A human vaccine against the H5N1 avian influenza virus is in the final stage of a Phase I clinical trial and the results are expected to be available in July 2007.
The vaccine, Panflu™ (Sinovac Biotech, China), is an adjuvanted, inactivated whole virus vaccine. It has shown good antigenicity at a dosage of 10 µg in earlier studies with a seroconversion rate of 78.3%, which is above the assessment criteria for vaccines set by the EU Committee for Proprietary Medicinal Products.
Among 88 volunteers who received the second dose of Panflu in March 2006, 57 have been given the third dose of the vaccine recently. They were divided into four groups that received four different dosages of the vaccine (1.25, 2.5, 5 and 10 µg). No side effects have been reported so far. Antibody test results will be available in July.
Besides Panflu, Sinovac is also developing vaccines against Japanese encephalitis and severe acute respiratory syndrome. Its successful vaccines include Healive™ (hepatitis A), Bilive™ (combined hepatitis A and B) and Anflu™ (influenza).
Source: Sinovac Biotech Ltd, China (www.sinovac.com).
Iomai’s vaccine patch for travelers’ diarrhea shows promise
Challenge study results of a patch-based vaccine against enterotoxigenic Escherichia coli (ETEC), the pathogen that causes travelers’ diarrhea, have appeared online ahead of print publication in Vaccine.
There are no ETEC vaccines available currently in the USA, despite 20–50% of travelers to endemic areas acquiring the disease. Antibiotics remain the prophylactic as well as treatment strategy, which raises concerns over the spread of antibiotic resistance.
The study enrolled 59 adult volunteers who randomly received a vaccine patch containing ETEC’s heat-labile toxin (LT) or a placebo patch. LT is a highly immunogenic protein and anti-LT antibodies are protective against ETEC infections. The patch-based vaccine is a patented technology of Iomai Corp. (MD, USA), which is designed so that the antigen (such as LT) on the patch is delivered transcutaneously to the skin’s antigen-presenting cells (Langerhans cells), triggering immune responses.
After receiving three patches at 3-week intervals, the volunteers were given the same dose of a pathogenic ETEC strain. Most volunteers presented with diarrhea; however, those who received the vaccine had a less severe illness (fewer loose stools), a decreased need for intravenous fluids and a delayed onset of diarrhea compared with those who received placebo.
“These compelling results suggest that Iomai’s patch-based, needle-free ETEC vaccine mitigates the severity of this common bacterial illness, which could help travelers avoid a debilitating illness during a vacation”, said Gregory Glenn, Iomai’s founder and chief scientific officer.
The research team also observed a fourfold increase in antibody production in the volunteers who received the vaccine patch.
“The in-patient challenge study is an extreme test of the travelers’ patch vaccine. We expect that the protective effects will be amplified in the field, where the disease is debilitating but not as severe as we saw in this challenge study”, said Glenn. A Phase III clinical trial of this ETEC vaccine patch will be launched next year.
Sources: Iomai Corp., MD, USA (www.iomai.com).
McKenzie R, Bourgeois AL, Frech SA et al. Transcutaneous immunization with the heat-labile toxin (LT) of enterotoxigenic Escherichia coli (ETEC): protective efficacy in a double-blind, placebo-controlled challenge study. Vaccine DOI: 10.1016/j.vaccine.2007.01.043 (2007).
Vaccine for multiple sclerosis enters Phase II clinical trial
An immune-based investigational vaccine, NeuroVax™ (Immune Response Corp., CA, USA), for the treatment of relapsing–remitting multiple sclerosis (MS), has entered a Phase II clinical trial in Bulgaria and several other central and Eastern European countries.
MS is an autoimmune disease, in which certain cytotoxic T cells attack myelin sheaths that cover nerve fibers, causing disruption in signal transmission. This leads to a range of neurological disorders, such as vision and hearing loss and disorientation.
The levels of functional regulatory T cells (Tregs), which regulate pathogenic T cells, are often low in patients with MS and other autoimmune diseases, such as rheumatoid arthritis, psoriasis and Crohn’s disease. NeuroVax is a T-cell receptor peptide vaccine that restores the functions of Tregs, thus resolving MS and preventing relapses of the disease.
“We are pleased to initiate this important trial”, said Joseph O’Neill of Immune Response Corp. “This study will allow us to examine the potential of NeuroVax to help patients with MS.”
Source: Immune Response Corp., CA, USA (www.imnr.com).