Disclosures: Joyce Oleszek, MD: Ipsen (Products/Services: Yes) (Consultant/Advisory Board)

Objective: We report dosing data from a phase 3 pivotal study of repeat, upper limb abobotulinumtoxinA (aboBoNT-A) injections in children with CP.

Design: Randomized, double-blind study (NCT02106351).Setting : International study in 32 specialist centers.Participants : Children (2-17y) with cerebral palsy and spasticity in ≥1 upper-limb.

Interventions: In the first treatment cycle, 210 children were randomly allocated to treatment with abobotulinumtoxinA 8U/kg, 16U/kg or a low 2U/kg control dose injected into the primary target muscle group (PTMG; elbow or wrist flexors) and additional upper-limb muscles according to presentation. During Cycles 2–4, children received 8U/kg or 16U/kg.

Main Outcome Measures: AboBoNT-A exposure was analyzed by the individual muscles treated, regardless of whether they were selected as PTMG; dose ranges (min-max) are presented across all 4 cycles for the 8U/kg and 16U/kg groups.

Results: 212 children were randomized, of which 210 received ≥1 aboBoNT-A injection. Across all 4 cycles, the brachialis was injected in 89.5% of children (dose range 0.8–6U/kg), the brachioradialis in 83.8% (0.4–3U/kg), the flexor carpi ulnaris in 82.4% (0.5–3U/kg) and the flexor carpi radialis in 79.5% (0.5–4U/kg). The next most frequently injected muscle was the pronator teres, which was targeted in 70.0% of children (0.3–3U/kg). Other frequently injected upper limb muscles were the adductor pollicis (54.3%, 0.3–1U/kg), pronator quadratus (44.8%, 0.1–2U/kg), flexor digitorum superficialis (39.0%, 0.5–4U/kg), flexor digitorum profundus (28.6%, 0.5–2U/kg), flexor pollicis brevis/opponens pollicis (27.6%, 0.3–1U/kg) and biceps (27.1%, 0.5–6U/kg). AboBoNT-A was generally well-tolerated at these doses. Muscular weakness was reported in 4.3% of children in the 8U/kg group and 5.7% in the 16U/kg group.Conclusions: These data provide information on the dose ranges used during this phase 3 study, which were well-tolerated. In line with the protocol, most children received injections into the elbow and wrist flexors. However, there was a wide variety of other upper-limb muscles injected as physicians tailored injection patterns to individual children.

Level of Evidence: Level I

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/dosing-from-a-phase-3-pivotal-study-of-abobotulinumtoxina-injection-in-upper-limb-muscles-in-pediatric-patients-with-cerebral-palsy/