Shares of Acorda Therapeutics (Nasdaq: ACOR) skyrocketed nearly 27% on the Nasdaq exchange to $27.13 today -- before being halted mid-afternoon -- when RBC Capital Markets speculated in a report that the patent on the company's multiple sclerosis (MS) drug, dalfampridine (Ampyra), might extend for longer than initially expected. RBC analysts noted that filings from the US Patent and Trademark Office suggested a possible "extension allowance" for the sustained-release formulation of the drug, as well as "ongoing active dialog" between the patent office and Acorda.

Ampyra was approved in January 2010 to improve the walking ability of people with MS. Acorda filed for the patent in December 2004, and it's still under review. If the company is awarded a full patent, it could extend to 2024, which RBC analysts say "would be worth at least $10/share in cash flow" in their model.

The drug works by affecting the demyelinated axons that cause nerves to short circuit. On April 11, the Hawthorne, NY-based company announced during a medical meeting that people with MS who responded to dalfampridine extended release tablets showed similar improvements in their walking regardless of baseline walking speed or their overall level of disability. They also showed clinically meaningful improvement on the MS Walking Scale (MSWS-12) questionnaire, which patients use to report their ability to perform daily activities related to walking.

Acorda spokesman Jeff Macdonald says, "We've seen the update on the USPTO's website but cannot provide further comment at this time." He added that it would be up to the folks at Nasdaq to decide when to resume trading of Acorda's stock.

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Arlene Weintraub is the editor of Xconomy New York. She can be reached at [email protected] and followed on Twitter @awjourn.