Category: Dystonia: Clinical Trials and Therapy
Objective: To compare efficacy and safety of two injection schedules of incobotulinumtoxinA for treating cervical dystonia (CD).
Background: In clinical practice, some CD patients receiving long-term botulinum toxin (BoNT) therapy report early waning of treatment benefit (even after favorable peak response) before a typical 3-month reinjection interval. This study addresses the safety and efficacy of incobotulinumtoxinA injection intervals <10 weeks to meet the needs of such patients.
Method: CD Flex (NCT01486264) was a phase IV, open-label, randomized, noninferiority study comparing 2 incobotulinumtoxinA injection schedules (short-flex: 8±2 weeks; long-flex: 14±2 weeks) in CD subjects. BoNT-responsive subjects (≥2 prior successful injections) reporting acceptable clinical benefit lasting <10 weeks were recruited. Efficacy and safety were evaluated after 8 injection cycles. The primary endpoint was the change in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) severity subscale (blinded rater) 4 weeks after injection 8. Secondary endpoints included TWSTRS total and other subscale scores. Immunogenicity was assessed in a subset of patients at baseline/post-injection 8. Safety was monitored throughout the study.
Results: 282 CD subjects were randomized (short-flex, N=142; long-flex, N=140), and 207 completed the study. Mean dosing was similar in the short-flex (272U) and long-flex (268U); mean intervals were 54 days (short-flex) and 86 days (long-flex). Significant improvements in TWSTRS-severity from study baseline to 4 weeks after cycle 8 were observed in both the short-flex (4.1 pts; P<0.0001) and long-flex (2.4 pts; P=0.002), and short-flex was noninferior to long-flex (LS mean difference=1.4 pts; P=0.0693). Responder rates (≥20% improvement in TWSTRS-severity) after injection 8 did not differ significantly between groups. Adverse events (AEs) were comparable between groups. There was no secondary loss of treatment effect due to neutralizing antibodies after 8 cycles among those tested.
Conclusion: Injection cycles <10 weeks for incobotulinumtoxinA are effective (and noninferior to longer intervals) for treating CD patients with early waning of clinical benefit. Shorter intervals did not increase AEs or lead to loss of treatment effect due to neutralizing antibodies.
To cite this abstract in AMA style:
C. Comella, R. Hauser, S. Isaacson, D. Truong, O. Oguh, J. Hui, E. Molho, M. Brodsky, E. Furr-Stimming, G. Comes, M. Hast, D. Charles. Injections of incobotulinumtoxinA at intervals less than 10 weeks are effective and safe for cervical dystonia patients with inadequate benefit from standard injection intervals [abstract]. Mov Disord. 2021; 36 (suppl 1). https://www.mdsabstracts.org/abstract/injections-of-incobotulinumtoxina-at-intervals-less-than-10-weeks-are-effective-and-safe-for-cervical-dystonia-patients-with-inadequate-benefit-from-standard-injection-intervals/. Accessed June 15, 2025.« Back to MDS Virtual Congress 2021
MDS Abstracts - https://www.mdsabstracts.org/abstract/injections-of-incobotulinumtoxina-at-intervals-less-than-10-weeks-are-effective-and-safe-for-cervical-dystonia-patients-with-inadequate-benefit-from-standard-injection-intervals/