Genetic ablation of epidermal EGFR reveals the dynamic origin of adverse effects of anti-EGFR therapy

Airway epithelial cell-specific deletion of EGFR modulates mucoinflammatory features of cystic fibrosis-like lung disease in mice

Mucoinflammatory lung disease in cystic fibrosis (CF) is characterized by airway surface liquid (ASL) layer dehydration and mucins hyperconcentration, which leads to airway obstruction, inflammation, bronchiectasis, and increased susceptibility to recurrent bacterial infections. Epidermal growth factor receptor (EGFR) is known to regulate airway mucous cell metaplasia (MCM) and mucins expression, but the role of EGFR pathway in the pathogenesis of CF-like lung disease remains unclear. Therefore, we hypothesized that airway epithelial cell-specific deficiency of EGFR mitigates mucoinflammatory responses in Scnn1b-transgenic (Tg+) mice that phenocopy human CF-like lung disease. To test this hypothesis, we examined the effect of airway epithelial cell-specific EGFR deficiency on the manifestation of mucoinflammatory outcomes in Tg+ mice. The airway epithelial cell-specific EGFR-deficient wild-type (WT) mice did not exhibit any obvious structural and functional defects in the lungs. The deletion of EGFR in airway epithelial cells in Tg+ mice, however, resulted in increased recruitment of neutrophils and macrophages into the lung airspaces, which was accompanied by significantly increased bronchoalveolar lavage fluid (BALF) levels of inflammatory mediators, including KC, G-CSF, MIP-2, MIP-1α, TNF-α, and MIP-1β. Additionally, as compared with the EGFR-sufficient Tg+ mice, the airway epithelial cell-specific EGFR-deficient Tg+ mice exhibited significantly increased postnatal mortality and compromised bacterial clearance. The deletion of EGFR in the airway epithelial cells of Tg+ mice resulted in an increased degree of mucus obstruction, which was associated with an increase in MCM and MUC5B production. Some of the molecular markers of type 2 inflammation, including Il13, Slc26a4, and Retnla, were significantly increased in airway epithelial cell-specific EGFR-deficient Tg+ mice versus EGFR-sufficient Tg+ mice. Taken together, our data show that EGFR deletion in the airway epithelial cells compromises postnatal survival, delays bacterial clearance, and modulates inflammatory and mucus obstruction-relevant endpoints, i.e., MCM, MUC5B production, and mucus obstruction, in Tg+ mice.

Improvement of classical therapy in EGFR inhibitors-induced cutaneous adverse reaction by microneedle delivery and Astragalus polysaccharide

EGFR (epidermal growth factor receptor) inhibitors, as the first-line drugs of targeted therapy, often cause additional distress for patients due to the induced cutaneous adverse reactions (EICAR), while classical therapies represented by topical minocycline and epidermal growth factor have limitations especially for exacerbating immune imbalance. Here, we used Astragalus polysaccharide (APS), which has modulatory effects on both the epidermis and the immune system, as an adjuvant drug to reduce EICAR and achieve immune balance. APS, combined with minocycline or epidermal growth factor, was delivered by dissolvable microneedles (MN), a novel drug delivery method that penetrates the stratum corneum to deliver the drug directly into the skin tissue. The results demonstrated that this therapy with the developed MN system not only restored local epidermal conditions, but also reestablished the balance of immune cells. Significantly, the addition of APS also promoted the alleviation of EICAR in non-treated areas, suggesting that local administration can result in systemic effects. The application of APS and the MN delivery system can provide new strategy for clinical treatment of EICAR and potential solutions for other skin diseases.

Epidermal growth factor dampens pro-inflammatory gene expression induced by interferon-gamma in global transcriptome analysis of keratinocytes

BACKGROUND

Epidermal growth factor receptor inhibitors (EGFRIs) are used to treat certain cancers but frequently cause cutaneous inflammation that can hinder treatment. This is due in part to the effects of EGFRIs on pro-inflammatory signaling by interferon-γ (IFN-γ). However, the impact of EGFR ligands (i.e. EGF) on interferon signaling is unclear. The purpose of this study was to investigate the impact of EGF on IFN-γ transcriptional responses on a genome-wide scale in keratinocytes.

METHODS

RNA-seq was performed in human keratinocyte (HaCaT) cells treated with IFN-γ, EGF, both, or neither (control). Differentially expressed genes in each treatment group, relative to control, were identified using DESeq2 with a false discovery rate (FDR) threshold of 0.01. Associated biologic processes and gene pathways were examined in gene-set enrichment analyses. Correlations between gene expression were investigated in vivo using RNA-seq data from biopsies of psoriatic and matched normal skin, which were collected from 116 individuals with psoriasis enrolled in the AMAGINE randomized clinical trials.

RESULTS

Of the 2,792 differentially expressed genes following IFN-γ treatment, 2,083 (75%) were no longer differentially expressed when EGF was added. IFN-γ-induced genes with significantly lower expression in the presence of EGF included CXCL10, IL-6, IL-1 A, HLA-DMA, and GBP5 (activator of the NLRP3 inflammasome); the top enriched biologic processes and pathways were related to MHC-class II antigen presentation (GO:0019886) and cytokine signaling (KEGG:04060). Consistent with our in vitro findings, the expression of CXCL10 and GBP5, as well as the combined expression z-scores of genes in the enriched MHC-class II and cytokine signaling pathways, were significantly lower in skin biopsies with higher EGF expression compared to those with lower EGF expression among individuals with psoriasis.

CONCLUSIONS

Our findings suggest that the pro-inflammatory IFN-γ-induced transcriptome may be globally attenuated by EGF in keratinocytes, supporting an immunomodulatory role of EGF in the skin. These studies provide insights for the non-canonical immunomodulatory role of EGF signaling and why blocking EGFR signaling (e.g., with EGFRIs) can cause cutaneous inflammation.

JAK-STAT1 as therapeutic target for EGFR deficiency-associated inflammation and scarring alopecia

The hair follicle stem cell niche is an immune-privileged microenvironment, characterized by reduced antigen presentation, thus shielding against permanent immune-mediated tissue damage. In this study, we demonstrated the protective role of hair follicle-specific epidermal growth factor receptor (EGFR) against scarring hair follicle destruction. Mechanistically, disruption of EGFR signaling generated a cell-intrinsic hypersensitivity within the JAK-STAT1 pathway, which, synergistically with interferon gamma expressing CD8 T-cell and NK-cell-mediated inflammation, compromised the stem cell niche. Hair follicle-specific genetic depletion of either JAK1/2 or STAT1 or therapeutic inhibition of JAK1/2 ameliorated the inflammation, restored skin barrier function and activated the residual stem cells to resume hair growth in mouse models of epidermal and hair follicle-specific EGFR deletion. Skin biopsies from EGFR inhibitor-treated and cicatricial alopecia patients revealed an active JAK-STAT1 signaling signature along with upregulation of antigen presentation and downregulation of key components of the EGFR pathway. Our findings offer molecular insights and highlight a mechanism-based therapeutic strategy for addressing chronic folliculitis associated with EGFR-inhibitor anti-cancer therapy and cicatricial alopecia.

