IL-7 producing immunotherapy improves ex vivo T cell functions of immunosenescent patients, especially post hip fracture.

Following acute stress such as trauma or sepsis, most of critically ill elderly patients become immunosuppressed and susceptible to secondary infections and enhanced mortality. We have developed a virus-based immunotherapy encoding human interleukin-7 (hIL-7) aiming at restoring both innate an adaptative immune homeostasis in these patients. We assessed the impact of this encoded hIL-7 on the ex vivo immune functions of T cells from PBMC of immunosenescent patients with or without hip fracture. T-cell ex vivo phenotyping was characterized in terms of senescence (CD57), IL-7 receptor (CD127) expression, and T cell differentiation profile. Then, post stimulation, activation status, and functionality (STAT5/STAT1 phosphorylation and T cell proliferation assays) were evaluated by flow cytometry. Our data show that T cells from both groups display immunosenescence features, express CD127 and are activated after stimulation by virotherapy-produced hIL-7-Fc. Interestingly, hip fracture patients exhibit a unique functional ability: An important T cell proliferation occurred compared to controls following stimulation with hIL-7-Fc. In addition, stimulation led to an increased naïve T cell as well as a decreased effector memory T cell proportions compared to controls. This preliminary study indicates that the produced hIL-7-Fc is well recognized by T cells and initiates IL-7 signaling through STAT5 and STAT1 phosphorylation. This signaling efficiently leads to T cell proliferation and activation and enables a T cell "rejuvenation." These results are in favor of the clinical development of the hIL-7-Fc expressing virotherapy to restore or induce immune T cell responses in immunosenescent hip fracture patients.

Intravenous injection of a novel viral immunotherapy encoding human interleukin-7 in nonhuman primates is safe and increases absolute lymphocyte count.

Persistence of an immunosuppression, affecting both the innate and adaptive arms of the immune system, plays a role in sepsis patients' morbidity and late mortality pointing to the need for broad and effective immune interventions. MVA-hIL-7-Fc is a non-replicative recombinant Modified Vaccinia virus Ankara encoding the human interleukin-7 fused to human IgG2 Fc fragment. We have shown in murine sepsis models the capacity of this new virotherapy to stimulate both arms of the immune system and increase survival. Herein, an exploratory study in nonhuman primates was performed following a single intravenous injection of the MVA-hIL-7-Fc used at the clinical dose to assess its safety and biological activities. Four cynomolgus macaques were followed for 3 weeks post-injection (p.i), without observed acute adverse reactions. Circulating hIL-7-Fc was detected during the first 3-5 days p.i with a detection peaking at 12 h p.i. IL-7 receptor engagement and downstream signal transduction were detected in T cells demonstrating functionality of the expressed IL-7. Expansion of blood lymphocytes, mainly CD4 and CD8 naïve and central memory T cells, was observed on day 7 p.i. together with a transient increase of Ki67 expression on T lymphocytes. In addition, we observed an increase in circulating B and NK cells as well as monocytes were albeit with different kinetics and levels. This study indicates that a vectorized IL-7-Fc, injected by intravenous route at a relevant clinical dose in a large animal model, is active without adverse reactions supporting the clinical development of this novel virotherapy for treatment of sepsis patients.

A novel virotherapy encoding human interleukin-7 improves ex vivo T lymphocyte functions in immunosuppressed patients with septic shock and critically ill COVID-19.

