Production of anti-neurotoxin antibody is enhanced by two subcomponents, HA1 and HA3b, of Clostridium botulinum type B 16S toxin–haemagglutinin

Complexing Protein-Free Botulinum Neurotoxin A Formulations: Implications of Excipients for Immunogenicity

The formation of neutralizing antibodies is a growing concern in the use of botulinum neurotoxin A (BoNT/A) as it may result in secondary treatment failure. Differences in the immunogenicity of BoNT/A formulations have been attributed to the presence of pharmacologically unnecessary bacterial components. Reportedly, the rate of antibody-mediated secondary non-response is lowest in complexing protein-free (CF) IncobotulinumtoxinA (INCO). Here, the published data and literature on the composition and properties of the three commercially available CF-BoNT/A formulations, namely, INCO, Coretox® (CORE), and DaxibotulinumtoxinA (DAXI), are reviewed to elucidate the implications for their potential immunogenicity. While all three BoNT/A formulations are free of complexing proteins and contain the core BoNT/A molecule as the active pharmaceutical ingredient, they differ in their production protocols and excipients, which may affect their immunogenicity. INCO contains only two immunologically inconspicuous excipients, namely, human serum albumin and sucrose, and has demonstrated low immunogenicity in daily practice and clinical studies for more than ten years. DAXI contains four excipients, namely, L-histidine, trehalosedihydrate, polysorbate 20, and the highly charged RTP004 peptide, of which the latter two may increase the immunogenicity of BoNT/A by introducing neo-epitopes. In early clinical studies with DAXI, antibodies against BoNT/A and RTP004 were found at low frequencies; however, the follow-up period was critically short, with a maximum of three injections. CORE contains four excipients: L-methionine, sucrose, NaCl, and polysorbate 20. Presently, no data are available on the immunogenicity of CORE in human beings. It remains to be seen whether all three CF BoNT/A formulations demonstrate the same low immunogenicity in patients over a long period of time.

"Pseudo"-Secondary Treatment Failure Explained via Disease Progression and Effective Botulinum Toxin Therapy: A Pilot Simulation Study

BACKGROUND

The objective of this study was to provide evidence from a simple simulation. In patients with focal dystonia, an initial good response to botulinum neurotoxin (BoNT) injections followed by a secondary worsening does not necessarily arise from an antibody-induced secondary treatment failure (NAB-STF), but may stem from a "pseudo"-secondary treatment failure (PSEUDO-STF).

METHODS

The simulation of the outcome after BoNT long-term treatment was performed in four steps: 1. The effect of the first single BoNT injection (SI curve) was displayed as a 12-point graph, corresponding to the mean improvement from weeks 1 to 12. 2. The remaining severity of the dystonia during the nth injection cycle was calculated by subtracting the SI curve (weighted by the outcome after n - 1 cycles) from the outcome after week 12 of the (n - 1)th cycle. 3. A graph was chosen (the PRO curve), which represents the progression of the severity of the underlying disease during BoNT therapy. 4. The interaction between the outcome during the nth BoNT cycle and the PRO curve was determined.

RESULTS

When the long-term outcome after n cycles of BoNT injections (applied every 3 months) was simulated as an interactive process, subtracting the effect of the first cycle (weighted by the outcome after n - 1 cycles) and adding the progression of the disease, an initial good improvement followed by secondary worsening results. This long-term outcome depends on the steepness of the progression and the duration of action of the first injection cycle. We termed this response behavior a "pseudo"-secondary treatment failure, as it can be compensated via a dose increase.

CONCLUSION

A secondary worsening following an initial good response in BoNT therapy of focal dystonia might not necessarily indicate neutralizing antibody induction but could stem from a "PSEUDO"-STF (a combination of good response behavior and progression of the underlying disease). Thus, an adequate dose adaptation must be conducted before diagnosing a secondary treatment failure in the strict sense.

Microtoxin for Improving Pore Size, Skin Laxity, Sebum Control, and Scars: A Roundtable on Integrating Intradermal Botulinum Toxin Type A Microdoses Into Clinical Practice

BACKGROUND

In aesthetic clinical practice, botulinum toxin type A (BoNT-A) is best known for its use as a neuromodulator for the treatment of dynamic facial lines; however, when injected intradermally as microdroplets, BoNT-A can improve skin quality and overall skin appearance.

OBJECTIVES

To discuss key aspects of microtoxin use in clinical practice and provide expert guidance on utilization.

METHODS

As part of a continuing medical education lecture series and roundtable, the authors discussed key aspects of microtoxin patient selection, injection technique, and safety.

RESULTS

The experiences of expert faculty are shared here. Clinical experience is consistent with reported data. Microtoxin can be used to reduce pore size, sebum production, rosacea, acne, and fine lines, and to improve jawline and neck definition. Intradermal injection can also be employed for the improvement of transverse neck lines as well as for the safe prevention and management of scars and keloids.

CONCLUSIONS

Expanding the use of BoNT-A, a predictable, minimally invasive, and affordable treatment to address commonly encountered complaints is appealing. The authors have found that making patients aware of microtoxin as a treatment option results in an increased interest in and utilization of BoNT-A, and high satisfaction among appropriately selected patients.

Therapeutic Applications of Botulinum Neurotoxins in Veterinary Medicine

Botulinum neurotoxins (BoNTs) are emerging as multipurpose therapeutic compounds for the treatment of several different syndromes involving peripheral and central nervous systems, and muscular and musculoskeletal disorders both in human and veterinary medicine. Therefore, the study of BoNTs is rapidly developing and identifying newly produced BoNT variants. Efforts should be made to clarify the biological and pharmacological characteristics of these novel BoNTs as well as the natural ones. The high potential of BoNTs as a therapeutic compound for medical syndromes lies in its ability to reach a specific cell type while bypassing other cells, thus having mild or no side effects. In this paper the recent developments in BoNTs are reviewed with the aim of analyzing the current knowledge on BoNTs' biological mechanisms of action, immunogenicity, formulations, and therapeutic applications in the veterinary field, highlighting advantages and drawbacks and identifying the gaps to be filled in order to address research priorities.

