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GSK to buy Cambridge vaccine startup Affinivax for $2.1b, with more payments possible

The local biotech is developing a shot that protects against 24 types of pneumococcal bacteria.

GSK headquarters in London.Luke MacGregor/Bloomberg

British pharma giant GSK said Tuesday that it plans to buy Cambridge biotech Affinivax for $2.1 billion upfront and up to $1.2 billion in potential milestone payments. Affinivax is nearing the advanced stages of testing a vaccine that protects against 24 types of pneumococcal bacteria that can cause ear and sinus infections, pneumonia, and meningitis.

If the shot proves effective, it would be an improvement to GSK’s commercial vaccine Synflorix, which only protects against 10 types of the bacteria Streptococcus pneumoniae. The new shot would also help GSK compete with Pfizer and Merck & Co., which sell vaccines that protect against 20 and 23 types of pneumococcal bacteria, respectively.


COVID-19 vaccines aside, Pfizer’s pneumococcal shots — Prevnar 20 and the older Prevnar 13 — are among the best-selling vaccines in the world, earning the firm nearly $5.3 billion last year. Merck posted $893 million in sales of its Pneumovax 23 last year, and GSK’s Synflorix brought in about $480 million. Sales of all three shots fell during the pandemic, likely due to fewer doctor visits for routine immunizations.

Until recently, Affinivax was developing its pneumococcal vaccine with the Japanese drug developer Astellas. In late February, Affinivax regained rights to the vaccine along with a $65 million payment from Astellas. A Phase 3 trial of the vaccine in adults and an earlier stage study of the vaccine for children could begin soon.

GSK will also gain the rights to Affinivax’s vaccine technology, called the Multiple Antigen Presenting System. The MAPS technology was developed by Boston Children’s Hospital infectious disease Dr. Richard Malley and licensed from the hospital when Affinivax launched in 2014. The startup has since raised more than $340 million from private investors, including the Bill & Melinda Gates Foundation, whose funding helped launch the company.

The MAPS technology allows Affinivax to easily link multiple sugar molecules and proteins from many subtypes of pneumococcal bacteria into a single vaccine. The company is in the early stages of applying the technology to develop vaccines for additional kinds of bacteria, as well as viruses and even cancer.


One of those preclinical programs is a COVID-19 vaccine that could potentially protect against several variants of the coronavirus. The company has up to $4.5 million in funding from the Coalition for Epidemic Preparedness Innovations for work on the so-called pan-coronavirus vaccine.

“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,” said GSK’s chief scientific officer Dr. Hal Barron, in a statement. GSK has research centers in Cambridge and Waltham.

Since Affinivax is still a private company, news of the acquisition offered little consolation to the struggling public biotech market. The rock-bottom prices of many biotech stocks have some investors hoping for a surge of acquisitions that could help lift them and reignite interest in the sector.

Ryan Cross can be reached at ryan.cross@globe.com. Follow him on Twitter @RLCscienceboss.