YF17D-based vaccines - standing on the shoulders of a giant

Live-attenuated yellow fever vaccine (YF17D) was developed in the 1930s as the first ever empirically derived human vaccine. Ninety years later, it is still a benchmark for vaccines made today. YF17D triggers a particularly broad and polyfunctional response engaging multiple arms of innate, humoral and cellular immunity. This unique immunogenicity translates into an extraordinary vaccine efficacy and outstanding longevity of protection, possibly by single-dose immunization. More recently, progress in molecular virology and synthetic biology allowed engineering of YF17D as a powerful vector and promising platform for the development of novel recombinant live vaccines, including two licensed vaccines against Japanese encephalitis and dengue, even in paediatric use. Likewise, numerous chimeric and transgenic preclinical candidates have been described. These include prophylactic vaccines against emerging viral infections (e.g. Lassa, Zika and SARS-CoV-2) and parasitic diseases (e.g. malaria), as well as therapeutic applications targeting persistent infections (e.g. HIV and chronic hepatitis), and cancer. Efforts to overcome historical safety concerns and manufacturing challenges are ongoing and pave the way for wider use of YF17D-based vaccines. In this review, we summarize recent insights regarding YF17D as vaccine platform, and how YF17D-based vaccines may complement as well as differentiate from other emerging modalities in response to unmet medical needs and for pandemic preparedness.

Impact of the Route and Schedule of Immunization on the Serological and Virological Response of Chronic Hepatitis B Patients Treated with HeberNasvac

HeberNasvac is a recently developed therapeutic vaccine for chronic hepatitis B (CHB) administered by intranasal (IN) and subcutaneous (SC) routes in a 14 days/10 doses schedule. To compare different schedules and routes of immunizations, a group of patients received four different vaccination regimens in a placebo-controlled factorial study. Subsequently, patients were followed for a minimum time of 48 weeks. Samples collected at the end of the follow-up were compared with initial samples. Groups I and II received the product by IN/SC routes, every 14 and 7 days, respectively. Groups III and IV were treated by SC route alone following a 14 and 7 days schedule. A group of 21 CHB patients received the vaccine in four different schedules and eight patients received placebo for a total of 29 patients enrolled. The 61.9% of vaccinees reduced their VL ≥2Log compared with baseline levels and 25% in placebo group. The 47.6% of vaccines reduced HBV levels to undetectable, 25% in placebo. HBeAg loss and seroconversion to anti-HBeAg was only achieved in vaccinees, 4 out of 9 (44.4%), and 40% (8 out of 20) developed anti-HBs response, none in placebo group. Reduction of HBsAg level in ≥1Log was achieved in the 35.0% of vaccinees and in none of the placebo-treated patients. Considering the individual and factorial analysis, significant HBV DNA reduction was detected in groups I and II, immunized by IN/SC routes. A significantly higher proportion of patients reducing VL to ≥2Log was also detected grouping the patients treated by IN/SC routes (G I + II) and grouping those inoculated every 14 days (G I + III), with 72.7% and 63.6%, respectively, compared with the placebo group (25.0%). The patients immunized every 14 days (G I + G III) also reduced the HBsAg levels compared with baseline. In conclusion, after more than 48 weeks of treatment-free follow-up, HeberNasvac-treated patients demonstrated superior responses compared with the placebo group in terms of antiviral and serological responses. The factorial analysis evidenced that the schedule combining the IN route of immunization and the frequency of 14 days resulted in the stronger antiviral and serological responses. Present results support the study of IN-only immunization schedules in future and was consistent with previous results. Long-lasting follow-ups were done to explore histological variables and the progression of serological variables in order to detect late responders.

How to cite this article

Freyre FM, Aguiar JA, Cinza Z, et al. Impact of the Route and Schedule of Immunization on the Serological and Virological Response of Chronic Hepatitis B Patients Treated with HeberNasvac. Euroasian J Hepato-Gastroenterol 2023;13(2):73-78.

