THERAPEUTIC VACCINATION USING NAKED DNA

A FIRST CLINICAL TRIAL OF THERAPEUTIC VACCINATION USING NAKED DNA DELIVERED BY IN VIVO ELECTROPORATION SHOWS ANTIVIRAL EFFECTS IN PATIENTS WITH CHRONIC HEPATITIS C

EASL 2009 April 23-26, 2009 Copenhagen, Denmark

M. Matti Sallberg1, L. Frelin1, H. Diepolder2, M.-C. Jung3, I. Mathiesen4, M. Fons5, R. Hultcrantz6, T. Carlsson6, O. Weiland6

1Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden, 2Medicine, Ludvig-Maximilian University, 3ImmuSystems GmbH, Munich, Germany, 4Inovio Biomedical, Oslo, Norway, 5Inovio Biomedical, San Diego, CA, USA, 6Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden

Background: Clearance of HCV infection correlates with activation of the host T cell response. We developed a T cell vaccine based on a codon-optimized HCV non-structural (NS) 3/4A DNA-gene expressed under the control of the cytomegalovirus immediate-early promoter (ChronVac-C®, Tripep AB, Sweden) delivered by in vivo electroporation (EP). A first phase I/IIa clinical trial in HCV infected patients is currently ongoing.

Methods: A volume of 0,5 mL saline containing ChronVac-C® DNA was injected at 1 cm depth in the deltoid muscle. This was followed by two 60ms electrical pulses adminstered using a 1,5 cm four-electrode array (Medpulser DDS; Inovio, CA, US). Study aims were safety, immunogenicity, and effects on the viral load. Twelve treatment naive patients infected with HCV genotype 1 and a viral load < 800,000 IU/mL were divided in four groups of 167 µg, 500 µg, and 1,500 µg given as four monthly doses of DNA.

Results: In the 167µg group no severe side effects appeared, two mounted transient T cell responses, and none had a reduced viral load. In the 500µg dose no severe side effects appeared, and two developed better sustained HCV-specific T cell responses. Simultaneous with these responses both had reductions in the viral load of up to 0,89log10 and 1,5 log10, respectively. In the third patient no immune response developed and no clear reductions in the viral load were seen. In the 1,500µg dose no severe side effects appeared, and one developed HCV-specific T cell response. Two patients had reductions in the viral load of up to 1,2 log10 and 2,4 log10, respectively. Thus, four out of six (67%) patients in the two highest dose groups had reductions in the viral load exceeding 0,5log10 lasting for two to >10 weeks. Of these, three had activations of the HCV-specific T cell responses at the time of the reductions in the viral load.

Conclusions: These data provides the first proof-of-concept for DNA-based therapeutic vaccination against chronic hepatitis C in humans using in vivo electroporation and encourage further clinical development. The data also provides further evidence for the antiviral role of the HCV-specific T cell response.

EASL 2009: Vaccination Against Chronic HCV Promises Sweeping Changes to HCV Management

Becky McCall

From Medscape Medical News

April 24, 2009 (Copenhagen, Denmark) — In vivo electroporation used in conjunction with naked DNA to deliver a T-cell vaccine has been shown to be effective as a therapeutic vaccination for hepatitis C virus (HCV) in a clinical trial for the first time. The finding was reported here at the European Association for the Study of the Liver 44th Annual Meeting.

The trial was conducted by Matti Sällberg, DDS, PhD, and colleagues from the Karolinska Institute in Stockholm, Sweden. He explained that in 50% to 80% of HCV cases, the immune system fails to eliminate the virus and the disease becomes chronic. The problem is significant: 3% of the world's population is infected with HCV, and in industrialized countries, HCV accounts for 70% of chronic hepatitis cases.

"There remains a tremendous need for new therapies in HCV. Considerable advances in therapies have been made in recent years but many treatments cause unpleasant side effects, such as depression, hyperthyroidism, and joint pain. Furthermore, these effects can be prolonged due to the need for long-term treatment in HCV," Dr. Sällberg told Medscape Gastroenterology.

Dr. Sällberg's study is the first phase 1/2a clinical trial in HCV-infected patients. The use of electroporation in combination with naked DNA has previously been used in cancer, but not infectious diseases. "With this method of vaccination, we inject part of the viral DNA into the cell, which then uses its own cell machinery to produce the vaccine. The cell effectively becomes the factory. Electrical stimulation via electroporation of the muscle cells enables [the uptake of] DNA across the cell membrane and encourages migration of antigen-presenting immune cells to the site stimulating the required immune reaction," Dr. Sällberg explained.

A volume of 0.5 mL saline containing ChronVac DNA was injected at a depth of 1 cm into the deltoid muscle. This T-cell vaccine was based on a codon-optimized HCV nonstructural 3/4A DNA gene expressed under the control of the cytomegalovirus immediate-early promoter. This was followed by two 60 ms electrical pulses administered using a 1.5 cm 4-electrode array (MedPulser DDS; Inovio, California).

Dr. Sällberg explained that it was important to deliver the DNA and to stimulate a T-cell reaction outside of the liver. "The liver is very tolerogenic and shuts down, so ideally, it is not suited to production of an immune reaction. So the immune system is educated outside the liver and these cells then migrate back into the liver to attack HCV."