No Secondary Treatment Failure during Incobotulinumtoxin-A Long-Term Treatment Demonstrated by the Drawing of Disease Severity

The aim of this study was to detect clinical hints regarding the development of secondary treatment failure (STF) in patients with focal dystonia who were exclusively treated with incobotulinumtoxin/A (incoBoNT/A). In total, 33 outpatients (26 with idiopathic cervical dystonia, 4 with Meige syndrome and 3 with other cranial dystonia) who were treated with repeated injections of incoBoNT/A for a mean period of 6.4 years without interruptions were recruited to draw the course of their disease severity (CoD) from the onset of symptoms to the onset of BoNT therapy (CoDB graph) and from the onset of BoNT therapy to recruitment (CoDA graph). At the time of recruitment, the patients assessed the change in severity as a percentage of the severity at the onset of BoNT therapy. Blood samples were taken to test the presence of neutralizing antibodies (NABs) using the mouse hemidiaphragm assay (MHDA). Patients reported an improvement of about 70% with respect to the mean. None of the patients tested positive for MHDA. Three different types of CoDB and three different types of CoDA graphs could be distinguished. The patients with different CoDB graphs reported different long-term outcomes, but there was no significant difference in long-term outcomes between patients with different CoDA graphs. None of the patients produced a CoDA graph with an initial improvement and a secondary worsening as a hint for the development of STF. A primary non-response was not observed in any of the patients. During long-term treatment with BoNT/A, NABs and/or STF may develop. However, in the present study on patients with incoBoNT/A long-term monotherapy, no hints for the development of NABs or STF could be detected, underlining the low antigenicity of incoBoNT/A.

Improving the Efficacy of Botulinum Toxin for Cervical Dystonia: A Scoping Review

Cervical dstonia (CD) is a chronic disorder with a significant detrimental impact on quality of life, requiring long-term treatment. Intramuscular injections of botulinum neurotoxin (BoNT) every 12 to 16 weeks have become the first-line option for CD. Despite the remarkable efficacy of BoNT as a treatment for CD, a significantly high proportion of patients report poor outcomes and discontinue the treatment. The reasons that drive sub-optimal response or treatment failure in a proportion of patients include but are not limited to inappropriate muscle targets and/or BoNT dosing, improper method of injections, subjective feeling of inefficacy, and the formation of neutralizing antibodies against the neurotoxin. The current review aims to complement published research focusing on the identification of the factors that might explain the failure of BoNT treatment in CD, highlighting possible solutions to improve its outcomes. Thus, the use of the new phenomenological classification of cervical dystonia known as COL-CAP might improve the identification of the muscle targets, but more sensitive information might come from the use of kinematic or scintigraphic techniques and the use of electromyographic or ultrasound guidance might ensure the accuracy of the injections. Suggestions are made for the development of a patient-centered model for the management of cervical dystonia and to emphasize that unmet needs in the field are to increase awareness about the non-motor spectrum of CD, which might influence the perception of the efficacy from BoNT injections, and the development of dedicated rehabilitation programs for CD that might enhance its effectiveness.

The Immunology of Botulinum Toxin Therapy: A Brief Summary

Like all proteins foreign to the human body, also botulinum toxin (BT) is antigenic and may stimulate an immune response with formulation of antibodies (BT-AB). Affected patients may no longer respond to BT therapy and various degrees of BT-AB related therapy failure (ABF) may result. We want to review the immunological interactions between BT and BT-AB, the prevalence, the time course and the risk factors for BT-AB formation as they are related to the treatment algorithms, the patient's immune system and to exogenic factors. Special emphasis is placed on various features of the BT drugs including the specific biological activity (SBA) as a predictor of their antigenicity. Quantitative detection of BT-AB by the mouse diaphragm assay will be demonstrated. As ABF may have serious consequences for patients affected, careful risk factor analysis is warranted to reduce them wherever possible.

Immunogenicity to Botulinum Toxin Type A: A Systematic Review With Meta-Analysis Across Therapeutic Indications

BACKGROUND

Botulinum toxin A (BTX-A) is commonly employed as a neuromodulator in several neurological diseases and aesthetic indications. Formation of neutralizing antibodies (NAbs) after BTX-A injections may be responsible for treatment failure.

OBJECTIVES

The authors sought to quantify the prevalence of NAbs following treatment with Abobotulinumtoxin A, Incobotulinumtoxin A, and Onabotulinumtoxin A for therapeutic indications.

METHODS

An electronic systematic search (2000-2020) of PubMed, Scopus, Web of Science, and Embase was conducted. Original studies reporting prevalence of NAbs were included. Data analysis was carried out through open meta-analysis softwares.

RESULTS

Forty-three studies involving 8833 patients were included in this meta-analysis. The incidence of NAbs was 1.8% (summary estimate = 0.018, 95% CI [0.012, 0.023]); a meta-regression analysis revealed that BTX-A duration was significantly associated with increased incidence of NAbs (P = 0.007). Patients with dystonia had the highest incidence (7.4%) of NAbs against BTX-A (summary estimate = 0.074, 95% CI = [0.045, 0.103], I2 = 93.%, P < 0.00) followed by patients with spasticity (6.7%) and urological indications (6.2%). Abobotulinumtoxin A was associated with the highest incidence of NAbs (7.4%) (summary estimate = 0.074, 95% CI = [0.053, 0.096], I2 = 97.24%, P < 0.00) by the Incobotulinumtoxin A and Onabotulinumtoxin A 0.3% (summary estimate <0.003%, 95% CI = [-0.001, 0.007], P < 0.003).

CONCLUSIONS

Although the overall incidence of NAbs following BTX-A injections is relatively low, patients with secondary nonresponse to BTX-A with no apparent causes should be investigated for NAbs. A consensus needs to be developed for the optimal management of such patients.

LEVEL OF EVIDENCE: 2

Immunogenicity of Botulinum Toxin Formulations: Potential Therapeutic Implications

Botulinum neurotoxins (BoNTs) are proteins produced by bacteria of the Clostridium family. Upon oral ingestion, BoNT causes the neuroparalytic syndrome botulism. There are seven serotypes of BoNT (serotypes A-G); BoNT-A and BoNT-B are the botulinum toxin serotypes utilized for therapeutic applications. Treatment with BoNT injections is used to manage chronic medical conditions across multiple indications. As with other biologic drugs, immunogenicity after long-term treatment with BoNT formulations may occur, and repeated use can elicit antibody formation leading to clinical nonresponsiveness. Thus, approaching BoNT treatment of chronic conditions with therapeutic formulations that minimize stimulating the host immune response while balancing patient responsiveness to therapy is ideal. Immunogenicity is a clinical limitation in many settings that use biologic drugs for treatment, and clinically relevant immunogenicity reduction has been achieved through engineering smaller protein constructs and reducing unnecessary formulation components. A similar approach has influenced the evolution of BoNT formulations. Three BoNT-A products and one BoNT-B product have been approved by the Food and Drug Administration (FDA) for therapeutic use: onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB; a fourth BoNT-A product, daxibotulinumtoxinA, is currently under regulatory review. Additionally, prabotulinumtoxinA is a BoNT-A product that has been approved for aesthetic indications but not therapeutic use. Here, we discuss the preclinical and clinical immunogenicity data that exist within the scientific literature and provide a perspective for considering immunogenicity as a key factor in choice of BoNT formulation.

