Clinical trials in ALS: what did we learn from recent trials in humans?
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. No treatment is currently able to stop the disease process. In the absence of new active compounds there is an urgent need to develop new strategies based on the neuroprotective activity of available drugs. ALS is a heterogeneous disease. To build up these therapeutic trials, we need to have a better understanding of the prognostic factors in this disease. During the Phase IV Rilutek Trial in France, we developed in a large population of patients a prognostic score based on clinical parameters available at the bedside. The most significant variables are vital capacity, spasticity, fasciculations, swallowing, cough and creatininemia. This score proved to be very useful in daily use in the clinic and for planning disease management in ALS as in the design of therapeutic trials. In ALS clinical trials, efficacy can be evaluated using survival or functional parameters. In phase II trials, function remains the most commonly used. In phase III trials, the gold standard endpoint remains the survival rate at month 18. We analyzed the most recent ALS trials published in the literature. This review suggests that in these trials there is a discrepancy between drug effects on survival versus function. These results suggest that a reappraisal of strategies to identify therapeutic targets for ALS is required.