Washington Editor

Shares in Acorda Therapeutics Inc. rocketed by more than 282 percent Monday on positive findings from a Phase III study of Fampridine-SR in multiple sclerosis.

The Hawthorne, N.Y.-based company's stock (NASDAQ:ACOR) gained $6.28 to $8.50 because the drug enabled MS patients to walk with far less difficulty, a benefit that stands in stark contrast to existing MS therapies, none of which are labeled for aiding mobility.

"There is no treatment out there that is indicated to improve function," Acorda President and CEO Ron Cohen told BioWorld Today, noting that standard MS agents work by slowing disease progressions and lesions over time. "But they don't affirmatively improve any type of neurological function for the patients in real time."

He said a meeting with the FDA would be scheduled as soon as possible to discuss the program's next steps. It's not yet clear whether another study could be in the offing, or if the agency would instead recommend filing on the data, which corroborate prior Phase II findings.

"We're going to take all the data we have and make the strongest case we know how regarding where we think we are and what we'd like to be able to do," Cohen said. "We'll see what they say and follow their guidance."

Joel Sendek, an analyst at Lazard Capital Markets LLC in New York, predicted a "higher probability of an accelerated regulatory pathway" for the product, which has orphan drug status. It works by helping electrical signals pass through damaged myelin.

If approved, Fampridine-SR would become the first product indicated for improving a functional ability and could "represent a new way" to treat the condition, Cohen said. The drug, a sustained-release tablet formulation of 4-aminopyridine or 4-AP, achieved statistical significance on all three efficacy criteria laid out in a special protocol assessment by the FDA.

Of note, 34.8 percent of people taking Fampridine-SR had improved walking speed, compared to 8.3 percent for those on placebo as measured by the Timed 25-Foot Walk, the study's primary outcome (p<0.001). That effect was maintained throughout the 14-week treatment period (p<0.001), and also there was an improvement in the 12-item MS Walking Scale for walking responders vs. non-responders (p<0.001).

"If you are a timed-walk responder," Cohen explained, "you also are statistically likely to say, blindly, that your walking is better at home. Your activities of daily life are better, and you've improved, clinically."

The average increase in walking speed over the treatment period compared to baseline was 25.2 percent among Fampridine-SR vs. 4.7 percent for the placebo group. Increased response rate on the Timed 25-Foot Walk was seen across all four major types of MS: primary-progressive, secondary-progressive, relapsing-remitting and progressive-relapsing. In addition, statistically significant increases in leg strength were seen in both the Fampridine-SR timed-walk responders (p<0.001) and the Fampridine-SR timed-walk non-responders (p=0.046) compared to placebo.

"It is possible to get discreet improvements," Cohen said, "depending on where your lesions are, as an individual, and what the drug is able to restore."

Worldwide, about 80 percent of MS patients have difficulty walking. Acorda plans to market the drug on its own in the U.S., where there is an overlap among prescribers its sales team already reaches with the spasticity drug Zanaflex (tizanidine), and find a European partner for regulatory and commercialization efforts there.

"We believe the Fampridine-SR would be a well accepted, complementary therapy to existing MS drugs," Sendek wrote in a research note in which he increased the stock's price target to $14, "with peak sales potential over $300 million."

The company is expected to price the product anywhere between $2,000 and $20,000 per year, depending on where the drug fits into today's treatment paradigm.

Among side effects, one patient had a seizure that was observed during an occurrence of sepsis associated with a urinary tract infection. While Acorda acknowledges that the risk of seizures increases with higher doses of Fampridine-SR, it's unclear whether it caused that one. Doses ranged from 10 mg, 15 mg and 20 mg, and a previous study tested up to 40 mg of the drug.

The trial enrolled 301 patients in the U.S. and Canada, all of whom were between 18 and 70 years old. Of them, 229 were randomized to 14 weeks of Fampridine-SR treatment, the remainder received placebo, and all were permitted to remain on a stable regimen of their current medications, including interferons. The company intends to present comprehensive data at an upcoming medical meeting.

Down the road, Acorda might again examine the drug's potential in spinal cord injury patients, an indication in which it missed in a previous Phase III study. In fact, it could find use in any condition characterized by myelin sheath damage, such as improving conduction in peripheral neuropathies.