Novavax jumps on positive flu vaccine results, while Acadia sinks on poor trials

Two weeks ago, Novavax (NVAX) shares soared some 10 percent after the small clinical-stage biotechnology company announced positive preclinical results for its new vaccine against H1N1 influenza. Shares jumped again today -- this time about 15 percent by late-afternoon trading -- after the vaccine maker announced positive results for its seasonal flu vaccine candidate in a mid-stage, or Phase II, trial. Shares reached a three-year high.

While media attention has quieted regarding H1N1, or swine flu, officials expect the outbreak, declared a pandemic by the WHO, to intensify during the Northern Hemisphere's winter. The outbreak has pressured the vaccine supply for seasonal influenza, which kills between 250,000 and 500,000 people a year.

Novavax says its seasonal flu vaccine, which uses proprietary viruslike particle technology, was well tolerated and induced robust immune responses against three influenza strains, H3N2, H1N1, and B. No serious vaccine-related adverse effects were reported in the study, and in some cases, recipients developed higher antibodies than those using Fluzone, the Sanofi Aventis (SNY) seasonal flu vaccine.

The Novavax viruslike particle technology, as the name suggests, develops a vaccine without the genetic material that the virus needs to reproduce. These particles are injected as non-infectious decoys. They attach to immune cells, which mistake the particles for viruses and spark a strong immune response, according to the company.

Unlike a standard influenza vaccine that uses weakened or dead flu viruses to stimulate the immune system, the Novavax decoy cannot replicate or infect cells. And producing the vaccine does not require growing the influenza virus in chicken eggs, as is the industry standard, or developing virus seed stocks, which can take months. This makes Novavax's development process relatively fast: the company says it could advance the vaccine into last-stage trials next year.

Rival Acadia Pharmaceuticals (ACAD) shares tanked by more than 60 percent after it said the Phase III trial of its drug pimavanserin, for patients with Parkinson's-related psychosis, did not meet its primary endpoint of antipsychotic efficacy. (An estimated 40 percent of the 1.5 million Americans with Parkinson's disease may develop psychotic symptoms, commonly consisting of visual hallucinations and delusions, according to Acadia. Parkinson's is a progressive neurological condition that causes tremors and other motor skills problems.)

Unfortunately for Parkinson's sufferers, as well as for investors, pimavanserin failed to significantly cut psychotic episodes compared with a placebo, despite early clinical successes. Pimavanserin met the key secondary endpoint of motoric tolerability.

Investing in small research pharmaceutical and biotech companies has always been risky. While Novavax is up today on earlier trials, there's no guarantee of the success of a later-stage trial, as Acadia demonstrated. Shares of larger Biovail (BVF), which is codeveloping pimavanserin with Acadia, are down about 2.5 percent by comparison.

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