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Final Program


Final Program

Spasticity / Movement Disorders

515 - Cycling of A and B Serotypes of Botulinum Toxins to Circumvent Secondary Nonresponse

Friday, February 20, 2026
5:00 PM - 6:30 PM AST
Case Diagnosis: Dystonia secondary to TBI 

Case Description: A 63-year-old male with right wrist and finger flexor dystonia secondary to traumatic brain injury began onabotulinumtoxinA treatment in 1994. After years of substantial benefit, he developed complete clinical nonresponse. In 2003, elevated neutralizing antibody titers confirmed immunoresistance to botulinum toxin type A, prompting a transition to rimabotulinumtoxinB with significant improvement. His care was transitioned to a different physiatrist in 2009, at which time, he surprisingly responded well to onabotulinumtoxinA again, achieving therapeutic benefit for 2 cycles before effectiveness was lost. He was switched back to rimabotulinumtoxinB treatments with good therapeutic response. However, its effectiveness gradually diminished, at which point in 2023, he transitioned to incobotulinumtoxinA with excellent response for 3 cycles before therapeutic effectiveness was lost. He returned back to rimabotulinumtoxinB treatments with good therapeutic response.

Discussions:

Neutralizing antibodies against onabotulinumtoxinA develop in upto 13.9% of patients. Risk increases with frequent, high-dose injections. While most patients with neutralizing antibodies don't experience complete treatment failure, some patients develop severe resistance to treatment. This case highlights a potential long-term solution to improve efficacy of treatments in this patient population. The patient’s transiently restored sensitivity to BotulinumNeurotoxin-A formulations after periods of using BotulinumNeurotoxin-B suggests that immunity to the neurotoxin may not be permanent.

Conclusions:

For patients with clinically significant neutralizing antibodies, alternating between both toxin types A and B may be a viable option. Immunity against the core neurotoxin itself may be transient, analogous to tetanus vaccine responses, making cycling between different toxins a potentially viable treatment option. Additionally, if antibodies target complex proteins, formulations without these proteins—such as incobotulinumtoxinA—may be effective. Finally, longer-acting formulations like daxibotulinumtoxinA could be advantageous by reducing the treatment frequency, allowing the immune system extended periods without booster treatments.