Cancer Therapy-induced Dermatotoxicity as a Window to Understanding Skin Immunity

Pruritus, rash, and various other forms of dermatotoxicity are the most frequent adverse events among patients with cancer receiving targeted molecular therapy and immunotherapy. Immune checkpoint inhibitors, macrophage-targeting agents, and epidermal growth factor receptor/MEK inhibitors not only exert antitumor effects but also interfere with molecular pathways essential for skin immune homeostasis. Studying cancer therapy-induced dermatotoxicity helps us identify molecular mechanisms governing skin immunity and deepen our understanding of human biology. This review summarizes new mechanistic insights emerging from the analysis of cutaneous adverse events and discusses knowledge gaps that remain to be closed by future research.

Topical JAK inhibition ameliorates EGFR inhibitor-induced rash in rodents and humans

Epidermal growth factor receptor inhibitors (EGFRis) are used to treat many cancers, but their use is complicated by the development of a skin rash that may be severe, limiting their use and adversely affecting patient quality of life. Most studies of EGFRi-induced rash have focused on the fully developed stage of this skin disorder, and early pathological changes remain unclear. We analyzed high-throughput transcriptome sequencing of skin samples from rats exposed to the EGFRi afatinib and identified that keratinocyte activation is an early pathological alteration in EGFRi-induced rash. Mechanistically, the induction of S100 calcium-binding protein A9 (S100A9) occurred before skin barrier disruption and led to keratinocyte activation, resulting in expression of specific cytokines, chemokines, and surface molecules such as interleukin 6 (Il6) and C-C motif chemokine ligand 2 (CCL2) to recruit and activate monocytes through activation of the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathway, further recruiting more immune cells. Topical JAK inhibition suppressed the recruitment of immune cells and ameliorated the severity of skin rash in afatinib-treated rats and mice with epidermal deletion of EGFR, while having no effect on EGFRi efficacy in tumor-bearing mice. In a pilot clinical trial (NCT05120362), 11 patients with EGFRi-induced rash were treated with delgocitinib ointment, resulting in improvement in rash severity by at least one grade in 10 of them according to the MASCC EGFR inhibitor skin toxicity tool (MESTT) criteria. These findings provide a better understanding of the early pathophysiology of EGFRi-induced rash and suggest a strategy to manage this condition.

Traditional Chinese Medicine Formulae QY305 Reducing Cutaneous Adverse Reaction and Diarrhea by its Nanostructure

Traditional Chinese medicine (TCM) is widely used in clinical practice, including skin and gastrointestinal diseases. Here, a potential TCM QY305 (T-QY305) is reported that can modulate the recruitment of neutrophil in skin and colon tissue thus reducing cutaneous adverse reaction and diarrhea induced by epidermal growth factor receptor inhibitors (EGFRIs). On another hand, the T-QY305 formula, through regulating neutrophil recruitment features would highlight the presence of N-QY305, a subunit nanostructure contained in T-QY305, and confirm its role as potentially being the biomaterial conferring to T-QY305 its pharmacodynamic features. Here, the clinical records of two patients are analyzed expressing cutaneous adverse reaction and demonstrate positive effect of T-QY305 on the simultaneous inhibition of both cutaneous adverse reaction and diarrhea in animal models. The satisfying results obtained from T-QY305, lead to further process to the isolation of N-QY305 from T-QY305, in order to demonstrate that the potency of T-QY305 originates from the nanostructure N-QY305. Compared to T-QY305, N-QY305 exhibits higher potency upon reducing adverse reactions. The data represent a promising candidate for reducing cutaneous adverse reaction and diarrhea, meanwhile proposing a new strategy to highlight the presence of nanostructures being the "King" of Chinese medicine formula as the pharmacodynamic basis.

Diseases categorized as autoinflammatory keratinization diseases (AiKDs), and their pathologies and treatments

Whole-exome and whole-genome sequencing have become widespread in approximately the last 15 years, and the predisposing factors and pathomechanisms of inflammatory keratinization diseases, which have been unknown for a long time, have gradually been revealed. Hence, various inflammatory keratinization diseases are recognized to cause innate immunity hyperactivation. Therefore, we have been advocating for the clinical entity, "autoinflammatory keratinization diseases (AiKDs)" since 2017. AiKDs are inflammatory keratinization diseases caused by autoinflammatory-related pathomechanisms in the skin. The aberrant activation of innate immunity and the resultant autoinflammation in the epidermis and the superficial dermis in AiKDs cause hyperkeratosis in the epidermis. Our initially proposed concept of AiKDs included generalized pustular psoriasis and related conditions, pityriasis rubra pilaris type V, and familial keratosis lichenoides chronica. Since then, the number of diseases known to be AiKDs has increased as previously unknown disease-causing factors and pathogenetic mechanisms of inflammatory keratinization diseases have been clarified one by one. To date, porokeratosis, hidradenitis suppurative, keratosis linearis with ichthyosis congenita and sclerosing keratoderma (KLICK) syndrome, and AiKDs associated with epidermal growth factor receptor (EGFR) deficiency or with hepatitis and autism have been recognized as AiKDs. The concept of AiKDs is considered extremely useful in our precise understanding of the pathogeneses behind inflammatory keratinization diseases and our appropriate treatment method selection. The number of AiKDs is expected to grow with the clarification of the pathomechanisms of further inflammatory keratinization diseases.

Menahydroquinone-4 may play a key role in regulating CCL5 expression induced by epidermal growth factor receptor inhibitors

Epidermal growth factor receptor (EGFR) inhibitors frequently cause severe skin rash as a side effect, which is a critical burden for patients who continuously receive drug treatments. Several recent clinical trials have shown that vitamin K is effective against these side effects; however, the underlying mechanisms remain unclear. EGFR inhibitors induce C-C motif chemokine ligand 5 (CCL5) in dermopathy. We hypothesized that menahydroquinone-4 (MKH), the active form of menaquinone-4 (MK-4, vitamin K2(20)), supplied by biosynthesis or external delivery, is essential for the suppressive effect on CCL5. The aim of this study was to explore the underlying mechanisms governing the relieving effects of MKH against skin rashes caused by EGFR inhibitors. The responses generated by EGFR inhibitors and the effect of MKH derivatives (two ester derivatives and MK-4) on them were evaluated using human skin cell lines (HaCaT and HSC-1). EGFR inhibitors downregulated UbiA prenyltransferase domain-containing protein-1 (UBIAD1, MKH synthetase) expression and MKH biosynthesis. Knockdown of UBIAD1 or γ-glutamyl carboxylase and treatment with warfarin upregulated CCL5 expression. MKH derivatives suppressed the CCL5 expression induced by EGFR inhibitors. Our data strongly suggest that MKH is involved in suppressing CCL5 expression and alleviating the skin damage caused by EGFR inhibitors.

