Opportunities for laser-assisted drug delivery in the treatment of cutaneous disorders.

Fractional laser-assisted drug delivery (LADD) is increasingly finding its way into clinical practice as a new means to enhance topical drug uptake and improve treatment of cutaneous disorders. To date, LADD has been used for a wide range of conditions, including photodamaged skin, neoplastic lesions, scars, cutaneous infections, and vitiligo as well as for topical anesthetic and aesthetic procedures. Substantiated by randomized controlled clinical trials, strong evidence is available for LADD's usefulness for photodynamic therapy (PDT), for which improved efficacy using laser-assisted photosensitizer treatment is established for actinic keratosis compared with conventional PDT. Over time, the modality has undergone increasing refinement and offers the potential advantages of reduced treatment durations, shortened incubation times, and the replacement of cumbersome, patient-dependent treatment regimens with quick, in-office procedures. Notwithstanding, LADD is still a new enhancement technique, and risks of both local and systemic adverse events are insufficiently explored. With conscientious development, however, LADD promises to improve existing regimens and make new pharmacological treatments a reality for a wide range of cutaneous disorders.

Exploring the use of ingenol mebutate to prevent non-melanoma skin cancer.

Non-melanoma skin cancer is the most frequently occurring cancer in Caucasians today. Incidence rates in Europe have increased steadily since the 1960s and more than tripled over the last 50 years. Despite primary preventative efforts, incidences of non-melanoma skin cancer continue to rise and development of effective chemopreventative strategies is needed. In 2013, ingenol mebutate was approved in Denmark as a new topical drug for field-directed treatment for actinic keratoses. Ingenol mebutate has a dual mechanism of action, causing initial cell death, followed by an immune activation. The treatment induces an acute inflammation, manifesting as local skin responses, often accompanied by pain and pruritus. The severity of local skin responses for a given patient is unpredictable, and some individuals may develop insufferable inflammation. The overall aim of the thesis was to investigate if ingenol mebutate could be used as a chemopreventive agent to prevent development of non-melanoma skin cancer with minimal side effects. Specific aims included: Determine if ingenol mebutate can prevent progression of histological photodamage and squamous cell carcinoma (murine). Determine if ingenol mebutate can reverse clinical actinic damage in patients with multiple actinic keratoses and fieldcancerized skin (clinical). Determine if a topical glucocorticoid (clobetasol propionate) can reduce ingenol mebutate-induced local skin responses, pain, and pruritus without compromising the treatment efficacy (murine clinical). In two in vivo murine studies, ingenol mebutate's effect on photodamage and squamous cell carcinoma formation was investigated. Mice were irradiated with solar simulated ultraviolet radiation. During the first 20 weeks, 5 single applications with ingenol mebutate were given at four-week intervals with and without concurrent application of clobetasol propionate. Prophylactic treatments with ingenol mebutate prevented progression of histological photodamage of all investigated characteristics, including keratosis grade, epidermal hypertrophy, dysplasia, and dermal actinic damage. In addition, tumor formation was postponed by 3 weeks. In the clinical trial, patients with multiple actinic keratoses and field-cancerized skin were treated with ingenol mebutate, according to label, with and without sequential application of clobetasol propionate. Ingenol mebutate treatments were found to clear overall 86% of all actinic keratoses, exerting a therapeutic effect on all severity grades; cure rates were 88%, 70%, and 60% for Grade I, II, and III actinic keratoses, respectively. Ingenol mebutate treatments generated erythema, flaking, crusting, vesiculation, swelling/bleeding, and ulceration. Concurrent application of clobetasol propionate increased local skin responses in murine skin, likely due to an enhanced penetration of ingenol mebutate that resulted in a greater therapeutic effect compared to ingenol mebutate alone. In patients with actinic keratoses, sequential application of ingenol mebutate and clobetasol propionate did not reduce local skin responses, pain, or pruritus, nor did it affect treatment efficacy compared to ingenol mebutate alone. In conclusion, the thesis highlights ingenol mebutate's potential as a prophylactic remedy for non-melanoma skin cancer with promise to support primary preventative efforts in reducing non-melanoma skin cancer incidence.

