An Open Label Study of an Occlusive Heat Patch in the Treatment of Warts
April 2019 | Volume 18 | Issue 4 | Original Article | 368 | Copyright © April 2019
Richard J. Antaya MD,a Maria del Carmen Fraile Alonso MD PhD,b Nitin Sukumar MS,c Fang Yong Li MPH,c Israel Dvoretzky MDb
aDepartments of Dermatology and Pediatrics, Yale University School of Medicine, New Haven, CT bDepartment of Dermatology, Yale University School of Medicine, New Haven, CT cMEDSPH Biostatistics, Yale University, New Haven, CT
BACKGROUND: Local hyperthermia has been demonstrated to be a safe and efficacious treatment for warts.
OBJECTIVE: We aimed to evaluate the safety and efficacy of an epicutaneous heat patch to induce local hyperthermia for the treatment
METHODS: We performed an uncontrolled, proof of concept study by applying a novel, reproducible, epicutaneous heat patch to a target
wart for 2 hours per day for 12 weeks. There were 15 evaluable participants. An untreated wart was also observed and measured. Wart
measurements included the diameter in two dimensions, an investigator global assessment (IGA) score, wart clearance, and monitoring
for adverse events as endpoints at week 12 (end of treatment) and week 24 (end of study).
RESULTS: No major adverse events were observed. 6.7% of participants reported minor cutaneous events. At week 24, 46.7% of participants
achieved complete clearance of both warts.
LIMITATIONS: The small sample size and lack of independent control in each participant were the main limiting factors.
CONCLUSION: Local hyperthermia delivered by epicutaneous heat patches was well-tolerated, safe, and achieved complete clearance in
both treated as well untreated warts in 46.7% of participants at week 24 after 12 weeks of daily use.
J Drugs Dermatol. 2019;18(4):368-373.
Warts are skin lesions caused by keratinocyte infection by human papillomavirus (HPV). They affect both sexes equally. The most frequently involved sites are the soles (43%), hands (34%), and the face (14%).1 Prevalence is estimated at around 20% in schoolchildren and declines thereafter with increasing age.1-4 Children (6-14 years old) and young adults (15-24 years old) are more frequently affected.1,5 In children, individual warts resolve in around 2 years, in contrast with adults in which the infection can persist for 5-10 years.2,6 The overall 5-year clearance rate is 92-96%.4 Immune system impairment, especially of cell-mediated immunity, usually prolongs the duration of warts,2 however, reinfection with the same HPV type appears uncommon after clearance, suggesting that protective type-specific immunity may develop.3,7Despite the high prevalence of this infection, there is no specific anti-HPV therapy.8 The cure rate in a period of 3-4 months for placebo-treated warts is around 20-30%.2 A wide range of therapeutic options2 is available. According to the 2014 British Association of Dermatologists’ guidelines for wart treatment,2 salicylic acid and cryotherapy demonstrated the highest cure rates and received the highest level of recommendation. Combined therapies are widely reported to achieve higher clearance rates than monotherapy.2Localized hyperthermia has been reported to hasten the resolution of warts. Numerous clinical studies employing various methods to increase the cutaneous surface temperature have yielded positive results.2 Despite this, the level of evidence and strength of recommendation remain low for this treatment modality. Although the exact mechanism of action remains unknown, local hyperthermia results in the upregulation of various proteins and cytokines that aid the immune system in wart recognition and enhance destruction of infected keratinocytes.9
MATERIALS AND METHODS
We conducted a proof of concept trial to evaluate safety and efficacy of a novel epicutaneous heat-patch (clinicaltrials.gov # NCT01746056). The trial was approved by Yale University’s Institutional Review Board (protocol #1209010850). The heat patch employed in this study contains a mixture of chemicals including ferric chloride, which in the presence of oxygen reacts to generate reproducible, rapid exothermic warming of the skin to a temperature of 42-43°C and is maintained for at least