Thoughts on the Affinivax Acquisition

We were very excited today when GSK announced their acquisition of our portfolio company Affinivax. This is a great move to advance their vaccines that combat novel and resistant infectious diseases that currently have no effective immunization strategies.

We first became acquainted with CEO Steven Brugger and the team at Affinivax in the fall of 2020, and made our initial investment in January 2021 as part of the company’s Series C. Given the Covid pandemic, we were looking at companies with novel approaches to vaccine development. My colleague, Managing Director Dorothy Margolskee, has a deep background in vaccine development from her time at Merck, and conducted much of the scientific diligence on Affinivax. I led the deal team (with much aid from my Foresite colleagues Richard Lau & Jim Tananbaum), and Dorothy joined the board as an observer. 

We were drawn to Affinivax by their new approach to vaccines, the size of the market for their initial products, and the strength of the team. Their MAPS platform (Multiple Antigen Presenting System) offers a fundamentally different approach to vaccines by combining polysaccharides and proteins via high affinity biotin- rhizavidin chemistry. This offers the potential for a more robust immune response to disease-specific polysaccharides and proteins. MAPS technology is plug-and-play, which supports tailored design of vaccines for each disease pathogen, and also leads to an efficient and scalable manufacturing process. 

Affinivax’s initial vaccine candidate focuses on pneumococcal disease (caused by the bacterium Streptococcus pneumoniae), which includes pneumonia, meningitis, bloodstream infections, and milder diseases such as sinusitis and otitis media. Pneumococcal disease remains a serious unmet medical need, as we don’t have adequate protection against strains in circulation. 

The Affinivax team, led by Steve Brugger, did an incredible job in a small amount of time! We’d like to give a special shout-out to Elizabeth Radcliffe, Stuart Chaffee and Kara Bickham. The investors as well, including our series C investor syndicate, did an amazing job supporting the transaction up until this point. We have complete confidence in the team to finish the job. 

We are very proud of the work the Affinivax team has done in less than five years, and look forward to seeing the continued advancement of their product pipeline under GSK.