Efficacy and Safety of Topical Cantharidin Treatment for Molluscum Contagiosum and Warts: A Systematic Review

Cantharidin Topical Solution 0.7%: First Approval

Cantharidin (YCANTH™) is a proprietary drug-device combination product containing a formulation of cantharidin 0.7% topical solution (a vesicant naturally derived from blister beetles) delivered via a single-use applicator that has been developed by Verrica Pharmaceuticals Inc. for the treatment of molluscum contagiosum and is also being developed for the treatment of warts. In July 2023, YCANTH™ (cantharidin 0.7% topical solution) was approved for the topical treatment of molluscum contagiosum in adult and pediatric patients 2 years of age and older in the USA. This article summarizes the milestones in the development of cantharidin 0.7% topical solution leading to this first approval for the topical treatment of molluscum contagiosum in adult and pediatric patients 2 years of age and older.

New Developing Treatments for Molluscum Contagiosum

A large variety of treatments for molluscum contagiosum (MC) are available, but none are Food and Drug Administration (FDA) approved and there is no consensus on the optimal approach, mainly owing to a lack of high-level data. Physical modalities are widely used, but require repeated outpatient visits for administration, are painful and difficult to perform in children, and are associated with the possibility of residual scarring and post-inflammatory hypo- or hyperpigmentation. Two experimental topical drugs, a new standardized preparation of topical cantharidin, called VP-102, and a topical nitric oxide (NO)-releasing product containing berdazimer, called SB206, represent promising products that have been designed to overcome the limitations of current treatments. They have recently shown good results in terms of safety and efficacy in large cohorts of patients in phase III studies and have the potential to be the first FDA-approved therapies for the treatment of MC.

British Association for Sexual Health and HIV national guideline for the management of Genital Molluscum in adults (2021)

This guideline offers recommendations on diagnosis, treatment regimens and health promotion principles needed for the effective management of genital molluscum, including management of the initial presentation and recurrences. The Primary focus of the guideline is on infection which affects the genital area and has a sexual mode of transmission. This is an update to the guideline previously published in this journal in 2014.

Male Accessory Glands of Blister Beetles and Cantharidin Release: A Comparative Ultrastructural Analysis

Simple Summary

Meloidae, also called blister beetles, are known to actively produce cantharidin, a toxic terpene with a defensive function that is released externally by reflex bleeding, and that is also stored in large quantities in the male accessory glands. These glands are involved in the transfer of terpene from males to females, which receive cantharidin via spermatophores as a nuptial gift to be used for their own protection and that of the eggs. However, it is still debated whether the male accessory glands can actively produce the terpene or if they only mediate its transfer, since neither the cantharidin-producing organ nor the metabolic pathway are known to date. The focus of the work is to analyze comparatively the accessory glands of males in representative Meloidae species to provide morphological evidences that can contribute to this debate. The results highlight the complexity of the accessory gland system, consisting of three different types of glands that are highly variable between species with the exception of one, which remains conserved even in independent phyletic lines. This gland is a good candidate for hypothesizing a direct role in cantharidin production and/or concentration.

Abstract

Members of the family Meloidae are known to produce cantharidin, a highly toxic monoterpene found in their hemolymph and exuded as droplets capable of deterring many predators. As a nuptial gift, males transfer large amounts of cantharidin to females via a spermatophore, which is formed by specific accessory glands containing high concentrations of this terpene. Using light, electron and ion beam microscopy, the ultrastructural features of the three pairs of male accessory glands as well as the glandular part of the vasa deferentia were comparatively investigated in seven species of blister beetles belonging to five different tribes and two subfamilies. All gland pairs examined share common features such as mesodermal derivation, the presence of muscle sheath, a developed rough endoplasmic reticulum, abundant mitochondria, secretory vesicles, and microvillated apical membranes. Within the same species, glands exhibit distinctive features, suggesting that each pair is responsible for the formation of a specific substance. The vasa deferentia, while showing many similarities within the family, often exhibit features unique to each of the individual species investigated, whereas the accessory glands of the first and second pairs display the highest degree of ultrastructural variability. A comparison across the species shows an interesting constancy limited to ultrastructural features in the third pair of accessory glands. The similarities and differences among the species are discussed in the light of the available literature and in relation to the potential role that blister beetles’ male accessory glands could play in the storage and management of cantharidin.

