Neutrophils are a key component of the antitumor efficacy of topical chemotherapy with ingenol-3-angelate

Natural Compounds in Non-Melanoma Skin Cancer: Prevention and Treatment

The elevated occurrence of non-melanoma skin cancer (NMSC) and the adverse effects associated with available treatments adversely impact the quality of life in multiple dimensions. In connection with this, there is a necessity for alternative approaches characterized by increased tolerance and lower side effects. Natural compounds could be employed due to their safety profile and effectiveness for inflammatory and neoplastic skin diseases. These anti-cancer drugs are often derived from natural sources such as marine, zoonotic, and botanical origins. Natural compounds should exhibit anti-carcinogenic actions through various pathways, influencing apoptosis potentiation, cell proliferation inhibition, and metastasis suppression. This review provides an overview of natural compounds used in cancer chemotherapies, chemoprevention, and promotion of skin regeneration, including polyphenolic compounds, flavonoids, vitamins, alkaloids, terpenoids, isothiocyanates, cannabinoids, carotenoids, and ceramides.

Factor-specific generative pattern from large-scale drug-induced gene expression profile

Drug discovery is a complex and interdisciplinary field that requires the identification of potential drug targets for specific diseases. In this study, we present FacPat, a novel approach that identifies the optimal factor-specific pattern explaining the drug-induced gene expression profile. FacPat uses a genetic algorithm based on pattern distance to mine the optimal factor-specific pattern for each gene in the LINCS L1000 dataset. We applied Benjamini-Hochberg correction to control the false discovery rate and identified significant and interpretable factor-specific patterns consisting of 480 genes, 7 chemical compounds, and 38 human cell lines. Using our approach, we identified genes that show context-specific effects related to chemical compounds and/or human cell lines. Furthermore, we performed functional enrichment analysis to characterize biological features. We demonstrate that FacPat can be used to reveal novel relationships among drugs, diseases, and genes.

Ingenol mebutate inhibits the growth of pancreatic cancer cells in vitro via STING with an efficacy comparable to that of clinically used anticancer agents

Pancreatic cancer is associated with a poor prognosis; thus, there is an urgent need to develop new and effective treatments. Ingenol mebutate (IM), which is isolated from the latex of Euphorbia peplus, was recently shown to be effective against pancreatic cancer cell lines; however, its mechanism of action has not been fully elucidated. In this study, we focused on the less drug-sensitive pancreatic cancer cell line Panc-1 and compared IM to commercially available anticancer drugs using cell survival assays. In addition, we aimed to identify novel biomolecules that may be involved in the mechanism of action of IM using RNA sequencing, western blotting, and inhibition assays. The IC50 values after 72 h of exposure to IM and SN-38, drugs to which the Panc-1 cells are most sensitive among the tested anticancer agents, were 43.1 ± 16.8 nM and 165 ± 37 nM, respectively. IM showed a cytostatic effect equal to or greater than that of the clinically used pancreatic cancer therapeutic drugs. RNA sequencing and protein expression analysis revealed that expression of stimulator of interferon genes (STING) increased at low IM concentration, whereas cell viability decreased. Co-exposure of IM and STING inhibitor, H-151, to Panc-1 or MIA PaCa-2 cell lines canceled the growth-inhibitory effects of IM alone. In conclusion, IM may have an efficacy comparable to that of existing pancreatic cancer therapeutic agents on the less drug-sensitive Panc-1 cell line and the immune-related molecule STING plays a role in the mechanism of action of IM.

Antitumor efficacy of CRISPR/Cas9-engineered ICP6 mutant herpes simplex viruses in a mouse xenograft model for lung adenocarcinoma

Oncolytic viruses (OVs), including oncolytic herpes simplex viruses (oHSVs), are promising therapeutics against cancer. Here, we report two ICP6-mutated HSVs (type I) generated by CRISPR/Cas9, rHSV1/∆RR (with ICP6 ribonucleotide reductase [RR] domain deleted) and rHSV1/∆ICP6 (with a complete deletion of ICP6), exhibiting potent antitumor efficacy against lung adenocarcinoma. Both the mutants showed strong cytotoxicity in vitro, comparable with the control viruses expressing intact ICP6, but in relatively lower titers. Moreover, these mutant viruses exhibited preferential killing ability against lung tumor cells rather than normal lung fibroblast cells. Further, unlike the control HSV-1 causing severe illness or death in the mouse model, the ICP6-mutated viruses did not induce significant pathogenicity but instead effectively reduced tumor burden in vivo and led to 100% survival of the animals, indicating notable antitumor activity and attenuated virulence. In addition, rHSV1/∆RR seemed to have even better antitumor efficacy than rHSV1/∆ICP6, albeit no statistical significance in inhibition of tumor volume. Histopathologically, rHSV1/∆RR induced massive neutrophil infiltration to the tumor microenvironment and consistently, triggered more antitumor immune and neutrophil chemotactic cytokines or higher expression levels of them (indicated by quantitative polymerase chain reaction and transcriptome analyses). These results demonstrate the anti-adenocarcinoma potential of the CRISPR/Cas9-engineered ICP6 mutant HSV1, especially the rHSV1/∆RR, which likely induces stronger innate antitumor immune response. Together, these findings may provide new valuable clues for further development of OV-based therapeutics against lung adenocarcinoma or other types of tumors.

