is unrealistic today to clear lyssaviruses from bats, while bat rabies is a growing concern for both public and animal health. As bat transmit divergent lyssavirus GTs which are not well prevented by available vaccine strains, there is a need to increase the protection spectrum of vaccines. DNA-based immunization with plasmids expressing chimeric G proteins (fusion of two halves from different GTs) was shown to be effective in inducing a complete immune response and to broaden the spectrum of rabies vaccines toward lyssavirus vaccines. Further, the lyssavirus G protein can carry foreign epitopes/antigens in the perspective of multivalent vaccines against various zoonoses of carnivores.

Antigen-based therapies using ignored determinants of beta cell antigens can more effectively inhibit late-stage autoimmune disease in diabetes-prone mice

As organ-specific autoimmune diseases do not become manifest until well-advanced, interventive therapies must inhibit late-stage disease processes. Using a panel of immunogenic peptides from various beta cell Ags, we evaluated the factors influencing the efficacy of Ag-based therapies in diabetes-prone NOD mice with advanced disease. The ability of the major beta cell autoantigen target determinants (TDs) to prime Th2 responses declined sharply between 6 and 12 wk of age, whereas the ability of immunogenic ignored determinants (IDs) of beta cell Ags to prime Th2 responses was unaffected by the disease process. The different patterns of TD and ID immunogenicity (even from the same beta cell Ag) may be due to the exhaustion of uncommitted TD-reactive, but not ID-reactive, T cell pools by recruitment into the autoimmune cascade. Therapeutic efficacy was associated with a peptide's immunogenicity and ability to promote Th2 spreading late in the disease process but not its affinity for I-Ag7 or its expression pattern (beta cell specific/nonspecific or rare/abundant). Characterization of some IDs revealed them to be "absolute" cryptic determinants. Such determinants have little impact on T cell selection, leaving large precursor T cell pools available for priming by synthetic peptides. Traditional Ag-based therapeutics using whole autoantigens or their TDs cannot prime responses to such determinants. These findings suggest a new strategy for designing more efficacious Ag-based therapeutics for late-stage autoimmune diseases.

Blockade of Interleukin-12 Function by Protein Vaccination Attenuates Atherosclerosis

Background— Interleukin-12 (IL-12) has been identified as a key inducer of a type 1 T-helper cell cytokine pattern, which is thought to contribute to the development of atherosclerosis. We sought to study the role of IL-12 in atherosclerosis by inhibition of IL-12 using a newly developed vaccination technique that fully blocks the action of IL-12.

Methods and Results— LDL receptor–deficient (LDLr −/− ) mice were vaccinated against IL-12 by 5 intramuscular injections of IL-12–PADRE complex in combination with adjuvant oil-in-water emulsion (low dose)/MPL/QS21 every 2 weeks. Two weeks thereafter, atherogenesis was initiated in the carotid artery by perivascular placement of silicone elastomer collars. IL-12 vaccination resulted in the induction of anti–IL-12 antibodies that functionally blocked the action of IL-12 as determined in an IL-12 bioassay. Blockade of IL-12 by vaccination of LDLr −/− mice resulted in significantly reduced (68.5%; P <0.01) atherogenesis compared with control mice without a change in serum cholesterol levels. IL-12 vaccination also resulted in a significant decrease in intima/media ratios (66.7%; P <0.01) and in the degree of stenosis (57.8%; P <0.01). On IL-12 vaccination, smooth muscle cell and collagen content in the neointima increased 2.8-fold ( P <0.01) and 4.2-fold ( P <0.01), respectively.

Conclusions— Functional blockade of endogenous IL-12 by vaccination resulted in a significant 68.5% reduction in atherogenesis in LDLr −/− mice. Vaccination against IL-12 also improved plaque stability, from which we conclude that the blockade of IL-12 by vaccination may be considered a promising new strategy in the treatment of atherosclerosis.