Unraveling the role of male reproductive tract and haemolymph in cantharidin-exuding Lydus trimaculatus and Mylabris variabilis (Coleoptera: Meloidae): a comparative transcriptomics approach

Background

Meloidae (blister beetles) are known to synthetize cantharidin (CA), a toxic and defensive terpene mainly stored in male accessory glands (MAG) and emitted outward through reflex-bleeding. Recent progresses in understanding CA biosynthesis and production organ(s) in Meloidae have been made, but the way in which self-protection is achieved from the hazardous accumulation and release of CA in blister beetles has been experimentally neglected. To provide hints on this pending question, a comparative de novo assembly transcriptomic approach was performed by targeting two tissues where CA is largely accumulated and regularly circulates in Meloidae: the male reproductive tract (MRT) and the haemolymph. Differential gene expression profiles in these tissues were examined in two blister beetle species, Lydus trimaculatus (Fabricius, 1775) (tribe Lyttini) and Mylabris variabilis (Pallas, 1781) (tribe Mylabrini). Upregulated transcripts were compared between the two species to identify conserved genes possibly involved in CA detoxification and transport.

Results

Based on our results, we hypothesize that, to avoid auto-intoxication, ABC, MFS or other solute transporters might sequester purported glycosylated CA precursors into MAG, and lipocalins could bind CA and mitigate its reactivity when released into the haemolymph during the autohaemorrhaging response. We also found an over-representation in haemolymph of protein-domains related to coagulation and integument repairing mechanisms that likely reflects the need to limit fluid loss during reflex-bleeding.

Conclusions

The de novo assembled transcriptomes of L. trimaculatus and M. variabilis here provided represent valuable genetic resources to further explore the mechanisms employed to cope with toxicity of CA in blister beetle tissues. These, if revealed, might help conceiving safe and effective drug-delivery approaches to enhance the use of CA in medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08118-8.

Oral ulcers in a finger-sucking child after cutaneous wart therapy

Common skin warts frequently appear on the fingers of children, a patient population in whom finger-sucking is a prevalent habit. Despite overlap between these two pediatric conditions, there are no well-reported specific precautions against the use of topical blistering wart treatments, such as trichloroacetic acid and cantharidin, in finger-sucking children with warts. We report the case of oral ulcers in a pediatric patient secondary to thumb-sucking after receiving treatment for multiple finger warts with combination cryotherapy, trichloroacetic acid, and cantharidin.

Safety and Efficacy of Nano-Pulse Stimulation Treatment of Non-Genital, Cutaneous Warts (Verrucae)

BACKGROUND AND OBJECTIVES

This study describes the effects of nano-pulse stimulation (NPS) technology on the common verruca with the objectives of demonstrating efficacy and safety. NPS technology applies nanosecond pulses of non-thermal electrical energy to induce highly localized regulated cell death in the cellular structures of the targeted zone with negligible effects on surrounding non-cellular structures. Previous clinical studies applying NPS to common, benign skin lesions have demonstrated safety and efficacy in clearing seborrheic keratoses and sebaceous hyperplasia.

STUDY DESIGN/MATERIALS AND METHODS

Sixty-two subjects were enrolled at a total of five sites. One hundred and ninety-five study verrucae up to 10 mm wide were treated with NPS delivered by a console-based handheld applicator (CellFX® System; Pulse Biosciences) and follow-ups occurred every 30 days with the option to retreat at 30, 60, and 90 days. There were 62 untreated controls and 46% of the treated verrucae were recalcitrant.

RESULTS

Overall, 75.3% (70/93) of the common verrucae, 72.7% (8/11) of the flat verrucae, and 43.8% (14/32) of the plantar verrucae treated with NPS were completely clear by 60 days following the last treatment and did not recur within the 120-day observation period. The majority (54%) of verrucae cleared with a single NPS procedure. The most common treatment site reactions were erythema (50.5%) and eschar formation (23.4%) on Day 30 and on Day 120 mild erythema was present in 14% of the cases and hyperpigmentation in 18.5%. No serious adverse events were reported. A particle counter was used during 11 NPS procedures on verrucae and no significant plume generation was detected during these procedures.

CONCLUSIONS

NPS is a safe and effective procedure for removing non-genital, cutaneous verrucae. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Blistering Beetle Dermatitis Mimicking Herpes Zoster Ophthalmicus: a Case Report

Blistering beetle dermatitis is an important dermatological disease of tropical countries. Although the clinical features are classical, little awareness amongst medical practitioners may cause difficulties in the diagnosis of this condition. Further, it may sometimes mimic an unrelated disease which can lead to delay in treatment causing prolonged suffering of the patient. We present a case of blistering beetle dermatitis that was initially misdiagnosed as a case of herpeszoster ophthalmicus. The case is presented to reinforce awareness on this dermatologicaldis-ease and discuss its atypical presentation and its management.