Immunothrombotic Mechanisms Induced by Ingenol Mebutate Lead to Rapid Necrosis and Clearance of Anogenital Warts

Ingenol mebutate (IM) is highly effective in the treatment of human papillomavirus (HPV)-induced anogenital warts (AGW) leading to fast ablation within hours. However, the exact mode of action is still largely unknown. We performed dermoscopy, in vivo confocal microscopy (CLM), histology, immunohistochemistry, and immunofluorescence to gain insights in mechanisms of IM treatment in AGW. In addition, we used in vitro assays (ELISA, HPV-transfection models) to further investigate in vivo findings. IM treatment leads to a strong recruitment of neutrophils with thrombosis of small skin vessels within 8 h, in a sense of immunothrombosis. In vivo and in vitro analyses showed that IM supports a prothrombotic environment by endothelial cell activation and von Willebrand factor (VWF) secretion, in addition to induction of neutrophil extracellular traps (NETosis). IM superinduces CXCL8/IL-8 expression in HPV-E6/E7 transfected HaCaT cells when compared to non-infected keratinocytes. Rapid ablation of warts after IM treatment can be well explained by the observed immunothrombosis. This new mechanism has so far only been observed in HPV-induced lesions and is completely different from the mechanisms we see in the treatment of transformed keratinocytes in actinic keratosis. Our initial findings indicate an HPV-specific effect, which could be also of interest for the treatment of other HPV-induced lesions. Larger studies are now needed to further investigate the potential of IM in different HPV tumors.

Custom 3D-printed applicators for high dose-rate brachytherapy in skin cancer

PURPOSE

This paper describes the protocol for the development of 3D-printed custom applicators in treating skin carcinoma, the evaluation of the materials used, and the methods for segmentation and rendering of the applicators.

MATERIAL AND METHODS

The segmentation and rendering process for the applicator had six phases: (i) determination of the volume of the lesion using a computed tomography (CT) scan; (ii) delineation of the patient surface, using the same CT images; (iii) creation of the applicator in the planner and segmentation of the mold; (iv) preliminary dosimetry and establishment of the route of the catheter from the brachytherapy unit; (v) creation of the 3D applicator using specialized software; and (vi) applicator printing. Following this process, the patient returned for a second CT to undergo the definitive dosimetry with the applicator in place. Radiation therapy was then administered.

RESULTS

We made a total of 16 applicators. Only three applicators had to be remade, two due to an error in the infill and the other due to incorrect catheter geometry. In all cases, correct coverage of the planning target volume was achieved with the prescribed isodose.

CONCLUSIONS

The creation of custom molds in plesiotherapy for skin cancer with 3D printing is feasible. Compared to manual methods, 3D printing increases precision in applicator geometry and optimization of the dosimetry.

Rebound increases in chemokines by CXCR2 antagonist in breast cancer can be prevented by PKCδ and PKCε activators

Activation of CXCR2 by chemokines such as CXCL1 and CXCL2 increases aggressiveness of breast cancer, inducing chemoresistance, hence CXCR2 antagonists are in clinical trials. We previously reported that inhibition of CXCR2 increases MIP-2 (CXCL2), which may inhibit anti-tumoral effects of CXCR2 antagonists. This seems to be due to inhibition of protein kinase C (PKC) by CXCR2 antagonist since specific inhibitor of PKC also enhances MIP-2 secretion. We here examined whether CXCR2 inhibitor also increases KC (CXCL1) secretion, ligand for CXCR2 involved in metastasis and PKC activators can prevent increases in chemokine secretion. We used SB 225002, which is a specific CXCR2 antagonist. The effects of PKC activators that have documented anti-tumoral effects and activates multiple isozymes of PKC such as Ingenol-3-angelate (I3A) and bryostatin-1 were examined here. In addition, FR236924, PKCε selective and 7α-acetoxy-6β-benzoyloxy-12-O-benzoylroyleanone (Roy-Bz), PKCδ selective activators were also tested. The effects of activators were determined using brain metastatic (4TBM) and heart metastatic (4THM) subset of 4T1 breast carcinoma cells because these aggressive carcinoma cells with cancer stem cell features secrete high levels of KC and MIP-2. Inhibition of CXCR-2 activity increased KC (CXCL1) secretion. PKC activators prevented SB225002-induced increases in KC and MIP-2 secretion. Different activators/modulators induce differential changes in basal and SB225002-induced chemokine secretion as well as cell proliferation and the activators that act on PKCδ and/or PKCε such as bryostatin 1, FR236924 and Roy-Bz are the most effective. These activators alone also decrease cell proliferation or chemokine secretion or both. Given the role of KC and MIP-2 in drug resistance including chemotherapeutics, activators of PKCε and PKCδ may prevent emerging of resistance to CXCR2 inhibitors as well as other chemotherapeutics.

The Tumor Microenvironment in SCC: Mechanisms and Therapeutic Opportunities

Squamous cell carcinoma (SCC) is the second most common skin cancer worldwide and, despite the relatively easy visualization of the tumor in the clinic, a sizeable number of SCC patients are diagnosed at advanced stages with local invasion and distant metastatic lesions. In the last decade, immunotherapy has emerged as the fourth pillar in cancer therapy via the targeting of immune checkpoint molecules such as programmed cell-death protein-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). FDA-approved monoclonal antibodies directed against these immune targets have provide survival benefit in a growing list of cancer types. Currently, there are two immunotherapy drugs available for cutaneous SCC: cemiplimab and pembrolizumab; both monoclonal antibodies (mAb) that block PD-1 thereby promoting T-cell activation and/or function. However, the success rate of these checkpoint inhibitors currently remains around 50%, which means that half of the patients with advanced SCC experience no benefit from this treatment. This review will highlight the mechanisms by which the immune checkpoint molecules regulate the tumor microenvironment (TME), as well as the ongoing clinical trials that are employing single or combinatory therapeutic approaches for SCC immunotherapy. We also discuss the regulation of additional pathways that might promote superior therapeutic efficacy, and consequently provide increased survival for those patients that do not benefit from the current checkpoint inhibitor therapies.

Activation of PKC supports the anticancer activity of tigilanol tiglate and related epoxytiglianes

The long-standing perception of Protein Kinase C (PKC) as a family of oncoproteins has increasingly been challenged by evidence that some PKC isoforms may act as tumor suppressors. To explore the hypothesis that activation, rather than inhibition, of these isoforms is critical for anticancer activity, we isolated and characterized a family of 16 novel phorboids closely-related to tigilanol tiglate (EBC-46), a PKC-activating epoxytigliane showing promising clinical safety and efficacy for intratumoral treatment of cancers. While alkyl branching features of the C12-ester influenced potency, the 6,7-epoxide structural motif and position was critical to PKC activation in vitro. A subset of the 6,7-epoxytiglianes were efficacious against established tumors in mice; which generally correlated with in vitro activation of PKC. Importantly, epoxytiglianes without evidence of PKC activation showed limited antitumor efficacy. Taken together, these findings provide a strong rationale to reassess the role of PKC isoforms in cancer, and suggest in some situations their activation can be a promising strategy for anticancer drug discovery.

