Botulinum toxin therapy, immunologic resistance, and problems with available materials

The Multispecialty Toxin: A Literature Review of Botulinum Toxin

Botulinum toxin (BoNT) is a potent biological exotoxin produced from Clostridium botulinum. Although it was first used therapeutically to treat strabismus, its clinical role has since expanded rapidly over the years to include treatment of a variety of head and neck, gastrointestinal, urogenital, musculoskeletal, neurological, dermatological, and cosmetic disorders. The main purpose of this review is to provide a brief updated overview of the history, mechanism of action, and clinical applications of BoNT therapy across multiple medical specialties, including the most common adverse effects and recommended Botox dosages.

Antibody Development in Patients Treated Long-Term With OnabotulinumtoxinA for Benign Essential Blepharospasm and Hemifacial Spasm

BACKGROUND

Report the development of onabotulinumtoxinA neutralizing antibodies in patients treated consecutively for 20 years or longer for benign essential blepharospasm (BEB), hemifacial spasm (HFS), and Meige Syndrome.

METHODS

Prospective, randomized, cross-sectional study of 12 randomly selected patients from a single clinical practice that have been treated consecutively for 20 or more years with onabotulinumtoxinA for BEB, HFS, or Meige Syndrome. Serum samples were collected from each subject and analyzed for neutralizing antibody formation using the Mouse Protection Assay.

RESULTS

None of the tested patients (0%) displayed neutralizing antibodies to onabotulinumtoxinA. The mean duration of treatment was 27.5 years (range 22.1-34.1, SD 3.1, 95% confidence interval 25.45-29.50). Nine of the patients had a diagnosis of BEB, 2 HFS, and one Meige. Eleven of the 12 patients were women. There was no statistically significant difference in treatment dosage or interval over the course of treatment.

CONCLUSIONS

The data support previous studies showing low incidence of antibody formation for botulinum A toxins with this subset of long-term treated patients. The results also provide further evidence for studies that have suggested increased onabotulinumtoxinA treatment volumes and/or decreased intervals between treatments are not due to neutralizing antibody formation and secondary non-response, but rather study designs that do not consider the titration phase of initial treatments. This study is specific to long-term treated patients, and the results cannot be generalized to patients naive to treatment.

Best Practices in the Clinical Management of Progressive Supranuclear Palsy and Corticobasal Syndrome: A Consensus Statement of the CurePSP Centers of Care

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS; the most common phenotype of corticobasal degeneration) are tauopathies with a relentless course, usually starting in the mid-60s and leading to death after an average of 7 years. There is as yet no specific or disease-modifying treatment. Clinical deficits in PSP are numerous, involve the entire neuraxis, and present as several discrete phenotypes. They center on rigidity, bradykinesia, postural instability, gait freezing, supranuclear ocular motor impairment, dysarthria, dysphagia, incontinence, sleep disorders, frontal cognitive dysfunction, and a variety of behavioral changes. CBS presents with prominent and usually asymmetric dystonia, apraxia, myoclonus, pyramidal signs, and cortical sensory loss. The symptoms and deficits of PSP and CBS are amenable to a variety of treatment strategies but most physicians, including many neurologists, are reluctant to care for patients with these conditions because of unfamiliarity with their multiplicity of interacting symptoms and deficits. CurePSP, the organization devoted to support, research, and education for PSP and CBS, created its CurePSP Centers of Care network in North America in 2017 to improve patient access to clinical expertise and develop collaborations. The directors of the 25 centers have created this consensus document outlining best practices in the management of PSP and CBS. They formed a writing committee for each of 12 sub-topics. A 4-member Steering Committee collated and edited the contributions. The result was returned to the entire cohort of authors for further comments, which were considered for incorporation by the Steering Committee. The authors hope that this publication will serve as a convenient guide for all clinicians caring for patients with PSP and CBS and that it will improve care for patients with these devastating but manageable disorders.

Antibody-induced botulinum toxin treatment failure: A review and novel management approach

BACKGROUND

Botulinum neurotoxin A (BoNT/A) has been used for cosmetic indications for many decades. Consumption of BoNT/A usage has been markedly increased for a few years. Even new formulations of BoNT/A to decrease immunogenicity have been released, repeated treatment to maintain efficacy outcome is inevitable and could finally provoke immune response. In the past, prevalence of botulinum treatment failure (BTF) in cosmetic indication was rare leading to less medical concern. Current decade, case reports on BTF, especially antibody-induced botulinum toxin treatment failure (ABTF), have been increasingly revealed and risk factors associated with ABTF have been intensively studied.

AIMS

In this article, we will review antibody-induced botulinum toxin treatment failure (ABTF), risk-associated ABTF, prevalence and recent case reports of ABTF, and new approach to deal with ABTF.

METHODS

Literature search was conducted using PubMed. The relevant literatures published between January 2000 and May 2020 concerning BTF and ABTF including investigation for ABTF were included and analyzed.

RESULTS

Possible causes of BTF were summarized. ABTF could be a tip of iceberg of BTF, its prevalence, and currently, 10-year case reports of ABTF were published evidence. Risk factors and investigation methods for ABTF were also summarized. Based on previous studies and our experience, novel approach to management of ABTF was described.

CONCLUSION

Effective management of BTF is to explore causes of treatment failure. Antibodies against BoNT/A complex could be one of many possibilities. Laboratory in vitro tests could be alternative tools to decrease adverse effect and rebooting immune responses in BTF patients.

