A vaccine for hypertension based on virus-like particles: preclinical efficacy and phase I safety and immunogenicity

Efficient induction of mucosal and systemic immune responses by virus-like particles administered intranasally: implications for vaccine design

Intranasal (i.n.) immunization aims to induce local as well as systemic immune responses. In the present study, we assessed a vaccine platform based on virus-like particles (VLP) derived from the RNA phage Qbeta for i.n. immunization. We found that both i.n. and subcutaneous (s.c.) administration of Qbeta-VLP elicited strong and comparable specific IgG responses in serum and lung. Surprisingly, both routes also induced high levels of specific IgA in serum. In contrast, only i.n. administration of Qbeta-VLP resulted in local IgA production in the lung. Efficient induction of B cell responses by i.n. administration of VLP was further supported by the presence of large numbers of germinal centers (GC) as well as memory B cells in the spleen and plasma cells in the bone marrow. Results obtained for the VLP itself could be extended to an antigen covalently attached to it. Specifically, i.n. immunization of mice with VLP displaying the influenza virus derived ectodomain of the M2 protein resulted in strong M2-specific antibody responses as well as anti-viral protection. In contrast, i.n. immunization with VLP displaying p33 peptide, the major CTL epitope of lymphocytic choriomeningitis virus, induced relatively inefficient cytotoxic T cell responses, resulting in low numbers of specific T cells and poor effector cell differentiation. Taken together, these results suggest that effective antibody-based vaccines are achievable by i.n. administration of Qbeta-VLP displaying specific antigens.

Effect of immunisation against angiotensin II with CYT006-AngQb on ambulatory blood pressure: a double-blind, randomised, placebo-controlled phase IIa study

BACKGROUND

Hypertension can be controlled adequately with existing drugs such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. Nevertheless, treatment success is often restricted by patients not adhering to treatment. Immunisation against angiotensin II could solve this problem. We investigated the safety and efficacy of CYT006-AngQb-a vaccine based on a virus-like particle-that targets angiotensin II to reduce ambulatory blood pressure.

METHODS

In this multicentre, double-blind, randomised, placebo-controlled phase IIa trial, 72 patients with mild-to-moderate hypertension were randomly assigned with a computer-generated randomisation list to receive subcutaneous injections of either 100 mug CYT006-AngQb (n=24), 300 mug CYT006-AngQb (24), or placebo (24), at weeks 0, 4, and 12. 24-h ambulatory blood pressure was measured before treatment and at week 14. The primary outcomes were safety and tolerability. Analyses were done by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00500786.

FINDINGS

Two patients in the 100 mug group, three in the 300 mug group, and none in the placebo group discontinued study treatment. All patients were included in safety analyses; efficacy analyses did not include the five dropouts, for whom no data were available at week 14. Five serious adverse events were reported (two in the 100 mug group, two in the 300 mug group, and one in the placebo group); none were deemed to be treatment related. Most side-effects were mild, transient reactions at the injection site. Mild, transient influenza-like symptoms were seen in three patients in the 100 mug group, seven in the 300 mug group, and none in the placebo group. In the 300 mug group, there was a reduction from baseline in mean ambulatory daytime blood pressure at week 14 by -9.0/-4.0 mm Hg compared with placebo (p=0.015 for systolic and 0.064 for diastolic). The 300 mug dose reduced the early morning blood-pressure surge compared with placebo (change at 0800 h -25/-13 mm Hg; p<0.0001 for systolic, p=0.0035 for diastolic).

INTERPRETATION

Immunisation with CYT006-AngQb was associated with no serious adverse events; most observed adverse events were consistent with local or systemic responses similar to those seen with other vaccines. The 300 mug dose reduced blood pressure in patients with mild-to-moderate hypertension during the daytime, especially in the early morning.

FUNDING

Cytos Biotechnology AG.

Pattern recognition by B cells: the role of antigen repetitiveness versus Toll-like receptors

Viruses induce excellent antibody responses due to several intrinsic features. Their repetitive, organised structure is optimal for the activation of the B cell receptor (BCR), leading to an increased humoral response and a decreased dependence on T cell help. Viruses also trigger Toll-like receptors (TLRs), which in addition to increasing overall Ig levels, drive the switch to the IgG2a isotype. This isotype is more efficient in viral and bacterial clearance and will activate complement, which in turn lowers the threshold of BCR activation. Exploiting these characteristics in vaccine design may help us to create vaccines which are as safe as a recombinant vaccine yet still as effective as a virus in inducing B cell responses.