[Clinical research progress and implications of therapeutic vaccines for cervical cancer and precancerous lesions: a qualitative systematic review]

Objective: To systematically summarize and analyze the clinical research progress of therapeutic vaccines for cervical cancer or precancerous lesions. Methods: English databases (PubMed, Embase, Web of Science, Cochrane library, Proquest, and ClinicalTrails.gov) and Chinese databases (SinoMed, CNKI, WanFang, and VIP Database) were systematically searched to collect literature on therapeutic vaccines for cervical cancer or precancerous lesions from inception to February 18, 2021. After screening, we evaluated the risk of bias of included studies, and combed the basic information of the literature, research designs, information of vaccines, study patients, outcome indicators and so on, qualitatively summarized the clinical research progress. Results: A total of 71 studies were included in this systematic review, including 14 random controlled trials, 15 quasi-random controlled trials, 4 cohort studies, 1 case-control study, 34 case series studies and 3 case reports. The study patients included women aged 15~79 with cervical cancer or precancerous lesions in 18 countries from 1989 to 2021. On the one hand, there were 40 studies on therapeutic vaccines for cervical precancerous lesions (22 867 participants), involving 21 kinds of vaccines in 6 categories. Results showed 3 marketed vaccines (Cervarix, Gardasil, Gardasil 9) as adjuvant immunotherapies were significant effective in preventing the recurrence of precancerous lesions compared with the conization only. In addition, MVA E2 vaccine had been in phase Ⅲ clinical trials as a specific therapeutic vaccine, with relative literature showing it could eliminate most high-grade precancerous lesions. Therapeutic vaccines for precancerous lesions all showed good safety. On the other hand, there were 31 studies on therapeutic vaccines for cervical cancer (781 participants), involving 19 kinds of vaccines in 7categories, with none had been marketed. 25 studies were with no control group, showing the vaccines could effectively eliminate solid tumors, prevent recurrence, and prolong the median survival time. However, the vaccines effectiveness couldn't be statistically calculated due to the lack of a control group. As for the safety of therapeutic vaccines for cervical cancer, 9 studies showed that patients experienced serious adverse events after treatments, where 7 studies reported that serious adverse events occurred in patients couldn't be ruled out as the results of therapeutic vaccines. Conclusions: The literature review shows that the literature evidence for the therapeutic vaccines for cervical precancerous lesions is relatively mature compared with the therapeutic vaccines for cervical cancer. The four kinds of vaccines on the market are all therapeutic vaccines for precancerous lesions, but they are generally used as vaginal infection treatments or adjuvant immunotherapies for cervical precancerous lesions, not used for the specific treatments of cervical precancerous lesions. Other specific therapeutic vaccines are in the early stage of clinical trials, mainly phase Ⅰ/Ⅱ clinical trials with small sample size. The effectiveness and safety data are limited, and further research is still needed.

Immunotherapy for visceral leishmaniasis: A trapeze of balancing counteractive forces

The protozoan parasite Leishmania donovani, residing and replicating within the cells of the monocyte-macrophage (mono-mac) lineage, causes visceral leishmaniasis (VL) in humans. While, Leishmania infantum, is the main causative agent for zoonotic VL, where dogs are the main reservoirs of the disease. The chemotherapy is a serious problem because of restricted repertoire of drugs, drug-resistant parasites, drug-toxicity and the requirement for parenteral administration, which is a problem in resource-starved countries. Moreover, immunocompromised individuals, particularly HIV-1 infected are at higher risk of VL due to impairment in T-helper cell and regulatory cell responses. Furthermore, HIV-VL co-infected patients report poor response to conventional chemotherapy. Recent efforts are therefore directed towards devising both prophylactic and therapeutic immunomodulation. As far as prophylaxis is concerned, although canine vaccines for the disease caused by Leishmania infantum or Leishmania chagasi are available, no vaccine is available for use in humans till date. Therefore, anti-leishmanial immunotherapy triggering or manipulating the host's immune response is gaining momentum during the last two decades. Immunomodulators comprised of small molecules, anti-leishmanial peptides, complex ligands for host receptors, cytokines or their agonists and antibodies have been given trials both in experimental models and in humans. However, the success of immunotherapy in humans remains a far-off target. We, therefore, propose that devising a successful immunotherapy is an act of balancing enhanced beneficial Leishmania-specific responses and deleterious immune activation/hyperinflammation just as the swings in a trapeze.

