NEW YORK (AP) -- Shares of ViroPharma Inc. and Halozyme Therapeutics Inc. rallied Friday after the companies said they can resume clinical studies of a new version of ViroPharma's drug Cinryze, which were halted in August because of safety concerns over a Halozyme ingredient added to help with drug absorption.
The companies are developing a drug that combines Cinryze with an enzyme discovered by Halozyme. The companies said the FDA wants ViroPharma to allow for increased measurement of antibodies that are produced in patients' bodies in response to the enzyme.
In August the Food and Drug Administration stopped several studies that involved Halozyme's enzyme rHuPH20. The agency was concerned about elevated levels of antibodies that were produced in response to the enzyme and the side effects those antibodies might have on fertility, reproduction, and fetal development. The agency's concerns were based on a clinical trial of another rHuPH20 product, and the companies say the FDA has concluded that the issue doesn't apply to Cinryze.
Cinryze is used to prevent and treat attacks of hereditary angioedema, a rare genetic disorder that can cause dangerous swelling of the throat or larynx. RHuPH20, or recombinant human hyaluronidase, is designed to temporarily break down a substance in the body that forms a barrier between cells so drugs can be absorbed faster. That would allow some drugs to be delivered by an injection instead of an IV drip.
Shares of ViroPharma, which is headquartered in Exton, Pa., rose $2.16, or 7.7 percent, to $30.34 in midday trading. Shares of San Diego-based Halozyme added $1.86, or 29 percent, to $8.27.