The Neutrophil: The Underdog That Packs a Punch in the Fight against Cancer

The advent of immunotherapy has had a major impact on the outcome and overall survival in many types of cancer. Current immunotherapeutic strategies typically aim to (re)activate anticancer T cell immunity, although the targeting of macrophage-mediated anticancer innate immunity has also emerged in recent years. Neutrophils, although comprising ≈ 60% of all white blood cells in the circulation, are still largely overlooked in this respect. Nevertheless, neutrophils have evident anticancer activity and can induce phagocytosis, trogocytosis, as well as the direct cytotoxic elimination of cancer cells. Furthermore, therapeutic tumor-targeting monoclonal antibodies trigger anticancer immune responses through all innate Fc-receptor expressing cells, including neutrophils. Indeed, the depletion of neutrophils strongly reduced the efficacy of monoclonal antibody treatment and increased tumor progression in various preclinical studies. In addition, the infusion of neutrophils in murine cancer models reduced tumor progression. However, evidence on the anticancer effects of neutrophils is fragmentary and mostly obtained in in vitro assays or murine models with reports on anticancer neutrophil activity in humans lagging behind. In this review, we aim to give an overview of the available knowledge of anticancer activity by neutrophils. Furthermore, we will describe strategies being explored for the therapeutic activation of anticancer neutrophil activity.

Prediction of modes of action of components of traditional medicinal preparations

Traditional medicine preparations are used to treat many ailments in multiple regions across the world. Despite their widespread use, the mode of action of these preparations and their constituents are not fully understood. Traditional methods of elucidating the modes of action of these natural products (NPs) can be expensive and time consuming e. g. biochemical methods, bioactivity guided fractionation, etc. In this review, we discuss some methods for the prediction of the modes of action of traditional medicine preparations, both in mixtures and as isolated NPs. These methods are useful to predict targets of NPs before they are experimentally validated. Case studies of the applications of these methods are also provided herein.

Topical treatments for skin cancer

Skin cancer is a broad term used to describe a number of different malignant indications of the skin. Skin cancers mostly comprise of the keratinocyte cancers [Basal Cell Carcinoma (BCC) and cutaneous Squamous Cell Carcinoma (SCC)], and melanoma. Surgical excision of these malignancies has been the preferred treatment of patients for decades. However, the decision to perform surgery can be affected by various considerations, including co-morbidities of the patient, the anatomical site of the lesion and potential intolerance for repeated excisions. Topical treatment of skin cancer may therefore be more appropriate in certain instances. Topical treatment potentially allows for higher drug levels at the tumor site, and may result in less overall toxicity than systemic agents. This review will specifically address the current agents used in topical treatment of skin cancers, and introduce emerging treatments from the natural product field that may also find utility in these indications.

Neutrophil Elastase and Neutrophil Extracellular Traps in the Tumor Microenvironment

Tumor-associated neutrophils (TANs) play a major role during cancer development and progression in the tumor microenvironment. Neutrophil elastase (NE) is a serine protease normally expressed in neutrophil primary granules. Formation of neutrophil extracellular traps (NETs), a mechanism used by neutrophils, has been traditionally associated with the capture and killing of bacteria. However, there are recent discoveries suggesting that NE secretion and NETs formation are also involved in the tumor microenvironment. Here, we focus on how NE and NETs play a key regulatory function in the tumor microenvironment, such as tumor proliferation, distant metastasis, tumor-associated thrombosis, and antitumor activity. Additionally, the potential use of NETs, NE, or associated molecules as potential disease activity biomarkers or therapeutic targets will be introduced.

Ingenol mebutate treatment in actinic keratosis - clinical effectiveness and potential side effects

Introduction

Actinic keratosis is a common skin disease that occurs in response to prolonged exposure to ultraviolet radiation. This problem affects up to 60% of the population over 40 years of age. Actinic keratosis is considered to be a precancerous lesion leading to squamous cell carcinoma (SCC). The new therapeutic option for the treatment of actinic keratosis is ingenol mebutate gel (0.015%, 0.05%).

Aim

Retrospective evaluation of response and potential side effects of ingenol mebutate treatment in clinical practice.

Material and methods

Eight patients with actinic keratosis lesions on the face or scalp self-applied a 0.015% gel for 3 consecutive days on the 25 cm² marked area. They were assessed at baseline and on day 4, 7, 14 and 57.

Results

All patients on day 57 presented a complete absence of AK lesions in the area of ingenol mebutate application. No adverse events were observed.

Conclusions

Our study shows that ingenol mebutate is highly efficacious field treatment for actinic keratosis.

Plasma Medicine: Applications of Cold Atmospheric Pressure Plasma in Dermatology

The ability to produce cold plasma at atmospheric pressure conditions was the basis for the rapid growth of plasma-related application areas in biomedicine. Plasma comprises a multitude of active components such as charged particles, electric current, UV radiation, and reactive gas species which can act synergistically. Anti-itch, antimicrobial, anti-inflammatory, tissue-stimulating, blood flow-enhancing, and proapoptotic effects were demonstrated in in vivo and in vitro experiments, and until now, no resistance of pathogens against plasma treatment was observed. The combination of the different active agents and their broad range of positive effects on various diseases, especially easily accessible skin diseases, renders plasma quite attractive for applications in medicine. For medical applications, two different types of cold plasma appear suitable: indirect (plasma jet) and direct (dielectric barrier discharge—DBD) plasma sources. The DBD device PlasmaDerm® VU-2010 (CINOGY Technologies GmbH), the atmospheric pressure plasma jet (APPJ) kINPen® MED (INP Greifswald/neoplas tools GmbH), and the SteriPlas (Adtec Ltd., London, United Kingdom) are CE-certified as a medical product to treat chronic wounds in humans and showed efficacy and a good tolerability. Recently, the use of plasma in cancer research and oncology is of particular interest. Plasma has been shown to induce proapoptotic effects more efficiently in tumor cells compared with the benign counterparts, leads to cellular senescence, and—as shown in vivo—reduces skin tumors. To this end, a world-wide first Leibniz professorship for plasmabiotechnology in dermatology has been introduced to establish a scientific network for the investigation of the efficacy and safety of cold atmospheric plasma in dermatooncology. Hence, plasma medicine especially in dermatology holds great promise.

