Acorda Therapeutics’ (ACOR) stock was up today (28% to almost $25) on news that the FDA had not only accepted the company’s NDA for Fampridine-SR, but that it received priority review. The move puts a yes-no decision date on the drug at or by October 22, 2009.

Just last month, the FDA refused to file the NDA because of some formatting issues regarding data from the Elan days. We ranted about it right here, but ACOR managed to get their stuff together and re-file.

Now, the clock will start and the questions that have been lingering for months, if not years, will be addressed when, or if, ACOR gets an advisory committee meeting date. All eyes will be on the committee when it reviews the data and surely the stock will be halted for the day – whenever the day comes.

So here’s the big concerns:

1. Are the results clinically meaningful? Yes, ACOR has an SPA and two well-designed Phase 3 trials, but the change in walking speed of 0.51 feet/second (average) will surely be questioned (placebo was 0.10 ft/sec). Additionally, the change was only seen in 35% of patients.

2. Baseline walking speeds on the 25-foot walk ranged from 8-45 seconds. To date, ACOR has not shared the individual patient data to determine which patients had the change and if there was any difference in faster (3 ft/sec) or slower (1.8 ft/sec) patients.

3. If approved, the labeling will be challenging: Despite being better than placebo, the 35% response rate is a low number to predict who will benefit from therapy. Additionally, there was no trend identified between the different MS subclasses in the two studies (MS-F203 and MS-F204) meaning that identification of specific treatable patients who can respond will be difficult.

4. Seizures – we do not put a lot of weight on this given than MS patients already have a rate of seizures.

5. ACOR admits that some non-responders showed a transient increase in walking speed in placebo patients during the first two weeks of treatment.

Ultimately, we believe that ACOR might have a good shot at approval, especially since they were able to correlate efficacy with solid MSWS-12 QOL improvements as judged by patients. The key questions will arise when the data is analyzed by advisory committee and the MSWS scores are directly correlated with each patient’s walking speed change from baseline to end. We don’t think the image above will happen AT THIS POINT, but we can not say anything due to the fact that the full data has not been made available.

Our concern is that even if Fampridine is approved, it will be difficult to asses an appropriate patient population, determine response clinical relevance, and larger Phase 4 studies will be needed.

As a side note, analysts said today’s news:

…could prompt a deal for the company, ranging from a buyout to a licensing agreement.

Also, check out this post on Seeking Alpha which also discusses the bears/concerns on Fampridine.

Stay tuned…

Sources: Lancet Neurology, ACOR press releases and SEC filings

No disclosures in ACOR or its competitors

Image from failblog

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