– Preclinical data show synergistic protective effect of anti-protein and anti-polysaccharide antibodies in a highly virulent model of serotype 3 invasive pneumococcal disease –

– Presentation at the 12th International Symposium on Pneumococci and Pneumococcal Diseases –

CAMBRIDGE, MA, USA I June 21, 2022 I Affinivax, Inc. (“Affinivax”), a clinical stage biopharmaceutical company pioneering the development of a novel class of vaccines with its MAPS™ (Multiple Antigen Presenting System) platform, announced the company is presenting preclinical data demonstrating that a next generation pneumococcal vaccine candidate incorporating a novel pneumococcal fusion protein conferred enhanced protection in a highly virulent model of serotype 3 invasive pneumococcal disease, at the 12th International Symposium on Pneumococci and Pneumococcal Diseases (ISPPD-12) taking place on June 19-23 in Toronto.

“The continued threat of Streptococcus pneumoniae in both the developed and developing world requires further innovation and novel strategies to provide enhanced protection against this pathogen,” said Rick Malley, MD, Chief Scientific Officer and Scientific Founder of Affinivax. “Serotype 3, in particular, has proven resistant to the effects of traditional conjugate vaccines. These new data presented by Affinivax reveal that the inclusion of a new conserved pneumococcal fusion protein using our versatile MAPS technology has the potential for next generation MAPS pneumococcal vaccines to enable enhanced protection against this serotype and provide broader coverage to patients.”

Streptococcus pneumoniae causes pneumonia, bacteremia and meningitis, especially in infant and older adult populations. Over 100 different serotypes, characterized by diverse capsular polysaccharides (CPS) which surround the pneumococcal bacterium, have been identified. Serotype 3, a major cause of morbidity and mortality worldwide, is a serotype resistant to anti-CPS antibody-mediated protection; the incidence rates of serotype 3 invasive pneumococcal disease have not significantly declined following the introduction of 13-valent pneumococcal conjugate vaccines1.

Highlights from the poster presentation, entitled “Synergistic protective effect of antibodies against polysaccharide type 3 and pneumococcal proteins in a highly virulent type 3 invasive disease model in mice,” are as follows:

  • The MAPS technology platform enabled flexible engineering of a multivalent vaccine by affinity-linking protein antigens from the target pathogen, Streptococcus pneumoniae, to a backbone of pneumococcal polysaccharides. In the study, the novel fusion protein antigen SPP2, which includes a pneumolysin toxoid, was incorporated in a pneumococcal MAPS vaccine candidate containing over 30 different serotypes, resulting in the generation of highly potent, neutralizing antibodies to the toxin.
  • A highly lethal type 3 pneumococcal invasive disease model was developed to evaluate whether antibodies to the SPP2 protein provide enhanced protection.
  • In an active immunization model, three groups of mice were immunized with either: the traditional conjugate vaccine, Prevnar 13® (PCV13) alone, the fusion protein antigen SPP2 alone, or the combination of PCV13 and SPP2. Protection against serotype 3 invasive pneumococcal disease was only seen in the latter group.
  • In a passive immunization model, in which mice received antibodies generated from PCV13 or a 30+ valent MAPS vaccine candidate containing CPS3 and SPP2, protection against serotype 3 invasive pneumococcal disease was only achieved with the MAPS vaccine candidate, even though the amounts of CPS3 antibodies were matched between the two groups.
  • These data indicate that SPP2 confers synergistic protection in a serotype 3 invasive pneumococcal disease model, where traditional conjugate vaccines fail.

“These data strongly support a vaccine approach that includes both pneumococcal polysaccharides and conserved pneumococcal proteins to overcome the resistance of serotype 3 to traditional conjugate vaccines,” said Gilles Besin, PhD, Vice President and Head of Discovery Research at Affinivax. “The MAPS platform offers the possibility of engineering next generation pneumococcal vaccines that can be broadly effective against Streptococcus pneumoniae.”

Affinivax’s lead MAPS pneumococcal vaccine candidate is AFX3772, which has successfully completed a Phase 2 study in older adults, with a current clinical study in toddlers and planned study in infants. AFX3772 includes 24 pneumococcal polysaccharides as well as two conserved pneumococcal proteins, and has been shown in clinical studies to elicit both B-cell (antibody) and T-cell immunity against 24 Streptococcus pneumoniae serotypes. The MAPS technology platform enables the inclusion of additional pneumococcal polysaccharides and conserved pneumococcal proteins into next generation MAPS pneumococcal vaccines.

About Affinivax, Inc.

Affinivax is a clinical stage biopharmaceutical company pioneering the development of a novel class of vaccines designed to induce a broad and robust protective immune response to both disease-relevant polysaccharides and disease-relevant proteins in a single vaccine. Affinivax designs each of its vaccine candidates to optimize the protective immune response to one or both of these antigens utilizing the distinctive plug-and-play nature of its proprietary MAPS™ technology platform, presenting the potential opportunity to make a significant step forward in addressing major healthcare challenges posed by novel and resistant infectious diseases. Affinivax was founded in 2014 with an exclusive license to the MAPS™ technology from Boston Children’s Hospital. For more information, visit www.affinivax.com.

1 “Sugar-Coated Killer: Serotype 3 Pneumococcal Disease,” Front. Cell. Infect. Microbiol., December 23, 2020. https://www.frontiersin.org/articles/10.3389/fcimb.2020.613287/full

SOURCE: Affinivax