A novel peptide screened by phage display can mimic TRAP antigen epitope against Staphylococcus aureus infections

Staphylococcus aureus is a major human pathogen. Pathogenic effects are largely due to production of bacterial toxins, whose synthesis is controlled by an mRNA molecule termed RNAIII. The S. aureus protein called RAP (RNAIII-activating protein) is secreted and activates RNAIII production by inducing the phosphorylation of its target protein TRAP (target of RAP). Antibodies to TRAP have been shown to suppress exotoxin production by S. aureus in vitro, suggesting that TRAP may be a useful vaccine target site. Here we showed that a peptide TA21 was identified by screening a phage display library using anti-TRAP antibodies. Mice vaccinated with Escherichia coli engineered to express TA21 on their surface (FTA21) were protected from S. aureus infections, using sepsis and cellulitis mice models. By sequence analysis, it was found that the TA21 is highly homologous to the C-terminal sequence of TRAP which is conserved among S. aureus and Staphylococcus epidermidis, suggesting that peptide TA21 may be a useful broad vaccine to protect from infection caused by various staphylococcal strains.

Antigen specific active immunotherapy: lessons from the first decade

Malignant melanoma is a tumour with a steeply rising incidence and scarce therapeutic options once metastatic. Approximately 1200 new cases are reported yearly in Switzerland with roughly 220 deaths/year. An important particularity of melanoma is its immunogenicity, which has long been recognized and investigated using various clinical immunization protocols in the last fifty years. The year 1991, when the first melanoma associated antigen was molecularly characterized, represents a turning point in the quest for a melanoma immunotherapy. This opened the era of antigen specific active immunotherapy. Many clinical centres have developed immunization strategies in an adjuvant setting for the treatment of metastatic melanoma. The molecular characterization of melanoma associated antigens allows a fine monitoring of the elicited immune response. Certain clinical responses to these efforts have been seen and a phase of reflection is now ongoing, with refinements and further sophistication taking place in order to fully realize the potential of antigen specific active immunotherapy. Here we provide an overview of the technologies used and of the progress reported in melanoma immunotherapy since 1991. Furthermore, we propose some research lines in basic and translational research aimed at improving our capacity to induce specific and clinically relevant immune responses against melanoma.

Variations in "rescuability" of immunoglobulin molecules from different forms of human lymphoma: implications for anti-idiotype vaccine development

Idiotypic (Id) vaccination has shown promising results in patients with follicular lymphoma (FL). However, it still remains unclear whether the same approach might be suitable for the treatment of other B-cell malignancies. For this reason, we recently performed an interim analysis of patients proposed to receive this treatment at our center. The feasibility of employing idiotype vaccines was evaluated for five different B-cell malignancies in their first relapse, both in terms of induction and fusion, as well as overall treatment. Our data suggest that, unlike follicular lymphoma (87%), this approach is not feasible to treat other B-cell malignancies (0-20%) such as mantle cell, small lymphocytic, diffuse large cell and Burkitt's lymphoma (P < 0.01). The main difficulties encountered were technical problems related to the survival of idiotype-producing hybridomas (83%) and the early loss of idiotype production by growing hybridomas (17%). However, it remains possible that an idiotype vaccine might still be produced through molecular means for most, if not all cases of relapsing B-cell malignancies.

[Development for a novel cancer vaccine]

Clinical trial using epitope peptides have been intensively performed in the world. From the results, it has been clarified that tumor specific CTLs were induced in the vaccinated cancer patients. In this manuscript, we demonstrated the problems to be clarified from clinical trial and recent advances for cancer vaccine using epitope peptides.

Schistosoma japonicum: isolation and identification of peptides mimicking ferritin epitopes from phage display library

In an attempt to isolate and identify the antigenic epitopes on ferritin of Schistosoma japonicum (SjFer) and to test their protective potentiality against Schistosoma japonicum (S.j), polyclonal antisera against SjFer was prepared to screen a 12-mer random peptide library. Three rounds of biopanning were performed and resulted in an enrichment. Six peptides selected randomly from the third elute were all found to be positive by evaluating the binding to anti-SjFer sera by ELISA and Western blotting. Three amino acid sequences were deduced from the six phage clones by sequencing. When they were used to vaccinate mice, the three peptides could induce significant reduction in adult worms (26.7%, 20.4%, and 25.9%) as well as in liver eggs per gram (LEPG) (40.0%, 38.2%, and 40.8%). This result showed that three mimotopes on SjFer were obtained and they could induce significant protective efficacy against S.j.