Preventing skin toxicities induced by EGFR inhibitors by topically blocking drug-receptor interactions

Epidermal growth factor receptor (EGFR) inhibitors are used to treat many advanced-stage epithelial cancers but induce severe skin toxicities in most treated patients. These side effects lead to a deterioration in the quality of life of the patients and compromise the anticancer treatment. Current treatment strategies for these skin toxicities focus on symptom reduction rather than preventing the initial trigger that causes the toxicity. In this study, we developed a compound and method for treating "on-target" skin toxicity by blocking the drug at the site of toxicity without reducing the systemic dose reaching the tumor. We first screened for small molecules that effectively blocked the binding of anti-EGFR monoclonal antibodies to EGFR and identified a potential candidate, SDT-011. In silico docking predicted that SDT-011 interacted with the same residues on EGFR found to be important for the binding of EGFR inhibitors cetuximab and panitumumab. Binding of SDT-011 to EGFR reduced the binding affinity of cetuximab to EGFR and could reactivate EGFR signaling in keratinocyte cell lines, ex vivo cetuximab-treated whole human skin, and A431-injected mice. Specific small molecules were topically applied and were delivered via a slow-release system derived from biodegradable nanoparticles that penetrate the hair follicles and sebaceous glands, within which EGFR is highly expressed. Our approach has the potential to reduce skin toxicity caused by EGFR inhibitors.

EGFR marks a subpopulation of dermal mesenchymal cells highly expressing IGF1 which enhances hair follicle regeneration

The skin harbours transcriptionally and functionally heterogeneous mesenchymal cells that participate in various physiological activities by secreting biochemical cues. In this study, we aimed to identify a new subpopulation of dermal mesenchymal cells that enhance hair follicle regeneration through a paracrine mechanism. Integrated single-cell RNA sequencing (scRNA-seq) data analysis revealed epidermal growth factor receptor (EGFR) as a marker of distinct fibroblast subpopulation in the neonatal murine dermis. Immunofluorescence staining and fluorescence-activated cell sorting (FACS) were used to validate the existence of the cell population in Krt14-rtTA-H2BGFP mouse. The difference of gene expression between separated cell subpopulation was examined by real-time PCR. Potential effect of the designated factor on hair follicle regeneration was observed after the application on excisional wounds in Krt14-rtTA-H2BGFP mouse. Immunofluorescence staining demonstrated the existence of dermal EGFR+ cells in neonatal and adult mouse dermis. The EGFR+ mesenchymal population, sorted by FACS, displayed a higher expression level of Igf1 (insulin-like growth factor 1). Co-localisation of IGF1 with EGFR in the mouse dermis and upregulated numbers of hair follicles in healed wounds following the application of exogenous IGF1 illustrated the contribution of EGFR+ cells in promoting wound-induced hair follicle neogenesis. Our results indicate that EGFR identifies a subpopulation of dermal fibroblasts that contribute to IGF1 promotion of hair follicle neogenesis. It broadens the understanding of heterogeneity and the mesenchymal cell function in skin and may facilitate the potential translational application of these cells.

Immune cells in residual disease and recurrence

Tumor recurrence following potentially curative therapy constitutes a major obstacle to achieving cures in patients with cancer. Recurrent tumors frequently arise from a population of residual cancer cells - also referred to as minimal residual disease (RD) or persister cells - that survive therapy and persist for prolonged periods prior to tumor relapse. While there has been significant recent progress in deciphering tumor-cell-intrinsic pathways that regulate residual cancer cell survival and recurrence, much less is known about how the tumor microenvironment (TME) of residual tumors impacts persister cancer cells or tumor recurrence. In this review, we highlight recent studies exploring the regulation and function of immune cells in RD and discuss therapeutic opportunities to target immune cells in residual tumors.

Xijiao Dihuang decoction relieves the erlotinib-induced dermatitis

BACKGROUND

Erlotinib treatment can lead to skin diseases that drastically affected the quality of life of patients. Quercetin (Que), the active component in Xijiao Dihuang Decoction (XDD), was identified to improve inflammatory skin diseases. However, the mechanism of XDD treating erlotinib-induced cutaneous toxicity was not clear at the molecular level.

METHODS

Keratinocytes were treated with erlotinib, and the expression of inflammatory cytokines and chemokines was revealed by ELISA and qRT-PCR. The macrophage polarization was determined by flow cytometry. The key component of XDD, Que, and the target genes of dermatitis were selected via network pharmacology analysis. The binding effects of Que and target genes were verified using molecular docking and cellular thermal shift assay (CETSA)-western blot assay. Animal experiments were performed in vivo to verify the therapeutic effect of XDD on erlotinib-induced skin toxicity.

RESULTS

Erlotinib induced M1 polarization of macrophages after stimulating epidermal keratinocytes. While this effect was associated with increased production of inflammatory cytokines and chemokines, such production was prominently decreased by XDD treatment. By combining network pharmacological analysis, molecular docking, and CETSA, it was confirmed that Que had a binding relationship with IL-2 and CXCL8. In vivo results implied that erlotinib abated tumor growth and stimulated dermatitis in HR-1 nude mice, while Que alleviated erlotinib-induced skin damage without affecting this tumor repression effect.

CONCLUSION

The results indicated that XDD could relieve the dermatitis induced by erlotinib and provide a favorable theoretical basis for the clinical relief by using this method.

Therapeutic targets and signaling mechanisms of dasatinib activity against radiation skin ulcer

Objective

To reveal the potential targets and signaling pathways of dasatinib in the treatment of radiation ulcers through network pharmacology and molecular docking technology.

Methods

Pathological targets of radiation ulcers were screened using GeneCards database. At the same time, the pharmacological targets of dasatinib were obtained through SwissTargetPrediction (STP), Binding DB and Drugbank databases. Subsequently, the potential targets of dasatinib for anti-radiation ulcers were obtained after intersection by Venn diagram. Next, a protein-protein interaction (PPI) network was constructed through the STRING database and core targets were screened. Finally, the identified core targets were subjected to GO and KEGG enrichment analysis, co-expression network analysis, and molecular docking technology to verify the reliability of the core targets.

Results

A total of 76 potential targets for anti-radiation ulcer with dasatinib were obtained, and 6 core targets were screened, including EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These genes were mainly enriched in Adherens junction, EGFR tyrosine kinase inhibitor resistance, Focal adhesion, Bladder cancer and PI3K-Akt signaling pathway. Molecular docking results showed that dasatinib binds well to the core target.

Conclusion

Dasatinib may play a role in the treatment of radiation ulcers by regulating EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These core targets may provide new insights for follow-up studies of radiation ulcers.

