When SutroVax was spun out of Sutro about four years ago, the biotech took along a conjugation platform that was repurposed for developing a new brand of vaccines. And now that they are aiming for the clinic with a lead pneumococcal vaccine, SutroVax has reeled in a whopping $64 million raise to get them well into human studies for a new vaccine that will challenge the megablockbuster Prevnar 13 for the heavyweight title in its field.
The big idea behind the conjugation tech at SutroVax is that the biotech believes it can more effectively stitch together antigens to a carrier protein that can ultimately target a laundry list of bacteria while amping up a T cell response directed at the target.
Prevnar 13 is a conjugated vaccine which goes after 13 strains of Streptococcus pneumoniae. It also earned about $6 billion last year, which is why some upstarts like Affinivax in Cambridge, MA are also looking at new and different ways to bind multiple polysaccharides to proteins and do Prevnar 13 multiple strains better. (Affinivax uses a different platform tech, steering clear of traditional conjugation.)
“If you could have Prevnar 24,” says SutroVax CEO Grant Pickering, “that would be the best case scenario. That is what we are looking to do.” And SutroVax is using a conventional approach that’s tweaked to greatly broaden its effectiveness.
“We took a pragmatic approach when we set out to put this program together,” says Pickering. “The reality is that Prevnar is a phenomenal vaccine. It’s wildly effective, but not as broad spectrum as people would like it.”
Half of the strains aren’t covered, which is why some patients are given Prevnar 13 with Pneumovax, “an inferior” vaccine, in Pickering’s view. Instead of trying to stitch all the antigens it needs to a single carrier protein, though, SutroVax is making multiple vaccines that can go after all the strains, using the traditional conjugation method but doing it in a way that leaves the carrier protein better equipped to generate the T cell response.
“We can put the polysaccharide on the same carrier, in the same site specific location every time,” he adds. By keeping the same precise region of the protein exposed to the immune system, they believe they can generate a strong immune response while using less of the protein carrier in each of the vaccines involved.
And they’ve been running tests on rabbits, the preferred animal model, to prove their point.
Making 24 vaccines is no simple task, and SutroVax isn’t planning to jump into the clinic overnight. The IND is likely going to arrive in 2019, says Pickering.
Frazier Healthcare Partners and the brand new biotech fund Pivotal bioVenture Partners led the round, joining a syndicate that included participation from all existing investors: Abingworth, Longitude Capital, Roche Venture Fund and CTI Life Sciences Fund. The existing investors also chipped in $4 million, on top of the $60 million round, to complete their Series A commitments. And Pickering says the total raised so far now comes to $88 million, a substantial bet in the vaccine field.
With the money, the Bay Area biotech will now about double its current staff of 14 — which also relies on a lineup of consultants to flesh out the organization.
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