How long does the effect of botulinum toxin in neurogenic patients last? An analysis of the subset of "good responders"

BACKGROUND

The aim of this study was to assess long-term efficacity of botulinum neurotoxin A (BoNT-A) in the treatment of neurogenic detrusor overactivity (NDO).

MATERIALS AND METHODS

This was a retrospective monocentric study in a reference center. We included patients who received intradetrusor BoNT-A for NDO between 2001 and 2015. The focus of our analysis was on patients defined as "good responders" (≥ 5 injections of intradetrusor BoNT-A over a period of ≥5 years). The primary endpoint was the evaluation of long-term efficacity of BoNT-A. Recurrent NDO was monitored by the use of cystomanometry before the first injection and 1 month after each injection. The secondary objective was to assess the influence of NDO's etiology, age, and sex on the long-term efficacity of the treatment.

RESULTS

A total of 107 patients were included (60.7% with spinal cord injury [SCI] and 36.4% with multiple sclerosis [MS]). The mean follow-up period was 83.7 months (66; 120). The mean number of injections was of 8.9 (5; 21). A total of 67.3% (n = 72) of patients were still controlled by treatment at the end of their follow-up period. Therapeutic failure occurred in 30 patients (26.1%) with a cessation of BoNT-A treatment at 76 months on average (median: 82.5 months). There was no significant impact of age (P = .42), sex (P = .35), or NDO's etiology (MS vs SCI; P = .54) on long-term efficacy of BoNT-A treatment.

CONCLUSION

The results of our study indicate that the application of BoNT-A seems to be an effective and durable treatment in a large number of neurogenic patients after more than 10 years of follow-up. However, botulinum toxin tolerance occurred in approximately 25% of patients.

Application of botulinum toxin in maxillofacial field: Part III. Ancillary treatment for maxillofacial surgery and summary

Botulinum toxin (BTX) has various therapeutic indications: bruxism, square jaw, facial wrinkle, oral ulcer and maxillofacial pain, etc. In this paper, we will discuss the effectiveness of using BTX in dental implant surgery and orthognathic and orthodontic treatment. We summarized the clinical application of botulinum toxin in the maxillofacial field at the finale.

Effect of 3 Commercially Available Botulinum Toxin Neuromodulators on Facial Synkinesis: A Randomized Clinical Trial

Importance

Botulinum toxin neuromodulators are an important treatment for facial synkinesis. Whether a difference in efficacy exists among the 3 different botulinum neuromodulators used in treating this condition remains unknown.

Objective

To evaluate the effectiveness of 3 commercially available botulinum toxin neuromodulators in the treatment of facial synkinesis.

Design, Setting, and Participants

In this single-blind, 3-arm comparison randomized clinical trial, 28 patients at the Facial Nerve Center, University of Utah, Salt Lake City, were randomized to onabotulinumtoxinA, abobotulinumtoxinA, or incobotulinumtoxinA treatment. Each patient was given the Synkinesis Assessment Questionnaire (SAQ) to assess severity of synkinesis before treatment and 1, 2, and 4 weeks after treatment, and improvements were compared among the groups. Data were collected from July 3, 2012, to March 31, 2015.

Interventions

Botulinum toxin type A neuromodulator (onabotulinumtoxinA, abobotulinumtoxinA, or incobotulinumtoxinA) injected into synkinetic areas of the face.

Main Outcomes and Measures

Synkinesis assessed using the SAQ (score range, 20-100; lower scores indicate less severe synkinesis) before treatment and 1, 2, and 4 weeks after treatment.

Results

A total of 28 patients (mean [SD] age, 49.1 [18.5] years; 8 [28.6%] male and 20 [71.4%] female), with 6 patients enrolled multiple times, received 38 treatments (15 onabotulinumtoxinA, 13 abobotulinumtoxinA, and 10 incobotulinumtoxinA). No significant difference existed in baseline pretreatment SAQ scores among the 3 groups. Mean (SD) SAQ score improvement at 4 weeks was 41% (31%) for the onabotulinumtoxinA, 42% (20%) for the abobotulinumtoxinA, and 17% (18%) for the incobotulinumtoxinA groups. No significant differences were noted in SAQ score improvements among the 3 groups at weeks 1 and 2 after treatment (week 1 mean improvements of 42% in the onabotulinumtoxinA, 45% in the abobotulinumtoxinA, and 26% in the incobotulinumtoxinA groups; P = .19; week 2 mean improvements of 43% in the onabotulinumtoxinA, 46% in the abobotulinumtoxinA, and 28% in the incobotulinumtoxinA groups; P = .20). The difference in mean SAQ score improvement for abobotulinumtoxinA vs incobotulinumtoxinA from pretreatment to 4 weeks after treatment was not significant (30 vs 12 points; P = .11) despite a significant difference in mean total SAQ score for abobotulinumtoxinA vs incobotulinumtoxinA (40.34 vs 58.00; P = .02).

Conclusions and Relevance

AbobotulinumtoxinA had similar efficacy to onabotulinumtoxinA and incobotulinumtoxinA for the management of facial synkinesis up to 4 weeks after treatment. IncobotulinumtoxinA had significantly less effect on SAQ score improvement than onabotulinumtoxinA at 4 weeks, perhaps because of the shorter duration of action. Shorter intervals between treatments or larger doses may be required when using incobotulinumtoxinA treatment for facial synkinesis.

Trial Registration

clinicaltrials.gov Identifier: NCT03048383.

Level of Evidence

1.

Immunogenicity induced by botulinum toxin injections for limb spasticity: A systematic review

BACKGROUND

The imputability of neutralizing antibodies (NABs) in secondary non-response (SnR) to botulinum toxin (BoNT) injections for limb spasticity is still debated.