Update on human papillomavirus - Part II: complementary diagnosis, treatment and prophylaxis

In this nonsystematic review, the complementary diagnosis, treatment, prevention, and control of human papillomavirus are discussed. The histopathology is addressed regarding its indications, main findings and limitations, as a complementary diagnostic method largely used by dermatologists. Electron microscopy is briefly reviewed, along with its contribution to the accumulated knowledge on HPV, as well as the relevance of research in using this technology for future advances in diagnosis and treatment. Molecular information about the virus is continuously increasing, and the practical applications of HPV serology, molecular identification and genotyping are discussed. Vaccines are a valuable tool in primary HPV infection prevention and are now available in many countries; their composition, indications, and adverse effects are revisited. Local and systemic treatment options are reviewed and off-label prescriptions are discussed. Finally, health education focusing on HPV infection as a sexually transmitted infection of worldwide relevance and the many barriers to improve primary and secondary prevention are addressed.

Topical treatment for plantar warts: A systematic review

There are a wide variety of treatments for plantar warts, but none has been shown to be effective in all patients. We aimed to perform a systematic review of the efficacy of different topical treatments on plantar warts. Systematic electronic searches (Pubmed, Cochrane Library, Embase, and Web of Science) were conducted in April 2020. Meta-analyses, systematic reviews, and retrospective or prospective clinical trials of the effects of topical and nonsurgical treatments of plantar warts were included. Two authors performed the study selection and data extraction. Any discrepancies between the two reviewers were discussed with a third reviewer. Forty-four studies were included. The average cure rates of the most frequent treatments were variable across the studies: cryotherapy (45.61%), salicylic acid (13.6%), cantharidin-podophyllin-salicylic acid formulation (97.82%), laser (79.36%), topical antivirals (72.45%), intralesional bleomycin (83.37%), and intralesional immunotherapy (68.14%). Twenty-two studies (50%) had a level of evidence 1b and grade of recommendation A, five studies (11.4%) had a level of evidence 2b and grade of recommendation B, two studies (4.5%) had a level of evidence 3b and grade of recommendation B, and 15 studies (34,1%) with a level of evidence 4 and grade of recommendation C. First-choice treatments for common warts, such as cryotherapy and salicylic acid, have low-cure rates for plantar warts. Other treatments, such as CPA formulation, immunotherapy, and intralesional bleomycin, which have compassionate use, have higher cure rates. This review should stimulate future high-quality research to evaluate these specialized treatments.

2020 European guideline on the management of genital molluscum contagiosum

Molluscum contagiosum is a benign viral epidermal infection associated with high risk of transmission. The guideline is focused on the sexually transmitted molluscum contagiosum. The diagnosis is clinical with characteristic individual lesions, termed 'mollusca', seen as dome-shaped, smooth-surfaced, pearly, firm, skin-coloured, pink, yellow or white papules, 2 - 5 mm in diameter with central umbilication. Dermoscopy may facilitate diagnosis. Therapeutic options are numerous, including physical treatments (cautery, curettage and cryotherapy), topical chemical treatments (e.g. podophyllotoxin and imiquimod) or waiting for spontaneous resolution in immunocompetent patients. In pregnancy, it is safe to use physical procedures (e.g. cryotherapy). Immunosuppressed patients develop severe and recalcitrant molluscum lesions that may require treatment with cidofovir, imiquimod or interferon. Patients with molluscum contagiosum infection should be offered to be screened for other sexually transmitted infections.

Recent patents in anti-wart treatment

Warts, small skin protuberances caused by human papillomavirus, are not life-threatening, but can be unsightly, embarrassing, uncomfortable and potentially contagious. They may regress naturally but over a prolonged time. Hence wart-afflicted people seek prescribed or over-the-counter therapies. Out of the innumerable marketable anti-wart medications, only a few are effective. Besides, frequent applications over months and certain undesirable side effects limit their success rates. Recurrences are also known. Hence the search for an effective, safe, cheap and quick medicine that is easy to apply continues. A number of patents for anti-wart therapies have been filed in the last few years. In this article, we enlist the recent anti-wart patents and find out those holding promise in the future.

A systematic review evaluating the efficacy and safety of a combination of ablative treatment and self administered treatment versus ablative treatment alone for external anogenital warts

BACKGROUND

External anogenital warts are proliferative lesions. Till now, there is no consensus on the standard treatment of external anogenital warts. The combination of ablative therapy and self-administered treatment has been reported to achieve sustained complete clearance than ablative therapy. The aim of this review was to compare the efficacy on achieving complete clearance of warts between the combination of ablative therapy with self-administered therapy and ablative therapy alone.

METHODS

We conducted a systematic review to evaluate the efficacy and safety of the combination of ablative therapy and self-administered treatment for external anogenital warts. The Cochrane Central Register of Controlled Trials, Medline, Embase and Science Citation Index Expanded, China National Knowledge Infrastructure and Wanfang were searched.

