IncobotulinumtoxinA for Post-stroke Upper Limb Spasticity in Neutralizing Antibody-positive Patients after Botulinum Toxin Therapy: A Report of Two Cases.

Background: Botulinum toxin type A is an effective treatment widely used to address post-stroke spasticity. Long-term repeated treatment with botulinum toxin type A may result in reduced efficacy due to the induction of neutralizing antibodies. Based on data from a phase 3 study of incobotulinumtoxinA for post-stroke upper limb spasticity, we describe the therapeutic response to botulinum toxin type A treatment in two neutralizing antibody-positive patients previously treated with other preparations of botulinum toxin type A. Case: Two patients (a 65-year-old woman and a 36-year-old woman) with post-stroke upper limb spasticity were previously treated with onabotulinumtoxinA, and neutralizing antibodies were detected in their sera at baseline using the mouse hemidiaphragm assay. After onabotulinumtoxinA had been discontinued for at least 16 weeks, incobotulinumtoxinA (400 U) was administered in three or four injection cycles. Good therapeutic responses, manifested by a reduction of 1-2 points on the modified Ashworth scale, were noted after each injection. The patients' sera remained positive for neutralizing antibodies throughout the incobotulinumtoxinA treatment period. Discussion: These patients, who were previously treated with onabotulinumtoxinA and were neutralizing antibody positive throughout the clinical study period, showed stable therapeutic responses following incobotulinumtoxinA treatment. IncobotulinumtoxinA could be initiated for patients with neutralizing antibodies induced by onabotulinumtoxinA.