With $22M Shot of Venture, Sutro Spinout Aims For Better Vaccines

Xconomy San Francisco — 

[Corrected 7/27/15, 1.49pm. See below.] Spun out of its namesake two years ago, vaccine maker SutroVax has reeled in a $22 million Series A round to push forward a type of vaccine that uses sophisticated chemistry to boost its power.

SutroVax came from South San Francisco, CA-based Sutro Biopharma, which has developed technology to stitch together monoclonal antibodies and cancer-killing chemical “warheads” into a combination cancer therapy known as antibody-drug conjugates. That capability is what prompted Celgene (NASDAQ: CELG) to build a deep relationship with Sutro that could end with Celgene buying the company, as Xconomy reported last fall.

SutroVax is using that same conjugate technology to create vaccines that also stitch two elements together: the snippet of bacterial or viral protein, or antigen, which trains a person’s immune system to be on guard for that bacterium or virus; and another protein, dubbed a carrier, which boosts the body’s immune response.

CEO Grant Pickering isn’t ready to discuss which bugs SutroVax wants to fight first. Instead, he says that the company wants to create conjugate vaccines that do a better job than current vaccines by protecting against a wider range of strains from a single bacterium or virus. SutroVax will also aim to develop vaccines for new diseases, he says.

Top selling vaccines include Prevnar, from Pfizer (NYSE: PFE), for the bacteria that causes pneumonia; Gardasil, from Merck (NYSE: MRK), which aims to prevent cancer and other diseases caused by the human papillomavirus; and several vaccines that prevent more than one kind of infection. [A previous version of this story incorrectly named the maker of Gardasil. We regret the error.]

Prevnar 13 is a conjugate vaccine and protects against 13 strains of the bacteria Streptococcus pneumoniae.

Several companies can do chemical conjugation in a precise manner. But Sutro—and now SutroVax—claim their method is better and provides much faster development time in the early, preclinical stages of finding a drug to move forward. That would make for better business, and potentially for better public health. Outbreaks, from avian flu to SARS to the current spread of Middle Eastern Respiratory Syndrome, or MERS, with its 30 to 40 percent mortality rate, continue to crop up.

For conjugate vaccines, the precision allows SutroVax to attach the antigen to the carrier in a spot that doesn’t block the carrier’s ability to recruit the body’s T cells—part of the extra boost conjugation provides. “We can use the technology to put antigens where the T cell regions aren’t,” says Pickering.

One test of the technology was creating a malaria vaccine for the Bill and Melinda Gates Foundation, as the San Francisco Business Times reported last fall. (Pickering declined to comment on the status of the malaria program, or on a vaccine program, partnered with Sanofi, that Sutro Bio transfered to SutroVax at the time of the spinout, according to the Business Times.)

When Sutro first teamed with Celgene in 2012 to focus on antibody drug conjugates (the deal was expanded in 2014), the firm decided to spin out the exploratory vaccine piece of the business and give it seed funding. Johnson & Johnson joined the seed round. Sutro then tabbed Pickering to run the new effort. At the time he was CEO of Juvaris BioTherapeutics, a vaccine maker backed by Silicon Valley venture firm Kleiner Perkins Caufield & Byers and others. (He remains CEO of Juvaris, which he says is now a holding company. From 2000 to 2005, Pickering was SVP of operations at Dendreon, the now-defunct prostate cancer vaccine maker.)

Juvaris shares an investor, SV Life Sciences, with Sutro Bio. But SutroVax has brought on a separate set of investors from Sutro. Abingworth led the Series A round, and Longitude Capital, Roche Venture Fund and CTI Life Science Fund joined. Celgene, which has an option to acquire Sutro Bio, has no rights or relationship to SutroVax, says Pickering.

Photo “syringe – gauge” courtesy of Flickr user Joe Flintham via Creative Commons license.