High-Dose Neuromodulators: A Roundtable on Making Sense of the Data in Real-World Clinical Practice

BACKGROUND

For aesthetic treatment with botulinum neurotoxin type A (BoNTA), interest in maximizing treatment duration and efficacy has prompted study of doses higher than those used in registration studies. As data emerge, it is important that physicians understand how to apply study findings to their own practice so that patient demand is satisfied.

OBJECTIVES

To bring together leading experts in neuromodulators for a roundtable discussion on the implications of high-dose BoNTA studies for patient care.

METHODS

The authors reviewed and discussed recent data from high-dose BoNTA studies for abobotulinum toxin A, incobotulinum toxin A, and Oonobotulinumtoxin A.

RESULTS

Discussion focused on the challenges of data interpretation and extrapolation of study findings for real-world patient care. The authors participated in a candid discussion of whether the observed improvements in treatment duration and patient satisfaction warrant treatment with high-dose regimens delivered as high-concentration injections. Safety was also discussed, as well as economic considerations for both practices and patients. Of note, for BoNTA products, the registration dose, when administered in a smaller total volume, appears to give rise to more durable results than those observed in pivotal trials, implicating product concentration as an important consideration. Importantly, at higher doses, extended duration of effect does not appear to be at the expense of natural-looking results.

CONCLUSIONS

While the authors provide considerations for the development of individual clinical practice, there is no one-size-fits-all recommendation. It may be that "high-dose" BoNTA is in reality the optimal dose; however, important economic considerations may prevent rapid uptake for all patients.

Clinical Improvement After Treatment With IncobotulinumtoxinA (XEOMIN®) in Patients With Cervical Dystonia Resistant to Botulinum Toxin Preparations Containing Complexing Proteins

This study investigated the clinical long-term effect of incobotulinumtoxinA (incoBoNT/A) in 33 cervical dystonia (CD) patients who had developed partial secondary therapy failure (PSTF) under previous long-term botulinum toxin (BoNT) treatment. Patients were treated four times every 12 weeks with incoBoNT/A injections. Physicians assessed treatment efficacy using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) at the baseline visit, week 12 and 48. Patients rated quality of life of CD with the Craniocervical Dystonia Questionnaire (CDQ-24). Titres of neutralizing antibodies(NAB) were determined at start of the study and after 48 weeks. All patients had experienced significant and progressive worsening of symptoms in the last 6 months of previous BoNT treatment. Repeated incoBoNT/A injections resulted in a significant reduction in mean TWSTRS at week 12 and 48. Patients' rating of quality of life was highly correlated with TWSTRS but did not change significantly over 48 weeks. During the 48 weeks -period of incoBoNT/A treatment NAB titres decreased in 32.2%, did not change in 45.2%, and only increased in 22.6% of the patients. Thus, repeated treatment with the low dose of 200 MU incoBoNT/A over 48 weeks provided a beneficial clinical long-term effect in PSTF and did not booster titres of NAB.

Therapeutically relevant features of botulinum toxin drugs

Botulinum toxin (BT) drugs were introduced in the late 1980s. They are now used worldwide in a large number of indications. This huge market and its future opportunities have attracted a number of companies about to enter the competition with projects to develop new BT drugs. We want to outline features of BT drugs that are relevant for their therapeutic use and - with that - are also relevant to compare and to evaluate new BT drugs and to guide their further development. BT drugs may vary in their content of botulinum neurotoxin, complexing proteins and excipients. Their manufacturing is complex and directly influences core features of the final drug. It includes breeding, purification, botulinum neurotoxin activation, stabilisation, potency control, labelling and testing, specific biological activity and packaging. The manufacturer's support concerning product documentation and support, reliability of drug supply, counterfeit protection and - last but not least - competitive pricing is also important. Further developments include the indication spectrum, the market penetration, the drug's duration of action, liquid preparations, transdermal applications, improving antigenicity and a bio-similarity registration process. Most projects, however, will try to produce Botox® analogs at reduced sale prices.

Immunogenicity Associated with Botulinum Toxin Treatment

Botulinum toxin (BoNT) has been used for the treatment of a variety of neurologic, medical and cosmetic conditions. Two serotypes, type A (BoNT-A) and type B (BoNT-B), are currently in clinical use. While considered safe and effective, their use has been rarely complicated by the development of antibodies that reduce or negate their therapeutic effect. The presence of antibodies has been attributed to shorter dosing intervals (and booster injections), higher doses per injection cycle, and higher amounts of antigenic protein. Other factors contributing to the immunogenicity of BoNT include properties of each serotype, such as formulation, manufacturing, and storage of the toxin. Some newer formulations with purified core neurotoxin devoid of accessory proteins may have lower overall immunogenicity. Several assays are available for the detection of antibodies, including both structural assays such as ELISA and mouse-based bioassays, but there is no consistent correlation between these antibodies and clinical response. Prevention and treatment of antibody-associated non-responsiveness is challenging and primarily involves the use of less immunogenic formulations of BoNT, waiting for the spontaneous disappearance of the neutralizing antibody, and switching to an immunologically alternate type of BoNT.

