Actinic keratosis: a clinical and epidemiological revision

Ingenol Disoxate: A Novel 4-Isoxazolecarboxylate Ester of Ingenol with Improved Properties for Treatment of Actinic Keratosis and Other Non-Melanoma Skin Cancers

Introduction

Ingenol mebutate gel (Picato^®, LEO Pharma A/S) is approved for the field treatment of actinic keratosis and is characterized by high sustained clearance of actinic lesions. The inherent propensity of ingenol mebutate towards chemical rearrangement necessitates refrigeration of the final product. We sought to identify novel ingenol derivatives with enhanced chemical stability and similar or improved in vitro potency and in vivo efficacy.

Methods

A number of ingenol esters were synthesized with full regiocontrol from ingenol. Chemical stability was determined in aqueous buffer at physiological pH and hydroalcoholic gel at lower pH. Acute cytotoxicity was determined in HeLa or HSC-5 cells. Keratinocyte proliferation, viability and caspase 3/7 activation was measured in primary epidermal keratinocytes. Relative gene expression levels were determined by real-time quantitative PCR. Evaluation of in vivo tumor ablating potential was performed in the murine B16 melanoma mouse model and in the UV-induced skin carcinogenesis model in hairless SKH-1 mice following topical treatment for two consecutive days with test compounds formulated at 0.1% in a hydroalcoholic gel.

Results

This work resulted in the identification of ingenol disoxate (LEO 43204) displaying increased stability in a clinically relevant formulation and in aqueous buffer with minimal pH-dependent acyl migration degradation. Ingenol disoxate exhibited a significantly higher cytotoxic potency relative to ingenol mebutate. Likewise, cell growth arrest in normal human keratinocyte was more potently induced by ingenol disoxate, which was accompanied by protein kinase C dependent transcription of markers of keratinocyte differentiation. Most notably, ingenol disoxate possessed a superior antitumor effect in a B16 mouse melanoma model and significantly increased median survival time relative to ingenol mebutate. A significant effect on tumor ablation was also observed in a murine model of ultraviolet irradiation-induced skin carcinogenesis.

Conclusion

These data illustrate that the favorable in vitro and in vivo pharmacological properties driving ingenol mebutate efficacy are either preserved or improved in ingenol disoxate. In combination with improved chemical stability to potentially facilitate storage of the final product at ambient temperatures, these features support further development of ingenol disoxate as a convenient and efficacious treatment modality of non-melanoma skin cancers.

Funding

LEO Pharma A/S.

Electronic supplementary material

The online version of this article (doi:10.1007/s13555-016-0137-2) contains supplementary material, which is available to authorized users.

Low-Dose 0.5% 5-Fluorouracil/10% Salicylic Acid Topical Solution in the Treatment of Actinic Keratoses

Background:

Actinic keratosis (AK) lesions have the potential to develop into invasive squamous cell carcinomas (SCCs), and approaches to treatment are evolving to try to reduce the burden of SCC.

Objective:

To present the published clinical research surrounding the use of 0.5% 5-fluorouracil with 10% salicylic acid (low-dose 5-FU/SA) for the treatment of hyperkeratotic AKs.

Method:

A review of published clinical evidence for low-dose 5-FU/SA for the treatment of AKs. The articles were selected following a MEDLINE database search of the combined terms fluorouracil, salicylic acid and actinic keratosis which represent the peer review publications of clinical studies that primarily investigate the use of Actikerall in AK.

Results:

Combining low-dose 5-FU with keratolytic SA is associated with high rates of histologic clearance, reduction in lesion number/area, and sustained clinical response in clinical study and the clinical practice setting. Low-dose 5-FU/SA has also been evaluated using imaging to detect the progression of subclinical AK lesions through a course of the field-directed treatment.

Conclusion:

Low-dose 5-FU/SA is an effective and well-tolerated treatment option licensed for the lesion-directed treatment of mild-to-moderate hyperkeratotic AK lesions.

