AFX3772: Lead MAPS vaccine program for Streptococcus pneumoniae

AFX3772, our lead vaccine candidate targeting Streptococcus pneumoniae, includes 24 pneumococcal polysaccharides, more than any other vaccine on the market, as well as two conserved pneumococcal proteins. Developed using Affinivax’s proprietary MAPS (Multiple Antigen-Presenting System) technology platform, AFX3772 is designed to elicit both B-cell (antibody) and T-cell immune protection against Streptococcus pneumoniae.

In Phase 1 and Phase 2 clinical trials, AFX3772 was observed to be well tolerated and highly immunogenic in adults, inducing robust responses at all three AFX3772 dose levels tested. AFX3772 exhibited an antibody response to each of the 24 polysaccharides, as well as an antibody response to the conserved pneumococcal proteins. In July 2021, the U.S. Food and Drug Administration (FDA) granted Breakthrough Therapy designation for AFX3772 for the prevention of pneumonia and invasive disease caused by Streptococcus pneumoniae serotypes included in AFX3772 in adults aged 50 years and older.

We expect a Phase 3 clinical trial in older adults to begin in 2022. The clinical program targeting the infant pneumococcal indication has been initiated with an ongoing Phase 1 study in healthy toddlers 12 to 15 months of age.

Disease Challenge:
Streptococcus pneumoniae is a bacterium frequently found in the upper respiratory tract of healthy children and adults, and can cause serious infections ranging from pneumonia, meningitis, and sepsis, representing a major global health problem. The World Health Organization estimates that half a million deaths in children under 5 years old occur each year worldwide due to infection by this bacterium. The U.S. Center for Disease Control estimates that about 900,000 cases of pneumococcal pneumonia occur in the U.S. alone, resulting in up to 150,000 hospitalizations annually. In 2019, there were over 3,000 deaths due meningitis/bacteremia due to pneumococcus. Streptococcus pneumoniae is the leading cause of lower respiratory infection morbidity and mortality globally, contributing to more pneumonia deaths than all other pneumonia etiologies combined in 2016.1 Prevnar 13 is currently a top selling product in Pfizer’s product portfolio, generating 2019 sales of $5.8 billion and more than $30 billion since 2015.2,3 By overcoming the technical challenges of conventional conjugate vaccine approaches and inducing a broader protective immune response, a more effective MAPS vaccine offers the potential to be a blockbuster product making a significant global impact on Streptococcus pneumoniae.

MAPS Solution:

In Affinivax’s MAPS vaccine against Streptococcus pneumoniae, pneumococcal polysaccharide and proprietary pneumococcal protein antigens enable the potential for more robust and comprehensive immune response beyond what is provided by today’s pneumococcal vaccines. In addition to B-cell protection provided by both the polysaccharide and protein antigens, the MAPS vaccine technology also enables protein antigens to elicit an additional T cell response that may reduce nasopharyngeal colonization (nasal carriage of pneumococcal bacteria), the first and essential step in pneumococcal infection.


1 GBD 2016 Lower Respiratory Infections Collaborators. Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory infections in 195 countries, 1990-2016: A systematic analysis for the Global Burden of Disease Study 2016. Lancet Infect Dis. 2018 Sep 19. pii: S1473-3099(18)30310-4. doi: 10.1016/S1473-3099(18)30310-4.

2 Top Vaccine Products Worldwide, Statista.

3 A vaccine is Pfizer’s best-selling drug. Axios. February 5, 2019.

Prevnar 13 is owned by Pfizer.

Trade marks are owned by or licensed to the GSK group of companies.
©2022 GSK group of companies or its licensor.

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