Secondary antibody-induced treatment failure under therapy with incobotulinumtoxinA (Xeomin®) in a patient with segmental dystonia pretreated with abobotulinumtoxinA (Dysport®)

Clinical Implications of Difference in Antigenicity of Different Botulinum Neurotoxin Type A Preparations: Clinical Take-Home Messages from Our Research Pool and Literature

The three different botulinum toxin type A (BoNT/A) preparations being licensed in Europe and the U.S. differ in protein content, which seems to be a major factor influencing the antigenicity of BoNT/A. In the present study, several arguments out of our research pool were collected to demonstrate that the clinical response and antigenicity were different for the three BoNT/A preparations: some results of (1) a cross-sectional study on clinical outcome and antibody formation of 212 patients with cervical dystonia (CD) being treated between 2 and 22 years; 2) another cross-sectional study on the clinical aspects and neutralizing antibody (NAB) induction of 63 patients having developed partial secondary treatment under abobotulinum (aboBoNT/A) onabotulinumtoxin (onaBoNT/A) who were switched to incobotulinumtoxin (incoBoNT/A) in comparison to 32 patients being exclusively treated with incoBoNT/A. These results imply that (1) the presence of NAB cannot be concluded from the course of treatment, that (2) an increase in the dose and variability of outcome with treatment duration indicates the ongoing induction of NABs over time, that (3) the higher protein load of BoNT/A goes along with a higher incidence and prevalence of NAB induction and that (4) the best response to a BoNT/A is also dependent on the protein load of the preparation.

Frequency and risk factors of antibody-induced secondary failure of botulinum neurotoxin therapy

Objective

To investigate the risk factors of neutralizing antibody (NAB)–induced complete secondary treatment failure (cSTF) during long-term botulinum neurotoxin (BoNT) treatment in various neurologic indications.

Methods

This monocenter retrospective cohort study analyzed the data of 471 patients started on BoNT therapy between 1995 and 2015. Blood samples of 173 patients were investigated for NABs using the mouse hemidiaphragm test (93 with suspected therapy failure, 80 prospective study participants). The frequency of NAB-cSTF was assessed for various indications: hemifacial spasm, blepharospasm, cervical dystonia, other dystonia, and spasticity. A priori defined potential risk factors for NAB-cSTF were evaluated, and a stepwise binary logistic regression analysis was performed to identify independent risk factors.

Results

Treatment duration was 9.8 ± 6.2 years (range, 0.5–30 years; adherence, 70.6%) and number of treatment cycles 31.2 ± 22.5 (3–112). Twenty-eight of 471 patients (5.9%) had NAB-cSTF at earliest after 3 and at latest after 103 treatment cycles. None of the 49 patients treated exclusively with incobotulinumtoxinA over 8.4 ± 4.2 (1–14) years developed NAB-cSTF. Independent risk factors for NAB-cSTF were high BoNT dose per treatment, switching between onabotulinumtoxinA and other BoNT formulations (except for switching to incobotulinumtoxinA), and treatment of neck muscles.

Conclusions

We present a follow-up study with the longest duration to date on the incidence of NAB-cSTF in patients treated with various BoNT formulations, including incobotulinumtoxinA. Whereas the overall risk of NAB-cSTF is low across indications and BoNT formulations, our findings underpin the recommendations to use the lowest possible dose particularly in cervical dystonia, and to avoid unnecessary switching between different formulations.

Effective long-term treatment with incobotulinumtoxin (Xeomin®) without neutralizing antibody induction: a monocentric, cross-sectional study

Background

Among the spectrum of licensed botulinum neurotoxin preparations incobotulinumtoxin (incoBoNT/A; Xeomin®) is the only one which does not contain complex proteins. Therefore, incoBoNT/A has been suggested to have a low antigenicity, but precise estimations on incidence and prevalence of neutralizing antibody formation during long-term treatment are outstanding so far.

Methods

For the present cross-sectional study, 59 patients having exclusively been treated with incoBoNT/A (mono group) and 32 patients having been treated with other BoNT/A preparations less than nine times and who were then switched to at least 14 sessions of incoBoNT/A treatment (switch group) were recruited from one botulinum toxin outpatient clinic. Side effects and doses were extracted from the charts, and the efficacy of treatment was assessed by the patients using a visual analogue scale (0–100). The prevalence of neutralizing antibodies was tested by means of the mouse hemi-diaphragm assay (MHDA).

Findings

None of the patients in the mono and only two in the switch group had a positive MHDA-test. Across all indications and patients, mean improvement exceeded 67%. Improvement did not depend on age at onset, sex, change of dose or duration of treatment, but on disease entity. In patients with cervical dystonia, improvement was about the same in the mono and switch subgroup, but the last dose was different.

Conclusions

The present study confirms the low antigenicity of incoBoNT/A, which has immediate consequences for patient management, and the use of higher doses and shorter durations of reinjection intervals in botulinum toxin therapy.

Injectable and topical neurotoxins in dermatology: Indications, adverse events, and controversies

The use of neuromodulators for therapeutic and cosmetic indications has proven to be remarkably safe. While aesthetic and functional adverse events are uncommon, each anatomic region has its own set of risks of which the physician and patient must be aware before treatment. The therapeutic usages of botulinum toxins now include multiple specialties and multiple indications. New aesthetic indications have also developed, and there has been an increased utilization of combination therapies to combat the effects of global aging. In the second article in this continuing medical education series, we review the prevention and treatment of adverse events, therapeutic and novel aesthetic indications, controversies, and a brief overview of combination therapies.

British Neurotoxin Network recommendations for managing cervical dystonia in patients with a poor response to botulinum toxin

Botulinum toxin (BoNT) injections are an effective treatment for cervical dystonia. Approximately 20% of patients eventually stop BoNT treatment, mostly because of treatment failure. These recommendations review the different therapeutic interventions for optimising the treatment in secondary poor responder patients. Immunoresistance has become less common over the years, but the diagnosis has to be addressed with a frontalis test or an Extensor Digitorum Brevis test. In case of immunoresistance to BoNT-A, we discuss the place the different therapeutic options (BoNT-A holidays, BoNT-B injections, alternative BoNT-A injections, deep brain stimulation). When poor responders are not immunoresistant, they benefit from reviewing (1) injections technique with electromyography or ultrasound guidance, (2) muscles selection and (3) dose of BoNT. In addition, in both scenarios, a holistic approach including drug treatment, retraining and psychological support is valuable in the management of these complex and severe cervical dystonia.