A majority of patients with sepsis surviving the first days in intensive care units (ICU) enter a state of immunosuppression contributing to their worsening. A novel virotherapy based on the non-propagative Modified Virus Ankara (MVA) expressing the human interleukin-7 (hIL-7) cytokine fused to an Fc fragment, MVA-hIL-7-Fc, was developed and shown to enhance innate and adaptive immunity and confer survival advantages in murine sepsis models. Here, we assessed the capacity of hIL-7-Fc produced by the MVA-hIL-7-Fc to improve ex vivo T lymphocyte functions from ICU patients with sepsis. Primary hepatocytes were transduced with the MVA-hIL-7-Fc or an empty MVA, and cell supernatants containing the secreted hIL-7-Fc were harvested for in vitro and ex vivo studies. Whole blood from ICU patients [septic shock = 15, coronavirus disease 2019 (COVID-19) = 30] and healthy donors (n = 36) was collected. STAT5 phosphorylation, cytokine production, and cell proliferation were assessed upon T cell receptor (TCR) stimulation in presence of MVA-hIL-7-Fc-infected cell supernatants. Cells infected by MVA-hIL-7-Fc produced a dimeric, glycosylated, and biologically active hIL-7-Fc. Cell supernatants containing the expressed hIL-7-Fc triggered the IL-7 pathway in T lymphocytes as evidenced by the increased STAT5 phosphorylation in CD3+ cells from patients and healthy donors. The secreted hIL-7-Fc improved Interferon-γ (IFN-γ) and/or Tumor necrosis factor-α (TNF-α) productions and CD4+ and CD8+ T lymphocyte proliferation after TCR stimulation in patients with bacterial and viral sepsis. This study demonstrates the capacity of the novel MVA-hIL-7-Fc-based virotherapy to restore ex vivo T cells immune functions in ICU patients with sepsis and COVID-19, further supporting its clinical development.

Viral Delivery of IL-7 Is a Potent Immunotherapy Stimulating Innate and Adaptive Immunity and Confers Survival in Sepsis Models.

Persistence of an immunosuppressive state plays a role in septic patient morbidity and late mortality. Both innate and adaptive pathways are impaired, pointing toward the need for immune interventions targeting both arms of the immune system. We developed a virotherapy using the nonpropagative modified vaccinia virus Ankara (MVA), which harbors the intrinsic capacity to stimulate innate immunity, to deliver IL-7, a potent activator of adaptive immunity. The rMVA-human IL-7 (hIL-7)-Fc encoding the hIL-7 fused to the human IgG2-Fc was engineered and shown to express a dimeric, glycosylated, and biologically active cytokine. Following a single i.v. injection in naive mice, the MVA-hIL-7-Fc increased the number of total and activated B, T, and NK cells but also myeloid subpopulations (Ly6Chigh, Ly6Cint, and Ly6Cneg cells) in both lung and spleen. It triggered differentiation of T cells in central memory, effector memory, and acute effector phenotypes and enhanced polyfunctionality of T cells, notably the number of IFN-γ-producing cells. The MVA vector contributed significantly to immune cell activation, particularly of NK cells. The MVA-hIL-7-Fc conferred a significant survival advantage in the cecal ligation and puncture (CLP) and Candida albicans sepsis models. It significantly increased cell numbers and activation in both spleen and lung of CLP mice. Comparatively, in naive and CLP mice, the rhIL-7-Fc soluble counterpart overall induced less vigorous, shorter lasting, and narrower immune activities than did the MVA-hIL-7-Fc and favored TNF-α-producing cells. The MVA-hIL-7-Fc represents a novel class of immunotherapeutic with clinical potential for treatment of septic patients.

Evaluation of heterologous prime-boost vaccination strategies using chimpanzee adenovirus and modified vaccinia virus for TB subunit vaccination in rhesus macaques.

Tuberculosis (TB) still is the principal cause of death from infectious disease and improved vaccination strategies are required to reduce the disease burden and break TB transmission. Here, we investigated different routes of administration of vectored subunit vaccines based on chimpanzee-derived adenovirus serotype-3 (ChAd3) for homologous prime-boosting and modified vaccinia virus Ankara (MVA) for heterologous boosting with both vaccine vectors expressing the same antigens from Mycobacterium tuberculosis (Ag85B, ESAT6, Rv2626, Rv1733, RpfD). Prime-boost strategies were evaluated for immunogenicity and protective efficacy in highly susceptible rhesus macaques. A fully parenteral administration regimen was compared to exclusive respiratory mucosal administration, while parenteral ChAd3-5Ag prime-boosting and mucosal MVA-5Ag boosting were applied as a push-and-pull strategy from the periphery to the lung. Immune analyses corroborated compartmentalized responses induced by parenteral versus mucosal vaccination. Despite eliciting TB-specific immune responses, none of the investigational regimes conferred a protective effect by standard readouts of TB compared to non-vaccinated controls, while lack of protection by BCG underpinned the stringency of this non-human primate test modality. Yet, TB manifestation after full parenteral vaccination was significantly less compared to exclusive mucosal vaccination.

