EXTON, Pa. and SAN DIEGO, Sept. 21, 2012 /PRNewswire/ -- ViroPharma Incorporated (Nasdaq: VPHM) and Halozyme Therapeutics, Inc. (Nasdaq: HALO) announced today that the U.S. Food & Drug Administration (FDA) has provided guidance enabling ViroPharma to resume clinical studies of the subcutaneous administration of Cinryze in combination with rHuPH20. The FDA informed ViroPharma that based upon their ongoing assessment, the FDA 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. According to Halozyme, the detected antibodies were non-neutralizing and not associated with any clinical adverse events. The FDA has advised ViroPharma to amend the study protocol, allowing for increased laboratory sampling to monitor rHuPH20 antibody levels, and keep the Agency informed of elevated antibody levels during the treatment phase of the study. ViroPharma intends to provide additional commentary on next steps and timing at ViroPharma's analyst day event scheduled to begin at 9:00 A.M. E.T. today. To access the webcast of ViroPharma's analyst day, please visit www.viropharma.com. About Cinryze® (C1 esterase inhibitor [human])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 HAE. In the E.U., the product is approved by the EMA for the treatment and pre-procedure prevention of angioedema attacks in adults and adolescents with hereditary angioedema (HAE), and routine prevention of angioedema attacks in adults and adolescents with severe and recurrent attacks of hereditary angioedema (HAE), who are intolerant to or insufficiently protected by oral prevention treatments or patients who are inadequately managed with repeated acute treatment. Cinryze is for intravenous use only. Severe hypersensitivity reactions to Cinryze may occur. Thrombotic events have occurred in patients receiving Cinryze, and in patients receiving off-label high dose C1 inhibitor therapy. Monitor patients with known risk factors for thrombotic events. With any blood or plasma derived product, there may be a risk of transmission of infectious agents, e.g. viruses and, theoretically, the CJD agent. The risk has been reduced by screening donors for prior exposure to certain virus infections and by manufacturing steps to reduce the risk of viral transmission including pasteurization and nanofiltration.