Time to Retreatment after AbobotulinumtoxinA (Dysport) Injections in Children with Dynamic Equinus Foot Deformity
26 April 2017 (online)
Introduction: Knowing when a child who is being treated with botulinum toxin for spasticity secondary to cerebral palsy (CP) will require retreatment is difficult. Minimum interval between injections is 12 weeks; however, longer duration of therapeutic benefit is of potential interest in this population. A recent Phase III study demonstrated superiority of a single injection of abobotulinumtoxinA versus placebo in improving hypertonia (Modified Ashworth Scale, MAS) of the gastrosoleus complex and in Physicians Global Assessment (PGA) of treatment response. We describe the different times when patients having received abobotulinumtoxinA met eligibility criteria for retreatment.
Methods: All patients attended post-injection visits at weeks 4 and 12. Discretionary visits were planned at weeks 16–22–28 to evaluate eligibility criteria for retreatment. Patients were then included if eligible in the open-label study. Investigators considered the need for retreatment based on efficacy (MAS <1 grade vs. baseline, PGA back to ≤0, or other criteria) and in absence of safety risks.
Results: Of 158 patients having received abobotulinumtoxinA in double-blind study, 134 patients entered open-label phase. The majority (74%) of abobotulinumtoxinA treated patients did not require retreatment for ≥16 weeks; of these, 17.7% did not meet eligibility criteria until week 28 or later ([Table 1]).
Conclusion: Majority of patients deriving a therapeutic benefit that lasted ≥16 weeks; time-to-retreatment did not appear to be dose related. Only 10.8% of patients met criteria for retreatment at week 12. These data highlight the need to determine injection intervals on an individual basis. Longer injection intervals may be beneficial in reducing number of injections (and associated burden) required in this pediatric population.
Keywords: abobotulinumtoxinA, disport, interval, cerebral palsy, duration of action