Safety and immunogenicity of the therapeutic vaccine TG1050 in chronic hepatitis B patients: a phase 1b placebo-controlled trial.

Treatment of chronic hepatitis B (CHB) typically requires life-long administration of drugs. Cohort and pre-clinical studies have established the link between a functional T-cell-mounted immunity and resolution of infection. TG1050 is an adenovirus 5-based vaccine that expresses HBV polymerase and domains of core and surface antigen and has shown immunogenicity and antiviral effects in mice. We performed a phase 1 clinical trial to assess safety and explore immunogenicity and early efficacy of TG1050 in CHB patients. This randomized, double blind, placebo-controlled study included two sequential phases: one single dose cohort (SD, n = 12) and one multiple (3) doses cohort (MD, n = 36). Patients, virally suppressed under nucleoside(d)tide analog NUC therapy, were randomized 1:1:1 across 3 dose levels (DL) and assigned to receive 109, 1010, 1011 virus particles (vp) of TG1050 and then randomized within each DL to placebo (3:1 and 9:3 vaccines/placebo in each DL, respectively, for the SD and MD cohorts). Cellular (ELISPOT) and antibody responses (anti-Adenovirus), as well as evolution of circulating HBsAg and HBcrAg, were monitored. All doses were well tolerated in both cohorts, without severe adverse event. TG1050 was capable to induce IFN-γ producing T-cells targeting 1 to 3 encoded antigens, in particular at the 1010vp dose. Overall, minor decreases of HBsAg were observed while a number of vaccinees reached unquantifiable HBcrAg by end of the study. In CHB patients under NUC, TG1050 exhibited a good safety profile and was capable to induce HBV-specific cellular immune response. These data support further clinical evaluation, especially in combination studies.

A multi-antigenic MVA vaccine increases efficacy of combination chemotherapy against Mycobacterium tuberculosis.

Despite the existence of the prophylactic Bacille Calmette-Guérin (BCG) vaccine, infection by Mycobacterium tuberculosis (Mtb) remains a major public health issue causing up to 1.8 million annual deaths worldwide. Increasing prevalence of Mtb strains resistant to antibiotics represents an urgent threat for global health that has prompted a search for alternative treatment regimens not subject to development of resistance. Immunotherapy constitutes a promising approach to improving current antibiotic treatments through engagement of the host's immune system. We designed a multi-antigenic and multiphasic vaccine, based on the Modified Vaccinia Ankara (MVA) virus, denoted MVATG18598, which expresses ten antigens classically described as representative of each of different phases of Mtb infection. In vitro analysis coupled with multiple-passage evaluation demonstrated that this vaccine is genetically stable, i.e. fit for manufacturing. Using different mouse strains, we show that MVATG18598 vaccination results in both Th1-associated T-cell responses and cytolytic activity, targeting all 10 vaccine-expressed Mtb antigens. In chronic post-exposure mouse models, MVATG18598 vaccination in combination with an antibiotic regimen decreases the bacterial burden in the lungs of infected mice, compared with chemotherapy alone, and is associated with long-lasting antigen-specific Th1-type T cell and antibody responses. In one model, co-treatment with MVATG18598 prevented relapse of the disease after treatment completion, an important clinical goal. Overall, results demonstrate the capacity of the therapeutic MVATG18598 vaccine to improve efficacy of chemotherapy against TB. These data support further development of this novel immunotherapeutic in the treatment of Mtb infections.

A meta-analysis of the antiviral activity of the HBV-specific immunotherapeutic TG1050 confirms its value over a wide range of HBsAg levels in a persistent HBV pre-clinical model.

