Is treatment of cervical dystonia patients with botulinum toxin type B affected by a previous response to a botulinum toxin type A? Analysis of a long-term open-label study (AN072-401 EU/CD)

Abstract

Objective: To evaluate the effects of previous response to botulinum toxin (BoNT) type A treatment on long-term BoNT-B therapy in patients with cervical dystonia (CD). Methods: BoNT-B-naive CD patients previously exposed to BoNT-A were enrolled in this 2-year open-label study. Patients were classified as BoNT-A-resistant (AR) or non-A resistant (NAR). All received an initial dose of 10,000 U BoNT-B; Investigators could subsequently increase/decrease the dose (maximum 25,000 U). Efficacy was assessed via a Patient Global Visual Analogue Scale (VAS) and a Treatment Assessment Scale (TAS). Safety was assessed by evaluating adverse events (AEs), clinical laboratory data and vital signs. Results: 130 BoNT-B naive patients (67 AR; 63 NAR) were enrolled. The mean dose of BoNT-B at treatment session 7 was not statistically different between AR and NAR groups (17,949 U vs. 17,256 U). There was no statistical difference between number of AR and NAR patients who withdrew from the study (29 vs. 26). Overall, BoNT-B treatment resulted in a statistically significant benefit at Week 4 following each injection in the Patient Global VAS and the TAS during the 2-year period. Regression analysis revealed no statistically significant differences between treatment response in the AR and NAR groups for Patient Global VAS or TAS. No study drug-related serious AEs were reported. No statistically significant differences in reports of moderate or severe xerostomia, dysphagia, or injection site pain occurred between AR and NAR groups. Conclusions: Prior response to BoNT-A does not affect the efficacy or safety profile of long-term BoNT-B treatment of CD patients. Supported by Eisai Europe Ltd.