MHC-based vaccination approaches: progress and perspectives

The major histocompatibility complex (MHC) harbours genes whose primary function in regulating immune responsiveness to infection is to present foreign antigens to cytotoxic T lymphocytes (CTLs) and T helper cells. In the case of infection by human immunodeficiency virus (HIV), defining the optimal HIV epitopes that are recognised by CTLs is important for vaccine design, and this in turn will depend on the characteristics of the predominant infecting virus. Moreover, the particular MHC human leukocyte antigens (HLAs) expressed by a geographical population is important since these are likely to determine which HIV epitopes are immunodominant in the anti-HIV immune response. Consideration of these aspects has lead to the dawn of a new era of MHC-based vaccine design, in which the CTL epitopes are selected on the basis of the frequency of restricting MHC alleles. This article reviews data on the distribution patterns of molecular subtypes of HLA class I and class II extended haplotypes, discussing distribution among Asian Indians but with reference to global distributions. These data provide a genetic basis for the possible predisposition and fast progression of HIV infections in the Indian population. Since there is selective predominance of different HLA alleles and haplotypes in different populations, a dedicated screening effort is required at the global level to develop MHC-based vaccines against infectious diseases. It is hoped that this might lead to the development of multivalent, poly-epitope, subtype-specific HIV vaccines that are specific for the target geographical location.

Disease-driven T cell activation predicts immune responses to vaccination against melanoma

Tumor vaccines may induce activation and expansion of specific CD8 T cells which can subsequently destroy tumor cells in cancer patients. This phenomenon can be observed in approximately 5-20% of vaccinated melanoma patients. We searched for factors associated with T cell responsiveness to peptide vaccines. Peptide antigen-specific T cells were quantified and characterized ex vivo before and after vaccination. T cell responses occurred primarily in patients with T cells that were already pre-activated before vaccination. Thus, peptide vaccines can efficiently boost CD8 T cells that are pre-activated by endogenous tumor antigen. Our results identify a new state of T cell responsiveness and help to explain and predict tumor vaccine efficacy.

Determinant spreading associated with clinical response in dendritic cell-based immunotherapy for malignant melanoma

PURPOSE

The purpose of this study was to determine the toxicity and immunological effects of three different doses and two routes of administration of autologous dendritic cells (DCs) pulsed with the MART-1(27-35) immunodominant epitope.

EXPERIMENTAL DESIGN

Eighteen HLA-A*0201-positive subjects with stage III-IV melanoma received three biweekly i.v. or intradermal injections of ex vivo generated myeloid DCs pulsed with MART-1(27-35) epitope. Repeated blood samples were processed to obtain peripheral blood mononuclear cells for immunological analysis using IFN-gamma ELISPOT, MHC class I tetramer, intracellular cytokine staining, and microcytotoxicity assays.

RESULTS

The frequency of MART-1/Melan-A (MART-1) antigen-specific T cells in peripheral blood increased in all dose levels as assessed by ELISPOT and MHC class I tetramer assays, but without a clear dose-response effect. The intradermal route generated stronger MART-1 immunity compared with the i.v. route. MART-1-specific immunity did not correlate with clinical outcome in any of the four immunological assays used. However, analysis of determinant spreading to other melanoma antigens was noted in the only subject with complete response to this single-epitope immunization.

CONCLUSIONS

Intradermal immunization with MART-1 peptide-pulsed DCs results in an increase in circulating IFN-gamma-producing, antigen-specific T cells. The frequency of these cells did not correlate with response. In contrast, spreading of immune reactivity to other melanoma antigens was only evident in a subject with a complete response, suggesting that determinant spreading may be an important factor of clinical response to this form of immunotherapy.