Pre-clinical models mimicking persistent hepatitis B virus (HBV) expression are seldom, do not capture all features of a human chronic infection and due to their complexity, are subject to variability. We report a meta-analysis of seven experiments performed with TG1050, an HBV-targeted immunotherapeutic, 1 in an HBV-persistent mouse model based on the transduction of mice by an adeno-associated virus coding for an infectious HBV genome (AAV-HBV). To mimic the clinical diversity seen in HBV chronically infected patients, AAV-HBV transduced mice displaying variable HBsAg levels were treated with TG1050. Overall mean percentages of responder mice, displaying decrease in important clinical parameters i.e. HBV-DNA (viremia) and HBsAg levels, were 52% and 51% in TG1050 treated mice, compared with 8% and 22%, respectively, in untreated mice. No significant impact of HBsAg level at baseline on response to TG1050 treatment was found. TG1050-treated mice displayed a significant shorter Time to Response (decline in viral parameters) with an Hazard Ratio (HR) of 8.3 for viremia and 2.6 for serum HBsAg. The mean predicted decrease for TG1050-treated mice was 0.5 log for viremia and 0.8 log for HBsAg, at the end of mice follow-up, compared to no decrease for viremia and 0.3 log HBsAg decrease for untreated mice. For mice receiving TG1050, a higher decline of circulating viremia and serum HBsAg level over time was detected by interaction term meta-analysis with a significant treatment effect (p = 0.002 and p<0.001 respectively). This meta-analysis confirms the therapeutic value of TG1050, capable of exerting potent antiviral effects in an HBV-persistent model mimicking clinical situations.

A Novel MVA-Based Multiphasic Vaccine for Prevention or Treatment of Tuberculosis Induces Broad and Multifunctional Cell-Mediated Immunity in Mice and Primates.

Bacille Calmette-Guérin (BCG) vaccination of new born babies can protect children against tuberculosis (TB), but fails to protect adults consistently against pulmonary TB underlying the urgent need to develop novel TB vaccines. Majority of first generation TB vaccine candidates have relied on a very limited number of antigens typically belonging to the active phase of infection. We have designed a multi-antigenic and multiphasic vaccine, based on the Modified Vaccinia Ankara virus (MVA). Up to fourteen antigens representative of the three phases of TB infection (active, latent and resuscitation) were inserted into MVA. Using three different strains of mouse (BALB/c, C57BL/6 and C3H/HeN), we show that a single vaccination results in induction of both CD4 and CD8 T cells, displaying capacity to produce multiple cytokines together with cytolytic activity targeting a large array of epitopes. As expected, dominance of responses was linked to the mouse haplotype although for a given haplotype, responses specific of at least one antigen per phase could always be detected. Vaccination of non-human primates with the 14 antigens MVA-TB candidate resulted in broad and potent cellular-based immunogenicity. The remarkable plasticity of MVA opens the road to development of a novel class of highly complex recombinant TB vaccines to be evaluated in both prophylactic and therapeutic settings.

Recognition of core-derived epitopes from a novel HBV-targeted immunotherapeutic by T-cells from patients infected by different viral genotypes.

Hepatitis B virus (HBV) infects millions of people worldwide and is a leading cause of liver cirrhosis and hepatocellular carcinoma. Current therapies based on nucleos(t)ide analogs or pegylated-interferon-α lead to control of viral replication in most patients but rarely achieve cure. A potential strategy to control chronic hepatitis B is to restore or induce functional anti-HBV T-cell immune responses using HBV-specific immunotherapeutics. However, viral diversity is a challenge to the development of this class of products as HBV genotypes display a sequence diversity of up to 8%. We have developed a novel HBV-targeted immunotherapeutic, TG1050, based on a non-replicative Adenovirus vector encoding a unique and large fusion protein composed of multiple antigenic regions derived from a HBV genotype D sequence. Using peripheral blood mononuclear cells from 23 patients chronically infected by five distinct genotypes (gt A, B, C, D and E) and various sets of peptides encompassing conserved versus divergent regions of HBV core we have measured ability of TG1050 genotype D core-derived peptides to be recognized by T-cells from patients infected by various genotypes. Overall, PBMCs from 78% of genotype B or C- and 100% genotype A or E-infected patients lead to detection of HBV core-specific T-cells recognizing genotype D antigenic domains located both in conserved and variable regions. This proof-of-concept study supports the clinical development of TG1050 in large patient populations independently of infecting genotypes.

The sero-prevalence of anti-adenovirus 5 neutralizing antibodies is independent of a chronic hepatitis B carrier state in China.

