Pharmacologic approaches to the treatment of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease for which no cure or effective treatment presently exists. Many different types of drugs have been tested; most are based on various hypotheses of mechanisms for neuronal death, including oxidative damage, loss of trophic factor support, glutamate-mediated excilotoxicity, and chronic inflammation. The discovery that a small percentage of ALS cases are familial and involve mutation in a superoxide dismutase gene (SOD1) led to the development of transgenic mouse models presently widely used for testing possible drugs. Mutations in the vascular endothelial growth factor gene (VEGF) also appear to be involved. Riluzole, an inhibitor of glutamate release and the only agent presently approved for clinical use, only extends survival by a few months. A number of trophic factors, anti-inflammatory agents, and inhibitors of oxidative stress have been reported to prolong survival in mouse models and some are now in clinical trials. Gene transfer of VEGF or glial cell-line derived neurotrophic factor, anti-inflammatory COX-2 inhibitors, and minocycline have had particularly promising results in mice. No breakthrough has yet occurred and present thinking is that combinations of drugs may be required to slow the multifactorial neurodegeneration process effectively.