NOVAVAX: A MODEL FLU VACCINE?
Is it a coincidence that every time Dendreon gets positive news, some vaccine developers have good results on their preventive or therapeutic vaccines to announce? Today, it is NOVAVAX (NVAX), which announced that very low doses of its pandemic influenza vaccine provided protection against a lethal challenge of live H5N1 viruses, according to preclinical data presented at the Second International Conference on Avian Influenza in Humans.
Two 0.6 microgram doses of Novavax’s virus-like particle (VLP) H5N1 vaccine — without the addition of an adjuvant — protected ferrets from challenges with live H5N1 bird flu viruses. This dose is 25-fold lower than the average human dose for most seasonal flu vaccines and more than 100 times lower than other H5N1 vaccines against avian influenza. Novavax plans to submit an investigational new drug application to the FDA in mid-2007 to commence human clinical trials with the novel H5N1 influenza vaccine.
VLPs mimic the three-dimensional structure of a virus but do not contain genetic material, so they cannot replicate or cause infection. As VLPs maintain functional properties of both influenza surface proteins (hemagglutinin and neuraminidase), they have been shown to activate multiple arms of the immune system to generate a broadly protective immune response.
In the study, ferrets were inoculated with a range of doses of the company’s VLP vaccine made from an Indonesian strain of H5N1 avian influenza. The ferrets were then challenged with live H5N1 virus. Here are some observations:
- All ferrets survived.
- The effective dose of Novavax vaccine was 0.6 micrograms, compared to the typical human dose of a seasonal influenza vaccine, which is 15 micrograms. Other pandemic vaccines with no adjuvant have shown only modest levels of immunogenicity in humans with doses as high as 90 micrograms.
- With the Novavax vaccine, the ferrets were protected against Indonesian strain of avian flu and cross-protected against a separate challenge strain originating in Vietnam.
The International Conference on Avian Influenza in Humans brings together leading bird flu experts at the Pasteur Institute to review and discuss the latest scientific advances in vaccine prevention strategies and treatments designed to stem a pandemic.
The U.S. Centers for Disease Control and Prevention currently is testing antibodies from these animals against a number of additional strains of H5N1 that have been detected in recent years to establish whether the vaccine is even more broadly cross-protective.
Prohost Comments: From the information gathered by the firm’s scientists and from their expressed vision, all we can say is that if and when the VLP vaccine’s dosage and immunogenicity are confirmed in clinical trials, Novavax’ vaccine would represent a model vaccine that could protect against varying strains of the virus that mutate as they travel around the globe. The minute dose that enabled ferrets to survive live H5N1 bird flu viruses makes us believe, asthe firm does, that the vaccine would also be sufficient to protect vulnerable populations. The VLP-based flu vaccine demonstrates that it induces broadly reactive antibodies, eliciting both B cell and T cell responses.
It is early but, nevertheless, very comforting news.