Patients may have to wait a little longer for access to an FDA-approved treatment for acute attacks of hereditary angioedema (HAE).

The FDA told the maker of a purified form of C1 esterase inhibitor (Cinryze) that the clinical data it had submitted on its safety and value in acute attacks are inadequate, according to the company, ViroPharma Inc. of Exton, Pa.

ViroPharma said the FDA has requested a whole new clinical trial. 

The product is currently approved for prevention of acute HAE attacks, but ViroPharma has also sought permission to market it for reducing the severity and duration of acute breakthrough attacks.

In a separate development, the company said the FDA had approved patient self-administration of Cinryze for routine prophylaxis.

HAE results from a genetic deficiency in C1 inhibitor, resulting in sporadic bursts of excessive complement production. Patients with C1 inhibitor deficiency experience recurrent, unpredictable, debilitating, and occasionally life-threatening attacks of inflammation affecting the larynx, abdomen, face, extremities and urogenital tract.

ViroPharma’s product - acquired last year when it bought the original developer, Lev Pharmaceuticals - is purified from human blood donations.

Studies indicating that the product shuts down acute attacks have been presented at recent meetings. (See: ACAAI: HAE Prophylaxis Drug Also Effective as Acute Treatment)

“The FDA has requested an additional clinical study, due to their opinion that the placebo-controlled study submitted in support of the [application] lacked robustness,” ViroPharma announced in a statement.

“Despite having a statistically significant result using the most conservative intent-to-treat analysis, the FDA feels that the data are not robust enough to support approval at this time. We intend to respond to the FDA about our plans,” the statement said.

Also awaiting FDA approval for treating acute HAE attacks is an investigational peptide drug, ecallantide, sponsored by Dyax Corp. of Cambridge, Mass. (See: ACAAI: Investigational Drug Cuts Off Acute Hereditary Angioedema Attacks)

In March, the FDA told Dyax to develop a risk evaluation and mitigation strategy for the drug, and also requested more data on the product’s manufacturing and quality control. It did not demand new clinical data, according to Dyax.

Primary source: http://phx.corporate-ir.net/phoenix.zhtml?c=92320&p=irol-newsArticle&ID=1296156&highlight=