Composition and Bioactivity of a Modified Huang-Lian-Jie-Du Decoction

Background. Epidermal growth factor receptor inhibitors (EGFRIs) and tyrosine kinase inhibitors (TKIs) are key drugs in targeted cancer therapy. However, they may cause skin toxicity. We previously prepared a modified Huang-Lian-Jie-Du (mHLJD) decoction cream using 10 herbs, which effectively alleviated EGFRI/TKI-induced skin toxicity. In the present study, we identified the reference markers of the mHLJD decoction and investigated the anti-inflammatory and antibacterial effects of the mHLJD decoction extract. Methods. We performed high-performance liquid chromatography (HPLC) to determine the composition of the mHLJD decoction. Human epidermoid A431 cells were treated with tumor necrosis factor (TNF)-α to induce inflammation; then, the effects of the mHLJD decoction extract on the cytokine expression were determined using a cytokine array and by performing real-time quantitative polymerase chain reaction (qPCR). The antibacterial effects of the extract were examined using disk diffusion and microdilution assays. Results. HPLC results revealed that the mHLJD decoction primarily consisted of geniposide, berberine chloride, baicalin, coptisine, and palmatine. TNF-α treatment increased the expression of certain cytokines, including IL-1β, IL-8, M-CSF, and TGF-β2; however, pretreatment with the mHLJD decoction extract reduced their expression. The qPCR results demonstrated a decreased mRNA expression of IL-8, M-CSF, and TGF-β2. The antibacterial assay revealed that the extract exerted inhibitory effects on Staphylococcus aureus, forming an inhibition zone at the minimum inhibitory concentrations of 3.125 and 6.25 mg/mL; however, the extract exerted no effects on Escherichia coli and Pseudomonas aeruginosa. Conclusions. We developed an HPLC method to quantify the reference markers of the mHLJD decoction. The bioactivity analysis provided the potential mechanisms underlying the effects of the mHLJD decoction on EGFRI/TKI-induced skin toxicity.

GPCR-mediated EGFR transactivation ameliorates skin toxicities induced by afatinib

Many G-protein-coupled receptor (GPCR) agonists have been studied for transactivating epidermal growth factor receptor (EGFR) signaling through extracellular or intracellular pathways. Accumulated evidence has confirmed that GPCR transactivation participates in various diseases. However, the clinical application of GPCR transactivation has not been explored, and more translational studies are needed to develop therapies to target GPCR-mediated EGFR transactivation. In cancer patients treated with EGFR inhibitors (EGFRi), especially afatinib, a unique acneiform rash is frequently developed. In this study, we first established the connection between GPCR transactivation and EGFRi-induced skin disease. We examined the ability of three different GPCR agonists to reverse signaling inhibition and ameliorate rash induced by EGFRi. The activation of different agonists follows unique time and kinase patterns. Rats treated with EGFRi show a similar skin phenotype, with rash occurring in the clinic; correspondingly, treatment with GPCR agonists reduced keratinocyte apoptosis, growth retardation and infiltration of inflammatory cytokines by transactivation. This phenomenon demonstrates that EGFR inhibition in keratinocytes regulates key factors associated with rash. Our findings indicate that maintaining EGFR signaling by GPCR agonists might provide a possible therapy for EGFR inhibitor-induced skin toxicities. Our study provides the first example of the translational application of GPCR transactivation in treating diseases.

The Desmosome-Keratin Scaffold Integrates ErbB Family and Mechanical Signaling to Polarize Epidermal Structure and Function

While classic cadherin-actin connections in adherens junctions (AJs) have ancient origins, intermediate filament (IF) linkages with desmosomal cadherins arose in vertebrate organisms. In this mini-review, we discuss how overlaying the IF-desmosome network onto the existing cadherin-actin network provided new opportunities to coordinate tissue mechanics with the positioning and function of chemical signaling mediators in the ErbB family of receptor tyrosine kinases. We focus in particular on the complex multi-layered outer covering of the skin, the epidermis, which serves essential barrier and stress sensing/responding functions in terrestrial vertebrates. We will review emerging data showing that desmosome-IF connections, AJ-actin interactions, ErbB family members, and membrane tension are all polarized across the multiple layers of the regenerating epidermis. Importantly, their integration generates differentiation-specific roles in each layer of the epidermis that dictate the form and function of the tissue. In the basal layer, the onset of the differentiation-specific desmosomal cadherin desmoglein 1 (Dsg1) dials down EGFR signaling while working with classic cadherins to remodel cortical actin cytoskeleton and decrease membrane tension to promote cell delamination. In the upper layers, Dsg1 and E-cadherin cooperate to maintain high tension and tune EGFR and ErbB2 activity to create the essential tight junction barrier. Our final outlook discusses the emerging appreciation that the desmosome-IF scaffold not only creates the architecture required for skin's physical barrier but also creates an immune barrier that keeps inflammation in check.

PROPHYLACTIC EFFECT OF NITRIC OXIDE DONORS ON RAT MODELS OF EGFR INHIBITORS-INDUCED CUTANEOUS TOXICITIES

Epidermal growth factor receptor inhibitors (EGFRIs) have been established as first-line standard-of-care therapies for non-small cell lung cancer (NSCLC) but are frequently accompanied by adverse dermatological effects, in particular, acneiform rash. There is no effective clinical intervention, partially because of its poorly understood etiology. Here, we show that inhibition of EGFR initiated keratinocyte HaCaT cell cycle arrest and apoptosis, which fueled a robust secondary inflammatory response. Rats gavaged with EGFRI showed a phenotype similar to that of clinical patients, which was in line with the interrupted functions observed in HaCaT keratinocytes. We found that a nitric oxide (NO) donor, nitroglycerin (GTN), was a feasible treatment alternative for EGFRI-induced rash. Restoration of epidermal extracellular signal-regulated kinase (ERK) and a reduction in STAT3 signaling via GTN treatment rescued the cellular functions that had been damaged in vitro and further ameliorated the rash in rat models. In addition, the efficacy of GTN was superior to that of existing clinical interventions. These data highlighted the importance of epidermal EGFR signaling and led to the identification of a small-molecule NO donor as a mediator that can maintain EGFR pathway functions during anti-EGFR therapies, providing a therapeutic anchor point for adverse EGFRI-induced skin effects.

Remodeling of dermal adipose tissue alleviates cutaneous toxicity induced by anti-EGFR therapy

Anti-epidermal growth factor receptor (EGFR) therapy–associated cutaneous toxicity is a syndrome characterized by papulopustular rash, local inflammation, folliculitis, and microbial infection, resulting in a decrease in quality of life and dose interruption. However, no effective clinical intervention is available for this adverse effect. Here, we report the atrophy of dermal white adipose tissue (dWAT), a highly plastic adipose tissue with various skin-specific functions, correlates with rash occurrence and exacerbation in a murine model of EGFR inhibitor-induced rash. The reduction in dWAT is due to the inhibition of adipogenic differentiation by defects in peroxisome proliferator-activated receptor γ (PPARγ) signaling, and increased lipolysis by the induced expression of the lipolytic cytokine IL6. The activation of PPARγ by rosiglitazone maintains adipogenic differentiation and represses the transcription of IL6, eventually improving skin functions and ameliorating the severity of rash without altering the antitumor effects. Thus, activation of PPARγ represents a promising approach to ameliorate cutaneous toxicity in patients with cancer who receive anti-EGFR therapy.

