VaxInnate Corporation presented preliminary Phase II data showing that its VAX125 seasonal flu vaccine was safe and highly immunogenic in elderly subjects at the National Foundation for Infectious Diseases' (NFID) Thirteenth Annual Conference on Vaccine Research here today. VaxInnate is a biotechnology firm pioneering breakthrough technology for developing novel vaccines.

The study data also suggest that VAX125, VaxInnate's investigational hemagglutinin (HA)-flagellin flu vaccine, may be capable of providing -- at much lower doses -- flu protection that surpasses that of a licensed high-dose flu vaccine indicated for adults 65 years of age and above.

Based on the study results, VaxInnate plans further development and clinical evaluation of the vaccine. VAX125 is the H1 component of what would ultimately be a trivalent seasonal flu vaccine.

VAX125 is the product of VaxInnate's proprietary combination of toll-like receptor-mediated (TLR) immune enhancement and recombinant bacterial production of vaccine antigen. In addition to improving vaccine potency, this technology confers significant speed and volume advantages, making it possible to produce hundreds of millions of vaccine doses in weeks instead of months.

"This study of VAX125 has shown that we should be able to provide a much-needed new option for protecting the elderly against seasonal flu," said Thomas Hofstaetter, PhD, President and CEO of VaxInnate. "With the first baby-boomers turning 65 in 2011 and the number of adults over age 65 anticipated to exceed 70 million people -- one in five Americans -- by 2030, the need is escalating for a flu vaccine that is truly effective in this key population."

VAX125 Safety & Immunogenicity Data

The Phase II study was designed to assess the safety and immunogenicity -- a patient's ability to make an immune response -- of six doses of VAX125 and to select the optimal dose for a trivalent vaccine for use by people aged 65 years of age and above.

VAX125 links the H1 hemagglutinin (HA) antigen, a key protective component used in flu vaccines for many years, to flagellin. Flagellin is a bacterial protein that interacts with the immune system's toll-like receptors (TLRs) to enhance VAX125's immunological potency.

The study was an open-label, escalating, dose-ranging Phase II study that assessed the safety and immunogenicity of six doses (0.5, 1, 2, 3, 5 and 8ug) of VAX125 in 120 community-living adults aged 65 and above who were enrolled at three clinical centers. The protocol was amended to add the 5ug and 8ug dose groups; results for the 8ug group are not yet available.

Each of the six VAX125 dosage levels was given as an intramuscular dose to 20 subjects, whose mean age was 71 years. Clinical and laboratory assessments took place 1, 7, 14 and 28 days post-vaccination. Immune response to VAX125 was assessed 7, 14 and 28 days after immunization. Seroresponse was defined as a serum anti-HA antibody titer of ≥ 1:40 and a four-fold rise in titer, with a minimum titer of 40. Seroprotection was defined as post-vaccination achievement of a minimum anti-HA titer of 1:40.

The vaccine was well tolerated at all dose levels from 0.5ug to 5ug, with no severe side effects or adverse events. VAX125 exhibited a seroresponse in 3 (15 percent) of the 0.5ug group; 8 (40 percent) of the 1ug group; 7 (35 percent) of the 2.0ug group; 8 (40 percent) of the 3ug group; and 16 (80 percent) of the 5ug group.

Seroprotection was seen in 84 percent (84/100) of the subjects. The breakdown: 65 percent (0.5ug group); 90 percent (1.0ug group); 70 percent (2.0ug group); 95 percent (3.0ug group); and 100 percent (5ug group).

A new high-dose (60ug of HA per serotype) flu vaccine indicated for people aged 65 and above is based upon studies showing that substantially increasing the dose of flu vaccine for the elderly improves the antibody response and the overall immune response. In a recent published study, the high-dose flu vaccine indicated for people aged 65 and above exhibited a seroresponse of 49 percent and seroprotection of 90 percent (n=2543). [Source: Falsey et al. JID 2009; 200:172-80]

As the population ages, the current egg-based method of producing flu vaccine cannot support the manufacture of sufficient standard flu vaccine for the general population as well as a high-dose version for the growing number of elderly.

"VAX125 has passed another critical test in this study of elderly subjects, demonstrating that it is well tolerated and highly immunogenic at doses up to at least 5ug," said Alan Shaw, PhD, Chief Scientific Officer. "Over the past 30 years, the flu vaccine community has struggled to overcome the limitations of the traditional influenza vaccine in people over 65 years of age. VaxInnate's modern vaccine design allows us to break through the barrier of declining immunity in the elderly."

The results of the 8ug arm of the study are expected later this year.

Elderly Vulnerable to Flu

People aged 65 and above suffer disproportionately from seasonal flu and its complications, which can lead to severe disease, hospitalization and death. Although the elderly comprise only 15 percent of the U.S. population, they account for 65 percent of the estimated 225,000 hospitalizations and 90 percent of the estimated 35,000 deaths attributable to flu each year.

Although the Centers for Disease Control and Prevention (CDC) and public health community fund and encourage vaccination of the elderly, multiple studies have shown that the elderly are less responsive to standard flu vaccines than younger people. That's because the body's immune response steadily declines with age.


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