CARB-X Places $22 Million Bet on Affinivax Staph Vaccine

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Less than two months after bacterial vaccine company Affinivax’s Series C financing, the company is getting a $22 million boost from infectious disease consortium Combating Antibiotic-Resistant Bacteria Biopharmaceutical Accelerator (CARB-X) to push forward a vaccine for tough-to-treat preclinical Staphylococcus aureus, funding the candidate through the end of Phase I testing.

In January, the Cambridge, Mass.-based company announced a $226 million venture round to support its lead Streptococcus pneumoniae vaccine, currently in Phase II testing, and several other vaccines in its preclinical pipeline.

Affinivax raised an additional $120 million last year in a Series B round.

Through the new grant, CARB-X will fund all development of Affinivax’s vaccine against S. aureus, which can cause nearly 120,000 infections and 20,000 deaths in the U.S. per year. S. aureus is a major contributor to healthcare-associated infections, particularly methicillin-resistant strains (MRSA), and efforts to control the rates of hospital-onset MRSA have stalled in recent years.

The bacteria is a common non-pathogenic presence in human hosts, but it can turn pathogenic following mucosal colonization, and the complexity of the immune response to it has hampered vaccine development in the past.

Affinivax’s platform is built to develop vaccines that present multiple protein antigens, which the company thinks can block mucosal colonization and induce a broader protective immune response than more common conjugate vaccines.

In 2018, the company’s scientific co-founders published a paper in mBio teasing out the roles of specific B-cell antibodies and T helper cells Th1 and Th17 in immune responses to different types of S. aureus infections. The authors showed a vaccine based on the company’s Multiple Antigen Presentation System (MAPS) vaccine technology combining six S. aureus proteins elicited an immune response in all three pathways, in mouse models of infection.

Currently, Affinivax is optimizing a lead candidate for preclinical studies that will enable an Investigative New Drug (IND) application.

CARB-X is funded by an international partnership of government bodies and charities, including the U.S. Department of Health and Human Services’ Biomedical Advanced Research and Development Authority (BARDA), and the Wellcome Trust.

The organization is backing several other anti-S. aureus efforts, including an anti-virulence agent from BioVersys and an anti-infective drug from Microbion Corporation. It is also backing a multi-valent vaccine from Integrated Biotherapeutics, which it first supported in 2017 with a grant worth up to $8.5 million.

CARB-X pledged an additional $1.6 million in November 2020 to expand vaccine development. Integrated Biotherapeutics’ vaccine is based on rationally designed toxoids that mimic S. aureus toxins to trigger an immune response without their pathogenic effects.

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