Twelve treatment-naïve patients infected with HCV genotype 1 who had a viral load of less than 800,000 IU/mL were divided into 3 groups — 167 μg, 500 μg, and 1500 μg — given as 4 monthly doses of DNA. In the 167-μg-dose group, 2 patients mounted transient T-cell responses, and none had a reduced viral load. In the 500-μg-dose group, 2 patients developed better sustained HCV-specific T-cell responses and simultaneously experienced a reduction in viral load of up to 0.89 log10 and 1.5 log10, respectively. In the third patient in this group, no immune response developed and no clear reduction in viral load was seen. In the 1500-μg-dose group, 1 patient developed an HCV T-cell-specific response and 2 patients showed a reduction in viral load of up to 1.2 log10 and 2.4 log10. No severe adverse effects were seen in any of the groups.

"So all in all, 67% of patients (4 out of 6 patients) in the 2 highest-dose groups showed reductions in viral load exceeding 0.5 log10. These effects lasted between 2 and more than 10 weeks. The vaccine probably kills infected cells through activation of cytotoxic T lymphocytes, either by killing or by producing cytokines, which shut off viral replication," said Dr. Sällberg.

Commenting on the study, Heiner Wedermeyer, MD, from the German Liver Foundation in Hanover, said that these results showed a very important proof of concept, with the vaccine demonstrating significant antiviral effect. "In the long term, it might be a very effective strategy to use this vaccine on top of new antiviral drugs to induce immunity in the host and prevent relapse so we can stop using antiviral drugs. It is my vision that in a few years' time, we will use 2 or 3 antivirals, combine these with a vaccine, and that's it," he explained.

The study was funded by Tripep AB, Inovio Biomedical, and the Stockholm County Council. Dr. Sällberg is a cofounder and board member of Tripep AB. Dr. Wedermeyer has disclosed no relevant financial relationships.

European Association for the Study of the Liver 44th Annual Meeting: Abstract 43. Presented April 23, 2009.

First Evidence For DNA-based Vaccination Against Chronic Hepatitis C
ScienceDaily (Apr. 24, 2009) — The first-proof-of-concept for a DNA-based therapeutic vaccination against chronic hepatitis C was announced April 23 at EASL 2009, the Annual Meeting of the European Association for the Study of the Liver in Copenhagen, Denmark.

In the first clinical trial of a therapeutic vaccination using naked DNA delivered by in vivo electroporation (EP), antiviral effects were shown in patients with hepatitis C (HCV). Researchers hope that this will encourage further clinical development. The data also provide further evidence for the antiviral role of the HCV-specific T cell response.

It is estimated that some 3% of the world's population is infected with HCV. In industrialised countries, hepatitis C accounts for 70% of chronic hepatitis cases. One of the main concerns is that HCV infection remains asymptomatic until advanced stages of the disease.

Clearance of HCV infection correlates with activation of the host T cell response. Therefore, in this study, researchers developed a T cell vaccine based on a codon-optimised HCV non-structural (NS) 3/4A DNA-gene expressed under the control of the cytomegalovirus immediate-early promoter (ChronVac-C®) delivered by in vivo electroporation (EP). A first phase I/IIa clinical trial in HCV infected patients is currently ongoing.

Professor Matti Sallberg of Laboratory Medicine, the Karolinska Institutet, Stockholm, Sweden, who led the study, said: "In 50-80% of adult cases, the immune system fails to eliminate the HCV virus and the disease becomes chronic. Given that only about 50% of HCV infected persons are diagnosed in most developed countries and that two-thirds need to undergo antiviral treatment, this new vaccination has huge implications in terms of the future management of this widespread disease."

In this study, a volume of 0.5 ml saline containing ChronVac-C® DNA was injected at 1 cm depth in the deltoid muscle. This was followed by two 60ms electrical pulses administered using a 1.5 cm four-electrode array (Medpulser DDS; Inovio, CA, US). The study aims were safety, immunogenicity, and effects on the viral load. Twelve treatment naive patients infected with HCV genotype 1 and a viral load <800,000 IU/ml were divided in four groups of 167 µg, 500 µg, and 1,500 µg given as four monthly doses of DNA.

In the 167µg group, no severe side effects were observed, two patients mounted transient T cell responses, and none had a reduced viral load. In the 500µg dose, no severe side effects were observed, and two developed better sustained HCV-specific T cell responses. Simultaneous with these responses, both patients had reductions in the viral load of up to 0.89 log10 and 1.5 log10, respectively. In the third patient, no immune response developed and no clear reductions in the viral load were seen. In the 1,500µg dose, no severe side effects were observed, and one patient developed HCV-specific T cell response. Two patients had reductions in the viral load of up to 1.2 log10 and 2.4 log10, respectively. Thus, 67% (four out of six) of patients in the two highest dose groups had reductions in the viral load exceeding 0.5 log10 lasting for two to >10 weeks. Of these, three had activations of the HCV-specific T cell responses at the time of the reductions in the viral load.