Unraveling the crosstalk between melanoma and immune cells in the tumor microenvironment

Cutaneous melanoma is the most common skin cancer with an incidence that has been rapidly increasing in the past decades. Melanomas are among the most immunogenic tumors and, as such, have the greatest potential to respond favorably to immunotherapy. However, like many cancers, melanomas acquire various suppressive mechanisms, which generally act in concert, to escape innate and adaptive immune detection and destruction. Intense research into the cellular and molecular events associated with melanomagenesis, which ultimately lead to immune suppression, has resulted in the discovery of new therapeutic targets and synergistic combinations of immunotherapy, targeted therapy and chemotherapy. Tremendous effort to determine efficacy of single and combination therapies in pre-clinical and clinical phase I-III trials has led to FDA-approval of several immunotherapeutic agents that could potentially be beneficial for aggressive, highly refractory, advanced and metastatic melanomas. The increasing availability of approved combination therapies for melanoma and more rapid assessment of patient tumors has increased the feasibility of personalized treatment to overcome patient and tumor heterogeneity and to achieve greater clinical benefit. Here, we review the evolution of the immune system during melanomagenesis, mechanisms exploited by melanoma to suppress anti-tumor immunity and methods that have been developed to restore immunity. We emphasize that an effective therapeutic strategy will require coordinate activation of tumor-specific immunity as well as increased recognition and accessibility of melanoma cells in primary tumors and distal metastases. This review integrates available knowledge on melanoma-specific immunity, molecular signaling pathways and molecular targeting strategies that could be utilized to envision therapeutics with broader application and greater efficacy for early stage and advanced metastatic melanoma.

Nanotechnology-mediated immunochemotherapy with Ingenol-3-Mebutate for Systematic Anti-tumor Effects

Cancer-Immunotherapy was the most exciting topic. However, either insensitivity due to singleness of therapeutic target or immune evasion leads to the failure of the treatment. Ingenol-3-mebutate (I3A) can inhibit cancer through synergy between immunotherapy and chemotherapy, however, the speculation and accurate mechanism haven't been confirmed in vivo limited by its hydrophobicity and pH-instability, which also hindered its clinical translation. Herein we developed a polymeric micelle with 'acidic core' provided by single alcoholic hydroxyl (-CH(CH3)-OH) encapsulating I3A (I3A-PM), which successfully overcome the aforementioned problems and reduce the toxicity in vivo. To test the synergy, S180 tumor-bearing mice were subjected to I3A-PM through intravenous and intratumoral administration, we found I3A-PM presented significant antitumor effect, and promoted Th1 polarization by upregulating the level of Th1 cytokines (IL-12, IL-2, IFN-γ and TNF-α), and accelerated the expansion of CD4⁺ and CD8⁺ T cells, meanwhile, I3A-PM depleted regulatory T cells, Th2 cytokine IL-6 through inhibiting TGF-β signaling pathway. Furthermore, we appealed to virtual screening of tumor target, and found a new pathway of I3A as a TGF-β receptor type I inhibitor to improve immunostimulatory effects. These results demonstrated I3A-PM as a promising nanoagent for cancer immunotherapy strategy. The synergistic therapeutic effects are encouraged to further evaluate in different cancer model compared with commercial products to facilitate research finding (I3A-PM) entering the clinic.

Monocytes Latently Infected with Human Cytomegalovirus Evade Neutrophil Killing

One site of latency of human cytomegalovirus (HCMV) in vivo is in undifferentiated cells of the myeloid lineage. Although latently infected cells are known to evade host T cell responses by suppression of T cell effector functions, it is not known if they must also evade surveillance by other host immune cells. Here we show that cells latently infected with HCMV can, indeed, be killed by host neutrophils but only in a serum-dependent manner. Specifically, antibodies to the viral latency-associated US28 protein mediate neutrophil killing of latently infected cells. To address this mechanistically, a full proteomic screen was carried out on latently infected monocytes. This showed that latent infection downregulates the neutrophil chemoattractants S100A8/A9, thus suppressing neutrophil recruitment to latently infected cells. The ability of latently infected cells to inhibit neutrophil recruitment represents an immune evasion strategy of this persistent human pathogen, helping to prevent clearance of the latent viral reservoir.

Mediators of Inflammation in Topical Therapy of Skin Cancers

Taking into consideration that the immune system plays a very important role in the development of melanoma and non-melanoma skin cancers, which have a high prevalence in immunosuppressed patients and after prolonged ultraviolet radiation, the interest in developing novel therapies, in particular targeting the inflammation in cancer, has increased in the past years. The latest data suggest that therapies such as imiquimod (IMQ), ingenol mebutate (IM), 5-fluorouracil (5-FU), retinoids, and nonsteroidal anti-inflammatory drugs (NSAIDs) have been used with success in the topical treatment of some cancers. Herein, we review the topical treatment targeting the inflammation in skin cancer and the mechanisms involved in these processes. Currently, various associations have shown a superior success rate than monotherapy, such as systemic acitretin and topical IMQ, topical 5-FU with tretinoin cream, or IMQ with checkpoint inhibitor cytotoxic T lymphocyte antigen 4. Novel therapies targeting Toll-like receptor-7 (TLR-7) with higher selectivity than IMQ are also of great interest.

