Imiquimod for Actinic Keratosis: Systematic Review and Meta-Analysis

Imiquimod for the treatment of oral leukoplakia: A two-center retrospective study

OBJECTIVES

We aimed to assess the effectiveness of the use of topical imiquimod for the management of oral leukoplakia (OL).

METHODS

This was a retrospective study. Medical chart reviews were conducted to identify patients with biopsy-proven OL treated with topical 5% imiquimod. Data included OL characteristics, histopathological diagnosis, treatment outcome, and adverse events (AEs). Treatment response was assessed by measuring the percentage reduction in the size of OL lesions.

RESULTS

33 patients (51.5% females; median age: 65 years) with 38 lesions were included. OLs were either localized (23.7%) or multifocal lesions (76.3%), with the majority on the gingiva (86.8%). Pretreatment histopathological diagnoses were dysplasia in 84.2% and nonreactive hyperkeratosis in 15.8%. Most regimens consisted of 60-minute applications, 5-days-a-week, for 6 weeks. At the end of treatment, 81.6% of 38 lesions showed a reduction in size with 68.4% exhibiting ≥50% reduction in size, and 42.1% exhibiting complete resolution. Application site reactions were the most common with pain/soreness/sensitivity occurring in 86.8%. Fatigue was the most frequently reported systemic AE (28.9%).

CONCLUSION

Two-thirds of OL lesions had ≥50% reduction in size. Most AEs were temporary and resolved upon treatment discontinuation. Prospective studies are needed to further assess Imiquimod's effectiveness in OL management.

Systemic IFN-I combined with topical TLR7/8 agonists promotes distant tumor suppression by c-Jun-dependent IL-12 expression in dendritic cells

Dendritic cell (DC) activation by pattern recognition receptors like Toll-like-receptors (TLRs) is crucial for cancer immunotherapies. Here, we demonstrate the effectiveness of the TLR7/8 agonist imiquimod (IMQ) in treating both local tumors and distant metastases. Administered orally, IMQ activates plasmacytoid DCs (pDCs) to produce systemic type I interferons (IFN-I) required for TLR7/8 upregulation in DCs and macrophages, sensitizing them to topical IMQ treatment, which is essential for therapeutic efficacy. The mechanism involves c-Jun/AP-1 mediating TLR7/8 signaling in IFN-I-primed DCs, upregulating the pDC-recruiting chemokine CCL2 and the anti-angiogenic cytokine interleukin-12, which suppresses VEGF-A production leading to tumor necrosis and regression. Combining topical and systemic IMQ or IFN-I generates a CD8+ T cell-dependent response at metastatic sites, reinforced by PD-1 blockade, leading to long-lasting memory. Analysis of cohorts of patients with melanoma demonstrates DC-specific TLR7/8 upregulation by IFN-I, supporting the translational potential of combining systemic IFN-I and topical IMQ to improve immunotherapy of topically accessible tumors.

Topical Calcipotriol Plus 5-Fluorouracil in the Treatment of Actinic Keratosis, Bowen's Disease, and Squamous Cell Carcinoma: A Systematic Review

BACKGROUND/OBJECTIVES

Actinic keratoses (AK) are premalignant skin lesions caused by chronic sun exposure, topically managed by 5-fluorouracil (5-FU), diclofenac 3% gel, and imiquimod. Despite their effectiveness, long treatment duration and severe adverse local skin reactions have limited patient concordance. Calcipotriol has recently been used as a combination agent for existing topical AK treatments. A systematic review was performed to determine the clinical efficacy of 5-FU and calcipotriol for the treatment of AK, Bowen's disease, and squamous cell carcinoma (SCC).

METHODS

A systematic literature search was conducted on Medline, Embase, and Cochrane Library. Among the 84 records screened, 12 were retrieved for full-text review and 8 were included in the final analysis.

RESULTS

Among the 8 studies, there were 214 control patients and 288 patients who received the intervention. The combination 5% 5-FU with calcipotriol resulted in a significant reduction in the number of AKs on the face, scalp, right upper extremity, and left upper extremity for all sites at 8 weeks (P < .0001). No significant difference in SCC incidence was observed at 1 or 2 years, but there was a significant reduction observed at 3 years for SCC on face and scalp. No study assessed the combination for Bowen's disease.

CONCLUSIONS

Combination 5% 5-FU with calcipotriol is an effective treatment for Aks; however, future trials may consider longer treatment and follow-up periods for the treatment and prevention of AK, SCC in situ, and SCC.

European consensus-based interdisciplinary guideline for diagnosis, treatment and prevention of actinic keratoses, epithelial UV-induced dysplasia and field cancerization on behalf of European Association of Dermato-Oncology, European Dermatology Forum, European Academy of Dermatology and Venereology and Union of Medical Specialists (Union Européenne des Médecins Spécialistes)

A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology, the European Dermatology Forum, the European Academy of Dermatology and Venereology, and the European Union of Medical Specialists was formed to develop European recommendations on AK diagnosis and treatment, based on current literature and expert consensus. This guideline addresses the epidemiology, diagnostics, risk stratification and treatments in immunocompetent as well as immunosuppressed patients. Actinic keratoses (AK) are potential precursors of cutaneous squamous cell carcinoma (cSCC) and display typical histopathologic and immunohistochemical features of this malignancy in an early stage. They can develop into cSSC in situ and become invasive in a low percentage of cases. AK is the most frequent neoplasia in white populations, frequently occurring within a cancerous field induced by ultraviolet radiation. Since it cannot be predicted, which lesion will progress to cSCC and when treatment is usually recommended. The diagnosis of AK and field cancerization is made by clinical examination. Dermatoscopy, confocal microscopy, optical coherence tomography or line-field confocal-OCT can help in the differential diagnosis of AK and other skin neoplasms. A biopsy is indicated in clinically and/or dermatoscopically suspicious and/or treatment-refractory lesions. The choice of treatment depends on patients' and lesion characteristics. For single non-hyperkeratotic lesions, the treatment can be started upon patient's request with destructive treatments or topical treatments. For multiple lesions, field cancerization treatment is advised with topical treatments and photodynamic therapy. Preventive measures such as sun protection, self-examination and repeated field cancerization treatments of previously affected skin areas in high-risk patients are advised.