Non-melanoma Skin Cancer in Canada Chapter 3: Management of Actinic Keratoses

Background

Actinic keratosis (AK) and cheilitis (AC) are lesions that develop on photodamaged skin and may progress to form invasive squamous cell carcinomas (SCCs).

Objective

To provide guidance to Canadian health care practitioners regarding management of AKs and ACs.

Methods

Literature searches and development of graded recommendations were carried out as discussed in the accompanying introduction (chapter 1 of the NMSC guidelines).

Results

Treatment of AKs allows for secondary prevention of skin cancer in sun-damaged skin. Because it is impossible to predict whether a given AK will regress, persist, or progress, AKs should ideally be treated. This chapter discusses options for the management of AKs and ACs.

Conclusions

Treatment options include surgical removal, topical treatment, and photodynamic therapy. Combined modalities may be used in case of inadequate response. AKs are particularly common following the longterm immunosuppression in organ transplant patients, who should be monitored frequently to identify emerging lesions that require surgery.

Reviewing Challenges in the Diagnosis and Treatment of Lentigo Maligna and Lentigo-Maligna Melanoma

Lentigo maligna (LM) and lentigo-maligna melanoma (LMM) are pigmented skin lesions that may exist on a continuous clinical and pathological spectrum of melanocytic skin cancer. LM is often described as a "benign" lesion and is accepted as a melanoma in situ; LM can undergo malignant transformation to particularly aggressive melanoma. LMM is an invasive melanoma that shares properties of LM, as well as exhibiting the metastatic potential of malignant melanoma. Unfortunately, LM/LMM diagnosis based on dermoscopy is rather ambiguous, and these lesions are often mistaken for junctional dysplastic nevi over sun-damaged skin, pigmented actinic keratosis, solar lentigo, or seborrheic keratosis. Diagnosis must be made on biopsy using distinct dermatopathologic features. These include a pagetoid appearance of melanocytes, melanocyte atypia, non-uniform pigmentation/distribution of melanocytes, and increased melanocyte density in a background of extensive photodamage. Advancements in immunohistochemical staining techniques, including soluble adenylyl cyclase (antibody R21), makes diagnosis easier and allows the definition of borders down to a single cell. After a pathologic diagnosis, there are a variety of treatment options, both surgical and non-surgical. Although surgical removal with a wide excision border is the preferred treatment due to decreased recurrence rates, experimental combination therapies are gaining popularity. However, no matter the treatment, LM/LMM carries a high recurrence rate, and patients must be monitored rigorously for recurrence as well as the appearance of additional skin lesions/cancers.

Primary care review of actinic keratosis and its therapeutic options: a global perspective

Actinic keratosis (AK) is a common skin condition caused by long-term sun exposure that has the potential to progress to non-melanoma skin cancers. The objective of this review is to examine the therapeutic options and management of AK globally, particularly in Australia, Canada, and the United Kingdom. Despite its potentially malignant nature, general awareness of AK is low, both in the general population and in the primary health care setting, especially in countries with low incidence. There is no standard therapeutic strategy for AK; it is treated through a variety of lesion-directed or field-directed therapies or a combination of both. A variety of treatment options are used depending on the experience of the primary care physician, the pathology of the lesion, and patient factors. Studies have shown that the physicians do not always use the optimal treatment option because of a lack of knowledge. The higher incidence of AK in fair-skinned people in Australia has resulted in well-established management strategies and guidelines for its treatment, compared with countries with lower incidence. It is essential to raise the awareness of AK because of its potential to progress to invasive squamous cell carcinoma. Primary care physicians are often the first to see this condition in their patients and are perfectly placed to educate the public and raise awareness. It is therefore desirable that their education and knowledge about AK and its treatment are up to date.

Invasive head and neck cutaneous squamous cell carcinoma: clinical and histopathological characteristics, frequency of local recurrence and metastasis

BACKGROUND

squamous cell carcinoma is the second most common type of skin malignancy and may evolve to regional lymph node and distant metastases.

OBJECTIVE

The objective of this study was to evaluate patients with head and neck cutaneous squamous cell carcinoma to identify its clinical and histopathological characteristics, as well as the frequency of local recurrence and metastasis.

