A Randomised Controlled Trial of Neuroprotection With Lamotrigine in Secondary Progressive Multiple Sclerosis: Single Centre, Phase 2 Trial

At present, there is no safe, widely applicable treatment that is capable of reducing the rate at which disability advances in secondary progressive multiple sclerosis (SPMS). There is good evidence that the primary cause of disability is axonal degeneration within the CNS, so there is considerable interest in developing treatments which can protect axons from degeneration. Experimental work by members of our group has established that axons may degenerate upon exposure to the inflammatory mediator nitric oxide. The mechanism of the damage implies that protection might be afforded by the novel approach of partially blocking sodium channels, and our group and others have recently demonstrated that drugs including flecainide, phenytoin and lamotrigine can reduce axonal degeneration when optic nerves or spinal roots are exposed to nitric oxide, and in experimental autoimmune encephalomyelitis.

Aims: To assess whether the sodium channel blocker lamotrigine has a neuroprotective, disease modifying effect on a) the rate of axonal degeneration and b) the accumulation of disability in patients with SPMS.

Methodology: We propose to recruit 120 people with SPMS in whom progression rather than relapse is the major cause of increasing disability into a double blind parallel group controlled trial lasting two years in which random allocation would be made to receive treatment with either lamotrigine or placebo. We anticipate that patient recruitment, follow-up and trial management could be achieved readily across four proposed sites in London. The primary endpoint would be an effect of treatment on cerebral atrophy, which correlates with other MR markers of axonal loss, and which can be measured reliably and sensitively using recently developed MR techniques. The trial is powered to detect a 60% beneficial effect on the rate of development of cerebral atrophy. Secondary endpoints would include effects of treatment on spinal cord atrophy and on clinical measurements of impairment/disability. MR measures of brain volume and cervical spinal cord cross-sectional area and scores of clinical impairment/disability would be determined at entry, and then after 12 and 24 months. Brain volume would be measured additionally at 6 and 18 months. Clinical follow-up would occur every 3 months, and interim analysis is planned at 12 months.

Utilization of results: A phase 2 trial of sodium channel blockade in SPMS is timely, given recent advances arising from experimental and imaging work. A successful outcome would enable sufficiently powered phase 3 trials to be implemented, but perhaps more significantly would demonstrate a novel, safe neuroprotective strategy to reduce long-term disability in this disorder.