Repeated Treatments with Ingenol Mebutate Prevents Progression of UV-Induced Photodamage in Hairless Mice.

BACKGROUND AND AIM: Ingenol mebutate (IngMeb) is an effective treatment for actinic keratosis. In this study, we hypothesized that repeated treatments with IngMeb may prevent progression of UV-induced photodamage, and that concurrent application of a corticosteroid may reduce IngMeb-induced local skin responses (LSR). METHODS: Hairless mice (n = 60; 3 groups of 20 mice) were irradiated with solar simulated ultraviolet radiation (UVR) throughout the study. Five single treatments with IngMeb were given at 4-week intervals (Days 21, 49, 77, 105, and 133). Clobetasol propionate (CP) was applied once daily for 5 days prior to each IngMeb application, as well as 6 h and 1 day post treatment. One week after IngMeb treatment No. 1, 3, and 5 (Days 28, 84, and 140), biopsies from four mice in each group were collected for histological evaluation of UV-damage on a standardized UV-damage scale (0-12). LSR (0-24) were assessed once daily (Days 1-7) after each IngMeb treatment. RESULTS: IngMeb prevented progression of photodamage in terms of keratosis grade, epidermal hypertrophy, dysplasia, and dermal actinic damage with a lower composite UV-damage score on day 140 (UVR 10.25 vs. UVR+IngMeb 6.00, p = 0.002) compared to UVR alone. IngMeb induced LSR, including erythema, flaking, crusting, bleeding, vesiculation, and ulceration. Concurrent CP increased LSR (max LSR Tx 1-5: UVR+IngMeb+CP 3.6-5.5 vs. UVR+IngMeb 2.6-4.3) and provided better prevention of photodamage compared to IngMeb alone (Day 140: UVR+IngMeb 6.00 vs. UVR+IngMeb+CP 3.00 p < 0.001). CONCLUSION: Repeated field-directed treatments with IngMeb prevent progression of cutaneous photodamage in hairless mice, while CP cannot be used to alleviate IngMeb-induced LSR. The findings suggest that IngMeb may potentially serve as a prophylactic treatment for UV-induced tumors.

Topical corticosteroid has no influence on inflammation or efficacy after ingenol mebutate treatment of grade I to III actinic keratoses (AK): A randomized clinical trial.

BACKGROUND: Ingenol mebutate (IngMeb) is approved for treatment of actinic keratoses (AK) and may cause unpredictable local skin responses (LSR). OBJECTIVES: We sought to investigate whether IngMeb-induced LSR, pain, and pruritus could be alleviated with a topical glucocorticoid and, further, to assess efficacy, cosmetic outcome, and patient satisfaction in patients with severe photodamage. METHODS: In this blinded, randomized controlled clinical trial, patients with multiple AK and field cancerization of the face or scalp were treated in 2 areas with IngMeb (0.015%) daily for 3 days. After finalized IngMeb treatment, 1 area was randomized to receive topical clobetasol propionate (0.05%) twice daily for 4 days. Assessments included LSR (0-24; days 1, 4, 8, 15, 57), pain (0-10) and pruritus (0-3; days 1-15), AK clearance (days 15, 57), and cosmetic outcome (0-3; day 57). RESULTS: Clobetasol propionate application had no influence on LSR (P = .939), pain (P = .500), pruritus (P = .312), or AK cure rate (P = .991). Overall, IngMeb cleared 86% of all AK lesions, exerting a therapeutic effect on all AK severity grades; cure rates were 88%, 70%, and 60% for grade I, II, and III AK, respectively. Skin texture improved significantly in remedied areas (2.0 vs 1.0; P < .001); no hypopigmentation, hyperpigmentation, or scarring were observed. LIMITATIONS: These results do not provide safety and efficacy beyond 2 months of follow-up. CONCLUSION: Application of clobetasol propionate does not alleviate IngMeb-induced LSR after 3 days of IngMeb treatment.