METHODS

A retrospective cohort of patients with head and neck cutaneous squamous cell carcinoma. Inclusion criteria: histopathological confirmation, follow-up for longer than one year after diagnosis. Exclusion criteria: immunosuppression; lip and oral cavity squamous cell carcinoma; and non-surgical resection of the lesion. We evaluated demographic, clinical and anatomopathologic findings and explored their associations.

RESULTS

Sixty-one patients with 79 tumors and followed by 4.8±3.0 years were selected. The average age was 67.1 years, and 63% of tumors had up to two centimeters. Seven tumors (8.9%) recurred and two of them had positive margins. Recurrence was associated with higher Broders' grade (p<0.01). Two patients (3.3%) had regional lymph node metastases. There were no distant metastases. Seventy tumors were considered to be usual tumors (89.7%), and 68 (87.2%) were classified as Broders' grade 1 and 2. Additionally, 64.1% of tumors had a depth of invasion below four millimeters. Thirteen tumors (16.7%) had positive histological margins.

CONCLUSIONS

Most patients had good prognosis in the first year of follow-up, confirming that head and neck cutaneous squamous cell carcinoma has a better prognosis than squamous cell carcinoma of other regions such as mucosa, oral cavity, and internal organs.

Spanish adaptation of the European guidelines for the evaluation and treatment of actinic keratosis

Current trends in our setting indicate that the prevalence of actinic keratosis and similar diseases will increase in coming years and impose a greater burden on health care resources. A long list of clinical features must be taken into account when approaching the treatment of actinic keratosis. Until recently, therapeutic approaches focused solely on ablative procedures and the treatment of individual lesions and did not take into account areas of field cancerization. Now that the therapeutic arsenal has grown, standardized criteria are needed to guide the optimal choice of treatment for each patient. The elaboration of evidence-based consensus recommendations for the diagnosis and treatment of actinic keratosis generates knowledge that will help clinicians to deliver the highest level of care possible, standardizing decision-making processes and enhancing awareness among all the health professionals involved in the care pathway.

Penetration of normal, damaged and diseased skin--an in vitro study on dendritic core-multishell nanotransporters

A growing intended or accidental exposure to nanoparticles asks for the elucidation of potential toxicity linked to the penetration of normal and lesional skin. We studied the skin penetration of dye-tagged dendritic core-multishell (CMS) nanotransporters and of Nile red loaded CMS nanotransporters using fluorescence microscopy. Normal and stripped human skin ex vivo as well as normal reconstructed human skin and in vitro skin disease models served as test platforms. Nile red was delivered rapidly into the viable epidermis and dermis of normal skin, whereas the highly flexible CMS nanotransporters remained solely in the stratum corneum after 6h but penetrated into deeper skin layers after 24h exposure. Fluorescence lifetime imaging microscopy proved a stable dye-tag and revealed striking nanotransporter-skin interactions. The viable layers of stripped skin were penetrated more efficiently by dye-tagged CMS nanotransporters and the cargo compared to normal skin. Normal reconstructed human skin reflected the penetration of Nile red and CMS nanotransporters in human skin and both, the non-hyperkeratotic non-melanoma skin cancer and hyperkeratotic peeling skin disease models come along with altered absorption in the skin diseases.

Retinoids for prevention and treatment of actinic keratosis

Actinic keratosis is a common cause of dermatological consultations and it presents a strong association with squamous cell carcinoma. Many substances are used for treatment and prevention, such as retinoids. Nevertheless, many studies on retinoids emphasize their application in treating and preventing non melanoma skin cancers. In this article, we reviewed studies about systemic and topical retinoids used with immunocompetent patients and organ transplant recipients with actinic keratosis, as primary or secondary outcomes. The majority of these papers pointed to a reduction in actinic keratosis count after treatment with retinoids. However, studies need to be better-defined in order to address the lack of a standardized dose, the absence of control groups, the low number of patients and short follow-up periods. Blind, randomized and controlled clinical trials with adequate sample sizes, specifically focused on actinic keratosis, are needed to clarify the real benefit of topical and/or oral retinoids. Comparison of efficacy and safety between oral and topical retinoids in the prevention and treatment of non-melanoma skin cancers and actinic keratosis is an essential pre requisite to establish new strategies to control these conditions.