The role of human serum albumin and neurotoxin associated proteins in the formulation of BoNT/A products

Botulinum neurotoxin (BoNT) is synthesized as a progenitor toxin complex (PTC) by Clostridium botulinum. This PTC comprises, in addition to the neurotoxin itself, neurotoxin associated proteins (NAPs) which are composed of three hemagglutinins and one non-toxic, non-hemagglutinin protein. After oral ingestion, these NAPs protect the neurotoxin from the low pH and proteases in the gastrointestinal tract and play a role in the entry via the intestinal barrier. Two of the three therapeutically used botulinum neurotoxin serotype A (BoNT/A) products (onabotulinumtoxinA and abobotulinumtoxinA) contain different amounts of NAPs, while incobotulinumtoxinA, lacks these proteins. In addition, human serum albumin (HSA) that is supposed to stabilize BoNT/A is added at different concentrations. Up to now, the function of the NAPs and HSA after parenteral therapeutic application is not completely understood. To investigate the influence of NAPs and HSA on potency of BoNT/A, we used the ex vivo mouse phrenic nerve hemidiaphragm assay. Increasing doses of HSA resulted dose-dependently in a more pronounced effect of BoNT/A. Though, a plateau was reached with concentrations of 0.8 mg/ml HSA and higher, the accessory addition of NAPs in a relevant amount (4 ng/ml) did not further enhance the effect of BoNT/A. In conclusion, in our ex vivo assay an adequate concentration of HSA prevented BoNT/A from loss of effect and supplementary NAPs did not alter this effect. A confirmation of these data in an in vivo assay is still lacking. However, it might be supposed that even in clinically applied BoNT/A products an increase of HSA accompanied by the avoidance of NAPs could potentially reduce the injected dose and, thus, the risk of unwanted side effects, the treatment costs as well as the risk of a secondary therapy failure due to BoNT/A neutralizing antibodies.

Clinical Pharmacology of Botulinum Toxin Drugs

Botulinum toxin (BT) has changed from a deadly poison to a novel therapeutic principle for a large number of disorders in many medical areas.BT drugs are special in many ways: they are biologicals, their active ingredient BT is not patentable, their spectrum of clinical applications is extremely broad, their dose range is enormous, their mode of action is local and their life cycles are special.This review covers BT's therapeutic mode of action, time course of action, target tissues, pharmacological profile, adverse effects, interactions, potency labelling and antigenicity as well as BT's therapeutic preparations.

Comparison of neurotoxic potency between a novel chinbotulinumtoxinA with onabotulinumtoxinA, incobotulinumtoxinA and lanbotulinumtoxinA in rats

Four botulinumtoxin type A (BoNT/A) products, onabotulinumtoxinA (A/Ona), incobotulinumtoxinA (A/Inco), lanbotulinumtoxinA (A/Lan) and chinbotulinumtoxinA (A/Chin), are applied in the present study, among which A/Chin is newly produced. We aimed to compare the neurotoxic potency of these toxins by the gauge of muscle strength reduction. Furthermore, potential molecular and cellular mechanisms were also explored. According to our data, muscle strengths in the four toxin groups were all significantly decreased after injection for 1 week. A/Chin achieved the most obvious reduction in muscle strength as compared to the other three products at the dose of 0.5 U. However, there was no difference between the four toxins when increased to 2 U. As the toxins wore off, muscle strength recovered to basal level 12 weeks postinjection. We further measured the expression levels of key factors involved in neuromuscular junction stabilization and muscle genesis. Our results showed that nicotinic acetylcholine receptor, myogenic regulatory factors and muscle-specific receptor tyrosine kinase were all significantly upregulated upon BoNT/A treatment. Consistent with the result of muscle strength, A/Chin had the most obvious induction of gene expression. Moreover, we also found local inflammation response following BoNT/A injection. Owing to lack of complexing proteins, both A/Inco and A/Chin stimulated relatively lighter inflammation compared to that of A/Ona and A/Lan groups. In conclusion, our study provided evidence for the efficacy of the novel A/Chin and its similar functional mode to that of A/Ona, A/Inco and A/Lan. In addition, A/Chin has superiority in inducing muscle paralysis and inflammation stimulation, which may indicate faster onset and longer duration of this novel A/Chin.

Characterization of Hemagglutinin Negative Botulinum Progenitor Toxins

Botulism is a disease involving intoxication with botulinum neurotoxins (BoNTs), toxic proteins produced by Clostridium botulinum and other clostridia. The 150 kDa neurotoxin is produced in conjunction with other proteins to form the botulinum progenitor toxin complex (PTC), alternating in size from 300 kDa to 500 kDa. These progenitor complexes can be classified into hemagglutinin positive or hemagglutinin negative, depending on the ability of some of the neurotoxin-associated proteins (NAPs) to cause hemagglutination. The hemagglutinin positive progenitor toxin complex consists of BoNT, nontoxic non-hemagglutinin (NTNH), and three hemagglutinin proteins; HA-70, HA-33, and HA-17. Hemagglutinin negative progenitor toxin complexes contain BoNT and NTNH as the minimally functional PTC (M-PTC), but not the three hemagglutinin proteins. Interestingly, the genome of hemagglutinin negative progenitor toxin complexes comprises open reading frames (orfs) which encode for three proteins, but the existence of these proteins has not yet been extensively demonstrated. In this work, we demonstrate that these three proteins exist and form part of the PTC for hemagglutinin negative complexes. Several hemagglutinin negative strains producing BoNT/A, /E, and /F were found to contain the three open reading frame proteins. Additionally, several BoNT/A-containing bivalent strains were examined, and NAPs from both genes, including the open reading frame proteins, were associated with BoNT/A. The open reading frame encoded proteins are more easily removed from the botulinum complex than the hemagglutinin proteins, but are present in several BoNT/A and /F toxin preparations. These are not easily removed from the BoNT/E complex, however, and are present even in commercially-available purified BoNT/E complex.

Cost-Effectiveness of Incobotulinumtoxin-A with Flexible Treatment Intervals Compared to Onabotulinumtoxin-A in the Management of Blepharospasm and Cervical Dystonia

BACKGROUND

Incobotulinumtoxin-A (Xeomin(®), Merz Pharmaceuticals, Sydney, New South Wales) is a formulation of botulinum neurotoxin type A that is free of complexing proteins.

OBJECTIVE

To assess the cost-effectiveness of incobotulinumtoxin-A administered with flexible treatment intervals compared to onabotulinumtoxin-A (Botox(®), Sydney, New South Wales) in blepharospasm and cervical dystonia from the perspective of Australian health care providers.