Imiquimod as a new treatment in refractory idiopathic granulomatous mastitis: report of two cases

INTRODUCTION

Idiopathic granulomatous mastitis (IGM) is a rare chronic inflammatory lesion of the breast that mimics breast cancer or infection. Immunological pathogenesis is strongly suggested for the disease.

REASON FOR THE REPORT

The treatment remains controversial, comprising a spectrum from observation or NSAIDs to immunosuppressive agents and surgery. Intractable cases are not uncommon and represent a major treatment challenge. Therefore in this study, we examine the effect of a topical immunomodulator agent, imiquimod, on refractory IGM. Patient 1 had IGM for 9 months and had not responded to the existing treatments. She responded to a 7-week course of imiquimod. In patient 2, the disease had begun 4 months sooner and had been resistant to all treatments; it responded to imiquimod after 4 weeks. Ulcers appeared on the skin of both patients but resolved safely.

OUTCOME

Both patients were very satisfied with the results. Imiquimod can be an appropriate local treatment with limited adverse effects in refractory IGM. We propose similar studies to assess the efficacy of imiquimod in IGM further, paying attention to the possibility of developing skin wounds.

Glutamine promotes human CD8+ T cells and counteracts imiquimod-induced T cell hyporesponsiveness

T cells protect tissues from cancer. Although investigations in mice showed that amino acids (AA) critically regulate T cell immunity, this remains poorly understood in humans. Here, we describe the AA composition of interstitial fluids in keratinocyte-derived skin cancers (KDSCs) and study the effect of AA on T cells using models of primary human cells and tissues. Gln contributed to ∼15% of interstitial AAs and promoted interferon gamma (IFN-γ), but not granzyme B (GzB) expression, in CD8+ T cells. Furthermore, the Toll-like receptor 7 agonist imiquimod (IMQ), a common treatment for KDSCs, down-regulated the metabolic gatekeepers c-MYC and mTORC1, as well as the AA transporter ASCT2 and intracellular Gln, Asn, Ala, and Asp in T cells. Reduced proliferation and IFN-γ expression, yet increased GzB, paralleled IMQ effects on AA. Finally, Gln was sufficient to promote IFN-γ-production in IMQ-treated T cells. Our findings indicate that Gln metabolism can be harnessed for treating KDSCs.

Development and application of an in vitro assay to assess target-independent B-cell activation by targeted TLR7 immune agonists

Targeted immune agonist (TIA) comprising a TLR7 agonist conjugated to tumor-targeting antibodies have been shown to induce potent anti-tumor responses in various preclinical models. However, the clinical proof-of-concept of a TIA has been hampered by systemic dose-limiting immune-related toxicities, including rapid induction of anti-drug antibodies in patients. We have developed ELISPOT-based assay to measure activation of antibody-secreting cells (ASCs), intended to simulate the interaction between TIA and peripheral B cells as a tool to pre-clinically de-risk tumor target-independent peripheral B-cell activation by TIA. This method has proven to be robust and has fast turn-around time to evaluate the induction of spontaneous B-cell activation by TIA in a tumor target- and FcγR-independent manner. This novel ASC assay platform may serve as a preclinical tool to de-risk TIAs that can potentially induce immune-related adverse effects in the clinic.

Melanoma: An update on systemic therapies

Despite advances in early detection as described in part 1 of this continuing medical education series, melanoma continues to be a large contributor to cutaneous cancer-related mortality. In a subset of patients with unresectable or metastatic disease, surgical clearance is often not possible; therefore, systemic and local therapies are considered. The second article in this series provides dermatologists with an up-to-date working knowledge of the treatment options that may be prescribed by oncologists for patients with unresectable stage III, stage IV, and recurrent melanoma.

NCCN Guidelines® Insights: Squamous Cell Skin Cancer, Version 1.2022

The NCCN Guidelines for Squamous Cell Skin Cancer provide recommendations for diagnostic workup, clinical stage, and treatment options for patients with cutaneous squamous cell carcinoma. The NCCN panel meets annually to discuss updates to the guidelines based on comments from panel members and the Institutional Review, as well as submissions from within NCCN and external organizations. These NCCN Guidelines Insights focus on the introduction of a new surgical recommendation terminology (peripheral and deep en face margin assessment), as well as recent updates on topical prophylaxis, immunotherapy for regional and metastatic disease, and radiation therapy.

Soluble Factors and Receptors Involved in Skin Innate Immunity-What Do We Know So Far?

The pattern recognition receptors, complement system, inflammasomes, antimicrobial peptides, and cytokines are innate immunity soluble factors. They sense, either directly or indirectly, the potential threats and produce inflammation and cellular death. High interest in their modulation has emerged lately, acknowledging they are involved in many cutaneous inflammatory, infectious, and neoplastic disorders. We extensively reviewed the implication of soluble factors in skin innate immunity. Furthermore, we showed which molecules target these factors, how these molecules work, and how they have been used in dermatological practice. Cytokine inhibitors have paved the way to a new era in treating moderate to severe psoriasis and atopic dermatitis.

Assessing the compliance of systematic review articles published in leading dermatology journals with the PRISMA statement guidelines: A systematic review

Background

Reporting quality of systematic reviews and meta-analyses is of critical importance in dermatology because of their key role in informing health care decisions.

Objective

To assess the compliance of systematic reviews and meta-analyses in leading dermatology journals with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement guidelines.

Methods

This review was carried out in accordance with PRISMA guidelines. Included studies were reviews published across 6 years in the top 4 highest-impact-factor dermatology journals of 2017. Records and full texts were screened independently. Data analysis was conducted with univariate multivariable linear regression. The primary outcome was to assess the compliance of systematic reviews and meta-analyses in leading dermatology journals with the PRISMA statement.