OBJECTIVE

This systematic literature review aimed to determine the prevalence of NABs after BoNT injections for limb spasticity and analyze their determinants and their causal role in SnR.

METHODS

We searched MEDLINE via PubMed, Cochrane and Embase databases for articles published during 1990-2018. Two independent reviewers extracted the data and assessed the quality of studies with a specific scale (according to PRISMA and STROBE guidelines). Because the techniques used to detect NABs did not influence the results, we calculated the global (all studies) sensitivity and specificity of NAB positivity to reveal SnR.

RESULTS

We included 14 articles published from 2002 to 2018 (including an epublication) describing 5 randomized controlled trials and 5 interventional and 4 observational studies. The quality was satisfactory (mean score 18/28 arbitrary units). NAB detection was the primary criterion in 5 studies and a secondary criterion in 9. In total, 1234 serum samples for 1234 participants (91% with stroke) were tested after injection. NAB prevalence was about 1%, with no significant difference among formulations. NAB positivity seemed favoured by long-duration therapy with high doses and a short interval between injections. The identification of non-response by NAB positivity had poor global sensitivity (56%) but very high specificity (99.6%). No consensual criteria were used to diagnose non-response to BoNT injection.

CONCLUSIONS

NAB prevalence is much lower after BoNT treatment for limb spasticity than cervical dystonia. Consensual criteria must be defined to diagnose non-response to BoNT injection. Because immunogenicity is not the most common cause of non-response to BoNT injection, NABs should be sought in individuals with SnR with no other cause explaining the treatment inefficacy. A test with 100% specificity is recommended. In cases for which immunogenicity is the most likely cause of non-response to BoNT injections, some biological arguments suggest trying another BoNT, but no clinical evidence supports this strategy.

Neutralizing Antibody and Botulinum Toxin Therapy: A Systematic Review and Meta-analysis

The formation of neutralizing antibodies (NAbs) directed specifically against the active neurotoxin part of the botulinum neurotoxin (BoNT) complex is often cited as a major cause of secondary non-responsiveness (SnR) to treatment. This systematic and meta-analytic review evaluates the frequency of NAbs among patients treated with BoNT therapy for any clinical indication. A comprehensive database search strategy was designed to retrieve relevant clinical data from the published literature up to April 2013. All English-language publications that analyzed NAbs prevalence in more than ten patients were included, regardless of BoNT formulation, assay method, and study design. For the meta-analysis, patients were divided into three categories: secondary nonresponse (SnR) patients, clinically responding patients and all patients, independently of BoNT responsiveness. The meta-analysis included 61 studies reporting data for 8525 patients; 4972 dystonic patients, 1170 patients with spasticity, 294 patients with urologic indications, 396 patient with hyperhidrosis, 1659 patients with glabellar line, and 34 patients with hypersalivation. Among the ‘‘all patients’’ group NAbs frequency was 20%for dystonia, 5.9%for spasticity, and 2.7% for urologic patients and 1.1% for other conditions. The prevalence of NAbs was lower (3.5%) among clinically responding patients and higher in 53.5%SnR patients. About a half of patients with SnR do not have NAbs. NAbs was high among patients treated with RIMA but it was not associated with clinical non-responsiveness. Meta-analysis of the frequency of NAbs and SnR are limited by the heterogeneity of study design and reported outcomes. Indeed the analysis of several factors that can influence the development of NAbs, i.e.,MHCof patients, frequency and site of injection, injection technique, cumulative dose, and toxin denaturation, was not specifically evaluated due to the paucity and heterogeneity of data. The identification of all these missing data should be taken into account in order to improve the methodology of future studies.

Long-Term Botulinum Toxin Dose Consistency for Treatment of Adductor Spasmodic Dysphonia

Objectives:

Botulinum toxin (BTX) injection is currently the primary and most common treatment for adductor spasmodic dysphonia (ADSD). A variety of injection strategies and dosage regimens have been described. This study reports on our experience with the dosage schedule and dosing consistency of BTX for the treatment of ADSD.

Methods:

We retrospectively reviewed our laryngeal BTX database for the period 1991 to 2005. Our strict inclusion requirements limited our selection to 13 patients who had received a minimum of 6 injections (average, 11.5; range, 6 to 19) of BTX for ADSD.

Results:

The average total dose of BTX to the larynx for each treatment episode was 3.9 units (range, 1.5 to 7.5). The total dose administered tended to trend downward among patients who began treatment from 1991 to 1998, indicating that the initial dose (usually 2.5 units per side) may have been high. Those patients who began from 1999 onward had a more stable dose, indicating that the initial dose (usually 1.5 units per side) was more suitable. The subjects underwent an average of 2.2 injections (range, 1 to 5) before reaching their optimal BTX dose. The total number of treatments performed in this group of patients was 150, of which 145 were successful (96.7%).

Conclusions:

The BTX dose for the optimal treatment of ADSD usually remains consistent over time, as does the treatment interval. An initial dose of 1.5 units per side or less appears to improve dosing stability, indicating that the initial dosing of 2.5 units per side in our study was often greater than required. The optimal BTX dose was usually ascertained by the second or third injection. In our patient population, the long-term dosing consistency of BTX confirmed that neither tachyphylaxis nor increasing sensitivity to BTX occurred during the course of treatment for ADSD.