We investigated the prevalence of neutralizing antibodies (NA) to human Adenovirus (Ad) 5 both in healthy subjects (HS) and Chronic Hepatitis B (CHB) patients in Shanghai. Detection of anti-Ad5 NA (percentage of detection and titers) was similar between HS and CHB patients. A high percentage of subjects harbored no detectable antibodies (32.2 %) while proportion of subjects displaying very high antibody titers was low (4 %). Neither demographic factors (gender, age, health) nor AST/ALT or HBV circulating DNA titers affected detection of Ad5-specific NA. These observations pave the ground for development of Ad5-based immunotherapeutics aiming at treating CHB patients in China.

TG1050, an immunotherapeutic to treat chronic hepatitis B, induces robust T cells and exerts an antiviral effect in HBV-persistent mice.

OBJECTIVE: To assess a new adenovirus-based immunotherapy as a novel treatment approach to chronic hepatitis B (CHB). METHODS: TG1050 is a non-replicative adenovirus serotype 5 encoding a unique large fusion protein composed of a truncated HBV Core, a modified HBV Polymerase and two HBV Envelope domains. We used a recently described HBV-persistent mouse model based on a recombinant adenovirus-associated virus encoding an over length genome of HBV that induces the chronic production of HBsAg, HBeAg and infectious HBV particles to assess the ability of TG1050 to induce functional T cells in face of a chronic status. RESULTS: In in vitro studies, TG1050 was shown to express the expected large polyprotein together with a dominant, smaller by-product. Following a single administration in mice, TG1050 induced robust, multispecific and long-lasting HBV-specific T cells detectable up to 1 year post-injection. These cells target all three encoded immunogens and display bifunctionality (i.e., capacity to produce both interferon γ and tumour necrosis factor α as well as cytolytic functions). In addition, control of circulating levels of HBV DNA and HBsAg was observed while alanine aminotransferase levels remain in the normal range. CONCLUSIONS: Injection of TG1050 induced both splenic and intrahepatic functional T cells producing cytokines and displaying cytolytic activity in HBV-naïve and HBV-persistent mouse models together with significant reduction of circulating viral parameters. These results warrant clinical evaluation of TG1050 in the treatment of CHB.

Comparative analysis of immunization schedules using a novel adenovirus-based immunotherapeutic targeting hepatitis B in naïve and tolerant mouse models.

Development of active targeted immunotherapeutics is a rapid developing field in the arena of chronic infectious diseases. The question of repeated, closely spaced administration of immunotherapeutics to achieve a rapid impact on the replicating agent is an important one. We analyzed here, using a prototype adenovirus-based immunotherapeutic encoding Core and Polymerase from the hepatitis B virus (Ad-HBV), the influence of closely spaced repeated immunizations on the level and quality of induced HBV-specific and vector-specific immune responses in various mouse models. Ad-HBV, whether injected once or multiple times, was able to induce HBV- and adeno-specific T cells both in HBV-free mice and in a HBV tolerant mouse model. Adenovirus-specific T cell responses and titers of neutralizing anti-Ad5 antibodies increased from time of the 3rd injection. Interestingly, single or multiple Ad-HBV injections resulted in detection of Polymerase-specific functional T cells in HBV tolerant mice. Overall no modulation of the levels of HBV-specific cytokine-producing (IFNγ/TNFα) and cytolytic T cells was observed following repeated administrations (3 or 6 weekly injections) when compared with levels detected after a single injection with the exception of two markers: 1. the proportion of HBV-specific IFNγ-producing cells bearing the CD27+/CD43+ phenotype appeared to be sustained in C57BL/6J mice following 6 weekly injections; 2. the percentage of IFNγ/TNFα Core-specific producing cells observed in spleens of HLA-A2 mice as well as of that specific of Polymerase observed in livers of HBV tolerant mice was maintained. In addition, percentage of HBV-specific T cells expressing PD-1 was not increased by multiple injections. Overall these data show that, under experimental conditions used, rapid, closely spaced administrations of an adenovirus-based HBV immunotherapeutics does not inhibit induced T-cell responses including in a HBV-tolerant environment.

Efficacy of immunotherapy with TG4040, peg-interferon, and ribavirin in a Phase 2 study of patients with chronic HCV infection.