Synthetic approaches to multivalent lipopeptide dendrimers containing cyclic disulfide epitopes of foot-and-mouth disease virus

The synthesis of a multiantigenic peptide dendrimer incorporating four copies of a cyclic disulfide epitope has been undertaken. Since standard chemoselective ligation procedures involving thioether formation are inadvisable in the presence of a preformed disulfide, conjugation through a peptide bond between the lipidated branched lysine scaffold and a suitably protected version of the cyclic disulfide has been used instead. Several synthetic approaches to the partially protected cyclic disulfide peptide have been explored. The most effective involves building a minimally protected version of the peptide by Boc solid phase synthesis, using fluorenyl-based anchorings and cysteine protecting groups. Peptide-resin cleavage and cysteine deprotection/oxidation are performed simultaneously by base-promoted elimination. The cyclic disulfide epitope is readily obtained in sufficient amounts by this procedure and subsequently incorporated to the lipidated lysine core by peptide bond formation in solution. A final acid deprotection step in anhydrous HF yields a peptide construction containing a maximum of three copies of the cyclic disulfide epitope, the lower substitution being attributable to steric constraints. This immunogen has been successfully used in an experimental vaccination trial against foot-and-mouth disease virus.

Mimotopes of viral antigens and biologically important molecules as candidate vaccines and potential immunotherapeutics

Antigen recognition by antibodies or ligand-receptor interactions involve small areas of the molecule named epitopes that are normally conformational in nature. The availability of combinatorial peptide libraries has provided a powerful tool for selecting novel sequences which mimic conformational epitopes (mimotopes) either structurally and/or immunologically. These mimotopes can be particularly useful in a number of situations, including: the development of vaccines against tumors, infectious diseases or allergic conditions; the design of molecules which can act as agonists or antagonists of various biologically-important molecules; and for the development of diagnostic assays. This article reviews the authors work on the application of combinatorial peptide libraries to identify mimotopes of protective B-cell epitopes from various pathogens, and the search for molecules able to block the biological activities of TNF-alpha, a cytokine which plays a key role in inflammation.

Epitope identification and vaccine design for cancer immunotherapy

The development of processes for engineering multi-epitope vaccines based on the identification and selection of epitope packages, along with vaccine design optimization using epitope placements and spacers to optimize processing efficacy, are reviewed. The Epimmune Inc epitope identification process has been applied to numerous cancer types, but also applies to infectious diseases. Epitope-analog efforts in novel vaccine design have also been explored and their uses in prophylactic and therapeutic applications are eagerly anticipated.

Prevention of new sensitizations in monosensitized subjects submitted to specific immunotherapy or not. A retrospective study

BACKGROUND

Specific immunotherapy is the only currently available allergen-orientated treatment able to modify the natural history of respiratory allergic diseases. Safety and clinical efficacy of this treatment are well documented, but evidence about the ability to reduce new sensitizations is still poor.

OBJECTIVE

We report a retrospective study conducted in order to assess the prevention of new sensitizations in monosensitized subjects treated with specific immunotherapy vs. monosensitized patients treated with anti-allergic drugs.

METHODS

8396 monosensitized patients with respiratory symptoms were selected according to an open, retrospective design. Group A included 7182 patients submitted to specific immunotherapy (and anti-allergic drugs when needed) for 4 years and then treated with drugs for at least 3 years. Group B included 1214 patients treated only with drugs for at least 7 years. All patients underwent prick test with a standard panel of allergens and total and specific IgE determination before and after 4 years of treatment and again 3 years later.

RESULTS

Groups were well balanced. Polysensitized subjects were 23.75% in Group A and 68.03% in Group B after 4 years (P < 0.0001) and 26.95% and 76.77%, respectively, after 7 years (P < 0.0001). Asthmatic subjects were more prone to develop polysensitization in comparison to subjects suffering only from rhinitis (32.14% instead of 27.29% after 4 years, 36.5% instead of 31.33% after 7 years; P < 0.0001). Specific IgE decreased by 24.11% in Group A and increased by 23.87% in Group B (P < 0.0001). Total IgE decreased by 17.53% in Group A and increased by 13.71% in Group B (P < 0.0001).

CONCLUSIONS

Specific immunotherapy was observed retrospectively to reduce new sensitizations in monosensitized subjects suffering from respiratory allergic diseases.

