Assistant Managing Editor

Following two successful Phase III studies last year, Acorda Therapeutics Inc. submitted its new drug application as expected for Fampridine-SR, hoping to gain approval of the first drug specifically aimed at improving walking ability in patients with multiple sclerosis.

While existing treatments such as Avonex (interferon beta-1, Biogen Idec Inc.) and Betaseron (beta interferon 1b, Bayer HealthCare) work to slow the progression of the disease by reducing the number of attacks resulting from damaged myelin, Fampridine-SR, a sustained-release version of 4-aminopyridine, is designed to address mobility. Data released to date have continually enthused Wall Street, sending the Hawthorne, N.Y.-based firm's stock on a dramatic rise over the past three years.

Shares of Acorda (NASDAQ:ACOR), which went public with a modest $6-per-share initial public offering initial in February 2006, closed Monday at $23.64, down 89 cents.

The company expects a standard 10-month review at the FDA, meaning Fampridine-SR could gain marketing approval late this year. Of the estimated 400,000 to 500,000 MS patients in the U.S., anywhere from 65 percent to 85 percent have walking disability, though those who already are wheelchair-bound would not be eligible for Fampridine-SR treatment, said Jeff Macdonald, spokesman for Acorda.

In clinical trials, which included MS patients from all four subtypes - relapsing-remitting, secondary progressive, primary progressive and progressive-remitting - about 35 percent to 43 percent responded to Fampridine-SR treatment, Macdonald told BioWorld Today.

Fampridine-SR is targeted to improve impulse conduction in nerve fibers where the myelin has been damaged by blocking potassium channels.

The company first tried that approach to treat spinal cord injury, but, after two Phase III trials failed to hit their primary endpoints in that indication, switched focus to walking disability in MS patients, where it had much better luck.

In the first Phase III trial, reported in 2006, Fampridine-SR improved walking speed in 34.8 percent of patients vs. 8.3 percent in the placebo group, and the average increase in walking speed was 25.2 percent for the treatment group compared to 4.7 percent for those on placebo.

The second Phase III, reported last year, was similarly successful, with 42.9 percent of patients receiving Acorda's drug boasting improved walking speed vs. 9.3 percent in the placebo arm. (See BioWorld Today, Sept. 26, 2006, and June 3, 2008.)

The Phase III program was conducted under a special protocol assessment agreed to by the FDA. It's likely the Fampridine-SR NDA will be subjected to an advisory panel discussion before final FDA review, but Piper Jaffray analyst Caroline Stewart wrote in a research note that she does "not anticipate it to be problematic," particularly since a QT study demonstrated that the drug does not increase the risk of cardiac arrhythmias.

Acorda plans to commercialize Fampridine-SR in the U.S. on its own. The company already has a sales force for its spasticity drug Zanaflex (tizanidine hydrochloride), which recorded sales of $13.7 million in the third quarter of 2008, and expects "a lot of overlap to the prescriber base," Macdonald said.

Neurologists are the leading prescribers for both drugs, and there are about 5,500 neurologists in the U.S. who handle about 85 percent of the market.

The company currently has about 65 members of its sales team, including 50 field reps, with plans to "roughly double that" for the anticipated Fampridine-SR launch, he added.

Acorda still is working on a strategy for overseas, but Macdonald said the firm had met with regulators from four European Union members and believes existing data will be sufficient to submit a marketing authorization application for European approval.

The firm has started discussion with potential partners for ex-U.S. sales and the timing of an application is dependent on the outcome of those partnership discussions, he added.

Based on patient numbers, the MS market in Europe is larger than the U.S., but Piper Jaffray's Stewart wrote that "enthusiasm is greater in the U.S." based on physician discussions. She has projected peak worldwide sales of Fampridine-SR to total more than $500 million.

Beyond Fampridine-SR, Acorda has a preclinical pipeline focused on remyelination and regeneration, including a glial growth factor-2 protein for which it expects to submit an investigational new drug application this year for development in cardiac indications.

The firm took advantage of two bits of good news last year, raising about $75 million through a February stock sale and adding another $114 million in an August offering, giving Acorda a solid cash position of $263.2 million as of Sept. 30. At that time, executives said those funds should sustain operations through 2010.

Published  February 3, 2009