Hemophilia A Candidate SHP656 Fails to Meet Once-Weekly Dosing Goal, Partners Announce

The Phase 1/2 trial looking at the Factor VIII protein SHP656 as a long-acting therapeutic to treat hemophilia A did not meet a pre-defined once-weekly dosing criterion, according to Xenetic Biosciences and Shire, which are jointly developing the drug.

The study demonstrated SHP656’s efficacy and pharmacokinetic data (the drug’s behavior once in the body) equal with the profile of an extended half-life rFVIII product. An extended half-life means the drug lasts longer in the body, therefore having greater activity.

While the study reported no drug-related adverse events, the trial wasn’t as successful as expected.

“Despite not achieving the principal objective of once-weekly dosing in this Phase 1/2 study, our PolyXen technology clearly works as a platform to successfully extend the circulating half-life of rFVIII with no drug-related serious adverse events,” Xenetic CEO M. Scott Maguire said in a press release.

SHP656 works by using Xenetic’s PolyXen platform tech, which joins polysialic acid (PSA, a biodegradable polymer found in living organisms) to therapeutic blood-clotting factors. It is designed to improve chemical metabolism and extend the active life of its biologic molecules.

Xenetic and Shire are developing the drug as an innovative molecule to prolong the circulating half-life of the FVIII protein, with the objective of providing once-a-week treatment or reaching higher activity levels for greater efficacy. Both companies are based in Lexington, Massachusetts.

Maguire said the study marked the second instance in which PolyXen, in a human clinical trial setting, extended half-life to a biotherapeutic while maintaining pharmacological activity and a favorable safety and tolerability profile.

“Moving forward, we believe data from Shire’s SHP656 program continues to support the broad utility of our proprietary PolyXen technology platform, and we remain focused on building a growing pipeline of partnerships utilizing this proven platform,” he said. “We truly value our continuing relationship with Shire and look forward to exploring other potential applications of PolyXen within the Shire portfolio.”

Added Philip Vickers, Shire’s global head of research and development: “While Shire is disappointed by this outcome, the company is encouraged by the knowledge gained through this research and remains committed to transforming the treatment landscape for patients with bleeding disorders. Given the potential application of polysialic acid technology, the companies will explore future collaborations.”