Immunotherapy and Biomarkers in Sarcoma

OPINION STATEMENT

Sarcoma describes a rare and heterogeneous group of diseases. Current treatment options for metastatic sarcoma are quite limited. Conventional treatments with chemotherapy or anti-angiogenic agents result in a non-durable response and a survival rate of approximately 12 to 18 months. In addition, the benefits of such treatments remain limited in some sarcoma subtypes only. Immunotherapy is an emerging treatment for several cancer types with promising outcomes. Studies at the cellular level have shown a relatively high immunogenicity in some subtypes of sarcoma. It is therefore hypothesized that sarcoma may respond to immunotherapy. However, sarcoma is a heterogeneous disease and differences in terms of immunogenicity exist. A multitude of immune-based treatment approaches for sarcoma have been explored. This includes immune checkpoint inhibitors, therapeutic vaccines, and adoptive cell therapy. Single-agent immunotherapy has exhibited efficacy against some sarcoma subtypes, including alveolar soft-part sarcoma, angiosarcoma, and undifferentiated pleomorphic sarcoma. Combination immunotherapy appears superior to single-agent immunotherapy in terms of response, and several ongoing studies of immunotherapy using single/combination immune checkpoint inhibitors and combination with anti-angiogenesis have begun to report beneficial results. Predictive and prognostic biomarkers are also under active investigations, with particular interest in tumor-infiltrating lymphocytes or high tumor mutational burden levels. However, the information is still limited and further studies are needed.

A review on the advances and challenges of immunotherapy for head and neck cancer

Head and neck cancer (HNC), which includes lip and oral cavity, larynx, nasopharynx, oropharynx, and hypopharynx malignancies, is one of the most common cancers worldwide. Due to the interaction of tumor cells with immune cells in the tumor microenvironment, immunotherapy of HNCs, along with traditional treatments such as chemotherapy, radiotherapy, and surgery, has attracted much attention. Four main immunotherapy strategies in HNCs have been developed, including oncolytic viruses, monoclonal antibodies, chimeric antigen receptor T cells (CAR-T cells), and therapeutic vaccines. Oncorine (H101), an approved oncolytic adenovirus in China, is the pioneer of immunotherapy for the treatment of HNCs. Pembrolizumab and nivolumab are mAbs against PD-L1 that have been approved for recurrent and metastatic HNC patients. To date, several clinical trials using immunotherapy agents and their combination are under investigation. In this review, we summarize current the interaction of tumor cells with immune cells in the tumor microenvironment of HNCs, the main strategies that have been applied for immunotherapy of HNCs, obstacles that hinder the success of immunotherapies in patients with HNCs, as well as solutions for overcoming the challenges to enhance the response of HNCs to immunotherapies.

Immunotherapy in Cervical Cancer

PURPOSE OF REVIEW

This review aims to summarize the current immunotherapy studies and the potential targeted therapies showing promise in the treatment of cervical cancer.

RECENT FINDINGS

There are promising ongoing monotherapy and combination therapy trials using different immune checkpoint inhibitors, poly adenosine diphosphate ribose polymerase inhibitors, tumor angiogenesis inhibitors (i.e., bevacizumab), antibody-drug conjugates, therapeutic vaccines, and tumor-infiltrating T lymphocytes (adoptive immunotherapy). Some of these novel modalities are also being evaluated in combination with standard platinum-based chemotherapy regimen. At this time, pembrolizumab is approved for the treatment of relapsed or metastatic programmed death ligand 1 (PD-L1) positive cervical cancer after frontline chemotherapy treatment. Multiple novel therapeutic modalities are emerging as safe and effective for the treatment of cervical cancer patients. Development and participation in investigative treatments can provide benefit and improve outcomes in cervical cancer.

