GlaxoSmithKline (GSK)GSK issued an update on its progress to develop a vaccine against the Pandemic (H1N1) 2009 influenza virus, and announced that it has commenced the clinical development programme for its adjuvanted pandemic vaccine. Enrolment into this first study has been completed.

Dr.Thomas Breuer, Head of Global Clinical R&D and Chief Medical Officer of GSK Biologicals, said "GSK is making good progress with the development of its pandemic vaccine. Enrolment into the first study has been completed and in total, GSK will conduct 16 clinical trials of its pandemic vaccine in over 9000 individuals across Europe, Canada and the US. We continue to work closely with regulators and governments to assess and develop this vaccine."

The first clinical trial, being conducted in Germany, will assess the use of the vaccine in healthy adults. Initial data is expected to be available for sharing with regulatory authorities in September.

Further trials of the Pandemic (H1N1) 2009 adjuvanted vaccine covering infants, children, adults and the elderly will commence over the coming weeks across Europe, Canada and the US. The clinical development programme, which has been designed in close partnership with regulatory authorities, will evaluate the immune response as well as tolerability and other safety aspects of the vaccine.

All the final data on the clinical development programme will be submitted to the regulators as soon as they are available and will be posted on GSK's Clinical Study Register.

About the pandemic (H1N1) 2009 vaccine
The vaccine will comprise antigen of the recently isolated Pandemic (H1N1) 2009 influenza strain and also contain GSK's proprietary adjuvant system AS03. In clinical studies using the bird flu influenza strain (H5N1), the adjuvanted formulation has been shown to stimulate a higher immune response while using a smaller amount of antigen as compared to a formulation without adjuvant. The vaccine containing the adjuvant system therefore helps to substantially increase the number of vaccine doses that can be provided for mass vaccination.(1) In addition, in clinical studies with the bird flu programme, the adjuvanted vaccine demonstrated the potential to provide protection even if the influenza strain drifts (changes slightly).(2,3) Both the antigen sparing approach as well as the potential for additional protection against drifting strains are features for an impactful vaccine for use in a pandemic setting.

GSK has received regulatory approvals in the European Union and some Asian countries for its pre-pandemic and pandemic H5N1 vaccines, both of which contain the AS03 adjuvant. Currently, clinical trials in over 39,000 people have demonstrated that the AS03 adjuvant system used with an influenza vaccine has an acceptable safety and reactogenicity profile.

About the clinical trials
The first clinical trial, being conducted in Germany, has started this week and enrolment has been completed. The trial will assess the use of the vaccine given as 2 doses, 21 days apart in 128 healthy adults, aged between 18 and 60. Initial data is expected to be available for submission to regulatory authorities in September. Additional trials planned in the clinical development programme are expected to commence shortly and include 8 trials in healthy adults, 5 trials in children (including infants) and 2 trials in the elderly. Details of the clinical development programme will be posted to

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1. Leroux-Roels et al. Antigen sparing and cross-reactive immunity with an adjuvanted rH5N1 prototype pandemic influenza vaccine: a randomised controlled trial. Lancet 2007; 370 (9587): 580–89.
2. Leroux-Roels I et al, Broad Clade 2 Cross-Reactive Immunity Induced by an Adjuvant systemed Clade 1 rH5N1 Pandemic Influenza Vaccine PLoS ONE 3(2): e 1665. doi:10.1371/jounal.pone.0001665
3. Baras et al. Cross-protection against lethal H5N1 challenge in ferrets with an adjuvanted pandemic influenza vaccine. PLoS ONE 2008; 3 (1): e1401.