Molecular methods for increasing the effectiveness of ovarian cancer treatment: a systematic review

Background: The aim of the current study is to analyze and summarize the latest research on improving therapy in ovarian cancer. Materials & methods: Data analysis was based on a review of publications from 2011 to 2021 in the PubMed database with use of the search terms including 'EGFR ovarian cancer', 'folate receptor inhibitors ovarian cancer', 'VEGF ovarian cancer', 'PDGF ovarian cancer' and 'CTLA-4 ovarian cancer'. Results: 6643 articles were found; 238 clinical trials and randomized control trials were analyzed; 122 studies were rejected due to inconsistency with the topic of the work. Conclusion: Extensive research on the treatment of ovarian cancer increases the chance of developing the most effective therapy suited to the individual needs of the patient.

Building vs. Rebuilding Epidermis: Comparison Embryonic Development and Adult Wound Repair

Wound repair is essential to restore tissue function through the rebuilding of pre-existing structures. The repair process involves the re-formation of tissue, which was originally generated by embryonic development, with as similar a structure as possible. Therefore, these two processes share many similarities in terms of creating tissue architecture. However, fundamental differences still exist, such as differences in the cellular components, the status of neighboring tissues, and the surrounding environment. Recent advances in single-cell transcriptomics, in vivo lineage tracing, and intravital imaging revealed subpopulations, long-term cell fates, and dynamic cellular behaviors in live animals that were not detectable previously. This review highlights similarities and differences between adult wound repair and embryonic tissue development with a particular emphasis on the epidermis of the skin.

Selective Immune Modulating Activities of Viscum album and Its Components; A Possibility of Therapeutics on Skin Rash Induced by EGFR Inhibitors

Viscum album var. coloratum (Kom.) Ohwi is a traditional herbal medicine used in East Asia to treat hypertension, skeletal muscle disorders, and cancer. The inhibitory effects of Viscum album (VA) extract on chemokines and its therapeutic potential in erlotinib-induced skin rash were investigated in this study. ELISA was used to measure the levels of chemokines, MCP-1 and RANTES, which are thought to be mediators of erlotinib-induced skin rash in RAW264.7 cells. Western blot analysis was used to look into the activation of signaling pathways like AKT, MAPK, and EGF. In order to investigate the active compounds in VA extract, solvent fractionation and preparative HPLC were performed sequentially. VA extract significantly reduced the production of TNF-α, MCP-1, and RANTES but not IL-1. Furthermore, macrophage transmigration was inhibited without causing cell toxicity. VA extract had no effect on the phosphorylation of EGF receptors stimulated by EGF or suppressed by erlotinib in both A549, a non-small cell lung cancer cells, and Hacat, a human skin keratinocyte. The isolated viscumneoside III and viscumneoside V from VA extract significantly suppressed the expression of MCP-1, according to activity guided fractionation with organic solvent fractionation and preparative HPLC. These findings suggest that VA extract and its active compounds, viscumneoside III and viscumneoside V, regulate MCP-1 production and may have the potential to suppress erlotinib-induced skin toxicity by modulating macrophage activity without neutralizing anti-cancer efficacy.

Skin Toxicity as Predictor of Survival in Refractory Patients with RAS Wild-Type Metastatic Colorectal Cancer Treated with Cetuximab and Avelumab (CAVE) as Rechallenge Strategy

The single-arm phase II CAVE mCRC trial evaluated the combination of cetuximab plus avelumab as rechallenge strategy in RAS wild-type (WT) metastatic colorectal cancer (mCRC) patients, with clinical response to first-line anti-EGFR-based chemotherapy, who progressed and received a subsequent line of therapy. The correlation of skin toxicity (ST) and different clinico-molecular variables with overall survival (OS), progression-free survival (PFS) and response rate (RR) was assessed at univariate and multivariate analysis. A total of 33/77 (42.9%) patients experienced grade 2-3 ST and displayed median OS (mOS) of 17.8 months (CI 95%, 14.9-20.6); whereas 44/77 (57.1%) patients with grade 0-1 ST exhibited mOS of 8.2 months (CI 95%, 5.5-10.9), (hazard ratio (HR), 0.51; CI 95%, 0.29-0.89; p = 0.019). Median PFS (mPFS) was 4.6 months (CI 95%, 3.4-5.7) in patients with grade 2-3 ST, compared to patients with grade 0-1 ST with mPFS of 3.4 months (CI 95%, 2.7-4.1; HR, 0.49; CI 95%, 0.3-0.8; p = 0.004). Grade 2-3 ST (HR, 0.51; CI 95%, 0.29-0.89; p = 0.019) and RAS/BRAF/EGFR WT circulating tumor DNA (ctDNA) (HR, 0.50; CI 95%, 0.27-0.9; p = 0.019) had a statistically significant effect on OS at univariate analysis. At the multivariate analysis, RAS/BRAF/EGFR WT ctDNA status maintained statistical significance (HR, 0.49; CI 95%, 0.27-0.9; p = 0.023), whereas there was a trend towards ST grade 2-3 (HR, 0.54; CI 95%, 0.29-1.01; p = 0.054). Skin toxicity is a promising biomarker to identify patients with mCRC that could benefit of anti-EGFR rechallenge.

Epithelial-immune crosstalk with the skin microbiota in homeostasis and atopic dermatitis - a mini review

The skin is a complex and dynamic ecosystem, wherein epithelial cells, immune cells and the skin microbiota actively interact and maintain barrier integrity and functional immunity. Skin microbes actively tune the functions of the resident immune cells. Dysbiosis - alterations in the resident microbiota - leads to the dysregulation of host immunity. Microbiome analyses in humans and dogs with atopic dermatitis (AD) have shown shifts in microbial diversity, and in particular, an increased proportion of staphylococci. Monogenic diseases that manifest AD-like symptoms provide insights into the pathogenesis of AD and the mechanisms of dysbiosis, from both the epithelial and immunological perspectives. The symbiotic relationships between the host and microbiota must be maintained constitutively. Detailed mechanisms of how host immunity regulates commensal bacteria in the steady state have been reported. The skin harbours multiple tissue-resident immune cells, including both innate and adaptive immune cells. Recent studies have highlighted the fundamental role of innate lymphoid cells (ILCs) in the maintenance of barrier functions and tissue homeostasis. ILCs directly respond to tissue-derived signals and are instrumental in barrier immunity. Epithelial cells produce alarmins such as thymic stromal lymphopoietin (TSLP) and interleukins (IL)-33 and IL-25, all of which activate group 2 ILCs (ILC2s), which produce type 2 cytokines, such as IL-5 and IL-13, boosting type 2 immune reactions. Dysregulation of the epithelial-ILC crosstalk results in allergic inflammation. This review highlights our understanding of the active interactions between the host epithelial and immune cells, and microbiota, providing a foundation for novel therapeutic strategies for inflammatory skin diseases.

[Establishment of animal models of epidermal growth factor receptor inhibitor-related rashes]

OBJECTIVE

To establish animal models epidermal growth factor receptor inhibitor-related skin rashes using cetuximab, gefitinib or erlotinib.