BACKGROUND & AIMS: TG4040 is a modified vaccinia Ankara (MVA) virus that expresses the hepatitis C virus (HCV) proteins NS3, NS4, and NS5B. We performed a phase II open-label study to determine the efficacy, safety, and immunotherapeutic properties of TG4040 in combination with pegylated interferon α-2a and ribavirin (PEG-IFNα/RBV) in patients with chronic HCV infection. METHODS: Treatment-naive patients with HCV genotype 1 infection were assigned randomly to 1 of the following groups: PEG-IFNα/RBV for 48 weeks (group A, n = 31), PEG-IFNα/RBV for 4 weeks followed by PEG-IFNα/RBV for 44 weeks with 6 injections of TG4040 (group B, n = 63), or TG4040 for 12 weeks (7 injections) followed by PEG-IFNα/RBV for 48 weeks with 6 injections of TG4040 (group C, n = 59). The primary end point was complete early virologic response (cEVR), defined as HCV-RNA level less than 10 IU/mL after 12 weeks of PEG-IFNα/RBV treatment. RESULTS: In group C, 64.2% of evaluable patients achieved cEVR, compared with 30.0% in group A and 45.9% in group B (P = .0003 for group C vs A). A higher percentage of patients achieved a sustained virologic response 24 weeks after therapy ended in group C (58.2%) than in groups A (48.4%) or B (50.8%). HCV- and MVA-specific T-cell responses were observed predominantly in group C. As expected, most patients given injections of TG4040 developed anti-MVA antibodies. The combination of TG4040 and PEG-IFNα/RBV was reasonably well tolerated. However, PEG-IFNα-associated thrombocytopenia developed in 3 patients who carried the class II HLA allele DRB01*04. CONCLUSIONS: A higher percentage of patients with chronic HCV infection who received immunotherapy with TG4040 followed by TG4040 and PEG-IFNα/RBV achieved a cEVR compared with patients who received only PEG-IFNα/RBV therapy. These findings show that immunotherapies that activate T cells are effective in patients with chronic HCV infection. ClinicalTrials.gov number, NCT01055821.

A heterologous prime/boost vaccination strategy enhances the immunogenicity of therapeutic vaccines for hepatitis C virus.

BACKGROUND: We explored the concept of heterologous prime/boost vaccination using 2 therapeutic vaccines currently in clinical development aimed at treating chronically infected hepatitis C virus (HCV) patients: prime with a DNA-based vaccine expressing HCV genotype 1a NS3/4A proteins (ChronVac-C) and boost with a modified vaccinia virus Ankara vaccine expressing genotype 1b NS3/4/5B proteins (MVATG16643). METHODS: Two ChronVac-C immunizations 4 weeks apart were delivered intramuscularly in combination with in vivo electroporation and subsequently 5 or 12 weeks later boosted by 3 weekly subcutaneous injections of MVATG16643. Two mouse strains were used, and we evaluated quality, magnitude, and functionality of the T cells induced. RESULTS: DNA prime/MVA boost regimen induced significantly higher levels of interferon γ (IFN-γ) or interleukin 2 (IL-2) ELISpot responses compared with each vaccine alone, independent of the time of analysis and the time interval between vaccinations. Both CD8⁺ and CD4⁺ T-cell responses as well as the spectrum of epitopes recognized was improved. A significant increase in polyfunctional IFN-γ/tumor necrosis factor α (TNF-α)/CD107a⁺ CD8⁺ T cells was detected following ChronVac-C/MVATG16643 vaccination (from 3% to 25%), and prime/boost was the only regimen that activated quadrifunctional T cells (IFN-γ/TNF-α/CD107a/IL-2). In vivo functional protective capacity of DNA prime/MVA boost was demonstrated in a Listeria-NS3-1a challenge model. CONCLUSIONS: We provide a proof-of-concept that immunogenicity of 2 HCV therapeutic vaccines can be improved using their combination, which merits further clinical development.

Therapeutic vaccination to treat chronic infectious diseases: current clinical developments using MVA-based vaccines.