Results

A total of 166 studies were included and mean PRISMA compliance across all articles was 73%. Compliance significantly improved over time (β = .016; P = <.001). The worst reported checklist item was item 5 (reporting on protocol existence), with a compliance of 15% of articles.

Conclusion

PRISMA compliance within leading dermatology journals could be improved; however, it is steadily improving.

Evolution of Toll-like receptor 7/8 agonist therapeutics and their delivery approaches: From antiviral formulations to vaccine adjuvants

Imidazoquinoline derivatives (IMDs) and related compounds function as synthetic agonists of Toll-like receptors 7 and 8 (TLR7/8) and one is FDA approved for topical antiviral and skin cancer treatments. Nevertheless, these innate immune system-activating drugs have potentially much broader therapeutic utility; they have been pursued as antitumor immunomodulatory agents and more recently as candidate vaccine adjuvants for cancer and infectious disease. The broad expression profiles of TLR7/8, poor pharmacokinetic properties of IMDs, and toxicities associated with systemic administration, however, are formidable barriers to successful clinical translation. Herein, we review IMD formulations that have advanced to the clinic and discuss issues related to biodistribution and toxicity that have hampered the further development of these compounds. Recent strategies aimed at enhancing safety and efficacy, particularly through the use of bioconjugates and nanoparticle formulations that alter pharmacokinetics, biodistribution, and cellular targeting, are described. Finally, key aspects of the biology of TLR7 signaling, such as TLR7 tolerance, that may need to be considered in the development of new IMD therapeutics are discussed.

Safety of topical interventions for the treatment of actinic keratosis

Introduction: Actinic keratosis (AK) are proliferations of atypical keratinocytes that may eventually progress to cutaneous squamous cell carcinoma. Therefore, AK requires consequent and early treatment. Areas covered: A variety of effective approaches is currently available for the clearance of AK. These interventions may be applied either in a lesion-directed or field-directed mode as AK can occur as single or multiple lesions. Field-directed approaches typically comprise topical drug-mediated interventions which aim at eliminating all visible lesions and also at clearing subclinical changes of the actinically damaged field. However, most treatment options are associated with local adverse events such as erythema, scaling, pain, and rarely with systemic symptoms. This expert review provides a comprehensive and up-to-date overview of the safety considerations of the commonly prescribed topical treatment agents cyclooxygenase inhibitors, 5-fluorouracil, imiquimod, ingenol mebutate, and photodynamic therapy. All these therapies have been proven efficient, yet they differ considerably regarding their safety profile. Expert opinion: In the future, safety concerns will relate to long-term and irreversible adverse drug events instead of application site reactions. In particular, the rate of treatment-associated non-melanoma skin cancers will increasingly come into focus and warrant investigation in postmarketing surveillance trials with a long-term follow-up.

Follicular extension of atypical keratinocytes predicts the resistance of actinic keratosis to topical imiquimod treatment: A single-center retrospective analysis

Topical imiquimod therapy has been widely used for actinic keratosis (AK). However, some cases are refractory to treatment. Therefore, an indicator that can predict its efficacy is desired. Herein, we retrospectively analyzed 52 AK lesions treated with imiquimod to investigate the characteristics of refractory lesions. Imiquimod was applied in a cycle of three times weekly for 4 weeks, followed by a 4-week break. This treatment cycle was repeated up to three times and treatment responses were evaluated. As a result, a complete response (CR) was observed in 78.8% (41/52) of lesions. Next, treatment response of lesions was correlated with clinicopathological characteristics including clinical morphology and thickness, pathological morphology and thickness, and presence of follicular extension (FE). Of these, lesions with FE were significantly less responsive to imiquimod treatment; while 92.6% of AK lesions without FE achieved a CR, only 64.0% of AK lesions with FE achieved a CR (p = 0.029). Logistic regression analysis revealed that FE was the sole significant predictor of its efficacy (p = 0.019). These results suggest that preliminary histological evaluation of FE may be useful to predict the efficacy of imiquimod for AK.

Vitiligo-Like Depigmentation following Treatment with Imiquimod 5% Cream for Condylomata Acuminata

Imiquimod cream is an immunomodulatory agent that has been approved by the US Food and Drug Administration for use in the treatment of anogenital warts (condylomata acuminata) due to its local immune effects in activating Toll-like receptors 7 and 8 on antigen-presenting cells, resulting in reduction of the viral load of human papillomavirus with subsequent wart regression. After its application, some side effects are commonly reported, including erythema, edema, scaling, erosion, and ulceration. While pigmentary changes, including vitiligo-like depigmentation, have been mentioned as a possible side effect, they have rarely been reported in the literature. Alterations in pigmentation occur because imiquimod application causes human melanocyte apoptosis and autodestruction resulting in loss of melanocytes. Herein, we report the rare case of a 34-year-old healthy male who developed vitiligo-like depigmentation following imiquimod application for his genital warts. This case report aims to increase physicians' awareness of this possible side effect that could be irreversible and difficult for the patient to accept.

Comparative study of imiquimod 3.75% vs. photodynamic therapy for actinic keratosis of the scalp

BACKGROUND/PURPOSE

To assess efficacy, tolerability, adverse effects, recurrence, and aesthetic results of imiquimod 3.75% vs. photodynamic therapy with 5-aminolaevulinic acid (MAL-PDT) for actinic keratosis (AK).

METHODS

A small randomized, intraindividual right-left pilot study for AK treatment of multiple scalp lesions was performed. Patients were treated with imiquimod and subsequently MAL-PDT (on opposite sides of the scalp) 14 days apart. Study end points were evaluated with clinical and dermoscopic examinations at 1, 3, 6, and 12 months.

RESULTS

Nine male bald patients were enrolled. Imiquimod achieved a slightly higher overall clearance rate than MAP-PDT (68.1% vs 56.5%). According to AK degree of severity, clearance rates were greater for degree I and III with imiquimod (68.8%, 64.5% and 75% with imiquimod vs. 48%, 69.8%, and 66.7% for MAL-PDT, respectively). At 12 months, a slightly higher total recurrence rate was noted for imiquimod compared with MAL-PDT (9.9% vs. 8.6%); new lesions were 2 degree I for imiquimod and 4 degree I for MAL-PDT. For both treatments, pain was moderate/strong (even if MAL-PDT seems to be less tolerable) adverse effects are common and transient; aesthetic results excellent.

