Clinical Relevance of Neutralizing Antibodies in Botulinum Neurotoxin Type A

The precise definition of prevalence of neutralizing antibodies (NABs) affords cross-sectional testing of a cohort. But in most studies, only selected patients are tested. This leads to gross underestimation of NAB-prevalence, and the opinion that induction of NABs is a rare phenomenon in botulinum neurotoxin (BoNT)/A-therapy. However, recent cross-sectional studies report annual incidences between 1 and 2% in patients being treated with a complex protein (CP)-containing preparation. This implies that NAB-prevalence above 10% has to be expected in patients being treated for more than 10 years. High dose per session and long duration of treatment are relevant risk factors for induction of NABs. In patients exclusively treated with the CP-free incobotulinumtoxin A (incoBoNT/A) preparation Xeomin® no NAB-induction has been reported so far. In patients with NABs switching to incoBoNT/A may lead to a decline of NAB-titers. In patients with NABs under treatment with a CP-containing BoNT/A-preparation it may take years of treatment until a second treatment failure (STF) becomes clinical manifest. In a cohort of 59 patients with partial STF patients’ reports on the reduction of BoNT-activity predicted the presence of NABs better than treatment related data produced by the treating physicians