METHODS

A Markov state transition model was developed to perform a cost-utility analysis to compare the cost and health benefits of incobotulinumtoxin-A to that of onabotulinumtoxin-A. The cost-utility analysis compared incobotulinumtoxin-A treatment, given at minimum intervals of 6 weeks and maximum intervals of 20 weeks, with onabotulinumtoxin-A treatment, given at minimum intervals of 12 weeks and maximum intervals of 20 weeks. The Markov model consisted of three health states and followed patients in weekly cycles for 5 years. Only direct health care costs associated with the acquisition and administration of type A botulinum neurotoxins were included. Utility values were derived from a prospective, open-labeled cohort study. The primary outcome measure was the incremental cost per quality-adjusted life-year. Univariate and probabilistic sensitivity analyses were conducted.

RESULTS

Incobotulinumtoxin-A was cost-effective compared to onabotulinumtoxin-A in both blepharospasm and cervical dystonia, with an incremental cost/quality-adjusted life-year gained of A$ 25,588 and A$ 23,794, respectively.

CONCLUSIONS

Incobotulinumtoxin-A administered at flexible treatment intervals determined by the needs of the patient was found to be a cost-effective treatment option when compared to the administration of onabotulinumtoxin-A in the Australian health care system. The option to administer incobotulinumtoxin-A according to the needs of the patient resulted in patients experiencing symptoms for a fewer number of weeks compared to onabotulinumtoxin-A given at minimum 12-week intervals.

The role of neurotoxins in the periorbital and midfacial areas

Initially popularized for the treatment of strabismus and blepharospasm, injection of botulinum neurotoxin has become the most commonly performed cosmetic treatment in the United States. Injection techniques have been particularly well-studied in the midface and periocular region, and patient satisfaction tends to be very high. We review the salient differences among available neurotoxins, how to optimally reconstitute them, how to inject the forehead, glabella, lateral canthal lines ("crow's feet"), infralid region, and transverse nasal lines ("bunny lines"), how to sculpt the brow, and how to manage potential complications.

Detection of the HA-33 protein in botulinum neurotoxin type G complex by mass spectrometry

Background

The disease botulism is caused by intoxication with botulinum neurotoxins (BoNTs), extremely toxic proteins which cause paralysis. This neurotoxin is produced by some members of the Clostridium botulinum and closely related species, and is produced as a protein complex consisting of the neurotoxin and neurotoxin-associated proteins (NAPs). There are seven known serotypes of BoNT, A-G, and the composition of the NAPs can differ between these serotypes. It was previously published that the BoNT/G complex consisted of BoNT/G, nontoxic-nonhemagglutinin (NTNH), Hemagglutinin 70 (HA-70), and HA-17, but that HA-33, a component of the protein complex of other serotypes of BoNT, was not found.

Methods

Components of the BoNT/G complex were first separated by SDS-PAGE, and bands corresponding to components of the complex were digested and analyzed by LC-MS/MS.

Results

Gel bands were identified with sequence coverages of 91 % for BoNT/G, 91 % for NTNH, 89 % for HA-70, and 88 % for HA-17. Notably, one gel band was also clearly identified as HA-33 with 93 % sequence coverage.

Conclusions

The BoNT/G complex consists of BoNT/G, NTNH, HA-70, HA-17, and HA-33. These proteins form the progenitor form of BoNT/G, similar to all other HA positive progenitor toxin complexes.

IncobotulinumtoxinA in aesthetics: Russian multidisciplinary expert consensus recommendations

BACKGROUND

Although there are various international consensus recommendations on the use of botulinum neurotoxin type A (BoNT/A) in facial aesthetics, there are no global or Russian guidelines on the optimal dose of incobotulinumtoxinA, free from complexing proteins, within specific aesthetic indications. This article reports the outcomes of two expert consensus meetings, conducted to review and analyze efficacy and tolerability data for incobotulinumtoxinA in various facial aesthetic indications and to give expert consensus recommendations to ensure best clinical practice among Russian clinicians.

METHODS

Thirteen dermatology and/or plastic surgery experts attended meetings held in Paris, France (November 2013), and Moscow, Russia (March 2014). The expert group reviewed and analyzed the existing evidence, consensus recommendations, and Russian experts' extensive practical experience of incobotulinumtoxinA in aesthetics to reach consensus on optimal doses, potential dose adjustments, and injection sites of incobotulinumtoxinA for facial aesthetics.

RESULTS

All experts developed guidance on the optimal doses for incobotulinumtoxinA treatment of different regions of the upper and lower face. The expert panel agreed that there are no differences in the efficacy and duration of the effect between the four BoNT/As that are commercially available for facial aesthetic indications in Russia and that, when administered correctly, all BoNT/As can achieve optimal results. Experts also agreed that nonresponse to BoNT/A can be caused by neutralizing antibodies.

CONCLUSION

On the basis of the scientific and clinical evidence available for incobotulinumtoxinA, coupled with the extensive clinical experience of the consensus group, experts recommended the optimal doses of incobotulinumtoxinA effective for treatment of wrinkles of the upper and lower face to achieve the expected aesthetic outcome. These first Russian guidelines on the optimal use of incobotulinumtoxinA for augmentation of glabellar lines, periorbital wrinkles, forehead lines, bunny lines, perioral wrinkles, depressor anguli oris, mentalis, masseters and platysmal bands, and performing the Nefertiti lift, are presented here.

Botulinum neurotoxin type A induces TLR2-mediated inflammatory responses in macrophages

Botulinum neurotoxin type A (BoNT/A) is the most potent protein toxin and causes fatal flaccid muscle paralysis by blocking neurotransmission. Application of BoNT/A has been extended to the fields of therapeutics and biodefense. Nevertheless, the global response of host immune cells to authentic BoNT/A has not been reported. Employing microarray analysis, we performed global transcriptional profiling of RAW264.7 cells, a murine alveolar macrophage cell line. We identified 70 genes that were modulated following 1 nM BoNT/A treatment. The altered genes were mainly involved in signal transduction, immunity and defense, protein metabolism and modification, neuronal activities, intracellular protein trafficking, and muscle contraction. Microarray data were validated with real-time RT-PCR for seven selected genes including tlr2, tnf, inos, ccl4, slpi, stx11, and irg1. Proinflammatory mediators such as nitric oxide (NO) and tumor necrosis factor alpha (TNFα) were induced in a dose-dependent manner in BoNT/A-stimulated RAW264.7 cells. Increased expression of these factors was inhibited by monoclonal anti-Toll-like receptor 2 (TLR2) and inhibitors specific to intracellular proteins such as c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 mitogen-activated protein kinase (MAPK). BoNT/A also suppressed lipopolysaccharide-induced NO and TNFα production from RAW264.7 macrophages at the transcription level by blocking activation of JNK, ERK, and p38 MAPK. As confirmed by TLR2-/- knock out experiments, these results suggest that BoNT/A induces global gene expression changes in host immune cells and that host responses to BoNT/A proceed through a TLR2-dependent pathway, which is modulated by JNK, ERK, and p38 MAPK.

