[chantell.reagan]

In January 2010, Acorda received FDA approval for a new oral treatment, Ampyra (dalfampridine) to improve walking in patients with multiple sclerosis (MS). This is the first symptomatic treatment approved for MS, which can be used in combination with disease-modifying therapies. Plans may want to take the following considerations into account with regards to formulary management and development of policies:

• What is the proportion of MS patients affected by walking impairment? In a patient survey facilitated by Acorda, approximately 64% of MS patients experience trouble walking, which they defined as the inability to walk or loss of balance at least twice each week.

•How is walking impairment assessed objectively in MS patients in the clinical practice setting? There are a number of scales and questionnaires used to measure walking speed in MS, including the MS Walking Scale 12 (MSWS-12), Timed 25-foot Walk (T25FW), and Walking Improvement Questionnaire (WIQ). Additionally as mentioned above, it can also be as simply defined as "the inability to walk or loss of balance at least 2 times/week. It is unknown whether any of these are used as a "standard" in clinical practice.

•What options are used to treat walking impairment in MS patients? Besides physical therapy, dalfampridine is the first pharmacological treatment approved for improving walking impairment in MS.

•What is the clinical data supporting the use of Ampyra in MS patients with walking impairment? The product was approved on the basis of 2 studies, involving 540 patients (with average EDSS score of 6). In a study published in Lancet in 2009, 35% of patients showed improvement in walking speed (vs 8% of placebo group). A later abstract from 6/09, demonstrated that 42.9% of patients found improvement in walking speed (vs. 9.3% for placebo).

•What patient subgroups are more likely to respond to Ampyra? How long should treatment continue in terms of response vs. nonresponse? In clinical trials, up to 43% of patients with all types of MS (from new-onset to relapsing-remitting) showed response to dalfampridine. Response was defined as faster walking speeds for most visits during treatment than the fastest speed at baseline. In both trials there no differences in baseline characteristics between responders and non-responders were noted. As mentioned in one of the study publications, “the selectivity of responsiveness might be related to the proposed mechanism of action—the improvement of conduction in demyelinated pathways via blockade of voltage-dependent potassium channels. Only some patients would be expected to have axons susceptible to the drug effects at any given time.” Unfortunately, differences in individual neuropathologies cannot be easily discerned and objectively assessed in clinical practice. In clinical trials, response was evaluated during a 14-week treatment period.

In terms of continuation, in the same clinical trials, a responder was defined as a patient who showed faster walking speed for a least 3 out of a possible 4 visits. Long-term treatment might be required for responders after the initial 14-week trial. In clinical trials, treatment discontinuation was associated with declines in mobility improvements.

•What are some of the safety considerations with Ampyra? From a safety perspective, the prescribing information notes that Ampyra should not be used in doses > 10mg bid, as higher doses can increase the risk of seizures and is contraindicated in those patients with seizure history.

•What is the cost of monthly Ampyra treatment? From a cost perspective, Acorda reports the wholesale cost to be $1056/per 30 day supply. Also of note, the product will be commercially available starting in March 2010.

•Which specialty pharmacies are participating in the limited distribution program? According to Ampyra Patient Support Services, the following network of specialty pharmacies will exclusively distribute Ampyra: Accredo, Aetna, BioScrip, Caremark/Curascript, Diplomat, Precision Rx, Prescription Solution, Specialty Care, Tel-Drug/Cigna, US Bioservices and Walgreens.

A policy comparison of Ampyra prior authorization criteria will be forthcoming, as policies become publically available.

Sources:
Ampyra (dalfampridine) website
Acorda press release 2/10
National MS Society news article 2/10
National MS Society news article 3/08
Acorda press release 6/08