Vaccination against nicotine: an emerging therapy for tobacco dependence

Tobacco dependence is an addiction characterised by compulsive drug-seeking and drug-taking behavior and intensive craving in the absence of tobacco. Nicotine is the major addictive component of tobacco and acts on the reward system in the brain. Together with strong conditional reinforcements, unaided smoking cessation attempts are notoriously unsuccessful and even the most recently introduced pharmacotherapy, varenicline, only achieves a 23% continuous abstinence rate after 1 year. Vaccination against nicotine represents a promising novel concept for treating nicotine addiction. Antibodies against nicotine inhibit the passage of nicotine to brain and thus inhibit its addiction-reinforcing activities. There are three nicotine vaccines that are in clinical development. The first proof-of-concept study in smoking cessation with the vaccine NicQb (Cytos Biotechnology), a nicotine vaccine based on virus-like particles, demonstrated that continuous abstinence rates can be significantly increased by vaccination; however, as expected from the mode of action, a sufficient antibody level had to be achieved. Antibody level dependence of abstinence was also observed with the nicotine vaccine NicVAX (Nabi Biopharmaceuticals). Vaccination against nicotine has the potential of becoming an important therapy against tobacco dependence.

Virus-like particles: flexible platforms for vaccine development

Virus-like particles (VLPs) consist of viral structural proteins that, when overexpressed, spontaneously self-assemble into particles that are antigenically indistinguishable from infectious virus or subviral particles. VLPs can be considered as dense, repetitive arrays of one or more protein subunits with properties that are highly advantageous for use as stand-alone vaccines or as vaccine platforms. This review discusses the development of VLP-based platform technologies for vaccines against pathogens, as well as nontraditional targets such as self-antigens involved in chronic diseases.

Vaccination, immune and gene therapy based on virus-like particles against viral infections and cancer

Virus-like particles (VLPs) are self-assembling, non-replicating particles lacking the viral genome that are formed by one or several viral structural proteins. VLPs can be purified after expression in yeast cells, insect cells using baculoviruses, Escherichia coli or mammalian cells. Recently, vaccines based on VLPs have come into focus with the FDA approval of a VLP-based vaccine against human papilloma viruses. However, this application of VLPs is just one of many developments within the VLP field. Other potential applications under development besides vaccines against viruses or cancers also include gene delivery and treatment of different disorders.

A Virus-Like Particle-Based Vaccine Selectively Targeting Soluble TNF-α Protects from Arthritis without Inducing Reactivation of Latent Tuberculosis

Neutralization of the proinflammatory cytokine TNF-alpha by mAbs or soluble receptors represents an effective treatment for chronic inflammatory disorders such as rheumatoid arthritis, psoriasis, or Crohn's disease. In this study, we describe a novel active immunization approach against TNF-alpha, which results in the induction of high titers of therapeutically active autoantibodies. Immunization of mice with virus-like particles of the bacteriophage Qbeta covalently linked to either the entire soluble TNF-alpha protein (Qbeta-C-TNF(1-156)) or a 20-aa peptide derived from its N terminus (Qbeta-C-TNF(4-23)) yielded specific Abs, which protected from clinical signs of inflammation in a murine model of rheumatoid arthritis. Whereas mice immunized with Qbeta-C-TNF(1-156) showed increased susceptibility to Listeria monocytogenes infection and enhanced reactivation of latent Mycobacterium tuberculosis, mice immunized with Qbeta-C-TNF(4-23) were not immunocompromised with respect to infection with these pathogens. This difference was attributed to recognition of both transmembrane and soluble TNF-alpha by Abs elicited by Qbeta-C-TNF(1-156), and a selective recognition of only soluble TNF-alpha by Abs raised by Qbeta-C-TNF(4-23). Thus, by specifically targeting soluble TNF-alpha, Qbeta-C-TNF(4-23) immunization has the potential to become an effective and safe therapy against inflammatory disorders, which might overcome the risk of opportunistic infections associated with the currently available TNF-alpha antagonists.