Comparison between botulinum neurotoxin type A2 and type A1 by electrophysiological study in healthy individuals

Botulinum neurotoxin type A1 (BoNTs/A1) and type B (BoNT/B) have been used for treating hyperactive muscle contractions. In the present study, we compared the effect of botulinum neurotoxin subtype A2 (6.5 mouse LD50 units A2 neurotoxin, A2NTX) and onabotulinumtoxinA (10 mouse LD50 units BoNT/A1 product) by measuring the compound muscle action potentials (CMAPs) before and after administration. In total, 8 healthy subjects were examined in the present study. A2NTX was injected into the extensor digitorum brevis (EDB) muscle, followed by onabotulinumtoxinA injection into the contralateral EDB muscle after 16 weeks. The CMAP amplitudes from the EDB, abductor hallucis (AH), and abductor digiti minimi pedis (ADM) muscles were measured after each BoNT injection on days 1, 3, 7, 14, 28, 56, 84, and 112 to assess the effect of the toxin. On day 14, both A2NTX and onabotulinumtoxinA produced an approximately 70% decline in EDB CMAP amplitude compared to the baseline values; significant reduction of the CMAP continued through day 112. The CMAP amplitudes from neighboring muscles (AH and ADM) remained intact throughout the study period, except for a slight but significant drop at day 28 after onabotulinumtoxinA injection compared to A2NTX. The current findings indicate that small doses (6.5 units and 10 units) of A2NTX and onabotulinumtoxinA have at least comparable onset and duration of action, although similar clinical effects were obtained with lower dose using A2NTX.

Comparison of the immunogenicity of botulinum toxin type A and the efficacy of A1 and A2 neurotoxins in animals with A1 toxin antibodies

One issue with botulinum toxin type A products is a reduced therapeutic response in patients that have been injected with frequent dosing over a prolonged period. A possible cause of this is hemagglutinin, found in progenitor toxins, displaying adjuvant activity, enhancing antibody production against the toxin. We investigated whether there is any difference in immunogenicity between the LL toxin-derived subtype A1 (A1LL) and the neurotoxin-derived subtypes A1 and A2 (A1NTX and A2NTX, respectively), and investigated whether A2NTX is effective in animals which produce antibodies against A1LL. Neutralizing antibodies were detected in the A1LL-administered group; however, they were not detected in swine and rabbits administered multiple doses of A2NTX. These results indicate that A2NTX has a lower immunogenicity than A1LL. In rats with neutralizing antibodies, produced by the administration of A1LL, that were administered either A1NTX or A2NTX, A2NTX showed more potent inhibitory neuromuscular transmission than A1NTX. In human sera immunized with the botulinum toxoid vaccine (containing LL, L, and M toxoid derived subtype A1) reacted with either A1NTX or A2NTX, A2NTX showed more potent inhibitory neuromuscular transmission than A1NTX. This suggests that A2NTX has a greater therapeutic value in humans who have neutralizing antibodies against the A1 toxin.

C Terminal Half Fragment (50 kDa) of Heavy Chain Components ofClostridium botulinumType C and D Neurotoxins Can Be Used as an Effective Vaccine

Recombinant whole heavy chains (H, 100 kDa) and their N-terminal (Hn, 50 kDa) and C-terminal (Hc, 50 kDa) half fragments of Clostridium botulinum type C and D neurotoxins were expressed as glutathione S-transferase (GST) fusion proteins in Escherichia coli. GST eliminated-preparations of H (10 microg), Hn (5 microg), Hc (5 microg), or a mixture of Hn (5 microg) and Hc (5 microg) of types C and D were mixed with an equal volume of adjuvant, and then were twice injected into mice subcutaneously. After immunization, the mice were challenged with up to 10(6) the minimum lethal doses (MLD)/0.5 ml of C or D toxin, the type of which was same as that of the immunogens. All of the mice immunized with antigens except for Hn survived against 10(5) to 10(6) MLD/0.5 ml of the toxins, but the mice immunized with Hn were killed by 100 MLD/0.5 ml. The mice immunized with a mixture of C-Hc and D-Hc, each 5 microg, also showed a high level of resistance against both C and D toxins. Antibody levels immunized with GST fused-or GST eliminatedpreparation were quite similar. These results indicate that recombinant GST-fused Hc can be used as a safe and effective vaccine for type C and D botulism in animals. It also became clear that one time inoculation with a large amount of C-Hc or D-Hc, 100 microg, is useful for vaccine trials in mice.

Expression and purification of neurotoxin-associated protein HA-33/A from Clostridium botulinum and evaluation of its antigenicity

BACKGROUND

Botulinum neurotoxin (BoNT) complexes consist of neurotoxin and neurotoxin-associated proteins. Hemagglutinin-33 (HA-33) is a member of BoNT type A (BoNT/A) complex. Considering the protective role of HA-33 in preservation of BoNT/A in gastrointestinal harsh conditions and also its adjuvant role, recombinant production of this protein is favorable. Thus in this study, HA-33 was expressed and purified, and subsequently its antigenicity in mice was studied.

METHODS

Initially, ha-33 gene sequence of Clostridium botulinum serotype A was adopted from GenBank. The gene sequence was optimized and synthesized in pET28a (+) vector. E. coli BL21 (DE3) strain was transformed by the recombinant vector and the expression of HA-33 was optimized at 37°C and 5 h induction time.

RESULTS

The recombinant protein was purified by nickel nitrilotriacetic acid agarose affinity chromatography and confirmed by immunoblotting. Enzyme Linked Immunoassay showed a high titer antibody production in mice.

CONCLUSION

The results indicated a highly expressed and purified recombinant protein, which is able to evoke high antibody titers in mice.

IncobotulinumtoxinA (Xeomin): background, mechanism of action, and manufacturing

IncobotulinumtoxinA is the third botulinum neurotoxin type A (BoNTA) to be approved for aesthetic use in the United States. This article introduces the new product with an overview of clinical applications and a discussion of the neurotoxin's molecular structure. The role and clinical relevance of complexing proteins in BoNTA products are discussed. Finally, incobotulinumtoxinA's mechanism of action is described.