RESULTS

Of 1138 initially identified publications, 37 studies in English and Chinese were included. The combination of ablative therapy and self-administered treatment therapy showed significantly high complete clearance rates at 4, 8, 12, or 24 weeks after treatment compared to ablative therapy alone. In a subgroup analysis based on the treatment duration of imiquimod cream therapy, 4 and 8 weeks of imiquimod 5% cream plus CO₂ laser produced similar efficacy on clearance. The combination therapy is tolerable for patients.

CONCLUSIONS

In conclusion, this review provided evidence to support the use of the combination of ablative therapy and self-administered treatment for external anogenital warts to maintain sustained clearance.

Characterization of the Complete Mitochondrial Genome of Epicauta impressicornis (Coleoptera: Meloidae) and Its Phylogenetic Implications for the Infraorder Cucujiformia

The complete mitochondrial genome (mitogenome) of Epicauta impressicornis Pic (Coleoptera: Meloidae) was determined. The circular genome is 15,713-bp long, and encodes 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a control region (CR). The 13 PCGs start with the typical ATN codon and terminate with the typical stop codon TAA (ND2, ND4L, ND6, ATP6, ATP8, and CYTB), TAG (ND1 and ND3), and T- (COX1, COX2, COX3, ND4, and ND5). The two rRNA genes (rrn12S and rrn16S) are encoded on the minority strand. All tRNAs genes except trnS1 (AGN) are predicted to fold into the typical cloverleaf structure. The longest overlap (10 bp) is observed between ATP8 and ATP6. CR mainly harbors a conserved poly-T stretch (15 bp), a short repeat unit (17 bp), some universal microsatellite-like repeats, and a canonical poly-A tail. Phylogenetic analysis using Bayesian inferences and maximum likelihood based on nucleotide and corresponding amino acid sequences of the 13 PCGs showed that E. impressicornis is closely related to E. chinensis, this relationship is and supported within Cucujiformia belonging to Meloidae (Tenebrionoidea). Our results further confirmed the monophyly of Tenebrionoidea, Lymexyloidea, Curculionoidea, Chrysomeloidea, Cucujoidea, Coccinelloidea, and Cleroidea within Cucujiformia, and revealed the sister relationships of (Cleroidea + Coccinelloidea), (Lymexyloidea + Tenebrionoidea), and ((Chrysomeloidea + Cucujoidea) + Curculionoidea). We believe that the complete mitogenome of E. impressicornis will contribute to further studies on molecular bases for the classification and phylogeny of Meloidae or even Cucujiformia.

A comparative study of topical cantharidin and intralesional PPD to treat molluscum contagiosum

Background: The immune system plays an important part in the clearance of molluscum contagiosum (MC) and, therefore, there has lately been a trend in using immunotherapy in MC therapy. Tuberculin-purified protein derivatives (PPDs) and topical cantharidin have not earlier been compared with their effectiveness in therapyAim: The aim of this research was to determine the effectiveness and security of intralesional immunotherapy in the therapy of MC with tuberculin PPD versus topical cantharidinPatients and methods: Twenty patients with various MC lesions received topical cantharidin as control (group A) and 20 MC patients received intralesional tuberculin PPD following prior intradermal immunity tests (group B‏).Results: Complete clearance of lesions was detected in 90.0% of patients in the cantharidin group; the partial response was detected in10.0% of the patients. However, in the PPD group, 85% of the patients showed a complete response and 15% showed a partial response, with no significant difference in the clinical response between the two groups. Mild side effects were detected‏.Conclusion: The results suggest that intralesional PPD and topical cantharidin 0.7% are effective and safe treatment modalities, but benefits of intralesional PPD is being a simple, effective and safe treatment with tolerable pain and can be an alternative treatment for multiple resistant types‏.

Molluscum contagiosum: an update and review of new perspectives in etiology, diagnosis, and treatment

Molluscum contagiosum (MC) is a self-limited infectious dermatosis, frequent in pediatric population, sexually active adults, and immunocompromised individuals. It is caused by molluscum contagiosum virus (MCV) which is a virus of the Poxviridae family. MCV is transmitted mainly by direct contact with infected skin, which can be sexual, non-sexual, or autoinoculation. Clinically, MC presents as firm rounded papules, pink or skin-colored, with a shiny and umbilicated surface. The duration of the lesions is variable, but in most cases, they are self-limited in a period of 6–9 months. The skin lesions may vary in size, shape, and location, which is more frequent in immunosuppressed patients, and could present complications such as eczema and bacterial superinfection. The diagnosis is based on clinical findings. A useful clinical tool is dermoscopy. If the diagnostic doubt persists, confocal microscopy or skin biopsy could be performed. The need for active treatment for MC is controversial; however, there is a consensus that it should be indicated in cases of extensive disease, associated with complications or aesthetic complaints. There are several treatment modalities which include mechanical, chemical, immunomodulatory, and antivirals. The objective of this article is to review the current evidence in etiology, clinical manifestations, diagnosis, and management alternatives of MC.