Disclosures: Khashayar Dashtipour, MD, PhD: Allergan: Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received, Speaker/Honoraria includes speakers bureau, symposia, and expert witness
Ipsen: Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received, Speaker/Honoraria includes speakers bureau, symposia, and expert witness
Merz: Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received
Revance: Consultant/Advisory Board
US World Meds: Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received, Speaker/Honoraria includes speakers bureau, symposia, and expert witness

Objective: Evaluate long-term safety and efficacy of repeat treatment cycles of abobotulinumtoxinA (aboBoNTA) in the management of cervical dystonia (CD) using 2mL dilution.

Design: This was an open-label extension of a 12-week, randomized, placebo-controlled trial (NCT01753336).

Setting: U.S. Outpatient neurology clinics.

Participants: Adults (≥18 years) with idiopathic CD who completed the double-blind phase or who entered the open-label phase early due to lack of efficacy.

Interventions: In open-label Cycle 1, patients previously in the placebo group either received aboBoNT-A 500U if they were toxin-naïve at baseline or 250-500U, based on their onabotulinumtoxinA dose prior to study entry. Patients previously in the aboBoNT-A group continued with their previous dose. In Cycles 2 and 3, dose adjustments were limited to ≤250U/cycle and maximal total dose limited to 1000U/cycle. Retreatment occurred every 12-16 weeks for ≤3 open-label cycles (clinical judgment).

Main Outcome Measures: Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and adverse events (AEs).

Results: Of 112 treated patients, 92 completed the Week 36 visit (Cycle 3, Week 12). Mean TWSTRS-Total score decreased from 42.2 at baseline to 30.1 at Week 36 (change: -11.7). At each cycle, TWSTRS scores decreased from Day 1 to Week 4 and increased from Week 4 to Week 12 without returning to Day 1 values. Mean TWSTRS scores at Weeks 4 and 12 were lower for each successive cycle (no worsening to baseline). Seventy patients reported AEs (most frequent: dysphagia, muscular weakness, neck pain, 10.7% each). Most were not considered treatment-related and none led to discontinuation/death.

Conclusions: Results were consistent with the double-blind study and showed aboBoNTA at approved doses using 2mL injection volume remained effective and well-tolerated over 4 treatment cycles in patients with CD. Results with aboBoNTA using 2mL dilution were similar to those with 1mL dilution, allowing dosing flexibility for clinicians and greater individualized care.

Level of Evidence: Level II

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/abobotulinumtoxina-using-2-ml-dilution-maintain-durable-functional-improvements-across-multiple-treatment-cycles/