Positive results for onaBoNT-A in two pivotal trials in chronic migraine that were published since the last guidelines give the formulation the only FDA-approved indication for a botulinum toxin in chronic migraine and earned it a level A recommendation from the guidelines committee. However, in the trials it had a relatively small magnitude of efficacy in reducing the number of headache days by 15% versus placebo. The guidelines also advise not using onaBoNT-A in episodic migraine based on three negative trials. No high-quality trials have evaluated any formulation to change the overall 2008 guidelines’ advice that botulinum toxin is probably ineffective for treating chronic tension-type headaches.
Familiarity with appropriate dosing and side effects may allow clinicians to use the products off-label for indications in the guidelines for which clinical trials were not available, Dr. Richard L. Barbano of the movement disorders division at the University of Rochester noted in an editorial about the guidelines (Neurol Clin Pract. 2016 Apr 18. doi: 10.1212/CPJ.0000000000000244). “Off-label use is common in clinical practice. Little data exist to indicate that any of the different formulations, with attention to appropriate dosing and side effects, would not be effective in treating these other conditions. There are also a number of other neurologic conditions not discussed in the guideline in which botulinum toxin has shown efficacy, such as hemifacial spasm and other focal dystonias. Lack of sufficient high-level evidence to support a level A or B guideline recommendation does not negate their potential utility and likewise, there is little evidence to recommend one formulation over another.”
“In some circumstances where the drugs are relatively equivalent, some people prefer to stick with one so they get used to it more, and they can have more of a sense of what the dosing is, given that the doses may be different with the compounds and have different side effects,” Dr. Hallett said in an interview, noting that availability and price also might enter into a clinician’s decision on what to do.
Dr. Barbano also said that cost and value are becoming more important, and neurologists should consider when botulinum toxin therapy should be chosen among existing alternative treatment options, particularly for chronic migraine.
The guidelines are endorsed by the American Association of Neuromuscular & Electrodiagnostic Medicine and the American Society of Plastic Surgeons.
Dr. Hallett reported serving as chair of the Neurotoxin Institute Advisory Council and has received research grants from Allergan and Merz Pharmaceuticals. Dr. Simpson reported receiving research grants from and served as a consultant for Allergan, Ipsen, Merz Pharmaceuticals, and Acorda Therapeutics. Five other coauthors of the guidelines disclosed relationships with manufacturers of botulinum toxin formulations. Dr. Barbano reported serving on a scientific advisory board for Allergan and receiving research support from Allergan, Vaccinex, and Biotie.