Consensus panel's assessment and recommendations on the use of 3 botulinum toxin type A products in facial aesthetics

In this summary article, the authors discuss the characteristics of abobotulinumtoxinA, incobotulinumtoxinA, and onabotulinumtoxinA. With 3 neuromodulators available in the US market, comparisons between and among products will invariably be made, so arguments for the most effective facial aesthetic uses of each neuromodulator are presented. Topics addressed in this article include patient expectations, toxin reconstitution and preparation, patient positioning, differences among products, the role of complexing proteins, and dosing and injection strategies. Recommendations are also provided by treatment area.

Immunogenicity of botulinum toxins

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response.

Immunogenicity of botulinum toxins

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response.

Botulinum neurotoxins: mechanism of action

Botulinum neurotoxins are used clinically for conditions characterized by hyperexcitability of peripheral nerve terminals and hypersecretory syndromes. These neurotoxins are synthesized as precursor proteins with low activity, but their effects are mediated by the active form of the neurotoxin through a multistep mechanism. Following a high-affinity interaction with a protein receptor and polysialogangliosides on the synaptic membrane, botulinum neurotoxins enter the neuron and causes a sustained inhibition of synaptic transmission. The active neurotoxin is part of a high-molecular-weight complex that protects the neurotoxin from proteolytic degradation. Although complexing proteins do not affect diffusion of therapeutic neurotoxin, they may lead to the development of neutralizing antibodies that block responsiveness to it. Nerve terminal intoxication is reversible and its duration varies for different BoNT serotypes. Although it was previously assumed that botulinum neurotoxins exert effects only on the peripheral synapses, such as the neuromuscular junction, there is now substantial evidence that these neurotoxins affect neurotransmission at distal central nervous system sites as well.

Immunogenicity of botulinum toxins

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response.

Application of purified botulinum type a neurotoxin to treat experimental trigeminal neuropathy in rats and patients with urinary incontinence and prostatic hyperplasia

Type A neurotoxin (NTX) of Clostridium botulinum was purified by a simple procedure using a lactose gel column. The toxicity of this purified toxin preparation was retained for at least 1 year at -30°C by supplementation with either 0.1% albumin or 0.05% albumin plus 1% trehalose. When purified NTX was used to treat 49 patients with urinary incontinence caused by either refractory idiopathic or neurogenic detrusor overactivity, 36 patients showed significant improvement in symptoms. These beneficial effects were also observed in cases of prostatic hyperplasia. The results obtained with NTX were similar to that of Botox. The effects of NTX on trigeminal neuralgia induced by infraorbital nerve constriction (IoNC) in rats were also studied. Trigeminal ganglion neurons from ipsilateral to IoNC exhibited significantly faster onset of FM4-64 release than sham-operated contralateral neurons. Intradermal injection of NTX in the area of IoNC alleviated IoNC-induced pain behavior and reduced the exaggerated FM4-64 release in trigeminal ganglion neurons.

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.

Compositional differences among commercially available botulinum toxin type A

PURPOSE OF REVIEW

Since the advent of botulinum neurotoxin (BoNT) in the facial cosmetic field, it has become the leading nonsurgical cosmetic procedure in the USA, and several different formulations are currently in use. The aim of this study is to review the major 'players' in order to help the physician understand the clinically relevant dissimilarities between the products and by that promote treatment efficacy and patient satisfaction.

RECENT FINDINGS

The different available formulations can be classified into two groups by the existence of absence of complexing proteins. Most of the influence that was previously attributed to these proteins has been found to be less relevant clinically, the immune response being the only remaining issue with supporting evidence in the literature.

SUMMARY

Botulinum toxin type A is widely utilized in the cosmetic field, and it seems that all available and approved formulations are both well tolerated and effective in treating facial rhytids. The treating physician must be familiar with the differences between all the products, especially the fact that they are not interchangeable in respect to their recommended dosage.

Antibody-induced secondary treatment failure in a patient treated with botulinum toxin type A for glabellar frown lines

Botulinum toxin type A (BTX-A) preparations are widely used nonsurgical treatments for facial wrinkles. Higher doses of BTX-A are also used for therapeutic purposes in the treatment of conditions involving increased muscle tone, such as cervical dystonia. The phenomenon of antibody-induced treatment failure is well known in the therapeutic setting, but reports are also emerging following cosmetic use of BTX-A. We describe the case of a 41-year-old female nurse who developed secondary treatment failure during 6 years of BTX-A treatment for glabellar lines. After a good response to the first BTX-A injection, the intensity and duration of effect decreased after subsequent treatments. Antibody tests revealed a high titer of neutralizing anti-BTX-A antibodies. This case shows secondary treatment failure due to the production of neutralizing antibodies following administration of BTX-A formulations for cosmetic purposes and demonstrates that immunogenicity of BTX-A preparations is an important consideration, even in the cosmetic setting.

Five-year experience with incobotulinumtoxinA (Xeomin(®) ): the first botulinum toxin drug free of complexing proteins

In 2005, incobotulinumtoxinA (Xeomin(®) ), a new botulinum toxin (BT) type A drug without complexing proteins (CPs), became available. This paper reviews the specific features of Xeomin(®) and the experience gathered with it during the last 5 years. Compared with conventional BT drugs, Xeomin(®) 's extended shelf live and its simplified temperature restrictions indicate that CPs are not necessary for BT drug stability. Its reduced molecular size does not translate into diffusion differences, and its potency labelling is identical to that of onabotulinumtoxinA (Botox(®) ). With a reduced content of inactivated botulinum neurotoxin, Xeomin(®) should have reduced antigenicity. Lack of CP's may further reduce antigenicity. Xeomin(®) 's therapeutic efficacy against cervical dystonia, blepharospasm and spasticity has been proven in large randomised, double-blind and placebo-controlled studies leading to registrations in many countries. Additional successful clinical use in axillary hyperhidrosis, hemifacial spasm, re-innervation synkinesias and hypersalivation as well as in dystonia and spasticity in extended doses and throughout extended observation periods has been documented meanwhile. Lack of reported cases of antibody-induced therapy failure (ABF), as to date, support the hypothesis of an improved antigenicity.