Immunotherapy in treatment of leishmaniasis

Leishmaniasis caused by various species of protozoan transmitted by sand fly vectors occurs as a spectrum of clinical features including cutaneous, mucocutaneous and visceral forms. It is a geographically distributed parasitic disease and a major public health problem in the world. The clinical syndromes are highly variable depending on the parasite species, host genetics, vectors and environment. To date, there is no effective vaccine and traditional treatments are toxic, expensive with long administration duration and many adverse side effects and/or drug resistance. Instead of treatments based on chemotherapy, certain strategies aim to recover leishmaniasis and reduce the parasitic burden. Immunotherapy has focused on the induction of effective immune response to rapidly control the disease. Recent studies have indicated that a single dose of a suitable therapeutic vaccine induces a quick and lasting recovery in patients. Immunotherapy reduces the toxicity of drug and the emergence of resistance dramatically. It could be an effective addition to chemotherapy with a safe and potent drug compared with monotherapy, resulting in a prophylactic and therapeutic cure of leishmaniasis. This review has focused on treatment of leishmaniasis with particular emphasis on immunotherapy as an alternative to conventional drug treatment.

Liposomes as tunable platform to decipher the antitumor immune response triggered by TLR and NLR agonists

Liposomes are powerful tools for the optimization of peptides and adjuvant composition in cancer vaccines. Here, we take advantage of a liposomal platform versatility to develop three vaccine candidates associating a peptide from HA influenza virus protein as CD4 epitope, a peptide from HPV16 E7 oncoprotein as CD8 epitope and TLR4, TLR2/6 or NOD1 agonists as adjuvant. Liposomal vaccine containing MPLA (TLR4 liposomes), are the most effective treatment against the HPV-transformed orthotopic lung tumor mouse model, TC-1. This vaccine induces a potent Th1-oriented antitumor immunity, which leads to a significant reduction in tumor growth and a prolonged survival of mice, even when injected after tumor appearance. This efficacy is dependent on CD8⁺ T cells. Subcutaneous injection of this treatment induces the migration of skin DCs to draining lymph nodes. Interestingly, TLR2/6 liposomes trigger a weaker Th1-immune response which is not sufficient for the induction of a prolonged antitumor activity. Although NOD1 liposome treatment results in the control of early tumor growth, it does not extend mice survival. Surprisingly, the antitumor activity of NOD1 vaccine is not associated with a specific adaptive immune response. This study shows that our modulable platform can be used for the strategical development of vaccines.

Delivery of nucleic acid therapeutics for cancer immunotherapy

Cancer immunotherapy has shown great potential as witnessed by an increasing number of immuno-oncology drug approvals in the past few years. Meanwhile, the field of nucleic acid therapeutics has made significant advancement. Nucleic acid therapeutics, such as plasmids, antisense oligonucleotides (ASO), small interfering RNA (siRNA) and microRNA, messenger RNA (mRNA), immunomodulatory DNA/RNA, and gene-editing guide RNA (gRNA) are attractive due to their versatile abilities to alter the expression of target endogenous genes or even synthetic genes, and modulate the immune responses. These abilities can play vital roles in the development of novel immunotherapy strategies. However, limited by the intrinsic physicochemical properties such as negative charges, hydrophilicity, as well as susceptibility to enzymatic degradation, the delivery of nucleic acid therapeutics faces multiple challenges. It is therefore pivotal to develop drug delivery systems that can carry, protect, and specifically deliver and release nucleic acid therapeutics to target tissues and cells. In this review, we attempted to summarize recent advances in nucleic acid therapeutics and the delivery systems for these therapeutics in cancer immunotherapy.

