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

Real-world Implications of Botulinum Neurotoxin A Immunoresistance for Consumers and Aesthetic Practitioners: Insights from ASCEND Multidisciplinary Panel

Background

As long-term, regular aesthetic botulinum neurotoxin A (BoNT-A) use becomes more commonplace, it is vital to understand real-world risk factors and impact of BoNT-A immunoresistance. The first Aesthetic Council on Ethical Use of Neurotoxin Delivery panel discussed issues relating to BoNT-A immunoresistance from the health care professionals' (HCPs') perspective. Understanding the implications of BoNT-A immunoresistance from the aesthetic patient's viewpoint allows HCPs to better support patients throughout their aesthetic treatment journey.

Methods

A real-world consumer study surveyed 363 experienced aesthetic BoNT-A recipients across six Asia-Pacific territories. The survey mapped participants' BoNT-A aesthetic treatment journey and characterized awareness and attitudes relating to BoNT-A immunoresistance and treatment implications. At the second Aesthetic Council on Ethical use of Neurotoxin Delivery meeting, panelists discussed survey findings and developed consensus statements relating to the impact of BoNT-A immunoresistance on the aesthetic treatment journey.

Results

Aesthetic BoNT-A patients' depth of knowledge about BoNT-A immunoresistance remains low, and risk/benefit communications need to be more lay-friendly. The initial consultation is the most important touchpoint for HCPs to raise awareness of BoNT-A immunoresistance as a potential side effect considering increased risk with repeated high-dose treatments. HCPs should be cognizant of differences across BoNT-A formulations due to the presence of certain excipients and pharmacologically unnecessary components that can increase immunogenicity. Standardized screening for clinical signs of secondary nonresponse and a framework for diagnosing and managing immunoresistance-related secondary nonresponse were proposed.

Conclusion

These insights can help patients and HCPs make informed treatment decisions to achieve desired aesthetic outcomes while preserving future treatment options with BoNT-A.

[Five-year follow-up after neurosurgery complicated by facial neuropathy]

BACKGROUND

Botulinum toxin A (BTA) injections are effective for facial neuropathy. However, there is insufficient number of studies devoted to long-term management of these patients.

OBJECTIVE

To evaluate the effectiveness and safety of BTA therapy in patients with facial neuropathy after neurosurgical interventions.

MATERIAL AND METHODS

The study included 86 patients with facial neuropathy after surgical treatment of posterior cranial fossa and cerebellopontine angle tumors. All ones were divided into 2 groups: group I (main) - 57 patients with BTA prescribed early after facial nerve injury, group II (control) - 29 people undergoing exercise therapy, as well as special exercises and acupressure of painful muscle cords. The Sunnybrook Facial Grading Scale (SFGS) was used to assess facial symmetry and synkinesis, the Facial Disability Index (FDI scale) - to assess the quality of life. Overall duration of the study was 5 years (control points: 6 months, 1, 2, 3 and 5 years).

RESULTS

The SFGS scores after 1, 2, 3 and 5 years were significantly better in the main group (resting symmetry p<0.01, voluntary movement symmetry p<0.01, synkinesis p<0.01, general condition of facial muscles p<0.01). Scores of physical and social functioning were significantly higher in the main group after 1 (p<0.01), 2 (p<0.01), 3 (p<0.01) and 5 years (p<0.01) after surgery. There was no need to change BTA dosage over 5 years. Thus, this form of BTA may be the most effective for synkinesis of facial muscles.

CONCLUSION

Correction of synkinesis caused by facial neuropathy requires long-term follow-up and long-term treatment. BTA is effective and may be recommended for long-term treatment of these patients.

