A Study of the Effectiveness of Fampridine in Improving Upper Limb Function in MS

Overview

The purpose of this study is to examine the effect of treatment with fampridine in patients with secondary progressive MS (SPMS) or primary progressive MS (PPMS) with upper limb dysfunction (as defined by a 9-HPT time of between 15-90 seconds) and Kurtzke EDSS scores in the range 4.0-7.0 on upper limb function assessed by the nine-hole peg test (9-HPT) and the Jebson Taylor Hand Function Test (JTT). Fampridine has been shown to be effective in improving motor function, specifically walking ability in prior studies in this patient population and is currently licensed for this use in Europe and the United States. Upper limb dysfunction is common in SPMS and PPMS and often underestimated. Fampridine effects action potential conduction in demyelinated nerve fibres and we would hypothesise that the improvement previously reported in walking ability would be similar to that on upper limb dysfunction. Our study aims to address this question using both independent and patient reported outcomes in the context of a randomised placebo controlled crossover trial.

BACKGROUND INFORMATION Patients with secondary progressive MS (SPMS) and primary progressive MS (PPMS) have significant walking disability and impaired upper limb function due to repeated demyelination and axonal injury affecting the corticospinal pathways. In some patients this motor deficit may be predominantly due to demyelination resulting in motor conduction slowing and/or block which is potentially reversible by blocking potassium channels of demyelinated axons. Fampyra® (fampridine-PR) is a prolonged-release formulation of the active drug substance 4-aminopyridine {4-AP; fampridine \[International Nonproprietary Name (INN)\]. Fampridine is able to block certain voltage-gated K+ channels in neurons, particularly in demyelinated nerves. Blockade of repolarising K+ currents can increase synaptic transmission throughout the nervous system by increasing the duration of the presynaptic action potential. Demyelinated nerves lose their ability to effectively conduct action potentials and fampridine can help reverse this. This effect was demonstrated clinically in a proportion of multiple sclerosis (MS) patients who showed a significant improvement in motor function, specifically walking ability, with Fampyra treatment. Fampridine-PR 10 mg every 12 hours or twice daily (BID) was approved in Europe (20 July 2011) for this indication under the brand name of Fampyra®. RATIONALE FOR THE STUDY Treatment with fampridine (4-aminopyridine), a potassium channel blocker,1,2 has been shown to cause significant improvement in walking speed in one third of MS patients with motor disability.3-5 In those patients who respond, approximately a 25% improvement in walking speed was obtained with a self-reported 7 point improvement in the Multiple Sclerosis Walking Scale (MSWS-12), a patient-rated measure of walking quality and ability, 6,7 in comparison to non-responding patients and placebo control subjects. Pharmacologically, the K+ channel blocking properties of fampridine and its effects on action potential conduction in demyelinated nerve fiber preparations have been extensively characterized. At low concentrations that are relevant to clinical experience (in the range of 0.2 to 2 μM \[18 to 180 ng/mL\]), fampridine is able to block certain voltage-dependent K+ channels in neurons. It is this characteristic that appears to explain the ability of the drug to restore conduction of action potentials in some critically demyelinated nerve fibers. At higher (millimolar) concentrations, fampridine affects other types of K+ channels in both neural and non-neural tissues. Blockade of repolarising K+ currents may increase synaptic transmission throughout the nervous system by increasing the duration of the presynaptic action potential. A range of neurological effects consistent with increased excitability of nerve cells occurs with clinically relevant doses of fampridine. The FDA has recently approved Fampridine, a slow release preparation, for use in the MS patient population.8 It has also recently been approved in Europe (20th July 2011).17 Most studies of fampridine assessed timed walking over twenty-five feet and the Multiple Sclerosis Walking Scale-12 (MSWS-12).3-5 Deficits in arm and hand function are commonly found in patients with SPMS and PPMS and can have an impact in performing many activities of daily living. We propose to examine the efficacy of fampridine in upper limb function and in overall disease impact in a single centre, double blind, randomized, placebo-controlled, crossover study of patients attending St Vincent's University Hospital with significant walking and upper limb disability due to SPMS and PPMS. STUDY OBJECTIVE The objective of this study is to assess the affect of PR-fampridine medication compared to placebo for upper limb function in patients with progressive multiple sclerosis TRIAL DESIGN This will be a single centre, phase IV, double blind, randomized, placebo controlled, crossover study on the effectiveness of oral Fampridine-PR 10mg tablets BID on upper limb function for patients with progressive multiple sclerosis. The trial will consist of a two week run in period followed by an eight week treatment period were enrolled subjects will be randomised to receive either study drug or placebo