CONCLUSION

Both imiquimod and MAL-PDT were effective in the reduction in the number of AK. In the long-term, both present a good effectiveness maintained over time with excellent aesthetic results. A combination or sequential therapy could optimize the management of the cancerization field.

Actinic Keratoses: Reconciling the Biology of Field Cancerization with Treatment Paradigms

This Perspective briefly reviews the relationship between UV-induced mutations in habitually sun-exposed human skin and subsequent development of actinic keratoses (AKs) and skin cancers. It argues that field therapy rather than AK-selective therapy is the more logical approach to cancer prevention and hypothesizes that treatment early in the process of field cancerization, even prior to the appearance of AKs, may be more effective in preventing cancer as well as more beneficial for and better tolerated by at-risk individuals. Finally, the Perspective encourages use of rapidly advancing DNA analysis techniques to quantify mutational burden in sun-damaged skin and its reduction by various therapies.

A review of actinic keratosis, skin field cancerisation and the efficacy of topical therapies

While a wide range of treatments exist for actinic keratosis and skin field cancerisation, the long‐term benefits of the most common topical therapies are poorly defined. This report reviews the efficacy of the most commonly used topical therapies to treat regional or field lesions. Limited clinical and histopathological data are available on clearance rates at 12 months post‐treatment for the most commonly used agents, with varied outcome measures making any comparison difficult. In general, total field clearance rates at 12 months are suboptimal for the most commonly employed agents. Given the increasing incidence of actinic keratosis and skin field cancerisation due to an ageing population, further research into the efficacy of therapies is critical to guide treatment choice.

[Actinic keratoses : Current guideline and practical recommendations]

The S3 guideline "Actinic keratosis and squamous cell carcinoma of the skin" was published on 30 June 2019. Subsequently, publications, reviews and meta-analyses appeared with new questions regarding the comparability of study data and heterogeneity of the evaluations, which are caused, among other things, by divergent measurement parameters as well as insufficient consideration of pretreatments and combined treatments. This concise overview was written in the context of criticism and in view of necessary developments and research. Topics include epidemiology, pathogenesis, prevention, clinical presentation, therapy and BK5103. Therapy is divided into local destructive procedures and topical applications. Recommendations with quotation marks are based on the actual guideline. Corresponding evidence levels are given. For the implementation in daily routine basic data, side effects and features of therapeutic options are mentioned. The current developments and questions concerning actinic keratoses become clear.

Earliest stage treatment of actinic keratosis with imiquimod 3.75% cream: Two case reports-Perspective for non melanoma skin cancer prevention

Imiquimod 3.75% cream is licensed for the treatment of actinic keratosis (AK). Two case reports on the treatment of facial UV-exposed skin shall open the discussion if subclinical AKs can be detected by the use of imiquimod cream in UV-exposed areas even if no lesions can be found clinically. A 87-year old female showing small scaly AK lesions on her right cheek was treated with imiquimod 3.75% cream. A 59-year old female without obvious clinical signs of UV-damage on the face experimentally applied imiquimod 3.75% cream twice daily on the entire face for 2 weeks. In the 87-year old, inflammatory reaction developed from day 3 onward and showed field cancerization, the lesions healed without scarring. In the 59-year old at the end of the treatment phase, distinct signs of inflammation appeared, then taking 2 weeks for healing without sequalae. These results open the discussion if the use of imiquimod 3.75% cream could be recommended preventively in UV-exposed skin areas to obviate a later development of AKs/squamous cell carcinoma/nonmelanoma skin cancer.

Field cancerization: Treatment

The goal of field cancerization treatment is to reduce the risk of developing keratinocyte carcinoma. Selecting the appropriate therapy depends on the degree of field cancerization and the number of invasive cutaneous squamous cell carcinomas. Other considerations include treatment efficacy, cost, side effects, and patient preference. Field therapies are preferred because they address clinically visible disease and subclinical atypia. However, lesion-directed therapies are useful for lesions that are more difficult to treat or those where a histologic diagnosis is required. Patients with extensive field cancerization benefit from a combination of field-directed and lesion-directed treatments. The second article in this continuing medical education series provides a framework to guide evidence-based decision making for field cancerization treatment.

The Toll-like receptor agonist imiquimod is metabolized by aryl hydrocarbon receptor-regulated cytochrome P450 enzymes in human keratinocytes and mouse liver

The Toll-like receptor 7 agonist imiquimod (IMQ) is an approved drug for the topical treatment of various skin diseases that, in addition, is currently tested in multiple clinical trials for the immunotherapy of various types of cancers. As all of these trials include application of IMQ to the skin and evidence exists that exposure to environmental pollutants, i.e., tobacco smoke, affects its therapeutic efficacy, the current study aims to elucidate the cutaneous metabolism of the drug. Treatment of human keratinocytes with 2.5 µM benzo[a]pyrene (BaP), a tobacco smoke constituent and aryl hydrocarbon receptor (AHR) agonist, for 24 h induced cytochrome P450 (CYP) 1A enzyme activity. The addition of IMQ 30 min prior measurement resulted in a dose-dependent inhibition of CYP1A activity, indicating that IMQ is either a substrate or inhibitor of CYP1A isoforms. Incubation of 21 recombinant human CYP enzymes with 0.5 µM IMQ and subsequent LC-MS analyses, in fact, identified CYP1A1 and CYP1A2 as being predominantly responsible for IMQ metabolism. Accordingly, treatment of keratinocytes with BaP accelerated IMQ clearance and the associated formation of monohydroxylated IMQ metabolites. A co-incubation with 5 µM 7-hydroxyflavone, a potent inhibitor of human CYP1A isoforms, abolished basal as well as BaP-induced IMQ metabolism. Further studies with hepatic microsomes from CD-1 as well as solvent- and β-naphthoflavone-treated CYP1A1/CYP1A2 double knock-out and respective control mice confirmed the critical contribution of CYP1A isoforms to IMQ metabolism. Hence, an exposure to life style-related, dietary, and environmental AHR ligands may affect the pharmacokinetics and, thus, treatment efficacy of IMQ.