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.

Ingenol mebutate induces a tumor cell-directed inflammatory response and antimicrobial peptides thereby promoting rapid tumor destruction and wound healing

BACKGROUND

Ingenol mebutat (IM)-gel is effective for the topical treatment of epithelial tumors, including actinic keratoses (AKs) or anogenital warts (AGW). AK patients treated with IM develop intensified inflammatory reactions on sights of prior clinical visible or palpable AKs as compared to the surrounding actinically damaged skin, suggesting the induction of a tumor cell-directed inflammation. AGW patients treated with IM develop even stronger inflammatory reactions with large erosions, suggesting a directed inflammatory response against HPV-infected keratinocytes. Of note, even widespread erosions heal very fast without any superinfections. Here, we set out to elucidate underlying molecular and cellular mechanisms of these clinical observations.

METHODS

The effects of IM (10-9-10-5 M) on the expression and translation of a comprehensive set of chemokines (CXCL1, CXCL8, CXCL9, CXCL10, CXCL11, CXCL14, CCL2, CCL5, CCL20, CCL27) and antimicrobial peptides (AMP) (HBD1, HBD2, HBD3, LL37, RNase7) were analyzed in primary human epithelial keratinocytes (HEK) and a set of epithelial cancer cell lines by RT-qPCR and ELISA in vitro. To study the possible effects of different concentrations of IM on migratory, respectively wound healing responses, an in vitro scratch assay was conducted on HEK.

RESULTS

Ingenol mebutat significantly and dose-dependently induced the expression of proinflammatory chemokines (CXCL8, CCL2) and AMP (RNase7, HBD3) in HEK and epithelial cancer cell lines. A significantly stronger induction of CXCL8 and CCL2 was observed in our tested tumor cells as compared to HEK. We did not observe any significant effect of IM on HEK migration, respectively wound healing responses in vitro for any tested concentration (10-9, 10-8, 10-6 M) except 10-7 M, which induced a significant inhibition.

CONCLUSIONS

Our data suggest that tumor cells are more susceptible to IM as compared to differentiated HEK. This is evident by a stronger IM-mediated induction of proinflammatory chemokines in tumor cells, which may result in a tumor cell-directed inflammatory response and rapid tumor destruction. In addition, IM induces AMP in keratinocytes and seems not to severely interfere with keratinocyte migration, which contributes to a fast and uncomplicated wound healing. Surprising is a selective inhibition of keratinocyte migration by IM at the concentration of 10-7 M pointing to very dose depending biological effects, induced by IM.

Effect of ingenol mebutate on actinic keratosis in a Korean population: A prospective clinical, dermoscopic and histopathological study from a single center

Actinic keratosis (AK) is an in situ squamous cell carcinoma which is mostly found on sun-damaged skin, and it is prevalent among Caucasians. However, there is a lack of research on evaluating the treatment efficacy of ingenol mebutate (IM) on AK in Asians. This study was intended to analyze the treatment outcomes of IM on AK in Korean patients with regards to clinical, dermoscopic and histopathological aspects. A prospective study on 46 Korean patients who were diagnosed with AK and treated with IM was conducted. Clinically, 80% (24/30) of the patients showed an improvement at 8 weeks. Twenty out of the 30 (66.7%) patients were found to have achieved histopathological clearance. All local skin responses had disappeared at T4 in all patients. Patients with Fitzpatrick skin type III were proven to exhibit better treatment outcomes, both clinically (P = 0.001) and histopathologically (P = 0.001), than those with Fitzpatrick skin type IV. The clinical and histopathological clearance rate of AK with IM in Korean patients was 80% and 66.7%, respectively. The patients with Fitzpatrick skin type IV showed a tendency to have residual AK, histopathologically after treatment with IM. In conclusion, IM could be an effective and safe treatment option on AK in Korean patients. In addition, it would be helpful to carry out a cautious check-up when treating AK with IM in patients with a darker skin color.

Treatment of facial actinic keratoses with a cream containing octatrienoic acid: a multicenter clinical experience

BACKGROUND

Actinic keratosis (AKs) are premalignant skin lesions characterized by high rate of transformation in squamous cell carcinoma if not treated. Preclinical published data on parrodiene-derivative 2,4,6-octatrienoic acid, encourages us to study and to evaluate the effect of a topical product containing it in patients affected by mild to moderate actinic keratosis.

METHODS

Seventy subjects with at least 1-3 clinically diagnosed actinic keratosis lesions, non-hyperkeratotic, non-hypertrophic, localized on the face (I-II degree actinic keratosis) were enrolled in the study. The product was applied twice/day for 60 consecutive days.

RESULTS

After 60 days of treatment, a significant improvement in lesions occurred as shown by the decrease in the AKESA Score (P<0.05). Moreover, octatrienoic acid containing cream induced a 90% response rate (63/70 patients P<0.5; 95% confidence interval) with 20% complete remission (14/70 patients, P<0.05). Compared to baseline, a significant number of patients reported improvement of each AKESA sub-score after 60 days of treatment: skin thickness improved in 46 patients (P<0.0001), erythema in 21 patients (P<0.0001) and atrophy in 57 patients (P<0.0348). The average pigmentation score significantly decreased from 1.50 to 0.79 (P<0.05).

CONCLUSIONS

The results of the study, confirmed also by self-assessment, allow us not only to state that the use of topical octatrienoic acid was effective and well tolerated for topical treatment of AKs leading to overall clinical improvement in approximately 90% of subjects treated for 60 days.

