Dyax Corp. is set to launch Kalbitor (ecallantide) for acute attacks of hereditary angioedema in the first quarter of next year after the drug cleared the FDA on its second pass, positioning it against recently approved C1 inhibitor Berinert in the orphan HAE space.
Shares of Cambridge, Mass.-based Dyax (NASDAQ: DYAX), trading nearly 40 times its average volume, shot up 73 cents, or 21 percent, to close Wednesday at $4.23, a nice boost for the company that developed the recombinant plasma kallikrein inhibitor in house through discovery and will bring it to market in the U.S. with its own 18-member sales team.
"It's a big day for Dyax," said Gustav A. Christensen, the company's president and CEO, as well as for patients, who now have a choice of products for treating acute HAE attacks.
A little more than a year ago, there were no treatments approved in the U.S. for HAE, a rare, genetic disorder characterized by severe and often painful swelling.
That changed in October 2008, when ViroPharma Inc.'s Cinryze, another C1 inhibitor, gained approval as a preventive HAE therapy. Exton, Pa.-based ViroPharma had hoped to secure the acute HAE market as well, but the FDA requested a new trial for that indication, a decision that gave King of Prussia, Pa.-based CSL Behring a chance to slide in with Berinert and keep Cinryze from being marketed as an acute drug for seven years, though it won't stop off-label use. (See BioWorld Today, Oct. 14, 2008, and June 5, 2009.)
Cinryze sales to date have blasted past analyst estimates, pulling in $25.6 million in second-quarter sales and $29 million in the third quarter. ViroPharma execs acknowledged in a July earnings call that some revenue probably stemmed from off-label usage, though the company had no specific breakdown of patient data. (See BioWorld Today, July 30, 2009.)
Berinert was approved in October, "so we'll be launching right on the back" of that drug, Christensen told BioWorld Today. But the fact that Kalbitor gained approval for treating all HAE symptoms, including the potentially deadly laryngeal attacks, which "most impacts the psychology of the patient," could give it a leg up over CSL's C1 inhibitor, which was approved only for abdominal and facial HAE attacks.
As a recombinant protein, Kalbitor also avoids the risk of viral contamination, and its subcutaneous delivery makes it convenient for any doctor's office or emergency room setting, he added.
A small risk of hypersensitivity reactions, including anaphylaxis, prompted a black-box warning, but that was hardly surprising given that an FDA advisory committee raised concerns earlier this year. But that might not prove much of a deterrent since the drug is administered subcutaneously in a hospital setting where patients are carefully monitored. (See BioWorld Today, Feb. 5, 2009.)
In terms of Cinryze, Kalbitor's competitive threat is expected to be minimal. "We believe prophylaxis and treatment will largely target different groups of HAE patients," Analyst Liisa Bayko, of JMP Securities, wrote in a research report.
She also noted that both Kalbitor and Berinert are administered by health care professionals, while more than half of Cinryze patients are able to self-administer that drug for preventive use.
Estimates for the HAE patient population vary, but are believed to affect somewhere between 1 in 10,000 people and 1 in 50,000, putting the U.S. number around 10,000. And patients suffer an average of more than 20 attacks per year.
Outside the U.S., Dyax is working on a marketing submission in Europe, which it will file after completing a required pediatric study.
The company initially had aimed at securing a European partner, but "we've recently been contacted by a number of companies with a broader reach than Europe," Christensen said.
Kalbitor, also known as DX-88, also is in development for ACE inhibitor-induced angioedema.
Dyax also has deals with Lexington, Mass.-based Cubist Pharmaceuticals Inc. to develop an intravenous formulation of the drug for the prevention of blood loss during surgery, and with Paris-based Fovea Pharmaceuticals SA for an ocular version to treat retinal diseases.
Dyax had about $41 million in cash, as of Sept. 30, though it added $20.5 million in net proceeds in October through the sale of 5.5 million shares. (See BioWorld Today, Oct. 1, 2009.)