Prise en charge thérapeutique des kératoses actiniques

Dermatologists have many therapeutic options for the management of actinic keratoses (AK), in order to treat individual lesions or wider areas. Field cancerization is an area of sun-damaged skin, where visible and subclinical lesions co-exist, and is prone to the development of further AK lesions and sun-related skin cancers (SC). Treatments available are instrumental or medical. Resistance to treatment or atypical symptoms must lead to a biopsy for histological exam. Cryotherapy is the most frequently used method to destroy small or isolated AK, whereas photodynamic therapy (PDT), 5-fluoro-uracil (5-FU), imiquimod, ingenol mebutate and diclofenac are required for large, multiple lesions, and for the treatment of field cancerization. Side-effects of these therapies are essentially local, including pain, irritation, erythema, edema and scars. There is no randomized comparative study reviewing all these treatments, therefore physicians must also consider clinical characteristics, patient's compliance, side-effects and cost when treating AK. Medicoeconomic data of these treatments have been analyzed in several countries, and annual costs are estimated between 250 € and 2 000 €, with an uncertain cost-effective relation. Finally, beyond treatment of AK lesions, patients with AK are at high risk of developing SC, and must therefore have regular full-body examination, in order to be detected and treated precociously. © 2019 Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Kératoses actiniques : comprendre et traiter réalisé avec le soutien institutionnel de Galderma International.

Recent advances in localized immunotherapy of skin cancers

Skin cancer is the most frequent malignancy in humans. The immune system has long been known to have an important role in defeating cancer. Immunotherapy, which includes various strategies to enhance tumor immunity, currently represents an exciting option for the treatment of skin cancers. Local immunotherapy is a promising therapeutic approach and may improve response rates without inducing systemic toxicity. Here, we review the main localized immunotherapies for the management of skin cancer with a special focus on advanced melanoma, nonmelanoma skin cancer and primary cutaneous lymphoma.

Current Basal and Squamous Cell Skin Cancer Management

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Characterize basal and squamous cell carcinomas as low or high risk based on size, location, histology, and clinical features. 2. Understand appropriate surgical margins in low- and high-risk lesions, and other management options, including Mohs micrographic surgery, electrodissection and curettage, topical agents, cryotherapy, photodynamic therapy, and radiation therapy. 3. Discuss adjuvant therapies for locally advanced and metastatic disease, including radiation therapy, chemotherapy, and targeted therapies such as hedgehog pathway inhibitors. 4. Educate patients on preventive measures such as skin examinations, sun protection, oral retinoids, and oral nicotinamide (vitamin B3). 5. Devise a reconstructive plan once clear oncologic margins are obtained.

SUMMARY

With the growing incidence of basal and squamous cell carcinoma, there is an increasing demand for appropriate oncologic management and aesthetic reconstruction. The goal of this CME article is to provide a foundation of knowledge to accurately diagnose, stage, and treat nonmelanoma skin cancers. In addition, it provides the practicing plastic surgeon alternate tools for managing these skin lesions, including topical agents, destructive therapies, and radiation therapy. Lastly, reconstructive plans for selected soft-tissue defects are discussed.

Current developments in pharmacotherapy for actinic keratosis

INTRODUCTION

Actinic keratosis (AK) is a superficial squamous cell carcinoma (SCC) where chronic sun exposure playing central role in its pathogenesis. UVB causes direct damage to DNA, producing pyrimidine dimers, and suppressing the protective role of p53. The stepwise progression of AK, with increased expression of anti-apoptotic Bcl-2, favors progression to SCC. Moreover, the dermal response characterized by inflammation and mediated by prostaglandins is a critical component of tumorigenesis that promotes tumor growth, tissue invasion, angiogenesis and metastasis. Other risk factors are represented by age, gender, phototype and drugs.

AREAS COVERED

In this review, the authors document the recent developments of different therapies used to treat AK and provide their perspectives on current and future treatment strategies.

EXPERT OPINION

The usefulness of long-term treatment with piroxicam and sun filters or diclofenac targeting the inflammation phases of skin tumorigenesis favors AK's healing and provides greater control of the cancerization field. Nonsteroidal anti-inflammatory drugs can be safely used in patients who use photosensitizing drugs and, therefore, are more at risk of developing skin tumors. Immunomodulatory therapies, which require shorter treatment, are characterized by more common local side effects, and need more attention by the dermatologist in the concern of patient education, resulting essential to improve adherence and outcomes.

Teledermatology-driven topical therapy of actinic keratosis: a comparative study of clinical effectiveness and compliance

BACKGROUND

Teledermatology (TD) provides efficient care for skin cancer patients.

OBJECTIVE

To compare the clinical effectiveness of imiquimod 5% for the treatment of AK with in-person care and through TD.

METHODS

Longitudinal prospective controlled study including patients with single AK diagnosed and treated at face-to-face visits (FTF group) or through teledermatology (TD group) with imiquimod 5% cream. The main outcome measures assessed were the complete and global response percentage (CR and GR) under per-protocol (PP) and intention-to-treat (ITT) analysis.

RESULTS

A total of 157 patients were enrolled (FTF = 75, TD = 82). PP analysis showed CR in 66.7% of FTF patients and 65.6% in TD patients (P > 0.05). The ITT yielded CR in 64.0% and 51.2% in FTF visits and TD, respectively (P = 0.073). The analysis showed an advantage of FTF care against TD in achieving GR (84.0% vs. 70.7%; P = 0.036). Facial location and local adverse reactions were the only explanatory factors of complete response in the ITT approach. Treatment completion was found in 90.7% and 72.0% in the FTF and TD groups, respectively (P = 0.004).

CONCLUSIONS

Improvements in patient counselling at the primary care centre are needed before the implementation of TD as a routine methodology for the management of AK.