Effects of intraplantar botulinum toxin-B on carrageenan-induced changes in nociception and spinal phosphorylation of GluA1 and Akt

Increasing evidence suggests that botulinum neurotoxins (BoNTs) delivered into the skin and muscle in certain human and animal pain states may exert antinociceptive efficacy though their uptake and transport to central afferent terminals. Cleavage of soluble N-methylaleimide-sensitive attachment protein receptor by BoNTs can impede vesicular mediated neurotransmitter release as well as transport/insertion of channel/receptor subunits into plasma membranes, an effect that can reduce activity-evoked facilitation. Here, we explored the effects of intraplantar botulinum toxin- B (BoNT-B) on peripheral inflammation and spinal nociceptive processing in an inflammatory model of pain. C57BL/6 mice (male) received unilateral intraplantar BoNT (1 U, 30 μL) or saline prior to intraplantar carrageenan (20 μL, 2%) or intrathecal N-methyl-D-aspartate (NMDA), substance P or saline (5 μL). Intraplantar carrageenan resulted in edema and mechanical allodynia in the injected paw and increased phosphorylation of a glutamate subunit (pGluA1ser845) and a serine/threonine-specific protein kinase (pAktser473) in spinal dorsal horn along with an increased incidence of spinal c-Fos positive cells. Pre-treatment with intraplantar BoNT-B reduced carrageenan evoked: (i) allodynia, but not edema; (ii) pGluA1 and pAkt and (iii) c-Fos expression. Further, intrathecal NMDA and substance P each increased dorsal horn levels of pGluA1 and pAkt. Intraplantar BoNT-B inhibited NMDA, but not substance P evoked phosphorylation of GluA1 and Akt. These results suggest that intraplantar toxin is transported centrally to block spinal activation and prevent phosphorylation of a glutamate receptor subunit and a kinase, which otherwise contribute to facilitated states.

Clinical differences between botulinum neurotoxin type A and B

In humans, the therapeutic use of botulinum neurotoxin A (BoNT/A) is well recognized and continuously expanding. Four BoNTs are widely available for clinical practice: three are serotype A and one is serotype B: onabotulinumtoxinA (A/Ona), abobotulinumtoxinA (A/Abo) and incobotulinumtoxinA (A/Inco), rimabotulinumtoxinB (B/Rima). A/Abo, A/Inco, A/Ona and B/Rima are all licensed worldwide for cervical dystonia. In addition, the three BoNT/A products are approved for blepharospasm and focal dystonias, spasticity, hemifacial spasm, hyperhidrosis and facial lines, with remarkable regional differences. These toxin brands differ for specific activity, packaging, constituents, excipient, and storage. Comparative literature assessing the relative safety and efficacy of different BoNT products is limited, most data come from reports on small samples, and only a few studies meet criteria of evidence-based medicine. One study compared the effects of BoNT/A and BoNT/B on muscle activity of healthy volunteers, showing similar neurophysiological effects with a dose ratio of 1:100. In cervical dystonia, when comparing the effects of BoNT/A and BoNT/B, results are more variable, some studies reporting roughly similar peak effect and overall duration (at a ratio of 1:66, others reporting substantially shorter duration of BoNT/B than BoNT/A (at a ratio 1/24). Although the results of clinical studies are difficult to compare for methodological differences (dose ratio, study design, outcome measures), it is widely accepted that: BoNT/B is clinically effective using appropriate doses as BoNT/A (1:40-50), injections are generally more painful, in most of the studies on muscular conditions, efficacy is shorter, and immunogenicity higher. Since the earliest clinical trials, it has been reported that autonomic side effects are more frequent after BoNT/B injections, and this observation encouraged the use of BoNT/B for sialorrhea, hyperhidrosis and other non-motor symptoms. In these indications the efficacy of toxins A and B are comparable and dose ratio is 1:25-30.

Efficacy and safety of incobotulinum toxin A in periocular rhytides and masseteric hypertrophy: side-by-side comparison with onabotulinum toxin A

BACKGROUND

Incobotulinum is a newly developed botulinum toxin A in which the complexing proteins had been removed.

OBJECTIVE

The aim was to compare the efficacy and safety of incobotulinum with onabotulinum in treating periocular rhytides and masseteric hypertrophy.

METHODS

A randomized, double-blind, split-face study was planned. Fifty-six patients were treated for periocular rhytides and the other 56 patients were treated for masseteric hypertrophy. Onabotulinum was injected on one side of the face and incobotulinum was injected on the other side of the face. The degree of periocular rhytides and masseteric hypertrophy was rated using Fitzpatrick Wrinkle Classification System (FWCS) and 10-point visual analogue scale (VAS) (0: the minimum to 10: the maximum). Objective and subjective rating was performed at pretreatment and every posttreatment follow-up visit by investigators and subjects.

RESULT

The efficacy and safety of incobotulinum were not inferior to those of onabotulinum in treating periocular rhytides and masseteric hypertrophy up to 16 weeks after injection. There were no noteworthy differences in the onset time of effect between two botulinum toxins for periocular wrinkles and masseteric hypertrophy. No adverse event was reported.

CONCLUSION

Incobotulinum provided non-inferior efficacy and safety for the treatment of periocular rhytides and masseteric hypertrophy compared with classic onabotulinum.