An Update on the Cosmetic Use of Botulinum Toxin: The Pattern of Practice among Korean Dermatologists

The efficacy and safety of botulinum toxin injection have made it a popular aesthetic procedure worldwide. A cross-sectional survey was performed in order to determine the pattern of type A botulinum toxin injections in cosmetic practice, for which an 18-item questionnaire was distributed to dermatologists. A total of 469 Korean board-certified dermatologists participated in the survey, with the following results: the main candidates for type A botulinum toxin injection were individuals in their 40–50 years (46.1%), followed by those in their 20–30 years (33.4%), and people over 60 years of age (20.5%). Overall, the upper face (the glabella, forehead, and crow’s line, in decreasing order) was the most favored area of injection (51%). In contrast, body contouring (i.e., shoulder, calf) and treatment for benign masseter hypertrophy were significantly more popular in the 20–30 years age group than their older counterparts. For wrinkle effacement, the most preferred dilution was 100 units/2.5 mL with isotonic sodium chloride injection (51.2%), and the most often used interval was six months (43.6%). About half (46.3%) of the dermatologists reported the experience of clinical cases which were suspicious of botulinum toxin resistance. Despite this, regarding the choice of the product, type A botulinum toxin products with greater cost-effectiveness were favored over products with a lower risk of antibody formation. Other than its cosmetic usage, botulinum toxin is applied for a variety of skin conditions. Further studies are suggested in order to identify the practice pattern of type A botulinum toxin for therapeutic uses in dermatology, such as hyperhidrosis and rosacea.

Immunogenicity Associated with Aesthetic Botulinumtoxin A: A Survey of Asia-Pacific Physicians' Experiences and Recommendations

Background:

Most botulinum toxin A (BoNT/A) products contain unnecessary bacterial components that increase the risk of developing neutralizing antibodies (nAbs). Reports of secondary nonresponse and treatment failures (STF) due to nAbs have accompanied a surge in new BoNT/A products.

Methods:

To formulate recommendations on managing toxin resistance, we reviewed the evidence on BoNT/A-associated immunogenicity and evaluated Asian physicians' current BoNT/A practices, knowledge, and real-world experiences, as provided by survey outcomes conducted with 128 Asian experts (regular botulinum toxin injectors).

Results:

Most doctors believe STF occurs, some patients exhibit partial symptoms, and impurities (eg, complexing proteins) in BoNT/A preparations risk STF. Bioassays that distinguish non-nAbs from nAbs that hinder toxin function remain unavailable to most doctors, though most would perform testing if given the option. Doctors in the Asia-Pacific region have differing strategies for managing STF, depending on the availability of alternatives or tests. They recommended switching to a highly-purified formulation free of complexing proteins and other impurities to lower the risk of immunogenicity, or offering treatment holidays of 2 -2.5 years. They suggested restarting treatment with the same highly purified formulation, especially for repeated treatments, large-dose injections, and younger patients who will accumulate higher lifetime doses, so as to minimize immunogenic risks and preserve long-term treatment outcomes. Importantly, doctors should always initiate patients on pure formulations rather than switching to these only after resistance develops.

Conclusion:

Choosing highly purified BoNT/A products at treatment initiation enhances long-term efficacy and patient satisfaction while minimizing the risk of immune activation and nAb formation.

Effect and longevity of botulinum toxin in the treatment of gummy smile: a meta-analysis and meta-regression

OBJECTIVE

The aim of this systematic review is to synthesize the evidence on the effectiveness and longevity of the botulinum toxin in the treatment of individuals with excessive gingival exposure.

METHODS

The search was adapted to six electronic databases and gray literature. The risk of bias was assessed using the Cochrane Risk of Bias Assessment Tool for Non-Randomized and Randomized Studies of Interventions. Meta-analyses and meta-regression were performed using random effects models.

RESULTS

A total of 5247 articles were collected during the final search in the database, resulting in 17 articles included. There was a mean decrease of 3.42 mm [95% CI = -4.50 to -2.34; I² = 97%] in the level of gingival exposure 2 weeks after the application of botulinum toxin. The application time explained 29.58% of the observed variance (p < 0.001), with a tendency for the effect size to decrease from the second week of application onwards, with values returning close to baseline levels in 24 weeks.

CONCLUSION

Botulinum toxin is an alternative technique considered effective for reducing gummy smile, especially for gummy smiles up to 4 mm, with a longevity of at least 12 weeks, returning close to initial values within 24 weeks after application.

CLINICAL RELEVANCE

The knowledge about the longevity and effectiveness of botulinum toxin in the treatment of gummy smile allows for a more adequate clinical planning for these cases, as well as for clinical decisions, as for prognostic factors.

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.