A placebo-controlled efficacy study of the intravesical immunomodulators TMX-101 and TMX-202 in an orthotopic bladder cancer rat model

Purpose

TMX-101 and TMX-202 are formulations of toll-like receptor 7 (TLR-7) agonists, under investigation for the treatment of urothelial carcinoma. Our goal was to evaluate the efficacy of intravesical instillations of TMX-101 or TMX-202 in an orthotopic bladder cancer rat model.

Methods

Four groups of 14 rats received an instillation with isogenic AY-27 tumor cells on day 0, starting tumor development. On day 2 and 5, the rats were treated with an intravesical instillation of TMX-101 0.1%, TMX-202 0.38%, vehicle solution or NaCl. On day 12 the rats were sacrificed and the bladders were evaluated histopathologically.

Results

No signs of toxicity were seen. The number of tumor-positive rats was 11 of 14 (79%) in the vehicle control group and in the NaCl control group, versus 9 of 14 (64%) in the TMX-101-treated group, and 8 of 14 (57%) in the TMX-20-treated group. The difference between tumor-bearing rats in the treated and control groups was not significant (p = 0.12). Bladder weight was significantly lower for TMX-202-treated rats compared to vehicle (p = 0.005).

Conclusions

TMX-101 and TMX-202 are TLR-7 agonists with antitumor activity. Treatment with TMX-101 and TMX-202 resulted in less tumor-bearing rats compared to vehicle or saline control groups, although not statistically significant. In this aggressive bladder cancer model, a lower number of tumor-positive rats after treatment with TLR-7 agonists indicates activity for the treatment of non-muscle invasive bladder cancer.

Electronic supplementary material

The online version of this article (10.1007/s00345-018-2334-3) contains supplementary material, which is available to authorized users.

A multicentre, open, investigator-initiated phase IV clinical trial to evaluate the efficacy and safety of ingenol mebutate gel, 0·015% on the face and scalp, and 0·05% on the trunk and extremities, in Korean patients with actinic keratosis (PERFECT)

BACKGROUND

Ingenol mebutate gel is a novel, field-directed topical treatment for actinic keratosis (AK). Most pivotal studies have targeted Western populations. No clinical study has been conducted to investigate its efficacy and safety in Asian populations.

OBJECTIVES

To evaluate the efficacy and safety of ingenol mebutate gel for treating AK of face/scalp and trunk/extremities in a large Asian (Korean) population.

PATIENTS AND METHODS

In this multicentre, open-label, interventional, parallel-group, prospective phase IV study (PERFECT, trial registration no.: NCT02716714), the eligible patients were allocated into either the face/scalp or the trunk/extremities group, according to their selected treatment area location. After application of ingenol mebutate gel, the participants were followed up for 6 months. The primary efficacy endpoint was complete clearance (CC) of AK lesions in the selected treatment area at day 57. Quality of life was evaluated using Skindex-29. Safety endpoints included local skin responses, scar, pigmentation, pain and adverse events.

RESULTS

In total, 78·1% [95% confidence interval (CI) 66·86-86·92%] of subjects had CC at day 57, with 76·6% (95% CI 64·31-86·25%) in the face/scalp group and 88·9% (95% CI 51·75-99·72%) in the trunk/extremities group. Among them, CC was sustained in 88·9% (48 of 54, 95% CI 77·37-95·81%) at month 6. The local skin responses significantly increased 1 day after the treatment compared with baseline, and decreased afterwards. Among the total subjects, 7·8% (6 of 77) had hyperpigmentation on the application area. Scars were not reported.

CONCLUSIONS

Ingenol mebutate is effective for the treatment of AK in Asians, with tolerable safety profiles.

A 12-Day Course of Imiquimod 5% for the Treatment of Actinic Keratosis: Effectiveness and Local Reactions

INTRODUCTION AND OBJECTIVES

Imiquimod is an excellent option for patients with actinic keratosis, although its use may be limited by the long course of treatment required (4 weeks) and the likelihood of local skin reactions. The objectives of the present study were to demonstrate the effectiveness of a 12-day course of imiquimod 5% for the treatment of actinic keratosis and to examine the association between treatment effectiveness and severity of local reactions.

PATIENTS AND METHODS

We included patients with at least 8 actinic keratoses treated with imiquimod 5% cream for 12 consecutive days. Local reactions were classified as mild, moderate, or severe. The statistical analysis of the association between local reactions and clinical response was based on the Pearson χ² test and the Spearman rank correlation test.

RESULTS

Sixty-five patients completed the study. Complete response was recorded in 52.3% and partial response in 75.4%. We found a statistically significant association between severity of the local reaction and response to treatment in both the Pearson χ² test and the Spearman rank correlation test.

CONCLUSIONS

A 12-day course of imiquimod 5% proved effective for the treatment of actinic keratosis. Severity of local reactions during treatment was correlated with clinical response.

Imiquimod in dermatology: an overview

Imiquimod is an immune response modifier commercially available as a 3.75 and 5% cream. Topical imiquimod stimulates the innate and adaptive immune responses and induces cytokine production. This allows its use for the treatment of a wide variety of benign and malignant skin conditions due to its potential antiviral, antitumor, and immunoregulatory effects. Currently, topical imiquimod is US Food and Drug Administration (FDA)-approved for the treatment of anogenital warts, actinic keratosis, and superficial basal cell carcinomas. However, it has also shown a beneficial effect in the treatment of many other skin disorders. In this review, we describe existing evidence on the mechanism of action of topical imiquimod, its FDA-approved indications, off-label uses, and side effects.

Cellulitis Secondary to Liquid Nitrogen Cryotherapy: Case Report and Literature Review

BACKGROUND

Liquid nitrogen cryotherapy is a commonly used technique to treat a wide variety of dermatologic conditions including actinic keratoses, non-melanoma skin cancers, verrucae, and seborrheic keratoses. The risks associated with liquid nitrogen cryotherapy are important to know and discuss with patients prior to treatment.