Clinical relevance of botulinum toxin immunogenicity

Botulinum toxin type A is a 150 kD protein produced by Clostridium botulinum, which exists in a complex with up to six additional proteins. The ability of botulinum toxin to inhibit acetylcholine release at the neuromuscular junction has been exploited for use in medical conditions characterized by muscle hyperactivity. As such, botulinum toxin is widely recommended by international treatment guidelines for movement disorders and it has a plethora of other clinical and cosmetic indications. The chronic nature of these conditions requires repeated injections of botulinum toxin, usually every few months. Multiple injections can lead to secondary treatment failure in some patients that may be associated with the production of neutralizing antibodies directed specifically against the neurotoxin. However, the presence of such antibodies does not always render patients non-responsive. The reported prevalence of immunoresistance varies greatly, depending on factors such as study design and treated indication. This review presents what is currently known about the immunogenicity of botulinum toxin and how this impacts upon patient non-response to treatment. The complexing proteins may act as adjuvants and stimulate the immune response. Their role and that of neutralizing and non-neutralizing antibodies in the response to botulinum toxin is discussed, together with an assessment of current neutralizing antibody measurement techniques. Botulinum toxin preparations with different compositions and excipients have been developed. The major commercially available preparations of botulinum toxin are Botox® (onabotulinumtoxinA; Allergan, Inc., Ireland), Dysport® (abobotulinumtoxinA; Ipsen Ltd, UK), and Xeomin® (incobotulinumtoxinA; botulinum toxin type A [150 kD], free from complexing proteins; NT 201; Merz Pharmaceuticals GmbH, Germany). The new preparations of botulinum toxin aim to minimize the risk of immunoresistance in patients being treated for chronic clinical conditions.

Profile of Xeomin® (incobotulinumtoxinA) for the treatment of blepharospasm

Even though conventional botulinum neurotoxin (BoNT) products have shown successful treatment results in patients with benign blepharospasm (BEB), the main, potential long-term side effect of BoNT use is the development of immunologic resistance due to the production of neutralizing antibody to the neurotoxin after repeated injections. Xeomin^® (incobotulinumtoxinA), a unique botulinum neurotoxin type A (BoNT/A) drug free of complexing proteins otherwise contained in all conventional BoNT/A drugs, was recently approved by US Food and Drug Administration for the treatment of cervical dystonia or blepharospasm in adults. The newly approved BoNT/A drug may overcome this limitation of previous conventional products, since it contains pure neurotoxin (150 kDa) through a manufacturing process that separates it from complexing proteins such as hemagglutinins produced by fermentation of Clostridium botulinum. Many studies have also shown that Xeomin^® has the same efficacy and safety profile as complexing protein-containing products such as Botox^® and is exchangeable with Botox^® using a simple 1:1 conversion ratio. Xeomin^® represents a new treatment option for the repeated treatment of patients with blepharospasm in that it may reduce antibody-induced therapy failure. But, long-term comparative trials in naïve patients between Xeomin^® and conventional BoNT/A drugs are required to confirm the low immunogenicity of Xeomin^®.

Meta-analysis of neutralizing antibody conversion with onabotulinumtoxinA (BOTOX®) across multiple indications

This meta-analysis evaluated the frequency of neutralizing antibody (nAb) conversion with onabotulinumtoxinA (BOTOX®; Allergan) across five studied indications. The analysis was based on large, controlled or prospective, open-label trials (durations 4 months to ≥2 years). Serum samples were analyzed for nAbs using the Mouse Protection Assay. Subjects who were antibody negative at baseline and had at least one analyzable postbaseline antibody assay result were included. The 16 clinical studies included 3,006 subjects; of these, 2,240 met the inclusion criteria for this analysis. Subjects received 1-15 treatments (mean 3.8 treatments) with onabotulinumtoxinA. Total doses per treatment cycle ranged from 10 or 20 units in glabellar lines to 20-500 units in cervical dystonia. The numbers of subjects who converted from an antibody-negative status at baseline to antibody-positive status at any post-treatment time point were: cervical dystonia 4/312 (1.28%), glabellar lines 2/718 (0.28%), overactive bladder 0/22 (0%), post-stroke spasticity 1/317 (0.32%), and primary axillary hyperhidrosis 4/871 (0.46%). Across all indications, 11/2,240 subjects (0.49%) converted from antibody negative at baseline to positive at one or more post-treatment time points, but only three subjects became clinically unresponsive to onabotulinumtoxinA at some point following a positive assay. Based on these large trials, the frequency of antibody conversion after onabotulinumtoxinA treatment is very low, and infrequently leads to loss of efficacy. © 2010 Movement Disorder Society.

Regions of botulinum neurotoxin A light chain recognized by human anti-toxin antibodies from cervical dystonia patients immunoresistant to toxin treatment. The antigenic structure of the active toxin recognized by human antibodies

This work was aimed at determining the BoNT/A L-chain antigenic regions recognized by blocking antibodies in human antisera from cervical dystonia patients who had become immunoresistant to BoNT/A treatment. Antisera from 28 immunoresistant patients were analyzed for binding to each of 32 overlapping synthetic peptides that spanned the entire L-chain. A mixture of the antisera showed that antibodies bound to three peptides, L11 (residues 141-159), L14 (183-201) and L18 (239-257). When mapped separately, the antibodies were bound only by a limited set of peptides. No peptide bound antibodies from all the patients and amounts of antibodies bound to a given peptide varied with the patient. Peptides L11, L14 and L18 were recognized predominantly. A small but significant number of patients had antibodies to peptides L27 (365-383) and L29 (379-397). Other peptides were recognized at very low and perhaps insignificant antibody levels by a minority (15% or less) of patients or had no detectable antibody with any of the sera. In the 3-dimensional structure, antibody-binding regions L11, L14 and L18 of the L-chain occupy surface areas and did not correlate with electrostatic potential, hydrophilicity/hydrophobicity, or temperature factor. These three antigenic regions reside in close proximity to the belt of the heavy chain. The regions L11 and L18 are accessible in both the free light chain and the holotoxin forms, while L14 appears to be less accessible in the holotoxin. Antibodies against these regions could prevent delivery of the L-chain into the neurons by inhibition of the translocation.

