Halozyme regrouping after ViroPharma trial flop

After ViroPharma ($VPHM) cut short its mid-stage drug trial for Cinryze due to unexpected problems with Halozyme's ($HALO) delivery platform, Halozyme is taking a step back to determine what exactly went wrong and where the company will go from here.

Halozyme CEO Gregory Frost

In an email to FierceDrugDelivery, Halozyme CEO Gregory Frost acknowledged the setback and mapped out the company's hopes for its continuing partnership with ViroPharma, as well as with the other companies developing drugs using Halozyme's subcutaneous enzyme-based delivery platform.

Halozyme's rHuPH20 is designed to improve subcutaneous absorption of biologics by opening short-lived nano-channels. Its use in Cinryze is intended to prevent swelling and painful attacks in patients with hereditary angioedema, a blood protein deficiency. But ViroPharma's Phase II trial elicited a surprise outcome.

"In terms of the Cinryze trial, an unexpected incidence and titer of non-neutralizing anti-PH20 antibodies were observed in a number of patients," Frost said. "These antibodies were not associated with any adverse clinical effects and are of unknown clinical significance. This could be due to a number of factors, including the specific formulation or the unique patient population, but further investigations would be needed to determine the root cause and path forward for Cinryze."

ViroPharma's decision came a year to the day from Halozyme's last clinical rHuPH20 disappointment: A similar antibody response occurred in a trial of Baxter's ($BAX) HyQvia. But in working with Baxter over the last year, Halozyme paved the way to recovery.

"Baxter has reported that discussions are positive and ongoing with the FDA," Frost said. "We're also proud to say that HyQvia has recently been approved in Europe and is now being introduced to physicians and adult patients with immunodeficiency."

And other versions of the rHuPH20 enzyme have shown promise, Frost noted, including a positive opinion from the EMA for Roche's ($RHHBY) Herceptin and the marketing of Halozyme's own ophthalmic surgery product Hylenex in the U.S.; both treatments successfully make use of the rHuPH20 platform.

"While it's disappointing when a particular program fails, we support ViroPharma's business decision," Frost said. "Compared to other products that we are preparing to launch, or have under development, with partners such as Roche, Pfizer and Baxter, the ViroPharma product was not factored into most analysts' models for Halozyme."

- here's the release
- and here's FierceBiotech's take