Deutetrabenazine used to treat chorea in patients with Huntington’s disease (HD) continues to be safe over the long term, with stabilization of motor symptoms at 1 year, results of a new extension trial show.
“The study showed there is continued suppression of chorea over time,” Samuel Frank, MD, associate professor, Department of Neurology, and Movement Disorders Clinic, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, told Medscape Medical News.
“Over a year, there is continued improvement of the total maximal chorea score, as well as stabilization of the total motor score. So motor issues beyond chorea are also stabilized over a year, which is important in a progressive process.”
The findings were presented here at the International Congress of Parkinson’s Disease and Movement Disorders (MDS) 2017.
Chorea is the most prominent motor dysfunction of HD. It can increase the risk for injury and interfere with daily functioning.
As well as motor dysfunction, HD is characterized by cognitive impairment and behavioral-emotional symptoms.
Deutetrabenazine is a highly selective vesicular monoamine transporter 2 (VMAT2) inhibitor that contains deuterium, a nontoxic naturally occurring form of hydrogen.
It was approved earlier this year to treat chorea in HD. The approval was based on a randomized controlled study (FIRST-HD) showing that the agent reduced Unified Huntington’s Disease Rating Scale (UHDRS) total maximal chorea (TMC) by 4.4 units at 12 weeks compared with 1.9 units in placebo recipients, with a mean between-group difference of –2.5 units (95% confidence interval, –3.7 to –1.3; P < .001).
The new open-label, single-arm extension study was conducted at 37 sites in the United States, Canada, and Australia. It enrolled 119 patients in two cohorts: rollover patients from the original study who were initially exposed to placebo or the active drug and patients switched to deutetrabenazine from a stable dose of tetrabenazine.
The two drugs are structurally similar, but the carbon-hydrogen bond in deutetrabenazine is stronger. This makes it “much smoother” in terms of the delivery, said Dr Frank.
“So even though you’re getting the same amount of drug, there are less peaks, fewer ups and downs over a longer period of time.”
The US Food and Drug Administration approved tetrabenazine in 2008 based on the TETRA-HD study (a randomized, placebo-controlled, double-blind study in patients with HD). It was the first approved treatment for HD in the United States (although other drugs had been used “off-label”)……