Identification of a new shared HLA-A2.1 restricted epitope from the melanoma antigen tyrosinase

Tyrosinase has many advantages as a target antigen for the immunotherapy of patients with melanoma because it is expressed in nearly all melanoma specimens with a high degree of cellular homogeneity, and its distribution in normal tissues is limited to melanocytes. To broaden our ability to direct cellular immune responses against this protein, we pursued an investigation to identify new shared human leukocyte antigen (HLA)-A2.1 restricted epitopes from tyrosinase. Peptides were synthesized that fit a permissive HLA-A2.1 binding motif and did not span common sites of polymorphism. The binding affinity of each peptide to HLA-A2.1 relative to a standard peptide with intermediate binding affinity was evaluated in a competitive inhibition assay. Twelve peptides were selected that had binding affinities within 80% of that of the standard peptide, and these were used to stimulate peripheral blood mononuclear cells (PBMC) in vitro from three HLA-A2.1+ patients with metastatic melanoma. Cytotoxic T lymphocytes that specifically recognized peptide-pulsed target cells as well as HLA-A2.1+ tyrosinase+ melanoma cells were raised from one patient with tyrosinase:8-17 (CLLWSFQTSA). To evaluate further the immunogenicity of this peptide, PBMC from 23 HLA-A2.1+ patients were stimulated in vitro with tyrosinase:8-17. Eleven bulk T-cell cultures demonstrated specific peptide recognition, and six of these also recognized HLA-A2.1+ tyrosinase+ melanoma cells. These data suggest that tyrosinase:8-17 may be clinically useful for the treatment of patients with melanoma.

Two epitopes shared by Taenia crassiceps and Taenia solium confer protection against murine T. crassiceps cysticercosis along with a prominent T1 response

Taenia crassiceps recombinant antigens KETc1 and KETc12 have been shown to induce high level of protection against experimental murine T. crassiceps cysticercosis, an experimental model successfully used to test candidate antigens for use in vaccination against porcine Taenia solium cysticercosis. Based on the deduced amino acid sequence, KETc1 and KETc12 were chemically synthesized in linear form. Immunization with KETc1 induced 66.7 to 100% protection against murine cysticercosis, and immunization with KETc12 induced 52.7 to 88.1% protection. The elicited immune response indicated that both peptides contain at least one B-cell epitope (as demonstrated by their ability to induce specific antibodies) and one T-cell epitope that strongly stimulated the proliferation of T cells primed with either the free peptide or total cysticercal T. crassiceps antigens. The high percentage of spleen cells expressing inflammatory cytokines points to the likelihood of a T1 response being involved in protection. The protective capacity of the peptides and their presence in all developmental stages of T. solium point to these two epitopes as strong candidates for inclusion in a polyepitopic synthetic vaccine against T. solium pig cysticercosis.

MHC: function and implication on vaccine development

The purpose of this State of the Art review is to present an overview of structural and functional aspects of human MHC molecules and how polymorphisms in HLA molecules determine the nature of the antigenic peptides bound and how such may impact upon rational vaccine development. The following areas will be discussed: elements of immune recognition, class I and class II structure and function, the class I antigen processing pathway, class II antigen processing and presentation, functional divergence among T-cells recognizing class I or class II MHC molecules, and rational vaccine development. While the first section will review our current understanding of MHC structure and function, the latter part will draw on my own work with Hepatitis C Virus (HCV) antigens.

Structure and biology of stinging insect venom allergens

Bees, fire ants and vespids cause insect sting allergy. These insects have unique as well as common venom allergens. Vespids, including hornets, paper wasps and yellow jackets, have common allergens. Bees and vespids have one common allergen with hyaluronidase activity; they also have unique allergens with different phospholipase activities. Fire ants and vespids have one common allergen, antigen 5 of unknown biologic activity. The common venom allergens with < 70% sequence identity have barely detectable levels of antigenic cross-reactivity. Possible uses of modified allergens for immunotherapy are described.

