Wyeth vs. GSK: A Vaccine Showdown?

Today Biohorizon will take its first look at two new vaccines that promise to make the prevention of pneumococcal disease far more interesting and complex. Both Wyeth and GSK have advanced emerging pneumococcal conjugate vaccine candidates to the filing stage in either the United States, European Union or both. In an effort to understand and scope out some of the questions and controversies surrounding these biologics we need to review a little bit of history…

Since its approval in the United States in 2000 Wyeth’s Prevnar vaccine against pneumococcal disease has helped to transform what was thought of as a mature, marginally profitable segment of the pharmaceutical business into a much more dynamic and profitable one. Prevnar has proven to be both effective and innovative while filling an unmet need in the prevention of serious pediatric infections caused by the pneumococcal bacteria. According to CNN Money.com, Prevnar sales surged 24% in 2007 to $2.4 billion, making it the first vaccine to exceed $2 billion in annual sales.

Prevnar has been the only conjugate pneumococcal vaccine available to immunization programs and clinicians throughout North America and European Union looking to prevent pneumococcal disease. However, GSK’s new 10-valent conjugate pneumococcal vaccine (Synflorix) could soon start changing this.

There are two significant differences between Synflorix and Prevnar that our readers should be aware of. First, Prevnar contains antigen from seven different serotypes of pneumococcal bacteria while Synflorix contains antigen from ten different types. The second difference is in the carrier protein that these polysaccharide antigens are attached to. In Prevnar the protein is called CRM-197 and it has been critical in the success of Wyeth’s product. The carrier protein is more than a passive molecule, it greatly enhances the immunogenicity of the vaccine and makes it more effective. In Synflorix, the carrier protein (NTHi) not only does this, but because it is derived from non-typable Haemophilus Influenza bacteria, provides protection against infections with this pathogen as well. GSK has filed for Synflorix approval in the EU and the vaccine has recently been approved for sale in Canada but we have no word on when or even if approval will be sought in the United States.

The story does not end here as Wyeth is countering with an enhanced version of Prevnar that contains protection against thirteen different serotypes of the pneumococcal bacteria and has filed for approval in both the United States and the European Union.

There are some fundamental questions that need to be explored further concerning the safety and effectiveness of these new vaccines, the changing epidemiology of pneumococcal disease, and of course the cost-effectiveness data that is all important to vaccine program planners. Readers should stay tuned as we plan to explore these crtical areas in the coming days. Thanks for joining us today on the BioHorizon.

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