Positive Phase I and Pre-Clinical Data Suggest Acambis' M2e-Based Universal Influenza Vaccine, ACAM-FLU-A(TM), Could Tackle Influenza Pandemics
Thursday January 3, 4:11 am ET
CAMBRIDGE, England and CAMBRIDGE, Mass.--(BUSINESS WIRE)--Acambis plc (Acambis) (LSE:ACM - News), a leading vaccine development company, today announced positive data from two trials of its universal influenza vaccine ACAM-FLU-A™. The novel vaccine targets the M2e peptide, which is found unchanged on the surface of all ‘A’ strains of the influenza virus, including all pandemic influenza strains. As such, this vaccine could overcome the current need to adapt influenza vaccines every year to correspond to circulating strains. The Phase 1 clinical trial showed the vaccine to be well tolerated and immunogenic and the pre-clinical challenge study suggests that this M2e-based vaccine can protect against highly pathogenic viruses such as pandemic influenza strains, including H5N1.
Currently, influenza vaccines are regularly reformulated owing to the rapid mutation of the virus. ACAM-FLU-A™ combines the conserved M2e peptide with a carrier molecule from Hepatitis B, which is used to help stimulate the immune system. This novel vaccine design means that ACAM-FLU-A™ could potentially provide protection against ‘A’ strains of influenza. Historically, influenza pandemics have only been caused by ‘A’ strains of the virus. Therefore ACAM-FLU-A™ has potential both as a vaccine against pandemic influenza and as part of seasonal influenza vaccination.
The Phase 1 trial was a double-blind, placebo-controlled study conducted at three centres in the USA. The study consisted of four arms: placebo, ACAM-FLU-A™ alone or combined with aluminium hydroxide or QS-21. Healthy volunteers aged between 18 and 40 were given two doses 30 days apart, their immune response against the M2 protein was tested after 60 days and any adverse events to the vaccine were recorded.
The vaccine was shown to be immunogenic and well-tolerated, with no serious adverse events. Whilst immune responses were seen in all the vaccinated groups, blood tests showed that the highest immune responses occurred in the group who received ACAM-FLU-A™ with QS-21. In this group, 90% of people who received ACAM-FLU-A™ plus QS-21 had antibodies to the M2 protein in their system. QS-21 Stimulon® adjuvant is an investigational adjuvant (immune stimulant) provided under an agreement with Antigenics Inc., which has recently been converted to a non-exclusive license and supply agreement.
The pre-clinical study tested the ability of an M2e-based vaccine to protect against the Vietnam 2004 strain(1) of H5N1 avian influenza (bird flu). The H5N1 virus was lethal in the placebo-treated group, whereas 70% of those in the group vaccinated with the M2e-based vaccine from the same influenza strain were protected.
Dr Michael Watson, Executive Vice President, Research & Development at Acambis commented: “Taken together, the data from these two trials demonstrate the potential of Acambis’ approach to offer protection against ‘A’ strains of the influenza virus, including pandemic influenza strains. As a universal vaccine, ACAM-FLU-A™ can potentially overcome many of the drawbacks of existing influenza vaccines. It can be manufactured at any time of the year, and could be stockpiled in advance of a pandemic or potentially used routinely to ensure population protection against future pandemics.”
Following these results, Acambis will explore partnering in parallel with continued development of ACAM-FLU-A™.
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About ACAM-FLU-A™
ACAM-FLU-A™ is a recombinant vaccine that uses a hepatitis B core protein (HBc) to present M2e, the extracellular domain of the ion channel protein M2(5). M2 is one of the three proteins expressed on the surface of the ‘A’ strain influenza virus and of infected cells alongside haemagglutinin (HA) and neuraminidase (NA). Unlike HA and NA, M2 is highly conserved, albeit under natural conditions not easily recognised by the immune system. M2e could elicit an immune response to all influenza ‘A’ strains. As such, ACAM-FLU-A™ has the potential to be both a universal pandemic or pre-pandemic influenza vaccine and part of a universal seasonal vaccine. Historically, influenza pandemics have been caused by ‘A’ strains of the virus while seasonal vaccines target both ‘A’ and ‘B’ strains of the virus.
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