OBJECTIVE

We report a case of cellulitis secondary to liquid nitrogen cryotherapy for actinic keratosis. We sought to review the literature for an estimate of secondary infection rates following cryotherapy treatment.

METHODS

We searched Pubmed using the terms cryotherapy and infection or cellulitis. We then looked at articles classified as clinical trials where cryotherapy was used to treat skin conditions. We then selected clinical trials that listed cellulitis or infection as an adverse event.

RESULTS AND CONCLUSION

There were no case reports, case series, or review articles detailing the risk of infection from liquid nitrogen cryotherapy. We found 8 articles classified as clinical trials on Pubmed that did list infection as an adverse event. The risk of infection from these studies varied from approximately 2% to 30%. There was a great degree of heterogeneity in treatment sites, length of treatment, and treatment targets. While it is difficult to determine the true incidence of infection from liquid nitrogen cryotherapy, clinicians should endeavor to inform patients of this potential risk.

In vitro effects of tetraiodothyroacetic acid combined with X-irradiation on basal cell carcinoma cells

We investigated radiosensitization in an untreated basal cell carcinoma (TE.354.T) cell line and post-pretreatment with tetraiodothyroacetic acid (tetrac) X 1 h at 37°C, 0.2 and 2.0 µM tetrac. Radioresistant TE.354.T cells were grown in modified medium containing fibroblast growth factor-2, stem cell factor-1 and a reduced calcium level. We also added reproductively inactivated (30 Gy) “feeder cells” to the medium. The in vitro doubling time was 34.1 h, and the colony forming efficiency was 5.09 percent. These results were therefore suitable for clonogenic radiation survival assessment. The 250 kVp X-ray survival curve of control TE.354.T cells showed linear-quadratic survival parameters of α_X-ray = 0.201 Gy⁻¹ and β_X-ray = 0.125 Gy⁻². Tetrac concentrations of either 0.2 or 2.0 µM produced α_X-ray and β_X-ray parameters of 2.010 and 0.282 Gy⁻¹ and 2.050 and 0.837 Gy⁻², respectively. The surviving fraction at 2 Gy (SF₂) for control cells was 0.581, while values for 0.2 and 2.0 µM tetrac were 0.281 and 0.024. The SF₂ data show that tetrac concentrations of 0.2 and 2.0 µM sensitize otherwise radioresistant TE.354.T cells by factors of 2.1 and 24.0, respectively. Thus, radioresistant basal cell carcinoma cells may be radiosensitized pharmacologically by exposure to tetrac.

A Way Forward for Cancer Chemoprevention: Think Local

As cells progress through carcinogenesis, the associated exponential expansion of genetic and molecular aberrations and resultant heterogeneity make therapeutic success increasingly unattainable. Therapeutic intervention at early stages of carcinogenesis that occurs within the primary organ and in the face of a lower burden of molecular aberrations, constitutes a basic tenet of cancer chemoprevention, and provides a situation that favors a greater degree of therapeutic efficacy compared with that of advanced cancer. A longstanding barrier to chemoprevention relates to the requirement for essentially no systemic toxicity, and the fact that when large numbers of people are treated, the emergence of systemic toxicity is almost universal. A rational means to address this in fact relates to a second basic tenet of the chemopreventive strategy: the focus of therapeutic intervention is to disrupt a process that is in essence localized to a single organ. Based upon this consideration, a strategy which is based upon local delivery of therapeutics to an at-risk organ will achieve therapeutic efficacy while avoiding systemic delivery and its associated toxicity. This article will review the rationale for undertaking such an approach, describe successful clinical achievements based on this strategy, describe ongoing efforts to expand the impact of this approach, and together will highlight the high impact that this approach has already had on the field as well as its extremely high potential for future impact. Cancer Prev Res; 10(1); 14-35. ©2016 AACR.

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.

Plasmacytoid dendritic cell role in cutaneous malignancies

Plasmacytoid dendritic cells (pDCs) correspond to a specialized dendritic cell population that exhibit plasma cell morphology, express CD4, CD123, HLA-DR, blood-derived dendritic cell antigen-2 (BDCA-2), and Toll-like receptor (TLR)7 and TLR9 within endosomal compartments. Through their production of type I interferons (IFNs) and other pro-inflammatory cytokines, pDCs provide anti-viral resistance and link the innate and adaptive immunity by controlling the function of myeloid DCs, lymphocytes, and natural killer (NK) cells. While lacking from normal skin, pDCs are usually recruited to the skin in several cutaneous pathologies where they appear to be involved in the pathogenesis of several infectious, inflammatory/autoimmune, and neoplastic entities. Among the latter group, pDCs have the potential to induce anti-tumour immunity; however, the complex interaction of pDCs with tumor cells and their micro-environment appears to contribute to immunologic tolerance. In this review, we aim at highlighting the role played by pDCs in cutaneous malignancies with special emphasis on the underlying mechanisms.

The phenotypic legacy of admixture between modern humans and Neandertals

Many modern human genomes retain DNA inherited from interbreeding with archaic hominins, such as Neandertals, yet the influence of this admixture on human traits is largely unknown. We analyzed the contribution of common Neandertal variants to over 1000 electronic health record (EHR)-derived phenotypes in ~28,000 adults of European ancestry. We discovered and replicated associations of Neandertal alleles with neurological, psychiatric, immunological, and dermatological phenotypes. Neandertal alleles together explained a significant fraction of the variation in risk for depression and skin lesions resulting from sun exposure (actinic keratosis), and individual Neandertal alleles were significantly associated with specific human phenotypes, including hypercoagulation and tobacco use. Our results establish that archaic admixture influences disease risk in modern humans, provide hypotheses about the effects of hundreds of Neandertal haplotypes, and demonstrate the utility of EHR data in evolutionary analyses.

