Molluscum contagiosum (molluscum) is a common cutaneous infection caused by a DNA poxvirus that primarily affects children. The molluscum contagiosum virus is trophic to epidermal keratinocytes, where it replicates, forming hyperplastic epithelial cells organized into focal lesions. The period from inoculation to presentation of lesions on the epithelial surface has been estimated at 2–8 weeks [1, 2].
With a prevalence of 5.1–11.5% in children aged 0–16 years , molluscum accounts for roughly 1% of all diagnosed skin disorders  and ranks in the top 50 most common causes of disease . Molluscum is the third most common viral skin infection, behind herpes simplex virus and human papilloma virus, in children and one of the five most prevalent skin diseases worldwide but may be under-recognized . Atopic dermatitis (AD), immune deficiency, and sexual activity are additional risk factors . Patients with AD or a family history of atopy are at higher risk for molluscum infection , and the virus can also trigger the onset of AD and/or AD flares .
Molluscum is easily transmitted to other individuals. A reported 42% of pediatric patients spread the disease to a sibling . Molluscum spreads to other skin sites via autoinoculation and to other people via skin-to-skin contact, co-bathing, or via fomites .
Molluscum is often described as benign and self-limited following acquisition of host immunity [2, 7, 11, 12]. However, the average duration of infection in untreated children aged 4–15 years was 13.3 months in the largest cohort study in the UK, including 306 patients. At 24 months, 13% of cases remained unresolved .
Treatment guidelines for molluscum have not been established. A 2003 survey of US physicians across specialties found that practices and preferences for the treatment of molluscum varied widely . No medications for this condition have yet been approved by the US FDA. Many clinicians recommend mechanical or pharmacologic methods not approved by the FDA for molluscum or an “active nonintervention” approach to allow for eventual spontaneous resolution . Active treatment is most often recommended to alleviate symptoms, minimize autoinoculation and transmission to others, improve cosmetic appearance, and prevent scarring [4, 12, 14].
Although no treatment for molluscum has been approved by the FDA, compounded cantharidin has been used to treat molluscum and warts for more than 60 years . The exact mechanism of action for treating molluscum with cantharidin is unknown, yet it is hypothesized that cantharidin’s vesicant properties cause weakening and degradation of keratinocyte desmosomes, with associated blister formation, promoting shedding of infected keratinocytes and viral clearance [16, 17]. Compounded cantharidin is typically formulated with volatile compounds and stored in screw-top bottles, which can lead to changes in cantharidin concentration once prepared . Guidance for the use of cantharidin is limited, and access to compounded cantharidin has been restricted [19, 20]. In addition to lack of access, few controlled studies have evaluated compounded cantharidin. Smaller studies have highlighted the need to identify an optimal dosing strategy and emphasize the problems with inconsistent formulations that contribute to efficacy and safety concerns, especially in sensitive skin areas [14, 19, 20]. Finally, compounded cantharidin is commonly applied using rudimentary, imprecise tools (such as cotton-tipped applicators) that could lead to inadvertent treatment of unaffected skin. Thus, there is an unmet need for a treatment that can leverage the unique mechanism of action of cantharidin but overcome obstacles of the compounded version, including a consistent and precise application method containing a controlled formulation with a proven dosing schedule, with testing completed in large populations of patients with molluscum.
VP-102 is a shelf-stable, proprietary drug–device combination product containing cantharidin (0.7% weight/volume [w/v]) and the inactive ingredients acetone, gentian violet, and denatonium benzoate in a film-forming topical solution. The applicator device containing the solution is composed of a glass ampule containing 450 µL of solution within a single-use applicator device that allows for a stable concentration of solution, along with a filter and precision (1 mm) applicator tip opening that allows for topical application of the solution to treatable molluscum lesions by a healthcare professional. The applicator allows for shelf stability, consistent formulation of the solution, and precise application to affected skin. Once applied, the acetone evaporates quickly, leaving a thin dry film that is then washed off within roughly 24 h. Gentian violet is a surgical dye inside the film that allows for distinction between treated and untreated lesions during application. Denatonium benzoate, one of the most bitter agents on the planet, is included to deter oral ingestion .
We present pooled analyses of two large vehicle-controlled phase III clinical trials, CAMP (Cantharidin Application in Molluscum Patients)-1 and -2, that were conducted to evaluate the safety and efficacy of VP-102 compared with vehicle in participants aged ≥2 years with molluscum. In addition, pooling data from these two large-scale phase III trials allows for a reduction in the variability seen in individual trials and may assist healthcare professionals make decisions about treatments and set expectations of safety and efficacy for their patients .