[Successful therapy of condylomata acuminata with ingenol mebutate]

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.

Fast Ablation of Anogenital Warts of the Urinary Meatus by Low-dose Ingenol Mebutate Gel

Therapeutic options of anogenital warts (AGW) at the urethral meatus are limited and often require effortful and time-consuming procedures under general anesthesia. Here, we present two cases of AGW at the urethral meatus, which we have successfully treated with low-dose topical ingenol mebutate gel.

Successful Treatment of Genital Warts with Ingenol Mebutate Monitored with Optical Coherence Tomography and Reflectance Confocal Microscopy

Ingenol mebutate (IM) is approved for the treatment of actinic keratosis and induces cell death in precancerous lesions. The efficacy of IM in the treatment of genital warts was investigated in a therapy-refractory patient. The 74-year-old male was treated with IM gel for three consecutive days. Treatment course and efficacy were evaluated by clinical inspection and non-invasive diagnostics namely optical coherence tomography (OCT) and reflectance confocal microscopy (RCM). Within 24 to 48 hours IM induced a strong local inflammatory reaction. One week later a complete response was observed. OCT and RCM showed a strong reaction after treatment with erosions, swelling of cells, and a subepidermal dark band in representative lesions. IM has the advantage of a short treatment period in contrast to other topical treatments and shows a promising clinical outcome. Larger studies are needed to validate the data.

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.

[Genital warts in HIV-infected individuals]

Anogenital warts (condylomata acuminata) are much more frequent in human immunodeficiency (HIV)-positive patients compared to HIV-negative individuals. Anogenital warts of HIV-infected patients differ from those of HIV-negative individuals with respect to their spread, occurrence on more unusual anatomical sites, human papillomavirus (HPV)-type spectrum, tendency to recur, and risk of malignant transformation. Between 18 and 56% of anogenital warts of HIV-positive patients harbor high-grade dysplasia. Therefore, anogenital warts of HIV-infected patients should be preferentially treated with ablative methods and should be evaluated histopathologically. Gender-neutral prophylactic HPV vaccination of HPV-naive boys and girls could also lead to a significant reduction of anogenital warts in this patient group in the future.