Oral acetylsalicylic acid and prevalence of actinic keratosis

Objective: To investigate the influence of a regular oral use of acetylsalicylic acid in the prevalence of actinic keratosis. Methods: A case-control study with dermatologic outpatients above 50 years of age assessed between 2009 and 2011. Cases were defined as those who had been under regular use of oral acetylsalicylic acid for more than six consecutive months. The assessment focused on: age, sex, skin-type, tobacco smoking, use of medication, occurrence of individual or family skin cancer, and sunscreen and sun exposure habits. Actinic keratoses were counted in the medial region of the face and upper limbs. Counts were adjusted by co-variables based on a generalized linear model. Results: A total of 74 cases and 216 controls were assessed. The median time of acetylsalicylic acid use was 36 months. Cases differed from controls as to the highest age, highest prevalence of use of angiotensin-converting enzyme inhibitors and fewer keratosis on the face and on the upper limbs (p<0.05). The multivariate model showed that the use of acetylsalicylic acid was associated to lower counts of face actinic keratosis and upper-limb erythematous actinic keratosis (p<0.05), regardless of other risk factors. Conclusion: The regular use of oral acetylsalicylic acid for more than six months was associated to a lower prevalence of actinic keratosis, especially facial and erythematous ones.

Prevalence and risk factors of actinic keratoses in Germany--analysis of multisource data

BACKGROUND

In Europe, only few and inconsistent data on the prevalence and treatment of actinic keratoses (AK) are available.

OBJECTIVES

To determine the prevalence of AK in Germany, to identify potential predictors and to estimate the number of AK cases treated in dermatological practices.

METHODS

In a multiple-source approach, prevalence was assessed from whole-body examinations in a cohort of 90 800 employees and from nationwide statutory health insurance (SHI) data of 2008. The number of cases documented in dermatological offices was estimated from statistics of a SHI Physicians Association.

RESULTS

Standardized prevalence of AK from dermatological examinations was 2.7%; the rate increased with age (11.5% in the group 60-70 years) and was higher for men (3.9%) than for women (1.5%). Significant associations were also identified for skin phototype I, sunburns in childhood and solar lentigines. Vitiligo and a history of melanoma were also, but not significantly, associated with AK. In the SHI data analysis, standardized AK prevalence was 1.8%. Age-specific rates were below 1.5% up to 60 years and rose to 8.2% (13.2% in men) in the group 80-89 years. The prevalence from these large data sets--which is at the lower limit of studies from other countries--suggests about 1.7 million estimated AK cases in Germany. In 2011, AK accounted for 8.3% of the hundred most frequently treated dermatological outpatient diagnoses. The proportion of AK cases has risen almost continuously over the last 10 years, compared to other dermatological conditions. Estimated annual number of AK cases documented by dermatologists in Germany is about 1.7 million.

CONCLUSIONS

Actinic keratosis is a frequent condition in higher age groups and more prevalent in men; a relevant need for health care is evident. Predictors and risk factors for AK are easy to identify in the population, which could also help to detect groups with special need for preventive measures.

Extrinsic aging: UV-mediated skin carcinogenesis

Age-associated skin lesions linked to UV radiation (UVR) include actinic keratosis, non-melanoma skin cancer-such as basal cell carcinoma and squamous cell carcinoma-lentigo senilis and lentigo maligna. Their incidence is increasing worldwide, mainly due to exaggerated UV exposure and to an aging population. Early diagnosis and therapy of pre-malignant cutaneous lesions is crucial for the secondary prophylaxis of invasive and highly aggressive skin cancers. Combined efforts to increase public awareness, patient education about self-examination, prophylactic modalities, such as consistent and sufficient UV protection, and rigorous follow-up of high-risk groups are of highest importance.