The complete genome sequence ofClostridium botulinumF str. 230613, insertion sites, and recombination of BoNT gene clusters

The genomic DNA of Clostridium botulinum F str. 230613 includes a chromosome (3 993 083 bp, 3502 coding sequences (CDs)) and a plasmid (17 531 bp, 25 CDs). The arrangement of the botulinum neurotoxin serotype F (BoNT/F) gene cluster, a 15-kb (or longer) fragment including the bont gene and other relevant genes, and its different insertion sites in C. botulinum A2 and C. botulinum F were formulated. Mobile elements and virulence factors were analysed. We also found a cell adhesion and pectin lyase domain–containing protein, which may function in attaching to the host and as a pectin lyase. The nine BoNT gene clusters of group I C. botulinum strains were located at three sites in the chromosome of C. botulinum F str. 230613. This study showed the inserting inclination of BoNT/A1 tend to have gene clusters inserted at site 3, BoNT/F at site 2, and BoNT/A2 at site 1. Additionally, we found the recombination event between the BoNT gene clusters of sites 2 and 3, a mechanism that contributed to the diversity of the BoNT gene cluster arrangement.

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^®.

Efficacy and safety of incobotulinumtoxinA (NT 201, Xeomin) in the treatment of blepharospasm-a randomized trial

IncobotulinumtoxinA (NT 201, Xeomin) is a highly purified botulinum neurotoxin type A formulation, free from complexing proteins. A randomized, placebo-controlled, double-blind trial of efficacy and safety compared incobotulinumtoxinA (up to 50 U per eye) to placebo administered in a single treatment session to patients with blepharospasm. All patients had documented satisfactory response to 2 previous treatments with botulinum neurotoxin type A other than incobotulinumtoxinA and had Jankovic Rating Scale severity subscores ≥ 2. Patients (n = 109) were randomized in a 2:1 ratio to incobotulinumtoxinA or placebo and followed up to 20 weeks; 94% completed the study. A significant difference was observed in the primary efficacy variable (change in Jankovic Rating Scale severity subscore rated by an independent rater 6 weeks following treatment), favoring incobotulinumtoxinA by 1.0 point (95% CI [0.5-1.4]; P < .001). Functional impairment, as measured by the Blepharospasm Disability Index, improved by 0.5 points (95% CI [0.2-0.7]; P = .002) compared with placebo. There was a strong correlation between the 2 scale scores. In addition, all secondary outcome measures favored incobotulinumtoxinA. Patients rated the mean therapeutic effect of incobotulinumtoxinA significantly better than placebo (P < .001). Adverse events were reported in 70.3% of incobotulinumtoxinA patients and 58.8% of placebo patients. Eyelid ptosis (18.9% vs 5.9%), dry eye (18.9% vs 11.8%), and dry mouth (14.9% vs 2.9%) occurred most frequently. Tolerability was rated good/very good by 91.9% of incobotulinumtoxinA versus in 85.2% of placebo patients. In conclusion, incobotulinumtoxinA was well tolerated and was associated with statistically significant and clinically relevant reductions in blepharospasm severity and functional impairment.

Complexing proteins in botulinum toxin type A drugs: a help or a hindrance?

Botulinum toxin type A is a high molecular weight protein complex containing active neurotoxin and complexing proteins, the latter of which, it is believed, protect the neurotoxin when in the gastrointestinal tract, and may facilitate its absorption. Comparisons of conventional botulinum toxin type A drugs that include complexing proteins with the complexing protein-free formulation of Xeomin^® strongly suggest that complexing proteins do not affect diffusion of the active neurotoxin. Studies of Xeomin have also shown that complexing proteins do not enhance product stability in storage. However, complexing proteins may stimulate antibody development against botulinum toxin type A. Numerous observational studies have been published showing that some patients receiving conventional botulinum toxin may develop neutralizing antibodies, leading to antibody-induced therapy failure. Studies have shown that Xeomin is not associated with the development of neutralizing antibodies in animal models or in patients. In conclusion, complexing proteins do not contribute to the stability of botulinum toxin type A drugs and do not contribute to their therapeutic effects, but may be associated with a secondary nonresponse due to the development of neutralizing antibodies.

An update on the neurologic applications of botulinum toxins

Initially used to treat strabismus in the 1970s, botulinum toxin now has more than a hundred possible medical applications. Its utility in neurologic conditions has largely involved treating movement disorders (particularly dystonia and conditions with muscle hyperactivity), although practically any hyperkinetic movement disorder may be relieved by botulinum toxin, including hemifacial spasm, tremor, tics, myoclonus, and spasticity. Although initially thought to inhibit acetylcholine release only at the neuromuscular junction, botulinum toxins are now recognized to inhibit acetylcholine release at autonomic cholinergic nerve terminals, as well as peripheral release of neurotransmitters involved in pain regulation. Thus, their use in neurology has been expanded to include headache and other pain syndromes, as well as hypersecretory disorders. This article highlights some of the common neurologic conditions currently improved by botulinum toxins and reviews the scientific evidence from research studies and clinical experience with these conditions.

Xeomin in the treatment of cervical dystonia

BACKGROUND AND PURPOSE

Botulinum toxin type A (BoNT/A) is a highly effective and well-tolerated treatment for focal dystonias. The BoNT/A in Botox and Dysport is part of a high-molecular-weight complex that contains hemagglutinins and other non-toxic proteins, whilst Xeomin is a highly purified BoNT/A free of such complexing proteins. In the largest controlled study of BoNT/A published to date (Neurology 2005; 64: 1949), it was demonstrated that Xeomin is non-inferior to Botox and has 1:1 efficacy in the treatment of cervical dystonia. A possible limitation of continued BoNT/A treatment is antibody development. Based on its physiochemical properties and toxicological evidence, Xeomin is expected to have a reduced incidence of non-responders after long-term treatment compared with other marketed BoNT/A products.

METHODS AND RESULTS

In our ongoing open-label study, 100 patients suffering from cervical dystonia are continuously treated with Xeomin; 50 patients were treated de novo, the remaining patients had been previously treated with Botox, Dysport or NeuroBloc/Myobloc. All patients showed negative results in antibody testing at the beginning of Xeomin treatment. During continuous treatment with Xeomin up to 2 years, patients continued to respond well to Xeomin treatment.

CONCLUSION

The treatment was well tolerated and no patient has developed neutralizing antibodies as measured using the sensitive mouse hemidiaphragma assay within these first 2 years.