Influenza Vaccine
Influenza remains a leading cause of illness and death around the world, causing an estimated $1 billion in direct
economic costs, as much as $15 billion in lost earnings due to illness, and 40,000 deaths annually in the U.S. alone.
In October of 2007, AlphaVax concluded a phase 1 placebo-controlled, randomized, double-blind trial in
216 healthy adults, which evaluated the safety and humoral and cellular immune responses after one or two
inoculations. The replicon vector expressed the hemagglutinin (HA) gene derived from the A/Wyoming (H3N2)
strain of influenza virus. The vaccine was administered either subcutaneously or intramuscularly at two
dosage levels, and was found to be safe and well tolerated irrespective of the route or the dose given.
Both antibody and T cell responses were efficiently stimulated and persisted for the duration of the
four-month study. Among volunteers with prevaccination influenza antibody titers (measured by
hemagglutination inhibition, or "HI") that were below levels thought to be protective, 77% and 80% of
these individuals receiving a single low or high dose, respectively, responded with protective HI antibody
titers. A second immunization in these individuals increased seroprotective responses to 86% for both dosage
levels. A rapid and dose-dependent T cell response (defined in antigen-specific IFN-gamma ELISPOT assays)
was also observed and remained significantly elevated for at least four months. A second immunization
extended the duration, but not the magnitude of these T cell responses. Comparable T cell responses are
typically not seen in adult populations with existing licensed influenza vaccines. HI antibody responses
are known to correlate with protection against influenza infection and reduction of clinical disease, and
influenza specific T cell responses are believed to function in eventual clearance of the virus from infected
individuals.
Based on the promising results in the initial influenza trial, AlphaVax has initiated a Phase I/II study
in a group of healthy, ambulatory elderly subjects (≥ 65 years old). Un-blinded results from that study
are expected in the second half of 2009.