Bropirimine inhibits osteoclast differentiation through production of interferon-β

Bropirimine is a synthetic agonist for toll-like receptor 7 (TLR7). In this study, we investigated the effects of bropirimine on differentiation and bone-resorbing activity of osteoclasts in vitro. Bropirimine inhibited osteoclast differentiation of mouse bone marrow-derived macrophages (BMMs) induced by receptor activator of nuclear factor κB ligand (RANKL) in a concentration-dependent manner. Furthermore, it suppressed the mRNA expression of nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1 (NFATc1), a master transcription factor for osteoclast differentiation, without affecting BMM viability. Bropirimine also inhibited osteoclast differentiation induced in co-cultures of mouse bone marrow cells (BMCs) and mouse osteoblastic UAMS-32 cells in the presence of activated vitamin D3. Bropirimine partially suppressed the expression of RANKL mRNA in UAMS-32 cells induced by activated vitamin D3. Finally, the anti-interferon-β (IFN-β) antibody restored RANKL-dependent differentiation of BMMs into osteoclasts suppressed by bropirimine. These results suggest that bropirimine inhibits differentiation of osteoclast precursor cells into osteoclasts via TLR7-mediated production of IFN-β.

Development of nanovesicular systems for dermal imiquimod delivery: physicochemical characterization and in vitro/in vivo evaluation

The aim of the current investigation was to develop and statistically evaluate nanovesicular systems for dermal imiquimod delivery. To this purpose, transethosomes were prepared with phospholipid, ethanol and different permeation enhancers. Conventional ethosomes, with soy phospholipid and ethanol, were used as control. The prepared vesicles were characterized for size, zeta potential, stability and entrapment efficiency. The optimal transethosomal formulation with mean particle size of 82.3 ± 9.5 nm showed the higher entrapment efficiency (68.69 ± 1.7%). In vitro studies, permeation results of accumulated drug and local accumulation efficiency were significantly higher for transethosomes (24.64 µg/cm(2) and 6.70, respectively) than control (14.45 µg/cm(2) and 3.93, respectively). Confocal laser scanning microscopy of rhodamine 6G-loaded transethosomes revealed an enhanced retention into the deeper skin layers as compared to conventional ethosomes. Besides, Fourier-transform infra-red spectroscopy studies were also performed to understand the mechanism of interaction between skin and carriers. What's more, results of in vivo studies indicated the transethosomes of imiquimod providing the most effectiveness for dermal delivery among all of the formulations. These results suggested that transethosomes would be a promising dermal carrier for imiquimod in actinic keratose treatment.

Toll receptor agonist therapy of skin cancer and cutaneous T-cell lymphoma

PURPOSE OF REVIEW

The use of agents which exhibit the ability to potently activate the innate immune response has gained significant interest as therapeutics to treat cancer. We will review the history and the current applications of these agents to treat skin cancer and cutaneous T-cell lymphoma.

RECENT FINDINGS

Particular attention has been focused upon Toll-like receptor (TLR) agonists, including imidazoquinolines, which can trigger TLR 7 and TLR 8, and cytosine-phosphate-guanine (CpG) oligodeoxynucleotides, which activate TLR 9-expressing cells. Imiquimod, a TLR 7 agonist, has been found to be efficacious for basal cell and squamous cell cancers, as well as cutaneous T-cell lymphoma and lentigo maligna melanoma. CpGs have demonstrated efficacy for cutaneous T-cell lymphoma. Additional more potent compounds, including resiquimod, are presently in clinical trials for several types of skin cancers.

SUMMARY

TLR agonists that can activate the innate immune response have been used to treat a variety of skin cancers including basal cell cancer, squamous cell cancer, lentigo maligna melanoma and cutaneous T-cell lymphoma. Significant clinical efficacy has been observed for all of these conditions. It is anticipated that additional members of the TLR agonist family will be available in the clinic for the future treatment of skin cancers as well as other malignancies.

Impact of different vehicles for laser-assisted drug permeation via skin: full-surface versus fractional ablation

PURPOSE

This study aimed to assess impact of different vehicles for laser-assisted skin drug delivery. We also tried to uncover the mechanisms by which different vehicles affect laser-aided skin permeation.

METHODS

Full-surface ablative (conventional) and fractional lasers were used to irradiate nude mouse skin. Imiquimod and 5-aminolevulinic acid (ALA) were used as lipophilic and hydrophilic permeants. Vehicles employed included water with 40% polyethylene glycol 400 (PEG 400), propylene glycol (PG), and ethanol. Lipid nanoparticles were also utilized as carriers.

RESULTS

In vitro permeation profiles showed improvement in imiquimod flux with conventional laser (2.5 J/cm2) producing a 12-, 9-, and 5-fold increase when loading imiquimod in 40% PEG400, PG, and ethanol, respectively, as compared with intact skin. Nanoparticulate delivery by laser produced a 6-fold enhancement in permeation. Fractional laser produced less enhancement of imiquimod delivery than conventional laser. Laser exposure increased follicular imiquimod accumulation from 0.80 to 5.81 μg/cm2. ALA permeation from aqueous buffer, PEG 400, and PG with conventional laser treatment was 641-, 445-, and 104-fold superior to passive control. In vivo skin deposition of topically applied ALA examined by confocal microscopy indicated the same trend as the in vitro experiment, with aqueous buffer showing the greatest proporphyllin IX signaling. Diffusion of cosolvent molecules into ablated skin and drug partitioning from vehicle to skin are two predominant factors controlling laser-assisted delivery. In contrast to conventional laser, lateral drug diffusion was anticipated for fractional laser.

CONCLUSIONS

Our results suggest that different drug delivery vehicles substantially influence drug penetration enhanced by lasers.

Solar keratoses: photodynamic therapy, cryotherapy, 5-fluorouracil, imiquimod, diclofenac, or what? Facts and controversies

Actinic keratosis is a common dermatologic condition that may regress, remain stable, or progress to squamous cell carcinoma. Some question whether all actinic keratoses should be routinely treated, whereas others contend that the unpredictable natural history of this disease necessitates treatment to prevent malignant transformation. Available treatments include photodynamic therapy, cryotherapy, 5-fluorouracil, imiquimod, and diclofenac. Each of these options has its advantages and disadvantages, although they all have a place in the management of actinic keratosis. An overview of these treatment modalities is presented, as are the controversies surrounding the treatment of actinic keratosis.