Objective: To assess clinical treatment intervals and duration of response for abobotulinumtoxinA in the management of pediatric and adult spasticity and assess preclinical data that might explain differences in the clinical profiles of botulinum toxin-A (BoNT-A) products.

Background: BoNT-A is recommended as a first-line treatment for patients living with spasticity. Guidelines recommend treatment no more frequently than every 12 weeks. However, many patients experience waning of effect with symptom recurrence in the final weeks of each injection cycle.

Method: We assessed currently available clinical evidence on duration of response in patients treated with abobotulinumtoxinA from pivotal trials in adults with upper limb or lower limb, or children with lower limb spasticity. Flexible study designs allowed patients to be reinjected after Week 12 according to clinical need. Data from recent non-clinical investigations into BoNT-A characteristics were also reviewed to investigate why differences in duration may be observed.

Results: At doses tested, a long duration of response was observed. Pivotal trials of abobotulinumtoxinA reveal a large proportion of patients did not require retreatment for >12 weeks (% patients injected Week-16 or later: adult upper limb: 35%; adult lower limb: 20.1%; pediatric lower limb: 74.0%).For certain outcomes, efficacy was dose dependent, though not assessed for duration. Pre-clinical research has established BoNT-A duration of response to be dose-dependent. Research showed no differences in relative molecular activity of BoNT-A products, but significantly more active neurotoxin in abobotulinumtoxinA (at total FDA recommended doses for adult upper and lower limb spasticity and total tested doses for pediatric lower limb spasticity) than either onabotulinumtoxinA or incobotulinumtoxinA.

Conclusion: AbobotulinumtoxinA, when dosed optimally, offers patients a long duration of response. This may give patients sustained symptom relief between injections and decrease the chance of patients experiencing a waning of effect before the next injection can be provided. We hypothesize that clinically observed long duration of response with abobotulinumtoxinA is a result of the amount of active BoNT-A.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/abobotulinumtoxina-evidence-for-long-duration-of-response/