Retroviral gene therapy with an immunoglobulin-antigen fusion construct protects from experimental autoimmune uveitis

Immunoglobulins can serve as tolerogenic carriers for antigens, and B cells can function as tolerogenic antigen-presenting cells. We used this principle to design a strategy for gene therapy of experimental autoimmune uveitis, a cell-mediated autoimmune disease model for human uveitis induced with the uveitogenic interphotoreceptor retinoid-binding protein (IRBP). A retroviral vector was constructed containing a major uveitogenic IRBP epitope in frame with mouse IgG1 heavy chain. This construct was used to transduce peripheral B cells, which were infused into syngeneic recipients. A single infusion of transduced cells, 10 days before uveitogenic challenge, protected mice from clinical disease induced with the epitope or with the native IRBP protein. Protected mice had reduced antigen-specific responses, but showed no evidence for a classic Th1/Th2 response shift or for generalized anergy. Protection was not transferable, arguing against a mechanism dependent on regulatory cells. Importantly, the treatment was protective when initiated 7 days after uveitogenic immunization or concurrently with adoptive transfer of primed uveitogenic T cells. We suggest that this form of gene therapy can induce epitope-specific protection not only in naive, but also in already primed recipients, thus providing a protocol for treatment of established autoimmunity.

Phase 1 study in patients with metastatic melanoma of immunization with dendritic cells presenting epitopes derived from the melanoma-associated antigens MART-1 and gp100

Dendritic cells (DCs) have been shown to enhance anti-tumor immune responses in several preclinical models. Furthermore, DC-like function can be elicited from peripheral blood monocytes cultured in vitro with interleukin-4 and granulocyte-macrophage colony-stimulating factor. For this reason, a phase 1 study was initiated at the Surgery Branch of the National Cancer Institute to test the toxicity and biological activity of the intravenous administration of peripheral blood monocyte-derived DCs. The DCs were generated by 5- to 7-day incubation in interleukin-4 (1,000 U/mL) and granulocyte-macrophage colony-stimulating factor (1,000 U/mL) of peripheral blood monocytes obtained by leukapheresis. Before administration, the DCs were pulsed separately with the HLA-A*0201-associated melanoma epitopes MART-1(27-35) and gp-100-209-2M. The DCs were administered four times at 3-week intervals. A first cohort of patients (n = 3) was treated with 6 x 10(7) DCs and a second cohort (n = 5) with 2 x 10(8) DCs (in either case, one half of the DCs were pulsed with MART-1(27-35) and the other half was pulsed with gp-100-209-2M). In a final cohort under accrual (n = 2) 2 x 10(8) DCs were administered in combination with interleukin-2 (720,000 IU/kg every 8 hours). The recovery of DCs after in vitro culture ranged from 3% to 35% (mean, 15%) of the original peripheral blood monocytes. Administration of DCs caused no symptoms at any of the doses, and the concomitant administration of interleukin-2 did not cause toxicity other than that expected for interleukin-2 alone. Monitoring of patients' cytotoxic T lymphocyte reactivity before and after treatment revealed enhancement of cytotoxic T lymphocyte reactivity only in one of five patients tested. Of seven patients evaluated for response, one had a transient partial response with regression of pulmonary and cutaneous metastases. A relatively large number of DCs can be safely administered intravenously. The poor clinical outcome of this study perhaps could be explained by the type of protocol used for DC maturation, the route of administration, or both. For this reason, this clinical protocol was interrupted prematurely, whereas other strategies for DC preparation and route of administration are being investigated at the authors' institution.

Antigen-specific cytotoxicity and cell number of adoptively transferred T cells are efficiently maintained in vivo by re-stimulation with an antigen/interleukin-2 fusion protein

