ALS Drug Extends Survival in Mice, Targets TDP-43 Low-Complexity Domain

In a new study published in Nature Aging titled, “Therapeutic targeting of the conserved region within the low-complexity domain of TDP-43 is neuroprotective and extends survival in amyotrophic lateral sclerosis mice,” researchers from University of Arizona present a new therapeutic target to shield nerve cells from the damage of ALS.  

“Current FDA-approved treatments for ALS provide only modest benefits. There is an urgent need for a real breakthrough,” said Xinglong Wang, PhD, corresponding author of the study a professor at the R. Ken Coit College of Pharmacy.  

ALS is difficult to treat because diagnosis occurs after substantial nerve cell damage. Causes of ALS are unclear. Fewer than one in 10 cases are inherited through a known genetic mutation. More than 90% of cases arise sporadically with no family history or clear genetic cause. However, nearly all cases demonstrate abnormal TDP-43 aggregation inside nerve cells, which often informs post-mortem diagnosis. 

“We asked a simple question that had never been tested: is there one specific part of TDP-43 that’s causing the harm, something a drug could switch off without disturbing the rest?” Wang said.  

The team found a region of TDP-43 were disease-causing mutations clustered. When this region was deleted in mice, the nerve cell death caused by TDP-43 dropped sharply while normal protein function remained intact. The researchers identified experimental drug, XL20, which could latch onto the target region in the TDP-43 protein. Notably, the drug could cross the blood-brain barrier. 

In mice, the XL20 extended median survival by approximately a week, protected nerve cells and reduced muscle weakness. When XL20 was tested on human motor neurons, the specialized nerve cells in the brain and spinal cord, the experimental drug reversed damage.

Wang says XL20 represents a promising candidate for future clinical development. As ALS typically develops over months to years after symptoms first appear, earlier treatment could provide greater opportunity to slow disease progression.  

Additionally, the study’s findings may have applications for other neurological diseases. The same TDP-43 pathology is central to limbic-predominant age-related TDP-43 encephalopathy (LATE), a common dementia which affects roughly one in three people over 80. TDP-43 pathology is also found in more than half of Alzheimer’s patients and is associated with faster cognitive decline. 

“The same TDP-43 pathology is implicated in several other neurodegenerative diseases,” Wang said. “If future studies show this approach works in those diseases as well, it could eventually benefit a much larger patient population.” 

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