OBJECTIVE

Female SCID mice were randomly divided into blank control group and high-, moderate-, and low-dose cetuximab groups. The mice in control group received intraperitoneal injection of saline, and those in the 3 cetuximab groups were injected with 80, 40, and 20 mg/kg cetuximab (3 times a week for 4 weeks), respectively. The general skin appearance and skin pathologies of the mice were observed. Female BN rats were randomly divided into blank group, ovalbumin group, gefitinib group and erlotinib group, and in the latter 3 groups, the rats were given ovalbumin (1 mg), gefitinib (37.5 mg/kg), and erlotinib (23.5 mg/kg) by lavage once daily for 45 days, respectively. Skin pathologies of the rats were observed, and serum levels of TNF-α, IL-6 and other inflammatory factors were detected using ELISA.

OBJECTIVE

Intraperitoneal injection of cetuximab did not induce typical skin rashes, scabs or obvious skin inflammation in the mice. In female BN rats, lavage of gefitinib caused obvious skin rashes, scabs and exudation, and obvious inflammatory cell infiltration, keratinosis, spinous layer release and epidermal thickening were observed in the skin. No obvious skin inflammation were observed in the rats in the control, ovalbumin or erlotinib groups. While IgE (P=0.061) and TNF-α concentrations (P=0.057) did not differ significantly among the groups, serum levels of IL-6 was significantly higher in gefitinib group than in the blank control group (P=0.016) but similar between erlotinib group and the blank group (P=0.910).

OBJECTIVE

Intraperitoneal injection of cetuximab can not induce epidermal growth factor receptor inhibitor-related skin rashes in SCID mice. Lavage of gefitinib, but not erlotinib, can be used to establish models of epidermal growth factor receptor inhibitor-related rashes in BN rats.

Oxidative stress induces EGFR inhibition-related skin cell death

Cutaneous side effects are often observed in patients treated with chemotherapeutic agents, including those treated with epidermal growth factor receptor (EGFR) inhibitors. These side effects are not fatal but often require dose reduction of chemotherapies. The mechanisms of epidermal growth factor receptor inhibition-related dermatologic toxicities are unclear, and prophylactic approaches are not well-established. To explore the mechanisms of the cutaneous side effects induced by epidermal growth factor receptor inhibition, we analyzed the metabolome using human keratinocyte cells. We first demonstrated that afatinib and lapatinib induced apoptosis in HaCaT cells. Using liquid chromatography-mass spectrometry, we detected 676 and 482 metabolites and compounds in the cells and media, respectively. We observed diverse metabolic alterations, including glycolysis, TCA metabolism, and polyamine metabolism, and also found a change in glutathione metabolites after epidermal growth factor receptor inhibition, which led to the accumulation of reactive oxygen species. Supplementation of N-acetyl cysteine partly rescued the afatinib-induced apoptosis, suggesting that reactive oxygen species are involved in the cytotoxicity of skin cells. We observed epidermal growth factor receptor inhibitor-associated comprehensive metabolic changes in human keratinocyte cells, suggesting that oxidative stress evokes cutaneous side effects induced by EGFR inhibition.

Comparison of gefitinib-induced skin adverse reactions (SAR) in C57BL/6 and FVB/N mice

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib, erlotinib, and afatinib, are widely used in clinical practice and remarkably effective in treatment of advanced non-small cell lung cancer. However, there are some adverse effects while taking EGFR-TKIs, among which skin adverse reactions (SAR) are the most common events. At present, the poor outcome of SAR and insufficient research on SAR models need to be addressed. In this study we focused on the SAR models to lay a foundation for mechanism researches. Gefitinib, one of the EGFR-TKIs, was used as SAR inducing agents. We chose C57BL/6 and FVB/N mice as experimental model and they were divided into four groups. The weight and skin moisture of mice were detected every 7 days, itching behavior and abnormal eyelids were tested at 35th day after gavage, and survival rate was also recorded. The weight of unit area hair, length of whiskers and inflammatory cells were evaluated after mice sacrificed. C57BL/6 animals treated with gefitinib showed significant differences in survival rate, weight of unit area hair, skin moisture changes, skin dryness, itching behavior, whisker irregular growth, abnormal eyelids, and inflammatory cells; FVB/N animals treated with gefitinib only showed significant differences in survival rate, whisker irregular growth and abnormal eyelids, compared with the control group, respectively. In this study, we compared the similarities and differences of gefitinib-induced SAR between C57BL/6 and FVB/N mice, which illustrated different patients probably showing different symptoms clinically and provided experimental basis for researching mechanism of EGFR-TKIs induced SAR.

Mobocertinib (TAK-788): A Targeted Inhibitor of EGFR Exon 20 Insertion Mutants in Non-Small Cell Lung Cancer

Most EGFR exon 20 insertion (EGFRex20ins) driver mutations in non-small cell lung cancer (NSCLC) are insensitive to approved EGFR tyrosine kinase inhibitors (TKI). To address the limitations of existing therapies targeting EGFR-mutated NSCLC, mobocertinib (TAK-788), a novel irreversible EGFR TKI, was specifically designed to potently inhibit oncogenic variants containing activating EGFRex20ins mutations with selectivity over wild-type EGFR. The in vitro and in vivo activity of mobocertinib was evaluated in engineered and patient-derived models harboring diverse EGFRex20ins mutations. Mobocertinib inhibited viability of various EGFRex20ins-driven cell lines more potently than approved EGFR TKIs and demonstrated in vivo antitumor efficacy in patient-derived xenografts and murine orthotopic models. These findings support the ongoing clinical development of mobocertinib for the treatment of EGFRex20ins-mutated NSCLC. SIGNIFICANCE: No oral EGFR-targeted therapies are approved for EGFR exon 20 insertion (EGFRex20ins) mutation-driven NSCLC. Mobocertinib is a novel small-molecule EGFR inhibitor specifically designed to target EGFRex20ins mutants. Preclinical data reported here support the clinical development of mobocertinib in patients with NSCLC with EGFR exon 20 insertion mutations.See related commentary by Pacheco, p. 1617.This article is highlighted in the In This Issue feature, p. 1601.

Role of epidermal growth factor receptor inhibitor-induced interferon pathway signaling in the head and neck squamous cell carcinoma therapeutic response

BACKGROUND

Epidermal growth factor receptor (EGFR) is frequently amplified or overexpressed in head and neck squamous cell carcinoma (HNSCC) and is a clinically validated target for the therapeutic antibody, cetuximab, in the management of this cancer. The degree of response to EGFR inhibitors measured by tumor shrinkage varies widely among HNSCC patients, and the biological mechanisms that underlie therapeutic heterogeneity amongst HNSCC patients remain ill-defined.

METHODS

EGFR-dependent human and murine HNSCC cell lines were treated with the EGFR/ERBB inhibitors, gefitinib and AZD8931, and submitted to RNAseq, GSEA, and qRT-PCR. Conditioned media was analyzed by ELISA and Luminex assays. Murine HNSCC tumors were stained for T cell markers by immunofluorescence. Primary HSNCC patient specimens treated with single agent cetuximab were stained with Vectra multispectral immunofluorescence.