Oral immunization of mice with a multivalent therapeutic subunit vaccine protects against Helicobacter pylori infection

Helicobacter pylori is a human class I carcinogen and no effective prophylactic or therapeutic H. pylori vaccine has yet been marketed. H. pylori can escape the host immune response, but the precise immune protection mechanisms in humans remain unknown. In this study, we developed a multivalent, subunit H. pylori vaccine candidate by formulating three commonly used H. pylori antigens, neutrophil-activating protein (NAP), urease subunit A (UreA) and subunit B (UreB) with the mucosal adjuvant, a double-mutant heat-labile toxin (dmLT) from Escherichia coli, and evaluated its immunogenicity and therapeutic efficacy in a mouse model of H. pylori infection. We found that oral immunization of H. pylori-infected mice significantly reduced gastric bacterial colonization at both 2 and 8 weeks after immunization. The reduction in bacterial burdens was accompanied with significantly increased serum antigen-specific IgG responses and mucosal IgA responses. Moreover, oral immunization also induced Th1/Th17 immune responses, which may play a synergistic role with the specific antibodies in the elimination of H. pylori. Thus, our vaccine candidate appears able to overcome the immune evasion mechanism of H. pylori, restore the suppression of Th2 immune responses with the induction of a strong humoral immune response. These results lay the foundation for the development of an optimized oral therapeutic H. pylori vaccine with increased immunogenicity of UreA and UreB, as well as providing long-term immunity.

Cancer immunotherapy: the art of targeting the tumor immune microenvironment

For many decades, cancer treatment has been strongly directed toward the development of cytotoxic and cytostatic drugs, quite often leading to disappointing results due to the inter- and intra-tumoral heterogeneity. Lately, this intra-cellular look has given way to the understanding of the tumor microenvironment, thus enabling modification of the immunological dynamics between tumor cells and their host. An era of new drugs aiming to unlock the host immune system against tumor cells is steadily increasing. Strategies involving adoptive cell therapy, therapeutic vaccines, immune checkpoint inhibitors and so on have provided spectacular clinical responses and increased survival in previously refractory settings and "hard-to-treat" cancers. Based on a comprehensive search in the main scientific databases, annals of recent renowned oncology congresses and platforms of ongoing trials, the clinical pharmacology characteristics of the main classes of immunotherapeutic agents, as well as the new treatment strategies related to immunotherapy in solid tumors, are carefully discussed throughout this review.

Comparative analysis and generation of a robust HIV-1 DNA quantification assay

HIV-1 infection cannot be cured due to the presence of the latent reservoir (LR). Novel cure or treatment strategies, such as "shock and kill" or therapeutic vaccination, aim to reduce or eradicate the LR. Cure strategies utilise robust DNA quantification assays to measure the change in the LR in low copy scenarios. No standard assay exists, which impedes the reliable comparison of results from different therapy and vaccine trials and HIV-1 total DNA quantification methods have not been previously compared. The HIV-1 long terminal repeat (LTR) has been shown to be the best target for DNA quantification. We have analysed two HIV-1 quantification assays, both able to differentiate between the variant HIV-1 DNA forms via the use of pre-amplification and primers targeting LTR. We identify a strong correlation (r=0.9759, P<0.0001) between assays which is conserved in low copy samples (r=0.8220, P<0.0001) indicating that these assays may be used interchangeably. The RvS assay performed significantly (P=0.0021) better than the CV assay when quantifying HIV-1 total DNA in patient CD4+ T lymphocytes. Sequence analysis demonstrated that viral diversity can limit DNA quantification, however in silico analysis of the primers indicated that within the target region nucleotide miss-matches appear infrequently. Further in silico analysis using up to-date sequence information led to the improvement of primers and enabled us to establish a more broadly specific assay with significantly higher HIV-1 DNA quantification capacity in patient samples (p=0.0057, n=17).