in a double blinded manner. This will be followed by a two-week wash out period followed by a further eight-week study period using active drug or placebo. There will be a two-week washout period at the end of the study. The total period of the study will be 22 weeks. Each subject will attend for a screening visit and 8 assessment visits (total number of visits, 9). STUDY ASSESSMENTS AND PROCEDURES Patients likely to fulfill the inclusion criteria and not meet any exclusion criteria will be provided with information on the study and invited to attend a subsequent screening visit. Only patients who have signed the informed consent form will participate in any study related procedures including blood testing and ECG. At screening visit (Assessment 1) subjects will have a physical examination and an expanded disability status scale (EDSS) score rated. Blood samples will be taken for renal and liver function and a baseline ECG performed. Patients will complete a nine-hole peg test (9-HPT) and a Jebsen Taylor Hand Function Test (JTT). Timed 25 foot walk (T25FW) will be recorded and the patients invited to complete the Multiple Sclerosis Impact Scale (MSIS-29), Multiple Sclerosis Walking Scale (MSWS-12), Disabilities of the Arm, Shoulder and Hand (DASH) score, Arm Function in Multiple Sclerosis Questionnaire (AMSQ) and SF-36 (quality of life) questionnaire. Patients with any abnormalities on ECG, blood tests will not be invited to a baseline visit and considered a screening failure. Following screening visit subjects fulfilling the inclusion / exclusion criteria will have two baseline visits (Assessments 2 and 3) at the end of week one and end of week two. The 9-HPT, JTT and T25FW will be repeated to allow for training effects. Patients will be randomised to group A or group B and receive study medication or placebo at baseline visit based on their blinded randomisation (Assessment 3). The first treatment period will be from the start of week 3 until the end of week 10. Patients will have an assessment at the end of week 6 (Assessment 4) and the end of week 10 (Assessment 5). At both assessments patients will have the 9-HPT, JTT, T25FW, MSIs-29, MSWS-12, DASH, AMSQ and SF-36 recorded. Weeks 11 and 12 will be a washout period (no drug/placebo). Assessment 6 will occur at the end of week 12 and will include recording of 9-HPT, JTT, T25FW, MSIs-29, MSWS-12, DASH, AMSQ and SF-36. Any adverse events will be recorded at each visit as will the use of concomitant medications. The second treatment period will begin at the start of week thirteen with groups A and B switching study drug / placebo in a blinded manner. The second treatment period will continue for a further 8 weeks with two more assessments ant week 16 (Assessment 7) and week 20 (Assessment 8). At both of these assessments subjects will complete the 9-HPT, JTT, T25FW, MSIs-29, MSWS-12, DASH, AMSQ and SF-36. At the end of week 20 and EDSS score will be recorded. Any adverse events will be recorded at each visit as will the use of concomitant medications. There will be a final washout period (weeks 21 and 22) after which a final visit (assessment 9) will occur and subjects once again completing 9-HPT, JTT, T25FW, MSIS-29, MSWS-12, DASH, AMSQ and SF-36 and having n EDSS score recorded. Once again adverse events will be recorded. Description of Study Assessments Medical and Surgical History will be recorded with particular attention on the diagnosis of MS, duration of MS and MS subtype. Demographics The date of birth, gender and race will be recorded. Physical Examination The complete physical examination will include the evaluation of the neurological system and a recording of the EDSS score and T25FW. ECG Test One ECG including a 12-lead examination will be performed at Screening (assessment 1). Abnormal findings will be noted for clinical significance. The report will be signed by the investigator. Clinical Laboratory Tests 1. Haematology: haemoglobin, WBC, RBC, platelet count 2. Biochemistry: creatinine or creatinine-clearance, sodium, potassium, liver function tests 3. All laboratory results will be reviewed and the reports signed by the investigator who will record in the CRF whether they are normal, abnormal but not clinically significant, or abnormal and clinically significant. Pregnancy Tests Serum pregnancy test and urine pregnancy test in women of childbearing potential will be performed. Concomitant Medication In addition to Fampyra, any other treatments or procedures that are considered necessary for the patient's welfare may be given at the discretion of the Investigator. Administration of continuous concomitant procedures and medications (including herbals and nutraceuticals) must be reported in the appropriate section of the CRF along with reasons for use. Continuous concomitant procedures and medications are defined as a treatment administered regularly for 2 weeks or more. The generic names for concomitant medications should be recorded, if possible. The total daily dose should be recorded in the CRF whenever possible. Concomitant use of medicinal products that are inhibitors of OCT2 for example, cimetidine will be noted and will be deemed exclusion criteria. Concomitant use medicinal products that are substrates of OCT2 for example, carvedilol, propanolol and metformin will also be noted and the investigator will decide if the subject should successfully complete screening.