In cases where standard therapies fail, an investigational medication called XEN1101 reduces seizure frequency by more than 50% in some patients and sometimes eliminates them altogether, a new study shows. Unlike several treatments that must be started at low doses and slowly ramped up, the new drug can safety be taken at its most effective dose from the start, the authors say.
Focal seizures, the most common type seen in epilepsy, occur when nerve cells in a particular brain region send out a sudden, excessive burst of electrical signals. Along with seizures, this uncontrolled activity can lead to abnormal behavior, periods of lost awareness, and mood changes. While many available therapies control or reduce seizures, they fail to stop seizures in about one-third of patients and may cause harsh side effects, experts say.
Researchers at NYU Grossman School of Medicine participated in a new phase 2b clinical trial, which found that patients who added XEN1101 to their current antiseizure treatments saw a 33% to 53% drop in monthly seizures, depending on their dose. By contrast, those given a placebo had on average 18% fewer seizures during the treatment phase of the trial, which lasted eight weeks. Most patients then volunteered to extend the trial, with about 18% of those treated with the new drug remaining entirely seizure free after six months, and about 11% having no seizures after a year or longer.
"Our findings show that XEN1101 may offer a swift, safe, and effective way to treat focal epilepsy," said study lead author, neurologist Jacqueline French, MD. "These promising results offer hope for those who have struggled for decades to get their symptoms under control."
French, a professor in the Department of Neurology at NYU Langone Health, notes that XEN1101 was well tolerated by the study participants, who reported side effects similar to other antiseizure treatments, including dizziness, nausea, and fatigue, and the majority felt well enough to continue the regimen. Another benefit of the drug, she adds, is that it takes more than a week to break down, so levels in the brain remain consistent over time. This steadiness allows the treatment to be started at full strength and helps to avoid dramatic spikes that worsen side effects, and dips that allow seizures to return. This lengthy breakdown time also allows for a "grace period" if a dose is accidently skipped or taken late.
XEN1101 is part of a class of chemicals called potassium-channel openers, which avert seizures by boosting the flow of potassium out of nerves, stopping them from firing. French, who is also a member of NYU Langone's Comprehensive Epilepsy Center, notes that while other drugs of this kind have been explored for epilepsy patients in the past, such treatments were taken out of use because the compounds were later found to gradually build up in the skin and eyes, prompting safety concerns, the researchers say.
A report on the phase 2b trial is publishing Oct. 9 in the journal JAMA Neurology.
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