The current status of immunotherapy for cervical cancer

Immunotherapy has been proven effective in several tumours, hence diverse immune checkpoint inhibitors are currently licensed for the treatment of melanoma, kidney cancer, lung cancer and most recently, tumours with microsatellite instability. There is much enthusiasm for investigating this approach in gynaecological cancers and the possibility that immunotherapy might become part of the therapeutic landscape for gynaecological malignancies. Cervical cancer is the fourth most frequent cancer in women worldwide and represents 7.9% of all female cancers with a higher burden of the disease and mortality in low- and middle-income countries. Cervical cancer is largely a preventable disease, since the introduction of screening tests, the recognition of the human papillomavirus (HPV) as an etiological agent, and the subsequent development of primary prophylaxis against high risk HPV subtypes. Treatment for relapsed/advanced disease has improved over the last 5 years, since the introduction of antiangiogenic therapy. However, despite advances, the median overall survival for advanced cervical cancer is 16.8 months and the 5-year overall survival for all stages is 68%. There is a need to improve outcomes and immunotherapy could offer this possibility. Clinical trials aim to understand the best timing for immunotherapy, either in the adjuvant setting or recurrent disease and whether immunotherapy, alone or in combination with other agents, improves outcomes.

[Research progress of HPV therapeutic vaccine]

Bivalent and quadrivalent HPV vaccine have been approved by CFDA successively in China. However, currently available prophylactic vaccines have no therapeutic effect for established infection or disease. In recent years, based on the application of genomics and proteomics for interpretation of tumor antigen, animal experiments and clinical trials of vaccines aiming at a wide variety of antigens have been conducted. In this review, we summarize about the preclinical and clinical research status of HPV therapeutic vaccine and find that the efficacy of HPV therapeutic vaccine alone or combined with other conventional cancer treatment is satisfying, which has potential clinical application value. As the further research of tumor immune regulation and optimization of strategies for the HPV therapeutic vaccine, the vaccine will play an important role in improving the quality of life in cancer patients and eventually become widely used in clinical practice.

Immune monitoring and TCR sequencing of CD4 T cells in a long term responsive patient with metastasized pancreatic ductal carcinoma treated with individualized, neoepitope-derived multipeptide vaccines: a case report

BACKGROUND

Cancer vaccines can effectively establish clinically relevant tumor immunity. Novel sequencing approaches rapidly identify the mutational fingerprint of tumors, thus allowing to generate personalized tumor vaccines within a few weeks from diagnosis. Here, we report the case of a 62-year-old patient receiving a four-peptide-vaccine targeting the two sole mutations of his pancreatic tumor, identified via exome sequencing.

METHODS

Vaccination started during chemotherapy in second complete remission and continued monthly thereafter. We tracked IFN-γ⁺ T cell responses against vaccine peptides in peripheral blood after 12, 17 and 34 vaccinations by analyzing T-cell receptor (TCR) repertoire diversity and epitope-binding regions of peptide-reactive T-cell lines and clones. By restricting analysis to sorted IFN-γ-producing T cells we could assure epitope-specificity, functionality, and T_H1 polarization.

RESULTS

A peptide-specific T-cell response against three of the four vaccine peptides could be detected sequentially. Molecular TCR analysis revealed a broad vaccine-reactive TCR repertoire with clones of discernible specificity. Four identical or convergent TCR sequences could be identified at more than one time-point, indicating timely persistence of vaccine-reactive T cells. One dominant TCR expressing a dual TCRVα chain could be found in three T-cell clones. The observed T-cell responses possibly contributed to clinical outcome: The patient is alive 6 years after initial diagnosis and in complete remission for 4 years now.

CONCLUSIONS

Therapeutic vaccination with a neoantigen-derived four-peptide vaccine resulted in a diverse and long-lasting immune response against these targets which was associated with prolonged clinical remission. These data warrant confirmation in a larger proof-of concept clinical trial.

Immunotherapy for cervical cancer: Can it do another lung cancer?

Cervical cancer, although preventable, is still the second most common cancer among women worldwide. In developing countries like India, where screening for cervical cancer is virtually absent, most women seek treatment only at advanced stages of the disease. Although standard treatment is curative in more than 90% of women during the early stages, for stage IIIb and above this rate drops to 50% or less. Hence, novel therapeutic adjuvants are required to improve survival at advanced stages. Lung cancer has shown the way forward with the use of Immunotherapeutic interventions as standard line of treatment in advanced stages. In this review, we provide an overview of mechanisms of immune evasion, strategies that can be employed to boost the immune system in order to improve the overall survival of the patients and summarize briefly the clinical trials that have been completed or that are underway to bring therapeutic vaccines for cervical cancer to the clinics.