Long-term efficacy of botulinum a toxin for blepharospasm and hemifacial spasm

OBJECTIVE

To determine whether the duration of relief from symptoms in patients with essential blepharospasm (EB) or hemifacial spasm (HFS) who receive serial treatments with botulinum toxin type A (BtA) changes over the long-term.

METHODS

Retrospective longitudinal comparative analysis. The main outcome measure is the mean duration of relief from symptoms after an injection with BtA. Participants included 34 patients who received 30 or more serial BtA treatments for facial dyskinesia (EB or HFS). Repeated measures and linear regression analyses were used to determine trends and the mean duration of relief from symptoms was compared between early (first ten effective treatments) and late (last ten treatments) sessions in each group.

RESULTS

In the EB group (18 patients), the mean duration of relief was 13.5 weeks for the early and 11.4 weeks for the late sessions (P = 0.04). In the HFS group (16 patients) the mean duration of relief was 12.4 weeks in both treatment periods (P = 0.91). The duration of relief had a small negative correlation with mean late session BtA dose in the EB group (P = 0.03) but no correlation in the HFS group (P = 0.12).

CONCLUSIONS

There was a trend towards a decreased duration of relief from symptoms in patients with EB over the long-term, but no changes for HFS. The treatment remains effective in relieving symptoms and signs for both conditions.

Intrastriatal botulinum toxin abolishes pathologic rotational behaviour and induces axonal varicosities in the 6-OHDA rat model of Parkinson's disease

Central pathophysiological pathways of basal ganglia dysfunction imply a disturbed interaction of dopaminergic and cholinergic circuits. In Parkinson's disease (PD) imbalanced cholinergic hyperactivity prevails in the striatum. Interruption of acetylcholine (ACh) release in the striatum by locally injected botulinum neurotoxin A (BoNT-A) has been studied in the rat 6-hydroxydopamine (6-OHDA) model of PD (hemi-PD). The hemi-PD was induced by injection of 6-OHDA into the right medial forebrain bundle. Motor dysfunction provoked by apomorphine-induced contralateral rotation was completely reversed for more than 3 months by ipsilateral intrastriatal application of 1-2 ng BoNT-A. Interestingly, BoNT-A injected alone into the right striatum of naïve rats caused a slight transient ipsilateral apomorphine-induced rotation, which lasted only for about one month. Immunohistochemically, large axonal swellings appeared within the striatum injected with BoNT-A, which we tentatively named BoNT-A-induced varicosities. They contained either choline acetyltransferase or tyrosine hydroxylase. These findings suggest a selective inhibition of evoked release of ACh by locally applied BoNT-A. Intrastriatal application of BoNT-A may antagonize localized relative functional disinhibited hypercholinergic activity in neurodegenerative diseases such as PD avoiding side effects of systemic anti-cholinergic treatment.

Treatment of Frey's syndrome with botulinum toxin type B

OBJECTIVE

Frey's syndrome is a frequent sequela of parotidectomy, causing facial sweating and flushing because of gustatory stimuli. Although botulinum toxin type A has become first-line therapy for Frey's syndrome, some patients become resistant. In this study, we investigated whether another serotype, botulinum toxin type B, might be an effective alternative.

STUDY DESIGN

Case series with planned data collection.

SETTING

Otolaryngology department in a university hospital.

SUBJECTS AND METHODS

Seven patients aged 30 to 68 years, with severe Frey's syndrome, underwent the Minor test and had 80 U of botulinum toxin type B per cm(2) (mean total dose, 2354 U) injected intracutaneously in the mapped area of gustatory sweating. All patients were followed up for 12 months.

RESULTS

One month after treatment, six of the seven patients reported that gustatory sweating and flushing had resolved, and, in the remaining patient, these symptoms had decreased. The Minor test confirmed a significant improvement. The subjective benefits remained stable for six months in four patients and for nine months in the remaining three patients; 12 months after treatment, all patients still reported some improvement.

CONCLUSION

Botulinum toxin type B afforded symptomatic relief in a small sample of patients with Frey's syndrome and might be considered a potential alternative to botulinum toxin type A.

Botulinum toxin type B (Myobloc, NeuroBloc): a new choice in cervical dystonia

Botulinum toxin has dramatically improved the treatment of cervical dystonia. Prior to the use of botulinum toxin for many neurologic disorders, patients had few effective therapeutic options. Botulinum toxin type B (Myobloc, NeuroBloc) is a new antigenically distinct botulinum toxin with a unique structure and mechanism of action. Preclinical studies have demonstrated that im. injections of botulinum toxin type B effectively induce a dose-dependent paralysis. Controlled clinical trials have shown that it is safe and effective in alleviating symptoms associated with cervical dystonia. Given its efficacy and safety profile, the clinical use of type B toxin is anticipated to expand into other therapeutic areas.

Neutralizing antibodies and secondary therapy failure after treatment with botulinum toxin type A: much ado about nothing?

OBJECTIVES

As the indications and duration of treatment of botulinum toxin type A (BoNT-A) increase, so do reports of patients who fail therapy after initially responding well. Although a loss of efficacy is commonly thought to be associated with neutralizing antibodies (NAbs), this relationship is not strongly correlated, and other factors may play a significant role. To explore this issue, we evaluated levels of NAbs in a large selected cohort of secondary nonresponders to BoNT-A using the highly sensitive mouse phrenic nerve-hemidiaphragm assay.