Tumor-associated neutrophils suppress pro-tumoral IL-17+ γδ T cells through induction of oxidative stress

Interleukin 17 (IL-17)–producing γδ T cells (γδ17 T cells) have been recently found to promote tumor growth and metastasis formation. How such γδ17 T-cell responses may be regulated in the tumor microenvironment remains, however, largely unknown. Here, we report that tumor-associated neutrophils can display an overt antitumor role by strongly suppressing γδ17 T cells. Tumor-associated neutrophils inhibited the proliferation of murine CD27⁻ Vγ6⁺ γδ17 T cells via induction of oxidative stress, thereby preventing them from constituting the major source of pro-tumoral IL-17 in the tumor microenvironment. Mechanistically, we found that low expression of the antioxidant glutathione in CD27⁻ γδ17 T cells renders them particularly susceptible to neutrophil-derived reactive oxygen species (ROS). Consistently, superoxide deficiency, or the administration of a glutathione precursor, rescued CD27⁻ Vγ6⁺ γδ17 T-cell proliferation in vivo. Moreover, human Vδ1⁺ γδ T cells, which contain most γδ17 T cells found in cancer patients, also displayed low glutathione levels and were potently inhibited by ROS. This work thus identifies an unanticipated, immunosuppressive yet antitumoral, neutrophil/ROS/γδ17 T-cell axis in the tumor microenvironment.

Tumors are infiltrated by many immune cells that influence many aspects of cancer progression and outcome, including tumor growth, invasion of healthy surrounding tissues, formation of metastasis, and response to treatments. Among tumor-infiltrating lymphocytes, γδ T cells play dual functions in the tumor milieu; whereas those that produce the antitumor cytokine interferon-γ are protective, their counterparts that make interleukin 17 (IL-17) support tumor growth. It is therefore critical to understand which mechanisms may limit IL-17–biased γδ T-cell responses. In this study, we unexpectedly found that IL-17⁺ γδ T cells express very low levels of the antioxidant, glutathione, and are very sensitive to reactive oxygen species (ROS), thus revealing their Achilles’ heel. Indeed, as ROS-producing neutrophils accumulate within tumors, they inhibit IL-17⁺ γδ T-cell proliferation and thereby suppress their pro-tumoral activities. We extended these findings, obtained in mouse models of cancer, to human γδ T cells and therefore believe that the modulation of local levels of oxidative stress may have important therapeutic implications.

Dermoscopy and reflectance confocal microscopy for monitoring the treatment of actinic cheilitis with ingenol mebutate gel: Report of three cases

Actinic cheilitis (AC) can precede the development of squamous cell carcinoma (SCC) of the lip, a location with higher risk of invasiveness and metastasis. Herein, we reported the use of ingenol mebutate (IngMeb) 0.015% gel on three consecutive days to treat three patients suffering from AC. All the three patients achieved complete clearance of AC with rapid clinical effect, favorable safety profile, good patient's compliance related to short time of applications, and few local skin reactions. So IngMeb is an attractive new therapy for AC. Moreover, the present case report adds further evidence to the usefulness of dermoscopy and Reflectance confocal microscopy (RCM) in the assessment and monitoring of treatment outcome.

Dangerous plants in dermatology: Legal and controlled

The plant and mushroom kingdoms have species used for intoxication, inebriation, or recreation. Some of these species are toxic. Given that many of these plants or substances are illegal and have histories of abuse, much of the research regarding therapeutic application is based on basic science, animal studies, and traditional use. This review examines Cannabis, Euphorbia, Ricinus, Podophyllum, Veratrum, mushrooms, and nightshades, along with resveratrol and cocaine as they relate to dermatology.

Time-lapse imaging points towards a non-toxic, mainly immune-driven mode of action of ingenol mebutate in the treatment of anogenital warts

Recently, it has been reported that ingenol mebutate (IM) is an effective treatment option for anogenital warts (AGW), inducing fast wart necrosis within 24 hours in vivo. With regard to its mode of action, IM is thought to act both as an inducer of direct cytotoxic effects and immunologic mechanisms. To distinguish whether the wart necrosis is mainly caused by cytotoxic effects, or whether immune mechanisms are leading, we used time-lapse imaging to analyse IM-treated warts ex vivo over 24 hours. Ex vivo IM-treated warts, which have been detached from the immune system, did not show destructive necrosis, pointing towards a primarily immune-driven mode of action of IM in the treatment of AGW.

Ingenol-3-Angelate Suppresses Growth of Melanoma Cells and Skin Tumor Development by Downregulation of NF-κB-Cox2 Signaling

Background

A recent focus in skin cancer prevention intervenes though modulating molecular links between inflammation and cell growth signaling, such as NF-κB. This study elucidates the effect of a non-tumor promoting phorbol ester, ingenol-3-angelate (I3A), on the growth of human melanoma cells and on the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation and 7,12-Dimethylbenz(a)anthracene (DMBA)-induced skin carcinoma in mice.

Material/Methods

Cell viability was assessed by MTT assay, cell proliferation by clonogenic assay, apoptosis and cell cycle arrest was analyzed by flow cytometry, protein expression was studied by IHC and Western blotting, and gene expression by qPCR.

Results

I3A suppressed the survival and proliferation of human melanoma cells with estimated IC50 values around 38 and 46 μM for A2058 and HT144 cell, respectively. I3A activated the protein levels of PKCδ and PKCɛ, which induced apoptosis by activating caspase-9 and caspace-3 followed by lowering of mitochondrial membrane potential and enhancing DNA fragmentation. I3A induced G1 phase cell cycle arrest as well as G2/M phase arrest in both cell lines. I3A inhibited the levels of NF-κB p65 protein as well as phosphorylation of p65 and its nuclear translocation. I3A suppressed the gene expression of NF-κB, COX-2 and iNOS. I3A inhibited TPA-induced inflammation and epidermal hyperplasia in female ICR mice by downregulating NF-κB and iNOS. I3A suppressed the growth of skin tumor in DMBA-induced mice in dose-dependent manner.

Conclusions

The mechanism of I3A induces apoptosis in human melanoma cells and suppresses skin inflammation and carcinoma via downregulation of NF-κB-iNOS-COX-2 signaling.

