Richard Sater

Why I Doubt the FDA Will Approve Acorda's Fampridine

I enjoyed reading your article but disagree with your conclusion. I've traded ACOR a few times in the past but currently have no position.

A few points:
1. An improvement of 0.5 feet per second sounds minimal to a healthy person who walks 25 feet in 5 seconds (5 feet per second to 5.5 fps). But a person who is only able to walk 25 feet in 16 seconds will have a perceptible improvement (1.5 fps to 2 fps) and will have a correspondingly greater range. A responder who goes from a walker to a cane has a re-discovered freedom that leads to a greater quality of life and becomes less dependent on others.

2. A responder rate of 35% is acceptable. Some drugs work for an individual and some don't. What's nice with 4-AP is that you will know within a week or two. With a background in pharmacy, how often have you seen people switch from one medicine to another to treat the same problem. Would they be switching if they were responding? Most meds I use have a response rate of 25-75%.

3. This is the first drug that will be FDA approved that can actually help some MS patients with primary progressive or more advanced secondary progressive MS who are unlikely to respond to immunomodulatory agents. This is a niche that needs to be filled and moderate response rates and side effects are more acceptable when no other option exists.

4. Side effects are acceptable. A 1% risk of seizures is high enough that anyone with a seizure history will need to be excluded, but others will need to understand the risk and determine if they are willing to take that 1% risk for a 35% chance of benefit. The other side effects (anxiety, agitation and loss of balance) are mild problems that may last for hours and are not much different from somnolence or dry mouth that may accompany other drugs.

5. I've used immediate release 4-AP in some of my MS patients and have had variable success. A couple noted improved strength and/or gait. Some had agitation (more likely to occur on immediate release than time release) and quit and others had no benefit and quit.