Future Therapy for Hepatitis B Virus: Role of Immunomodulators

Although currently available therapies for chronic hepatitis B virus infection can suppress viremia and provide long-term benefits for patients, they do not lead to a functional cure for most patients. Advances in our understanding of the virus-host interaction and the recent remarkable success of immunotherapy in cancer offer new and promising strategies for developing immune modulators that may become important components of a total therapeutic approach to hepatitis B, some of which are now in clinical development. Among the immunomodulatory agents currently being investigated to combat chronic HBV are toll-like receptor agonists, immune checkpoint inhibitors, therapeutic vaccines, and engineered T cells. The efficacy of some immune modulatory therapies is compromised by high viral antigen levels. Cutting edge strategies, including RNA interference and CRISPR/Cas9, are now being studied that may ultimately be shown to have the capacity to lower viral antigen levels sufficiently to substantially increase the efficacy of these agents. The current advances in therapies for chronic hepatitis B are leading us toward the possibility of a functional cure.

Vaccine R&D: past performance is no guide to the future

Vaccines offer the most cost-effective solution to prevent both communicable and non-communicable disease in poor countries. Published studies suggest that vaccine research is seeing declining success. This study updates the latest analyses on success rates in vaccine research, and examines the potential causes of decline and their ongoing impact. Success rates are shown to decline, the observed probability of market entry being just 1.8%, almost a fourfold decline over 5 years, but in the context of a very different product portfolio from that seen in earlier studies. DNA vaccines see high Phase I failures as expected, and therapeutic vaccines have lower success rates than prophylactic vaccines. The changing scientific challenge, lack of investment and lack of co-operation are highlighted as potential causes of the decline. Many issues have now been resolved, but co-operation between academia, regulators and industry remains a significant challenge, requiring links across new disciplines and technologies.

An overview of emerging therapies for the treatment of chronic hepatitis C

Advances in our understanding of the HCV lifecycle and refinement of in vitro methods to select candidate compounds with anti-HCV activity have led to development of DAA agents and other novel antiviral therapies capable of increasing the curative SVR rates in patients with CHC. The use of the liner protease inhibitors telaprevir and boceprevir, in combination with Peg-IFN-a and ribavirin has become the new SOC for treatment of CHC genotype 1. Rapid development of new protease inhibitors, NI and NNI NS5B polymerase inhibitors, NS5A inhibitors, Peg-IFN-l, cyclophilin inhibitors, caspase inhibitors, and therapeutic vaccines promises to provide even safer and more effective therapy. Combination therapies with 2 or more oral agents may permit elimination of Peg-IFN-a in the near future. Introduction of DAA therapies will confront physicians and patients with regimens of increased complexity, a greater need for compliance, and the necessity of monitoring for virological resistance. Patients with CHC should continue to consider participation in clinical trials of new therapies to accelerate progress.

T cell costimulatory molecules in anti-viral immunity: Potential role in immunotherapeutic vaccines

T lymphocyte activation is required to eliminate or control intracellular viruses. The activation of T cells requires both an antigen specific signal, involving the recognition of a peptide/major histocompatibility protein complex by the T cell receptor, as well as additional costimulatory signals. In chronic viral diseases, T cell responses, although present, are unable to eliminate the infection. By providing antigens and costimulatory molecules together, investigators may be able to increase and broaden the immune response, resulting in better immunological control or even elimination of the infection. Recent progress in understanding the function of costimulatory molecules suggests that different costimulatory molecules are involved in initial immune responses than are involved in recall responses. These new developments have important implications for therapeutic vaccine design. In this review the authors discuss the function of T cell costimulatory molecules in immune system activation and their potential for enhancing the efficacy of therapeutic vaccines.