The US Food and Drug Administration (FDA) recently informed ViroPharma Incorporated ( VPHM - Snapshot Report ) that the company may continue with its clinical studies of the subcutaneous administration of Cinryze in combination with its partner, Halozyme Therapeutics’ ( HALO - Snapshot Report ) recombinant human hyaluronidase enzyme (rHuPH20).

In early August, this year the FDA had advised ViroPharma and Halozyme to put a phase II study evaluating the combination of subcutaneous Cinryze and rHuPH20 on temporary clinical hold.

At that time, the US regulatory body had mentioned that the problem does not specify Cinryze and ViroPharma can continue evaluating the subcutaneous administration of Cinryze without rHuPH20. We note that the FDA detected some risks rHuPH20 in a separate study without Cinryze.

In the recent update, ViroPharma said that the US regulatory body believes that the potential safety concerns of the antibodies to rHuPH20 were limited to the clinical program in which they were detected. Halozyme believes the detected antibodies are non-neutralizing in nature. Halozyme further stated that the antibodies were not associated with any adverse events during the trials.

The FDA has asked ViroPharma to modify the trial protocol for the combination. The US regulatory body asked the company to monitor antibody levels and update the agency about elevated antibody levels during the study.

Though ViroPharma did not provide any information regarding its plans in Europe in its recent press release, the company had earlier decided to inform the European regulatory authorities of the FDA’s action to put the clinical trial on temporary hold. The company had also decided to postpone its enrollment process in Europe for the phase II combination study of Cinryze and rHuPH20, until the FDA confirmed the safety of the latter.

Our Recommendation

We currently have a Neutral recommendation on ViroPharma. The stock carries a Zacks #3 Rank (Hold rating) in the short run. We view the news as positive for the stock and the shares reacted favorably for the company. We expect that Cinryze sales will be benefited with the label expansion.