ViroPharma Inc. (VPHM) and Halozyme Therapeutics, Inc. (HALO) said Friday that the U.S. Food & Drug Administration has provided guidance that will enable ViroPharma to resume clinical studies of the subcutaneous administration of genetic disorder drug Cinryze in combination with Halozyme's recombinant human hyaluronidase enzyme, or rHuPH20.
Shares of ViroPharma are up more than 5 percent, while shares of Halozyme are gaining more than 26 percent following the news.
The FDA said it believes the potential safety signals regarding antibodies to rHuPH20 that were detected in the clinical development program of another company's product are limited to that specific program. Halozyme noted that the detected antibodies were non-neutralizing and not associated with any clinical adverse events.
Cinryze is a highly purified, pasteurized and nanofiltered plasma-derived C1 esterase inhibitor product. In the U.S., Cinryze is approved by the FDA for routine prophylaxis against angioedema attacks in adolescent and adult patients with hereditary angioedema.
Cinryze in IV formulation is approved for hereditary angioedema, a rare genetic disorder that is characterized by local swelling in subcutaneous tissues.
Hereditary angioedema or HAE is caused by a deficiency of the C1 esterase inhibitor, a protein of the complement system, which is a part of the immune system.
This condition causes unpredictable and debilitating attacks of inflammation affecting the larynx, abdomen, face, extremities and urogenital tract. There are estimated to be at least 6,500 people with HAE in the U.S. and at least 10,000 people in the European Union.
The FDA has advised ViroPharma to amend the study protocol, allowing for increased laboratory sampling to monitor rHuPH20 antibody levels, and also keep the agency informed of elevated antibody levels during the treatment phase of the study.
ViroPharma intends to provide additional information on next steps and timing at its analyst day event scheduled for today.
In August, the FDA approved ViroPharma's application for industrial-scale manufacturing of Cinryze.
Prior to that, the FDA had said it was evaluating potential safety concerns with rHuPH20. While the FDA did not disclose the specific concerns, Halozyme informed ViroPharma that FDA was evaluating the potential risk of long term effect of anti-rHuPH20 non-neutralizing antibodies associated with the use of rHuPH20 that were detected in a separate development program not involving Cinryze.
In the interim, FDA had indicated that studies of the combination of Cinryze and rHuPH20 were being placed on temporary clinical hold. However, the agency stated that the issues were not specific to Cinryze and that ViroPharma could continue to evaluate subcutaneous administration of Cinryze without rHuPH20.
Following the FDA action, ViroPharma said at that time that it was preparing to commence a Phase 2 study that will evaluate the safety and efficacy of two different doses of the subcutaneous administration of Cinryze as a stand alone therapy.
In Friday's regular session, VPHM is trading at $29.68, up $1.50 or 5.32 percent on a volume of 1.06 million shares.
HALO is trading at $8.10, up $1.69 or 26.37 percent on a volume of 2.30 million shares.
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June 05, 2026 16:18 ET A busy week for economic news flow saw a slew of reports being released that reflected the trends in the U.S. labor market. In Europe, economic growth and inflation data gained attention as the European Central Bank and Bank of England head for policy session later in the month. In Asia, the monetary policy session of the Indian central bank was in focus as the country, a major oil importer, reels under the pressures of a weaker rupee and rising inflation.