An investigative formulation of a botulinum neurotoxin (BoNT) for cervical dystonia may significantly reduce the risk of dysphagia after injection compared with existing injections, and may have a longer duration of beneficial effect, according to results of a phase 3 clinical trial presented at the virtual International Congress of Parkinson's Disease and Movement Disorders.
The ASPEN-1 trial evaluated 301 patients with moderate to severe cervical dystonia for up to 36 weeks and found that those receiving two doses of DaxibotulinumtoxinA, known as DAXI, versus placebo improved their scores on the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), said Joseph Jankovic, MD, professor of neurology and director of the Parkinson's Disease Center and Movement Disorders Clinic at Baylor College of Medicine in Houston.
"Botulinum neurotoxin is clearly the treatment of choice for cervical dystonia," Jankovic said in an interview. "While the majority of patients obtain satisfactory benefit from BoNT injections, some experience adverse effects such as neck weakness and difficulty swallowing." Another limitation of BoNT is that its effects wear off after about 3 months or less and patients have to be re-injected, he said.
"This is why I am quite encouraged by the results of the DAXI study that suggest that this formulation of BoNT (type A) may have a longer response and relatively few side effects," he said.
Patients in the study were randomized 1:3:3 to placebo, DAXI 125U or DAXI 250U. The average TWSTRS score upon enrollment was 43.3. The placebo group had a mean ± standard error TWSTRS improvement of 4.3 ± 1.8 at 4 or 6 weeks, while the treatment groups had mean ± SE improvements of 12.7 ± 1.3 for 125U and 10.9 ± 1.2 for 250U (P = .0006 vs. placebo). They translate into improvements of 12%, 31%, and 27% for the placebo and low- and high-dose treatment groups, respectively.
"Even though paradoxically it seems the high-dose group did slightly less well than the low-dose group, there was no difference between the two groups," Jankovic said in the presentation.
The median duration of benefit was 24 weeks in the low-dose group and 20.3 weeks in the high-dose group.
The treatment groups demonstrated similar benefit compared with placebo in TWSTRS subscales for disease severity, disability, and pain, Jankovic said. "The majority of the patients had little better, moderately better, or very much better from the botulinum toxin injection with respect to clinical global impression of change and patient global impression of change," he said.
Likewise, both the Clinician Global Impression of Change (CGIC) and Patient Global Impression of Change (PGIC) demonstrated improvement versus placebo: 77.6% and 76.9% in the 125U and 250U doses versus 45.7% for the former; and 71.2% and 73.1% versus 41.3% for the latter.
Side effects "were remarkably minimal," Jankovic said, "but I want to call attention to the low frequency of neck weakness or dysphagia in comparison with other studies of botulinum toxin in cervical dystonia." The rates of dysphagia were 1.6% and 3.9% in the 125U and 250U treatment groups, respectively. Sixteen of the 255 patients in the treatment groups reported muscular weakness or musculoskeletal pain, and seven had dysphagia.
The rate of dysphagia after injection is noteworthy, said David Charles, MD, professor and vice chair of neurology at Vanderbilt University in Nashville, Tenn., who was not involved in the research. "The one thing we worry about most in people with cervical dystonia are swallowing and choking – dysphagia – and the numbers are very modest: 2 out of 127 in the 125U dose and 5 of 130 in the 250U dose," he said. "That's a very low rate of that adverse event."
The duration of action for both doses is "rather remarkable," Charles said. "With the other formulations, my patients are coming back every 12 weeks for treatment; the BoNT helps so much that [these] patients make their appointments every 3 months for as far out as they can," he said. "This could potentially mean two or three trips a year as opposed to four trips a year."
The trial was funded by Revance Therapeutics. Jankovic is an investigator for Revance, and three coauthors are employees of Revance. Charles is a consultant to the company.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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Cite this: Investigative Botulinum Toxin More Effective in Cervical Dystonia? - Medscape - Sep 23, 2021.