RESULTS

The transcriptional reprogramming response to EGFR/ERBB-specific TKIs was measured in a panel of EGFR-dependent human HNSCC cell lines and interferon (IFN) α and γ responses identified as top-ranked TKI-induced pathways. Despite similar drug sensitivity, responses among 7 cell lines varied quantitatively and qualitatively, especially regarding the induced chemokine and cytokine profiles. Of note, the anti-tumorigenic chemokine, CXCL10, and the pro-tumorigenic factor, IL6, exhibited wide-ranging and non-overlapping induction. Similarly, AZD8931 exerted potent growth inhibition, IFNα/IFNγ pathway activation, and CXCL10 induction in murine B4B8 HNSCC cells. AZD8931 treatment of immune-competent mice bearing orthotopic B4B8 tumors increased CD8 + T cell content and the therapeutic response was abrogated in nu/nu mice relative to BALB/c mice. Finally, Vectra 3.0 analysis of HNSCC patient tumors prior to and after 3-4 weeks of single agent cetuximab treatment revealed increased CD8 + T cell content in specimens from patients exhibiting a therapeutic response relative to non-responders.

CONCLUSIONS

The findings reveal heterogeneous, tumor cell-intrinsic, EGFR/ERBB inhibitor-induced IFN pathway activation in HNSCC and suggest that individual tumor responses to oncogene-targeted agents are a sum of direct growth inhibitory effects and variably-induced participation of host immune cells.

Skin inflammatory response and efficacy of anti-epidermal growth factor receptor therapy in metastatic colorectal cancer (CUTACETUX)

Anti-epidermal growth factor receptor (EGFR) monoclonal antibody is a standard treatment of metastatic colorectal cancer (mCRC) and its most common adverse effect is a papulopustular acneiform rash. The aim of the CUTACETUX study was to characterize the skin inflammatory response associated with this rash and its relation to treatment efficacy. This prospective study included patients with mCRC treated with first-line chemotherapy plus cetuximab. Patients underwent skin biopsies before the initiation of cetuximab (D0) and before the third infusion (D28), one in a rash zone and one in an unaffected zone. Expression of Th17-related cytokines (IL-17A, IL-21, IL-22), antimicrobial peptides (S100A7 and BD-2), innate response-related cytokines (IL-1β, IL-6, TNF-α and OSM), T-reg-related cytokines (IL-10 and TGF-β), Th1-related cytokine (IFN-γ), Th2-related cytokine (IL-4), Thymic stromal lymphopoietin and keratinocyte-derived cytokines (IL-8, IL-23 and CCL20) were determined by RT-PCR. Twenty-seven patients were included. Levels of most of the cytokines increased at D28 in the rash zone compared to D0. No significant association was observed between variations of cytokines levels and treatment response in the rash zone and only the increase of IL-4 (p = .04) and IL-23 (p = .02) levels between D0 and D28 in the unaffected zone was significantly associated with treatment response. Increased levels of IL-8 (p = .02), BD-2 (p = .02), IL-1β (p = .004) and OSM (p = .02) in the rash zone were associated with longer progression-free survival. Expression of Th2-related and keratinocyte-derived cytokines in the skin was associated with anti-EGFR efficacy. If this inflammatory signature can explain the rash, the exact mechanism by which these cytokines are involved in anti-EGFR tumor response remains to be studied.

Establishment and application of a predictive model for gefitinib-induced severe rash based on pharmacometabolomic profiling and polymorphisms of transporters in non-small cell lung cancer

•

A total of 346 patients were enrolled in this study.

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Severe rash (grade 3&4) did not gain more bonification compare to grade 1&2 rash.

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Gefitinib and its four metabolites were detected in patients’ plasma.

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A specific and sensitive predictive model were established based on pharmacometabolomic profiling and pharmacogenomics approach.

Background

Rash is a well-known predictor of survival for patients with gefitinib therapy with non-small cell lung cancer (NSCLC). However, whether patients with more severe rash obtain the more survival benefits from gefitinib is still unknown, and predicted model for severe rash is needed.

Methods

The relationship between gefitinib-induced rash and progression free survival (PFS) was primarily explored in the retrospective cohort. The association between rash and gefitinib/metabolites concentration and genetic polymorphisms were determined by pharmacometabolomic and pharmacogenomics methods in the exploratory cohort and validated in an external cohort.

Results

The survival for patients with rash was significantly higher than that of patients without rash (p = 0.0002, p = 0.0089), but no difference was found between grade 1/2 or grade 3/4. Only the concentration of gefitinib, but not its metabolites, was found to be associated with severe rash, and the cutoff value of gefitinib was 204.6 ng/mL conducted by ROC curve analysis (AUC=0.685). A predictive model for severe rash was established: gefitinib concentration (OR = 11.523, 95% CI = 2.898-64.016, p = 0.0016), SLC22A8 rs4149179(CT vs CC, OR = 3.156, 95% CI = 0.958–11.164, p = 0.0629), SLC22A1 rs4709400(CG vs CC, OR = 10.267, 95% CI = 2.067–72.465, p = 0.0087; GG vs CC, OR = 5.103, 95% CI = 1.032–33.938, p = 0.061). This model was confirmed in the validation cohort with an excellent predictive ability (AUC = 0.749, 95% CI = 0.710–0.951).

Conclusions

Our finding demonstrated that the incidence, not the severity, of gefitinib-induced rash predicted improved survival, the gefitinib concentration and polymorphisms of SLC22A8 and SLC22A1 were recommended to manage severe rash.

Therapeutic targeting of FLT3 and associated drug resistance in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease caused by several gene mutations and cytogenetic abnormalities affecting differentiation and proliferation of myeloid lineage cells. FLT3 is a receptor tyrosine kinase commonly overexpressed or mutated, and its mutations are associated with poor prognosis in AML. Although aggressive chemotherapy often followed by hematopoietic stem cell transplant is the current standard of care, the recent approval of FLT3-targeted drugs is revolutionizing AML treatment that had remained unchanged since the 1970s. However, despite the dramatic clinical response to targeted agents, such as FLT3 inhibitors, remission is almost invariably short-lived and ensued by relapse and drug resistance. Hence, there is an urgent need to understand the molecular mechanisms driving drug resistance in order to prevent relapse. In this review, we discuss FLT3 as a target and highlight current understanding of FLT3 inhibitor resistance.

IL-36γ drives skin toxicity induced by EGFR/MEK inhibition and commensal Cutibacterium acnes

Epidermal growth factor receptor (EGFR) and MEK inhibitors (EGFRi/MEKi) are beneficial for the treatment of solid cancers but are frequently associated with severe therapy-limiting acneiform skin toxicities. The underlying molecular mechanisms are poorly understood. Using gene expression profiling we identified IL-36γ and IL-8 as candidate drivers of EGFRi/MEKi skin toxicity. We provide molecular and translational evidence that EGFRi/MEKi in concert with the skin commensal bacterium Cutibacterium acnes act synergistically to induce IL-36γ in keratinocytes and subsequently IL-8, leading to cutaneous neutrophilia. IL-36γ expression was the combined result of C. acnes–induced NF-κB activation and EGFRi/MEKi–mediated expression of the transcription factor Krüppel-like factor 4 (KLF4), due to the presence of both NF-κB and KLF4 binding sites in the human IL-36γ gene promoter. EGFRi/MEKi increased KLF4 expression by blockade of the EGFR/MEK/ERK pathway. These results provide an insight into understanding the pathological mechanism of the acneiform skin toxicities induced by EGFRi/MEKi and identify IL-36γ and the transcription factor KLF4 as potential therapeutic targets.