METHODS

Serum samples from 503 patients treated with BoNT-A who had a variety of diagnoses were tested for the presence of NAbs.

RESULTS

Fewer than half of the patients (n = 224, 44.5%) were found to be NAb-positive, indicating that in more than half of the secondary nonresponders, lack of efficacy is not due to NAb formation. The proportion of secondary nonresponders with NAbs was greater for higher dose indications (focal spasticity and spasmodic torticollis) than for lower dose indications (blepharospasm and hemifacial spasm) and increased with shorter injection intervals. Neutralizing antibody development was independent of the commercial preparation used.

CONCLUSIONS

Our results indicate that although NAb formation does play a role in secondary treatment failure with BoNT-A, this is not the cause in all patients, and the influence of other factors needs to be investigated. Gaining a better understanding of the underlying mechanisms for secondary treatment failure may help in the prediction, diagnosis, management, and prevention of this problem.

Initial experience with imaging-guided intramuscular botulinum toxin injection in patients with idiopathic cervical dystonia

OBJECTIVE

The objective of our study was to present our initial experiences of imaging-guided intramuscular botulinum toxin (BTX) injection in patients with idiopathic cervical dystonia.

CONCLUSION

Imaging-guided BTX injection is a useful treatment technique in patients with idiopathic cervical dystonia when target muscles are located deeply or an injection must be delivered to a focal muscle area.

Clinical comparisons of botulinum neurotoxin formulations

BACKGROUND

The expanding uses of botulinum neurotoxin (BoNT) for a growing number of clinical indications, including cervical and other dystonias, adult and childhood spasticity, and hyperhidrosis, in conjunction with the emergence of new formulations of BoNT, prompt discussion of the differences in formulations, serotypes, and indications for different neurologic diseases.

REVIEW SUMMARY

This review will evaluate evidence from preclinical studies, prospective treatment studies, and direct comparative trials to discuss the differences among BoNTs and the clinical implications of using these different drugs. Data from these sources indicate that formulations of BoNT are distinct; even the same serotype formulations of BoNT serotype A have different molecular structures and sizes and therapeutic indices (reflected in different safety and efficacy profiles).

CONCLUSION

Taken together, these findings confirm that the different BoNT serotypes, including the different BoNTA formulations, are distinct therapeutic entities.

Botulinum toxin type A for rehabilitation after a spinal cord injury: a case report

A 56-year-old man became quadriplegic, bed bound, and carer-dependent secondary to cervical osteomyelitis. Three years later, he presented with generalised spasticity, crouched posture, and a large sacral pressure sore. The severe spasticity in his hips and knees prevented ischial sitting. Injections of botulinum toxin type A to both hamstrings and gastrosoleuii controlled the flexor spasticity of his lower limbs and facilitated rehabilitation and wound healing through proper positioning, wound care, stretching, and weight-bearing exercises. A few weeks later, the patient could better position himself in bed (prone lying) and on his wheelchair (ischial sitting). His spasm-related pain lessened and his mobility and activities of daily living improved. The sacral pressure sore healed completely a few months later. The patient could sleep better, feed with set-up and adaptive aids, groom, dress, and transfer himself with minimal assistance. The effects of botulinum toxin extended beyond just spasticity reduction. His upper extremity function, mobility, and social well-being were all improved through better positioning.

Long-term treatment with botulinum toxin type A in cervical dystonia has low immunogenicity by mouse protection assay

To evaluate the immunogenicity of botulinum toxin type A (BoNTA; BOTOX) in cervical dystonia (CD). Subjects diagnosed with CD for > or =1 year and previously naïve to BoNTs were treated with BoNTA in a prospective, open-label, multicenter study. Serum samples were analyzed for BoNTA neutralizing antibodies using the Mouse Protection Assay (MPA). Clinical resistance was assessed with a test injection of 20 U BoNTA placed unilaterally into the frontalis (Frontalis Antibody Test; FTAT) or corrugator muscle (Unilateral Brow Injection; UBI). Efficacy was assessed and adverse events were recorded. Of 326 subjects enrolled, 251 (77%) completed the study. Subjects received a median of 9 BoNTA treatments (mean dose per session ranged from 148.4 to 213.0 U over a mean of 2.5 years [range: 3.2 months-4.2 years]). Only 4 of 326 subjects (1.2%) tested positive for antibodies in the MPA; three of these subjects stopped responding clinically to BoNTA (of whom one also showed clinical resistance in the FTAT) and one continued to respond. Consistent improvements in the signs/symptoms of CD were noted. The most frequent treatment-related adverse events were mild to moderate weakness, dysphagia, neck pain, and injection-site pain. The current formulation of BoNTA rarely causes neutralizing antibody formation in CD subjects treated < or =4 years.

Repeated treatments with botulinum toxin type a produce sustained decreases in the limitations associated with focal upper-limb poststroke spasticity for caregivers and patients

OBJECTIVE

To assess the safety and evaluate the effects of repeated treatments with botulinum toxin type A (BTX-A) on functional disability, quality of life (QOL), and muscle tone of patients with upper-limb poststroke spasticity, as well as its effect on caregivers.

DESIGN

Multicenter, open-label, repeated-dose study.

SETTING

Thirty-five clinical sites in North America.

PARTICIPANTS

Patients (N=279) with upper-limb poststroke spasticity at 6 months or more poststroke.