A famous milestone in the vaccine field has been the first successful vaccination against smallpox, in 1798, by Edward Jenner. Using the vaccinia cowpox virus, Jenner was able to protect vaccinees from variola or smallpox. The Modified Virus Ankara (MVA) poxvirus strain has been one of the vaccines subsequently developed to prevent smallpox infection and was selected by the US government in their Biodefense strategy. Progress in molecular biology and immunology associated with MVA infection has led to the development of MVA as vaccine platform, both in the field of preventive and therapeutic vaccines. This later class of therapeutics has witnessed growing interest that has translated into an increasing number of vaccine candidates reaching the clinics. Among those, MVA-based therapeutic vaccines have addressed four major chronic infections including viral hepatitis, AIDS, human papillomavirus-linked pathologies and tuberculosis. Clinical trials encompass phase 1 and 2 and have started to show significant results and promises.

A poxvirus vaccine is safe, induces T-cell responses, and decreases viral load in patients with chronic hepatitis C.

BACKGROUND & AIMS: Therapy for chronic hepatitis C (CHC) has limited efficacy, adverse effects, and high costs. Cohort and vaccine-based preclinical studies have indicated the importance of T-cell-based immunity in controlling viral infection. TG4040 is a recombinant poxvirus vaccine that expresses the hepatitis C virus (HCV) proteins NS3, NS4, and NS5B. We performed a phase I clinical trial to assess the safety, immunogenicity, and early antiviral efficacy of TG4040 in patients with CHC. METHODS: In an open-label, dose-escalating study, patients with mild CHC (genotype 1) were assigned to 3 groups of 3 patients each; they received subcutaneous injections of 106, 107, or 108 plaque-forming units of TG4040 on study days 1, 8, and 15. Six additional patients were given the highest dose of vaccine (108 plaque-forming units). Patients were followed for 6 months after the last injection. T-cell-based and antibody responses and levels of HCV RNA were measured. RESULTS: All 3 doses of TG4040 were well tolerated, without serious adverse events. Vaccine-induced HCV-specific cellular immune responses were observed in 5 of the 15 patients (33%). A transient decrease in circulating levels of HCV RNA, from -0.52 log10 to -1.24 log10, was observed in 8 patients; in 5 patients, the lowest level of HCV RNA was observed on day 37, after the first injection. The most pronounced decrease in viral load occurred in 2 patients, who also had marked vaccine-induced T-cell responses. CONCLUSIONS: In patients with CHC, the viral-vector-based vaccine TG4040 had a good safety profile, induced HCV-specific cellular immune responses, and reduced viral load. This vaccine should be investigated in further clinical studies, in combination with standard of care.

Single lysophosphatidylcholine components exhibit adjuvant activities in vitro and in vivo.

Improving vaccine immunogenicity by developing new adjuvant formulations has long been a goal of vaccinologists. It has previously been shown that a natural mix of lysophosphatidylcholine (LPC) from chicken eggs promotes mature dendritic cell (DC) generation in vitro and primes antigen-specific immune responses in mice. In the present study, we dissected the adjuvant potentials of five individual LPC components found in the chicken egg mixture. In vitro analyses of the impact of the individual components on the maturation of human DCs were performed by means of phenotypic analysis, chemokine secretion analysis, and analysis of the ability of mature DC to stimulate T lymphocytes. Two components, C16:0-LPC and C18:0-LPC, were identified to be capable of the upregulation of expression of CD86, HLA-DR, and CD40 on in vitro-cultured monocyte-derived DCs from healthy donors. Both induced the release of chemokines to high concentrations (macrophage inflammatory protein 1, monocyte chemoattractant protein 1) or moderate concentrations (interleukin-8 [IL-8], gamma interferon-inducible protein 10). In addition, C16:0-LPC engaged naïve T cells to produce gamma interferon. This suggests that C16:0-LPC and C18:0-LPC have the capacity to promote, at least in vitro, a Th1-oriented response. The intravenous injection of C16:0-LPC or C18:0-LPC into mice resulted in the detectable secretion of IL-6 and IL-5 in sera. Both LPC components were tested for their capacities to act as adjuvants for two selected immunogens: the hepatitis B virus surface antigen and the hepatitis C virus NS3 helicase. The secretion of specific IgG1 was observed with either or both C16:0-LPC and C18:0-LPC, depending on the immunogen tested, and was observed at an efficiency comparable to that of alum. These data identify C16:0-LPC and C18:0-LPC as the active components of the LPC natural mixture. Although discrepancies between the results of the in vitro and in vivo analyses existed, studies with animals suggest that these components can trigger significant and specific humoral-mediated immunity.