Affinivax, a biotechnology company, developed a novel class of vaccines designed to elicit a more comprehensive and robust protective immune response against infectious diseases. The company’s approach centers on a proprietary platform technology that fundamentally changes how antigens are presented to the immune system. This innovative method aims to overcome the limitations of older vaccine technologies, offering broader and more durable protection against a range of bacterial and viral pathogens.
The Multiple Antigen Presenting System (MAPS) Technology
The core of Affinivax’s innovation is the Multiple Antigen Presenting System (MAPS), a unique platform that relies on high-affinity, non-covalent binding to construct vaccine complexes. Unlike traditional conjugate vaccines, which use a chemical process to create a permanent, covalent bond between a polysaccharide antigen and a carrier protein, MAPS utilizes a molecular “Velcro” system. This system leverages the strong, non-covalent interaction between biotin, attached to the target polysaccharide, and rhizavidin, a protein fused to the pathogen-specific protein.
This precise interaction allows for the flexible assembly of a single vaccine particle containing multiple distinct polysaccharide and protein antigens. The resulting complex simultaneously stimulates both B-cells (which produce antibodies against the polysaccharide capsule) and T-cells (which respond to the protein components). The MAPS platform generates a multifaceted immune response often lacking in conventional vaccines. Furthermore, the non-covalent assembly supports a higher valency, allowing the vaccine to incorporate a greater number of distinct antigens without the immunological interference that limits traditional conjugation methods.
Advancing Pneumococcal Disease Prevention
The most advanced application of the MAPS technology is a vaccine candidate targeting Streptococcus pneumoniae, the bacterium responsible for pneumococcal disease, including pneumonia and meningitis. Current pneumococcal vaccines are limited in the number of serotypes they can cover, with the newest products covering up to 20 distinct serotypes. The lead MAPS candidate, AFX3772, is designed to provide broader coverage by including 24 of the most prevalent pneumococcal capsular polysaccharides.
Beyond increasing the number of serotypes, AFX3772 also includes two conserved pneumococcal proteins. These proteins are present across many different strains of the bacterium, and their inclusion stimulates T-cell-mediated immunity. This dual-antigen approach aims to generate protection against serotypes historically difficult to cover with traditional conjugate vaccines, such as serotype 3. The candidate has completed Phase 2 trials in older adults, demonstrating good immune responses compared to the standard of care, and received Breakthrough Therapy designation from the U.S. Food and Drug Administration for adults aged 50 and older.
Expanding the Pipeline to Other Pathogens
The modular nature of the MAPS platform allows for application beyond pneumococcal disease, offering a path to develop vaccines against pathogens where previous approaches have stalled. The principles of high-affinity binding and dual-antigen presentation are being applied to a pipeline targeting other serious bacterial threats, including those responsible for difficult-to-treat, healthcare-associated infections.
Specific targets in the pipeline include Clostridium difficile (C. diff), Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Many of these bacteria are becoming increasingly resistant to antibiotics, creating a pressing need for effective preventive strategies. Applying the MAPS technology aims to generate a comprehensive immune response against these diverse and evolving bacterial species.
Affinivax’s Integration into GSK
The potential of the MAPS technology led to the acquisition of Affinivax by GSK, a major pharmaceutical company focused on vaccine development. The transaction involved an upfront payment of $2.1 billion, with the potential for up to $1.2 billion more in development milestones, valuing the deal at up to $3.3 billion.
GSK made this strategic purchase to gain immediate access to the advanced 24-valent pneumococcal candidate and integrate the MAPS technology into its long-term research and development efforts. The integration of Affinivax’s platform accelerates GSK’s capacity to develop next-generation vaccines. Backed by GSK’s global resources in manufacturing and commercialization, the MAPS platform is positioned to accelerate the development and scale-up of its promising pipeline candidates.