New drug shows promise against Huntington's disease

A drug that would be the first to target the cause of Huntington's disease (HD) is effective and safe when tested in mice and monkeys, according to data released today that will be presented at the American Academy of Neurology's 68th Annual Meeting in Vancouver, Canada, April 15 to 21, 2016. A study to test the drug in humans has begun.

Huntington's disease is a rare, hereditary disease that causes uncontrolled movements, loss of intellectual abilities, emotional problems and eventually death. The disease is passed from parent to child through a mutation in the huntingtin gene. The mutation results in the production of a disease-causing huntingtin protein. Each child has a 50/50 chance of inheriting the gene mutation. Everyone who inherits the mutated gene will eventually develop the disease.

The new drug, called IONIS-HTTRx, is an antisense drug that acts as a "gene silencer" to inhibit the production of huntingtin protein in people with Huntington's disease.

"It is very exciting to have the possibility of a treatment that could alter the course of this devastating disease," said clinical study principal investigator Blair R. Leavitt, MD, of the University of British Columbia in Vancouver. "Right now we only have treatments that work on the symptoms of the disease." Leavitt notes the drug is still years away from being used in human clinical practice.

Earlier studies in mouse models of Huntington's disease showed that treatment with antisense drugs delays disease progression and results in sustained reversal of the disease phenotype. In YAC128 mice, a transgenic model of HD, motor deficits improved within one month of initiating antisense treatment and were restored to normal at two months after treatment termination. Motor skills of antisense-treated BACHD mice, another transgenic model of HD, improved eight weeks after initiation of treatment and persisted for at least nine months after treatment termination. In monkeys, dose-dependent reductions in HTT mRNA and Htt protein throughout the central nervous system were observed after intrathecal administration of an antisense drug. Reduction of cortical huntingtin levels by 50 percent was readily achieved in monkeys and correlated with 15 to 20 percent reduction in the caudate. In further tests in rodents and monkeys, IONIS-HTTRx was found to be well-tolerated without any dose-limiting side effects.

New drug shows promise against Huntington's disease

Latrepirdine (dimbon) may ease cognitive effects of Huntington's disease....

We know that Dimebon (latrepirdine), an investigational drug currently in  Phase 3 development, that halt the onset of advanced Alzheimer’s (AD) and dramatically improve the quality of life for patients. Dimebon has a unique mechanism of action, distinct from currently available treatments. In preclinical studies, dimebon has been shown to protect brain cells from damage and enhance brain survival, potentially stabilising and improving mitochondrial function.

Now researchers from School of Medicine and Dentistry at the University of Rochester in New York lead by Dr. Karl Kieburtz, have found that  Dimebon may improve thinking, learning and memory skills in people with Huntington's disease  an inherited neurodegenerative disorder. 

Mitochondria are critical to brain cell functioning as they are the primary source of energy for cells. Drugs that protect mitochondria or restore their function could potentially be a valuable treatment approach in AD and Huntington's disease.

As per the claim by the researchers, the drug stabilizes and improves the function of mitochondria, parts of cells that help convert food into energy. Researchers found that, Dimebon (Latrepirdine)  at a dosage of 20 mg three times daily, is well-tolerated for 90 days in patients with Huntington's disease and may have a beneficial effect on cognition. Though further studies are essential to substantiate the claim, its good to see at l(e)ast a drug for Huntington's disease (the only approved therapy for Huntington's is tetrabenazine, which treats movement problems but does not prevent cognitive decline or change the course of the disease).....more...

Memantine for Huntington's disease ?

Memantine is the first in a novel class of Alzheimer's disease medications acting on the glutamatergic system by blocking NMDA glutamate receptors. Memantine is marketed under the brands Axura and Akatinol by Merz, Namenda by Forest, Ebixa and Abixa by Lundbeck and Memox by Unipharm.

Now researchers from Burnham & University of California have found that, Memantine, which is approved to treat Alzheimer's disease, successfully treated Huntington's disease in a mouse model by preserving normal synaptic electrical activity and suppressing excessive extrasynaptic electrical activity.

Huntington's disease is a hereditary condition caused by a mutated huntingtin gene that creates a misfolded, and therefore dysfunctional, protein. The new research shows that normal synaptic receptor activity makes nerve cells more resistant to the mutant proteins. However, excessive extrasynaptic activity contributed to increased nerve cell death. The research team found that low doses of Memantine reduce extrasynaptic activity without impairing protective synaptic activity.

This finding is of great importance because of the fact that chronic neurodegenerative diseases like Huntington's, Alzheimer's and Parkinson's are all related to protein misfolding and the researchers have shown for the first time that that electrical activity controls protein folding, and if one has a drug that can adjust the electrical activity to the correct levels, one can protect against misfolding and also the research verifies that appropriate electrical activity is protective. They also found that normal synaptic activity was protective. Subsequently, they treated Huntington's disease model mice with both high and low doses of Memantine and found that the low doses were protective by blocking pathological extrasynaptic activity, while high-dose Memantine encouraged disease progression because it also blocked the protective synaptic NMDA receptor activity. Its really good achievement congratulations. After having small clinical trials, larger, international clinical trials are now being planned....


Source : http://www.eurekalert.org/pub_releases/2009-11/bi-rfp111309.php.