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Biosecurity BriefingInfluenza Vaccine Trials Report Positive Results; Diagnostic Test Approved by FDA By Kunal Rambhia, January 11, 2008 On January 4, 2008, BBC News reported that Acambis has reported positive results from phase I clinical trials of its new influenza vaccine, ACAM-FLU-A™. Unlike currently licensed influenza vaccines which target influenza’s two mutable surface proteins, hemagglutinin (HA) and neuraminidase (N), ACAM-FLU-A™ is designed to protect against all strains of influenza A by targeting another surface protein M2e, which does not mutate rapidly and is conserved among all influenza A strains.1 A company press release noted that scientists hope that a “universal” influenza vaccine based on the M2e protein could “overcome the need for annual vaccine reformulations” and may “be a potential vaccine against pandemics.”2 According to the press release, the randomized, double-blind, placebo-controlled phase 1 trial of ACAM-FLU-A™ involved 79 subjects from several centers in the United States. The study tested the safety and immune response associated with four versions of the vaccine: ACAM-FLU-A™ alone, ACAM-FLU-A™ plus an aluminium hydroxide adjuvant, ACAM-FLU-A™ plus an investigational adjuvant (QS-21 Stimulon, developed by Antigenics Inc.), and placebo. For each of the four vaccine versions tested, participants received two doses of vaccine. According to the press release, the study found that “ACAM-FLU-A(TM) is well tolerated” and while positive “immune responses were seen in all vaccinated groups, the highest immune responses occurred in the group vaccinated with ACAM-FLU-A(TM) plus QS-21.”2 The company reports that 90% of patients that received ACAM-FLU-A™ plus QS-21 exhibited a positive immune response. The Center for Infectious Disease Research and Policy (CIDRAP) reported that Acambis also tested the ability of the ACAM-FLU-A™ vaccine to protect ferrets against H5N1. Michael Watson, executive vice president of research and development at Acambis, stated, “these are exciting data as they show that our ACAM-FLU-A™ can generate a robust M2e antibody response and that M2e vaccines can protect against H5N1 avian influenza.”3 In the animal trials, 70% of vaccinated animals were protected from lethal challenge. In related news, Medical News Today reported that researchers at the University of Groningen in the Netherlands have devised a method for freeze-drying influenza vaccine in a powder form. According to the article, the vaccine is “extremely quickly frozen between millions of sugar molecules…[which] bunch together like miniscule balls around the vaccine, so that it can be stored stably in a dried form.”4 The researchers hope that this process will be able to increase the shelf life of a flu vaccine up to at least a year and may make the vaccine effective by oral or inhalational delivery. Investigator Jean-Pierre Amorij noted that, in mice, inhalational delivery produced an immune response that “was even more powerful than with an injection.”4 The freeze dried vaccine has not yet been tested in humans. In other flu-related news, the Food and Drug Administration (FDA) announced that “a test that simultaneously detects and identifies 12 specific respiratory viruses” has been cleared for marketing.5 The test, called the xTAG Respiratory Virus Panel (RVP), tests secretions from the back of the throat. It combines tiny beads coated with virus-specific reagents with a rapid polymerase chain reaction (PCR) amplification to test for the presence of up to 12 different viruses. xTAG is able to rapidly differentiate between subtypes H1 and H3 of the influenza A virus and represents the first test for human metapneumovirus (hMPV). It also tests for influenza B; respiratory syncytial viruses A and B; parainfluenza 1, 2, and 3; rhinovirus; and adenovirus. According to the FDA, the test is manufactured by Luminex Molecular Diagnostics and is “faster than conventional tests” for these 12 viruses.5 References
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