Chemical Proteomics Identifies SLC25A20 as a Functional Target of the Ingenol Class of Actinic Keratosis Drugs

The diterpenoid ester ingenol mebutate (IngMeb) is the active ingredient in the topical drug Picato, a first-in-class treatment for the precancerous skin condition actinic keratosis. IngMeb is proposed to exert its therapeutic effects through a dual mode of action involving (i) induction of cell death that is associated with mitochondrial dysfunction followed by (ii) stimulation of a local inflammatory response, at least partially driven by protein kinase C (PKC) activation. Although this therapeutic model has been well characterized, the complete set of molecular targets responsible for mediating IngMeb activity remains ill-defined. Here, we have synthesized a photoreactive, clickable analogue of IngMeb and used this probe in quantitative proteomic experiments to map several protein targets of IngMeb in human cancer cell lines and primary human keratinocytes. Prominent among these targets was the mitochondrial carnitine-acylcarnitine translocase SLC25A20, which we show is inhibited in cells by IngMeb and the more stable analogue ingenol disoxate (IngDsx), but not by the canonical PKC agonist 12-O-tetradecanoylphorbol-13-acetate (TPA). SLC25A20 blockade by IngMeb and IngDsx leads to a buildup of cellular acylcarnitines and blockade of fatty acid oxidation (FAO), pointing to a possible mechanism for IngMeb-mediated perturbations in mitochondrial function.

Cancer-Associated Fibroblasts Neutralize the Anti-tumor Effect of CSF1 Receptor Blockade by Inducing PMN-MDSC Infiltration of Tumors

Tumor-associated macrophages (TAM) contribute to all aspects of tumor progression. Use of CSF1R inhibitors to target TAM is therapeutically appealing, but has had very limited anti-tumor effects. Here, we have identified the mechanism that limited the effect of CSF1R targeted therapy. We demonstrated that carcinoma-associated fibroblasts (CAF) are major sources of chemokines that recruit granulocytes to tumors. CSF1 produced by tumor cells caused HDAC2-mediated downregulation of granulocyte-specific chemokine expression in CAF, which limited migration of these cells to tumors. Treatment with CSF1R inhibitors disrupted this crosstalk and triggered a profound increase in granulocyte recruitment to tumors. Combining CSF1R inhibitor with a CXCR2 antagonist blocked granulocyte infiltration of tumors and showed strong anti-tumor effects.

Neutrophils in Gliomas

Neutrophils are the most abundant white blood cells and are the first recruited to inflammatory sites. Neutrophils are an important component of the tumor stroma and can exert both anti-tumoral and pro-tumoral activities, depending on their maturation and activation state. In human gliomas, the number of circulating and infiltrating neutrophils correlates with the severity of the disease, indicating a prognostic and possible pro-tumoral role for these leukocytes. In glioma preclinical models, neutrophils promote tumor growth and orchestrate the resistance to anti-angiogenic therapies. Nevertheless, recent data indicate that neutrophils can be activated to directly kill tumor cells or to orchestrate the anti-tumoral response. Here, we review current knowledge about the role of neutrophils in glioma and their possible involvement in new strategies to improve current cancer therapies.

Clinical and Histologic Evaluation of Ingenol Mebutate 0.015% Gel for the Cosmetic Improvement of Photoaged Skin

BACKGROUND

No studies have examined the use of topical ingenol mebutate for improvement of photoaged skin.

OBJECTIVE

To evaluate clinical results of ingenol mebutate gel applied to photoaged skin and to quantify improvement at 7, 30, and 60 days after application.

MATERIALS AND METHODS

Twenty-five subjects were enrolled in the study. Picato (ingenol mebutate) (LEO Pharma, Parsippany, NJ) gel was applied to an area with a known actinic keratosis daily for 3 days. Subjects self-evaluated and were investigator evaluated on 6 characteristics on Days 7, 30, and 60 using an objective scale. The scale evaluated actinic keratosis, overall skin appearance, wrinkling, dyschromia, erythema, and texture. The subjects were also evaluated using the Griffiths' Photonumeric Photoaging Scale for overall improvement.

RESULTS

Twenty-two subjects completed the clinical study and demonstrated statistically significant improvement by Day 60 in actinic keratosis, overall skin appearance, wrinkling, dyschromia, erythema, and texture (p < .05).

CONCLUSION

Topical ingenol mebutate 0.015% gel produces cosmetic improvement of photoaged skin within 60 days of application.

Analysis of apoptosis-associated molecules Erythroid differentiation regulator 1, bcl-2 and p53 in actinic keratosis after treatment with ingenol mebutate

Actinic keratosis (AK) is the most common cutaneous premalignant neoplasm precursor of malignant skin tumors. The aberrant apoptotic pathway is thought to be associated with pathogenesis of AK. Ingenol mebutate has been shown to be effective and safe for treatment of AK. However, the effect of ingenol mebutate on apoptosis-related molecules using human skin samples has not been studied well. Erythroid differentiation regulator 1 (Erdr1) was recently reported to play a crucial role in malignant skin cancers like malignant melanoma. The role of Erdr1 in premalignant actinic keratosis (AK) has not been explored. The purpose of this study was to investigate whether the expression of apoptosis-associated molecules such as Erdr1, p53 and bcl-2 was affected by the treatment of ingenol mebutate in AK. Nine patients with AK underwent skin biopsy at baseline and 8 weeks after treatment with ingenol mebutate for immunohistochemical evaluation with Erdr1, p53 and bcl-2. In addition, skin samples from five control subjects were retrieved. Upregulation of Erdr1 and a significant decrease in expression of p53 and bcl-2 were observed after treatment with ingenol mebutate. Ingenol mebutate treatment for AK resulted in the modulation of apoptosis-associated molecules with an increase in the expression of Erdr1 and a decrease in the expression of p53 and bcl-2.

