Martin and others believe that designing drugs to block mPTP from forming may prevent neuron death, and thus slow the progression of diseases such as ALS, Huntington’s, and Parkinson’s disease. Scientists at Trophos have found that olesoxime binds with a membrane protein in mitochondria that is responsible for forming mPTP. “Our compound binds to the outer membrane of mitochondria, and prevents the pore from opening in pathological conditions,” says Trophos CEO Damian Marron. “This is how we believe [the compound] prevents neuronal cell death.”
The company screened thousands of compounds before discovering the drug. The researchers’ method involved depriving motor neurons of their neurotrophic factors in order to produce neurons that resemble those found in ALS. They then studied the effects of thousands of compounds on these neurons, and found that olesoxime, a cholesterol-like molecule, was best at promoting neuron survival and growth.
In tests on mice with ALS, olesoxime significantly improved survival rates. Researchers went on to determine the drug’s safety performance in healthy volunteers and ALS patients. The company determined the drug to be safe in both groups, and is now going forward with an 18-month clinical trial in Europe, testing the drug’s efficacy in 480 ALS patients.
Marron says that in the European trial, the compound will be used in combination with riluzole, the only drug currently approved by the U.S. Food and Drug Administration to treat ALS. Riluzole, which is marketed as Rilutek in the United States, has been found to increase survival in patients by three to five months. “What we’re looking for is a 12 percent improvement over 18 months, which is a six-to-nine-month increase in survival in patients,” says Marron. “We’ve set a high hurdle, but we feel that if that could be provided, it would be clinically worthwhile.”
Other researchers caution that there is more work to be done to tease out the exact mechanism of the drug. “This molecule has great potential for delaying the disease progress in ALS patients, but still, there is a lot more to be done,” says Hemachandra Reddy, assistant professor of physiology and pharmacology at Oregon Health and Science University, who investigates the role of mitochondria in neurodegenerative diseases. “If we know the mechanism, then this molecule can be used not just for ALS patients, but also for a broad range of diseases like Parkinson’s and Huntington’s.”