Syntonix Pharmaceuticals Inc. agreed to out-license overseas rights to FIX:Fc, its preclinical recombinant Factor IX product for hemophilia B, to Biovitrum AB.

"It's the third major collaboration that we've completed in the past year," Syntonix CEO John Ripple said.

Both companies will jointly develop and commercialize the long-acting product, which came out of Syntonix's SynFusion technology that produces so-called Fc-fusion therapeutics. They bind to the neonatal Fc receptor (FcRn) to harness the body's natural FcRn pathway for protecting antibodies against destruction, extending the drugs' circulating half-lives.

The result is a product that should require fewer doses, meaning it could become a popular alternative treatment in a Factor IX market that is estimated to annually exceed $600 million worldwide. Jack Morgan, Syntonix's vice president of commercial operations, said there is an increasing trend toward Factor IX's use as a prophylaxis for hemophilia B, which requires several infusions per week with currently available drugs to maintain certain levels of the protein to help patients avoid joint deterioration.

"We're confident, based on our animal work, that we'll be able to dose patients no more frequently than once a week, at least for the typical patient," he said. Preclinical data have shown FIX:Fc's half-life to be at least two and a half times as long as existing short-acting Factor IX products.

That kind of promise has proved to be the product's primary draw.

"We have been satisfied and very impressed by the results that Syntonix has been able to achieve here," Biovitrum CEO Mats Pettersson said. "That's why we believe it's time for us to step in and continue to prepare for clinical trials." He declined to discuss timelines for advancing FIX:Fc into humans, but noted that the program is "now entering into an interesting phase." Pettersson pointed to its prolonged half-life and said, "Convenience is extremely important in this area."

Syntonix is receiving an up-front fee and Biovitrum is making an undisclosed equity investment in Syntonix. Ripple noted that the latter commitment demonstrated the collaboration's "strategic importance" to both parties. Also, Syntonix will receive milestone payments and stands to receive an additional equity investment from Biovitrum based on the program's progress. Neither company disclosed more specific financial terms.

The partners will split FIX:Fc's development and commercialization costs and equally share in profits, with the latter being "the primary value driver" for both companies, Morgan said. The alliance will include full participation from both, with joint project teams and committees managing such products.

"We will be conducting a joint clinical program across the U.S., Canada and Europe," Morgan added, noting that because of the indication's close clinical and patient communities, there is "very considerable harmonization in hemophilia products" between the FDA and other regulatory agencies in those territories.

Should the drug receive approval, Waltham, Mass.-based Syntonix would be responsible for marketing in North America, while Stockholm, Sweden-based Biovitrum's territory would include Europe, Russia and the Middle East.

Biovitrum, which was spun out of the former Pharmacia Corp. to become one of Europe's largest biotech companies, has experience in proteins that lends itself to FIX:Fc. In the past, Biovitrum worked on the development of a Factor VIII product in partnership with Wyeth and a recombinant growth hormone.

So given its "large group of protein chemists and development people," Pettersson said Biovitrum would take care of FIX:Fc's process development and possibly its production, as well.

"We think niche products, specialty products and many protein products are better suited for us to build a pipeline," Pettersson said, noting that the company can market them "in a more efficient way."

In the future, Biovitrum and Syntonix can opt to expand the collaboration to include additional long-acting protein products based on the SynFusion technology.

On its own, Syntonix also is evaluating the potential of Factor VIII:Fc constructs to treat hemophilia A and has other early stage programs with potential application to improve therapy for hemophilia patients. Syntonix's focus also includes other chronic diseases, such as anemia, multiple sclerosis and autoimmune disorders. Its core technologies, SynFusion and Transceptor, underscore programs for long-acting biopharmaceuticals that may be injected less frequently or inhaled, and also are used to discover new drugs to treat antibody-mediated autoimmune and inflammatory disorders.

Its other partners include Dyax Corp., of Cambridge, Mass.; Serono SA, of Geneva; and Boehringer Ingelheim GmbH, of Ingelheim, Germany. Syntonix last raised about $36 million in venture capital funding nearly four years ago. Additional equity sales are on its horizon, though no specific timeline has been disclosed.

Some of Syntonix's staff, including Ripple and Morgan, come from the Genetics Institute unit of Madison, N.J.-based Wyeth, with which Biovitrum has retained a relationship principally centered on the Factor VIII product ReFacto. That past helped pave the way for this new deal. Biovitrum, which has about 500 employees, focuses on obesity, diabetes and inflammation, as well as niche indications within those therapeutic areas.