Tattoo removal with ingenol mebutate

An increasing number of people are getting tattoos; however, many regret the decision and seek their removal. Lasers are currently the most commonly used method for tattoo removal; however, treatment can be lengthy, costly, and sometimes ineffective, especially for certain colors. Ingenol mebutate is a licensed topical treatment for actinic keratoses. Here, we demonstrate that two applications of 0.1% ingenol mebutate can efficiently and consistently remove 2-week-old tattoos from SKH/hr hairless mice. Treatment was associated with relocation of tattoo microspheres from the dermis into the posttreatment eschar. The skin lesion resolved about 20 days after treatment initiation, with some cicatrix formation evident. The implications for using ingenol mebutate for tattoo removal in humans are discussed.

The Scourge of the Spurge Family-An Imitator of Rhus Dermatitis

The Euphorbiaceae family (commonly known as "spurge") is a large, diverse, and widely distributed family of plants that encompass around 300 genera and more than 8000 species. Their attractiveness and hearty nature have made them popular for both indoor ornamentation and outdoor landscaping. Despite their ubiquity, the potential to cause irritant contact dermatitis (ICD) is often overlooked in favor of more notorious causes of phytodermatitis, namely, Toxicodendron species and nettles. We examined case reports spanning 40 years and discovered that spurge-induced ICD tends to befall children and middle-aged adults who unwittingly encounter the plant through play or horticulture, respectively. Clinical presentation is pleomorphic. Erythema, edema, burning, vesicles, and pruritus of acute onset and rapid resolution are frequently observed. We present a classic case of ICD in a 12-year-old girl after exposure to Euphorbia myrsinites and review the literature on phytodermatitis caused by members of the Euphorbiaceae family.

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.

Neutrophils and Granulocytic MDSC: The Janus God of Cancer Immunotherapy

Neutrophils are the most abundant circulating blood cell type in humans, and are the first white blood cells recruited at the inflammation site where they orchestrate the initial immune response. Although their presence at the tumor site was recognized in the 1970s, until recently these cells have been neglected and considered to play just a neutral role in tumor progression. Indeed, in recent years neutrophils have been recognized to play a dual role in tumor development by either assisting the growth, angiogenesis, invasion, and metastasis or by exerting tumoricidal action directly via the secretion of antitumoral compounds, or indirectly via the orchestration of antitumor immunity. Understanding the biology of these cells and influencing their polarization in the tumor micro- and macro-environment may be the key for the development of new therapeutic strategies, which may finally hold the promise of an effective immunotherapy for cancer.

Tumor-Preferential Induction of Immune Responses and Epidermal Cell Death in Actinic Keratoses by Ingenol Mebutate

The rapid and strong clinical efficacy of the first-in-class, ingenol mebutate, against actinic keratosis (AK) has resulted in its recent approval. We conducted the first comprehensive analysis of the cellular and molecular mode of action of topical ingenol mebutate 0.05% gel in both AK and uninvolved skin of 26 patients in a phase I, single-center, open-label, within-patient comparison. As early as 1 day after application, ingenol mebutate induced profound epidermal cell death, along with a strong infiltrate of CD4⁺ and CD8⁺ T-cells, neutrophils, and macrophages. Endothelial ICAM-1 activation became evident after 2 days. The reaction pattern was significantly more pronounced in AK compared with uninvolved skin, suggesting a tumor-preferential mode of action. Extensive molecular analyses and transcriptomic profiling of mRNAs and microRNAs demonstrated alterations in gene clusters functionally associated with epidermal development, inflammation, innate immunity, and response to wounding. Ingenol mebutate reveals a unique mode of action linking directly to anti-tumoral effects.

Trial Registration: ClinicalTrials.gov NCT01387711

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.

Resistance of Nonmelanoma Skin Cancer to Nonsurgical Treatments. Part I: Topical Treatments

A wide range of treatments is now available for nonmelanoma skin cancer (NMSC), including 5-fluorouracil, ingenol mebutate, imiquimod, diclofenac, photodynamic therapy, methotrexate, cetuximab, vismodegib, and radiotherapy. All are associated with high clinical and histologic response rates. However, some tumors do not respond due to resistance, which may be primary or acquired. Study of the resistance processes is a broad area of research that aims to increase our understanding of the nature of each tumor and the biologic features that make it resistant, as well as to facilitate the design of new therapies directed against these tumors. In this article we review resistance to the authorized topical treatments for NMSC.

Relapse of pemphigus vulgaris after topical application of ingenol mebutate

Ingenol mebutate is a recently approved topical agent for the treatment of actinic keratosis. Its most common adverse effects are transient local skin reactions. We report a 63-year-old white man who presented with a red-brownish crusted plaque involving the dorsum of his nose and an eroded area on his lower lip, which appeared soon after topical application of ingenol mebutate gel. Clinical, histological and immunopathological features were consistent with a diagnosis of pemphigus vulgaris (PV). To our knowledge, this is the first report of relapse of PV after topical application of ingenol mebutate gel. The temporal relationship between the application of the drug and the outbreak of PV supports the involvement of this agent in triggering the disease. It is plausible that ingenol mebutate may have induced the disease by its action on the production of proinflammatory cytokines.

IL-1 Contributes to the Anti-Cancer Efficacy of Ingenol Mebutate

Ingenol mebutate is approved for the topical treatment of actinic keratoses and may ultimately also find utility in treating skin cancers. Here we show that relapse rates of subcutaneous B16 melanoma tumours treated topically with ingenol mebutate were not significantly different in C57BL/6 and Rag1^-/- mice, suggesting B and T cells do not play a major role in the anti-cancer efficacy of ingenol mebutate. Relapse rates were, however, significantly increased in MyD88^-/- mice and in C57BL/6 mice treated with the anti-IL-1 agent, anakinra. Ingenol mebutate treatment induces a pronounced infiltration of neutrophils, which have been shown to have anti-cancer activity in mice. Herein we provide evidence that IL-1 promotes neutrophil recruitment to the tumour, decreases apoptosis of infiltrating neutrophils and increases neutrophil tumour killing activity. These studies suggest IL-1, via its action on neutrophils, promotes the anti-cancer efficacy of ingenol mebutate, with ingenol mebutate treatment causing both IL-1β induction and IL-1α released from keratinocytes.