INTERVENTION

Up to 5 intramuscular injections of BTX-A (200-400U) divided among the wrist, finger, thumb, and elbow flexors, with at least 200U in the wrist and finger flexors. Retreatment was permitted at 12 weeks or more after the last treatment.

MAIN OUTCOME MEASURES

Investigators rated disability using the Disability Assessment Scale and muscle tone using the Ashworth Scale. Each patient's health-related QOL was assessed by using the Stroke Adapted Sickness Impact Profile and the visual analog scale of the European Quality of Life-5 Dimensions questionnaires.

RESULTS

Patients treated with BTX-A reported improvements in muscle tone, disability, and ability to function that were statistically significant and clinically meaningful. Significant improvements were observed at week 30 and at subsequent time points in QOL in the overall group and the high-dose group.

CONCLUSIONS

Up to 5 treatments with BTX-A every 12 weeks for up to 56 weeks in patients with poststroke spasticity was well tolerated and significantly improved muscle tone, lessened disability, and improved patients' QOL. Further research is required to examine the effectiveness of repeated injections of BTX-A in patients with poststroke spasticity.

A neuronal cell-based botulinum neurotoxin assay for highly sensitive and specific detection of neutralizing serum antibodies

Clostridium botulinum neurotoxin (BoNT) serotypes A and B are widely used as pharmaceuticals to treat various neurological disorders and in cosmetic applications. The major adverse effect of these treatments has been resistance to treatment after multiple injections. Currently, patients receiving BoNT therapies and patients enrolled in clinical trials for new applications and/or new formulations of BoNTs are not routinely monitored for the formation of neutralizing antibodies, since no assay other than the mouse protection procedure is commercially available that reliably tests for the presence of such antibodies. This report presents a highly sensitive and specific neuronal cell-based assay that provides sensitive and specific detection of neutralizing antibodies to BoNT/A.

Efficacy and safety of botulinum neurotoxin type A free of complexing proteins (NT 201) in cervical dystonia and blepharospasm

Botulinum neurotoxin type A (BTX-A) weakens voluntary muscle power and is an effective therapy for focal dystonia, including cervical dystonia (CD) and benign essential blepharospasm (BEB). Antibody formation against BTX-A may lead to failure of treatment. NT 201 (XEOMIN®) is a formulation of pure BTX-A that is free of complexing proteins and therefore may have a reduced immunogenic potential in comparison with other BTX-A preparations. In clinical trials, NT 201 was found to be effective, well-tolerated and at least noninferior to a BTX-A preparation containing complexing proteins in the treatment of CD and BEB. There were no differences between the two therapies in terms of onset of action, duration and waning of effect. Future research is aimed at evaluating the benefits of NT 201.

Formation of neutralizing antibodies in patients receiving botulinum toxin type A for treatment of poststroke spasticity: a pooled-data analysis of three clinical trials

OBJECTIVE

The purpose of this study was to investigate the incidence of neutralizing antibody (NAb) formation in patients with poststroke spasticity treated with a specific formulation of botulinum toxin type A (BoNTA).

METHODS

Data from 3 previous clinical trials of BoNTA in patients with upper and/or lower limb spasticity were pooled and evaluated. Study 1 was a randomized, double-blind, placebo-controlled, multicenter trial of BoNTA in patients aged >/=21 years who had experienced a stroke >6 months before the initiation of the study. Study 2 was an open-label extension of study 1. Study 3 was a randomized, double-blind, multicenter trial of a specific BoNTA formulation in patients aged >/= 21 years who had experienced a stroke >/=6 weeks before study entry. Patients with a fixed contracture of the studied limb were excluded from participation in studies 1 and 2. Serum samples were obtained from each patient before each BoNTA treatment and at the end of each study. The mouse protection assay (MPA) was used for detection of NAbs to BoNTA in serum.

RESULTS

A total of 235 individual patients with post-stroke spasticity were enrolled in the 3 trials, including 126, 111 (all of whom participated in study 1), and 109 in studies 1, 2, and 3, respectively. Study 1 had an equal (50.0%) distribution of male and female patients (63/63). The distribution of male and female patients was 56 (50.5%) and 55 (49.5%), respectively, in study 2, and 55 (50.5%) and 54 (49.5), respectively, in study 3. The mean (SD) ages of patients in studies 1, 2, and 3 were 61.4 (13.8), 61.5 (14.1), and 58.5 (13.9) years, respectively. The MPA was used for detection of NAbs to BoNTA in the serum samples of 191 patients, including 64 from study 1, 111 from study 2 (55 of these patients were placebo recipients and 56 received their first BoNTA injection in study 1), and 72 (a sample was not obtained for 1 patient who had not received an injection) from study 3. The median number of BoNTA treatments received by these patients was 2 (range, 1-4 treatments) over a period lasting from 12 to 42 weeks. The mean dose of BoNTA was 241 U (range, 100-400 U), with a maximum dose of 960 U in any 1 patient. NAbs to BoNTA were detected in the serum sample of 1/191 (0.5%) patient who had participated in studies 1 and 2. Based on muscle-tone scores (3 and 4 for wrist and fingers, respectively) on a 5-point Ashworth Scale (0 = none to 4 = severe), the patient did not appear to exhibit a clinical response to BoNTA at any time during the studies.

CONCLUSION

Formation of NAbs was rare (1/191) in this group of adults with poststroke spasticity from three 12- to 42-week clinical trials who received >/=1 treatment with a specific BoNTA formulation at doses ranging from 100 to 400 U.