In order to maintain in vivo anti-tumor efficacy of antigen (Ag)-specific T cells in adoptive immunotherapy for a prolonged period, we constructed a fusion protein (OVA/IL-2) containing ovalbumin (OVA) as a model tumor Ag, co-valently linked to murine interleukin-2 (IL-2). The OVA/IL-2 protein produced in a baculovirus expression system displayed potent IL-2 bio-activity. Immunization with the OVA/IL-2 protein after adoptive transfer of OVA-specific T cells maintained the OVA-specific cytotoxicity and cell number of adoptively transferred T cells long term in vivo, while a simple mixture of recombinant OVA (rOVA) and rIL-2 did not. The response was dependent on the injection doses and times of the OVA/IL-2 protein. Furthermore, weekly re-stimulation of adoptively transferred OVA-specific T cells with the OVA/IL-2 protein cured 70% of tumor-bearing mice. In contrast, re-stimulation with a mixture of rOVA and rIL-2 could not significantly prolong the survival period of tumor-bearing mice. These studies suggest that the co-valent linkage between IL-2 and antigen confines the effect of IL-2 to antigen-specific T cells, leading to efficient maintenance of the anti-tumor activity of adoptively transferred T cells.

Bone marrow-derived dendritic cells pulsed with a tumor-specific peptide elicit effective anti-tumor immunity against intracranial neoplasms

Although the central nervous system (CNS) is often regarded as an immunologically privileged site, it is well established that specific CNS immunoreactivity can be generated through peripheral vaccination with CNS antigens. Dendritic cells (DC) are potent antigen presenting cells of hematopoietic origin that have emerged as a promising tool for cancer immunotherapy capable of evoking significant anti-tumor immunity when pulsed with tumor-associated peptides. To explore a role for DC-based immunization strategies for the treatment of CNS tumors, we developed a brain tumor model using the C3 sarcoma cell line which expresses the tumor-specific, major histocompatibility complex (MHC) class I-restricted peptide epitope E7(49-57). Syngeneic C57Bl/6 mice receiving intravenous (i.v.) injections of bone marrow-derived DCs pulsed with E7 peptide were effectively protected against a subsequent intracerebral challenge with C3 tumor cells. More importantly, this systemic immunization strategy was effective in a therapy model as 67% of animals (10 of 15) with established (day 7) intracerebral C3 tumors treated with 3 weekly injections of E7 peptide-pulsed DCs achieved a long-term survival (>90 days) while no control animals survived beyond day 41. In vivo depletion of CD8+ cells, but not CD4+ or asialo-GM1+ cells, abrogated the efficacy of E7 peptide-pulsed DC therapy of established tumors, indicating a pivotal role of specific CD8+ T-cell responses in mediating the anti-tumor effect. Our findings support the hypothesis that effective CNS anti-tumor immunoreactivity can be generated with DC-based tumor vaccines.

Cell-mediated immunological responses in cervical and vaginal cancer patients immunized with a lipidated epitope of human papillomavirus type 16 E7

Human papillomavirus (HPV) infection has been causally associated with cervical cancer. We tested the effectiveness of an HLA-A*0201-restricted, HPV-16 E7 lipopeptide vaccine in eliciting cellular immune responses in vivo in women with refractory cervical cancer. In a nonrandomized Phase I clinical trial, 12 women expressing the HLA-A2 allele with refractory cervical or vaginal cancer were vaccinated with four E786-93 lipopeptide inoculations at 3-week intervals. HLA-A2 subtyping was also performed, and HPV typing was assessed on tumor specimens. Induction of epitope-specific CD8+ T-lymphocyte (CTL) responses was analyzed using peripheral blood leukapheresis specimens obtained before and after vaccination. CTL specificity was measured by IFN-gamma release assay using HLA-A*0201 matched target cells. Clinical responses were assessed by physical examination and radiographic images. All HLA-A*0201 patients were able to mount a cellular immune response to a control peptide. E786-93-specific CTLs were elicited in 4 of 10 evaluable HLA-A*0201 subjects before vaccination, 5 of 7 evaluable HLA-A*0201 patients after two vaccinations, and 2 of 3 evaluable HLA-A*0201 cultures after all four inoculations. Two of three evaluable patients' CTLs converted from unreactive to reactive after administration of all four inoculations. There were no clinical responses or treatment toxicities. The ability to generate specific cellular immune responses is retained in patients with advanced cervical cancer. Vaccination with a lipidated HPV peptide epitope appears capable of safely augmenting CTL reactivity. Although enhancements of cellular immune responses are needed to achieve therapeutic utility in advanced cervical cancer, this approach might prove useful in treating preinvasive disease.