Affinivax’s vaccines are based on its Multiple Antigen Presenting System (MAPS™), a technology designed to support higher valency than conventional conjugation technologies. MAPS is intended to enable broader coverage against prevalent pneumococcal serotypes and potentially create higher immunogenicity than current vaccines, through precise, high-affinity binding of disease-relevant polysaccharides to disease-relevant protein antigens in a single vaccine.

According to GSK and Affinivax, immunization with the resulting polysaccharide-protein complexes induces a broad and potentially protective B-cell (antibody) response to the polysaccharides and a separate B-cell and T-cell immune response to the proteins. As a result, the companies say, MAPS can be applied to targeting a broad range of infectious diseases.

The most advanced candidates within Affinivax’s novel class of vaccines are its next-generation pneumococcal vaccines. Affinivax’s lead vaccine candidate, AFX3772, includes 24 pneumococcal polysaccharides plus two conserved pneumococcal proteins, compared to up to 20 serotypes in currently approved vaccines. The company is also developing a 30-plus valent pneumococcal candidate vaccine that is in preclinical phases.

In adult Phase I/II clinical trials, AFX3772 showed positive immune responses compared to current standard of care, and was well tolerated in participants and demonstrated. The FDA granted Breakthrough Therapy designation last year for AFX3772 to prevent S. pneumoniae invasive disease and pneumonia in adults 50 years and above. Phase III is expected to start in the short term.

Phase I/II clinical trials to assess the use of the vaccine in children are planned to begin later this year.

While initial use of the MAPS technology has been directed primarily toward preventing pneumococcal disease, the technology has also been demonstrated for additional infectious disease pathogens, including those that cause hospital-acquired infections, according to Affinivax and GSK.

“The proposed acquisition further strengthens our vaccines R&D pipeline, provides access to a new, potentially disruptive technology, and broadens GSK’s existing scientific footprint in the Boston area,” Hal Barron, MD, GSK’s Chief Scientific Officer and President, R&D, said in a statement.

GSK agreed to acquire all outstanding shares of Affinivax for $2.1 billion upfront and up to $1.2 billion in payments tied to achieving development milestones, to consist of two payments of $600 million.

The deal is subject to customary closing conditions, including the expiration or early termination of the waiting period under the Hart-Scott-Rodino Anti-Trust Improvements Act of 1976. The transaction is expected to close in the third quarter.

Targeting Pfizer

GSK is looking to Affinivax’s pneumococcal vaccine portfolio to help it better compete with Pfizer. Read more here