When bugs and drugs conspire: driving acneiform skin toxicity

Therapy with antineoplastic agents that inhibit EGFR and MEK is frequently limited by cutaneous adverse reactions, most commonly acne-like eruptions. In this issue of the JCI, Satoh et al. define a mechanism for acneiform skin toxicity wherein EGFR/MEK inhibitors cooperate with the skin commensal Cutibacterium acnes to induce IL-36γ in keratinocytes via the combined actions of Krüppel-like factor 4 and NF-κB transcription factors at the IL-36γ promoter, resulting in neutrophil recruitment. In addition to elucidating why EGFR/MEK inhibitor-induced rashes are often pustular and folliculocentric, this mechanism provides justification for the long-standing practice of management with antibiotic therapy.

Light control of RTK activity: from technology development to translational research

Inhibition of receptor tyrosine kinases (RTKs) by small molecule inhibitors and monoclonal antibodies is used to treat cancer. Conversely, activation of RTKs with their ligands, including growth factors and insulin, is used to treat diabetes and neurodegeneration. However, conventional therapies that rely on injection of RTK inhibitors or activators do not provide spatiotemporal control over RTK signaling, which results in diminished efficiency and side effects. Recently, a number of optogenetic and optochemical approaches have been developed that allow RTK inhibition or activation in cells and in vivo with light. Light irradiation can control RTK signaling non-invasively, in a dosed manner, with high spatio-temporal precision, and without the side effects of conventional treatments. Here we provide an update on the current state of the art of optogenetic and optochemical RTK technologies and the prospects of their use in translational studies and therapy.

Gefitinib-Induced Cutaneous Toxicities in Brown Norway Rats Are Associated with Macrophage Infiltration

Gefitinib (Iressa), is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), used in the targeted treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC). Skin toxicity is the major adverse effect observed in patients treated with EGFR-targeted TKIs such as gefitinib and erlotinib. To date, a corresponding skin animal model has not been established to address the mechanisms of these effects. Therefore, we analyzed the skin rash phenotype and its pathological features in Brown Norway (BN) rats treated with gefitinib 2.5 mg, 5.0 mg, or 10 mg/100 g/day for 4 weeks. We found that treatment with gefitinib led to weight loss, rash, itching, and hair loss in a dose-dependent manner. We also investigated the skin pathology and found that the animal model showed thickening of the epidermis, loss of moisture, and apoptosis of keratinocytes. Immunohistochemistry, flow cytometry, and analysis of monocytes and leukocytes in the blood revealed increased macrophage infiltration was associated with the cutaneous toxicities induced by gefitinib in the BN rats. Finally, we found that gefitinib-induced cutaneous toxicity is significantly associated with three inflammatory cytokines known to be secreted by activated macrophages, TREM-1, CINC-2, and CINC-3.

Human skin biomarkers relationship to response to treatment with tyrosine kinase inhibitors in advanced EGFR-mutated lung adenocarcinoma

Background

A relationship between the EGFR signaling pathway expression in skin and the use of targeted cancer therapies has been previously demonstrated. Consistent evidence to support the use of skin biopsies as a surrogate for therapeutic evaluation is needed. The purpose of this study was to establish the relationship between the expression of EGFR signaling pathway markers in skin samples from EGFR‐mutated metastatic lung adenocarcinoma patients and their response to tyrosine kinase inhibitors.

Methods

This was a prospective single blind analysis of 35 skin biopsies from 31 patients with confirmed advanced EGFR‐mutated lung adenocarcinoma. Immunohistochemistry was performed: EGFR, p27, Ki67, STAT3 and MAPK, as well as H&E histopathological analysis, in order to determine their treatment response to tyrosine kinase inhibitors.

Results

EGFR, Ki67, STAT3, stratum corneum thickness (number of layers and millimeters) from skin samples had a statistical correlation with an adequate treatment response (P = 0.025, 0.015, 0.017, 0.041, 0.039 respectively). EGFR, p27 and number of layers of the stratum corneum were related to a better median progression‐free survival (P = 0.025 and P = 0.030).

Conclusions

The relationship between EGFR pathway inhibition in the skin and oncological outcomes obtained explains the parallel biological effects of tyrosine kinase inhibitors. We hope that our work incites future research to help validate and assess the use of these markers as potential prognostic and predictive factors.

Host-microbial dialogues in atopic dermatitis

Recent advances in sequencing technologies have revealed the diversity of microbes that reside on the skin surface which has enhanced our understanding on skin as an ecosystem, wherein the epidermis, immune cells and the microbiota engage in active dialogues that maintain barrier integrity and functional immunity. This mutual dialogue is altered in atopic dermatitis (AD), in which an impaired epidermal barrier, the skin microbial flora and aberrant immunity can form a vicious cycle that leads to clinical manifestations as eczematous dermatitis. Microbiome studies have revealed an altered microbial landscape in AD and genetic studies have identified genes that underlie barrier impairment and immune dysregulation. Shifting from the long-standing notion that AD was mediated by conventional allergic responses, emerging data suggest that it is a disorder of an altered host-microbial relationship with sophisticated pathophysiology. In this review, we will discuss recent advancements that suggest the roles of the skin microbiota in AD pathophysiology, genetic factors that mediate barrier impairment, dysbiosis and inflammation. Studies in mice, classic AD and monogenic disorders that manifest as AD collectively facilitate our understanding of AD pathophysiology and provide a foundation for novel therapeutic strategies.

Neurokinin-1 antagonist orvepitant for EGFRI-induced pruritus in patients with cancer: a randomised, placebo-controlled phase II trial

OBJECTIVE

To evaluate the efficacy of orvepitant (10 or 30 mg given once daily, orally for 4 weeks), a neurokinin-1 receptor antagonist, compared with placebo in reducing the intensity of epidermal growth factor receptor inhibitor (EGFRI)-induced intense pruritus.

DESIGN

Randomised, double-blind, placebo-controlled clinical trial.

SETTING

15 hospitals in Italy and five hospitals in the UK.

PARTICIPANTS

44 patients aged ≥18 years receiving an EGFRI for a histologically confirmed malignant solid tumour and experiencing moderate or intense pruritus after EGFRI treatment.

INTERVENTION

30 or 10 mg orvepitant or placebo tablets once daily for 4 weeks (randomised 1:1:1).

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary endpoint was change from baseline in mean patient-recorded numerical rating scale (NRS) score (over the last three recordings) at week 4. Secondary outcome measures were NRS score, verbal rating scale score, Skindex-16 and Leeds Sleep Evaluation Questionnaire at each study visit (baseline, weeks 1, 4, 8); rescue medication use; EGFRI dose reduction; and study withdrawal because of intense uncontrolled pruritus.

RESULTS

The trial was terminated early because of recruitment challenges; only 44 of the planned 90 patients were randomised. All patients were analysed for efficacy and safety. Mean NRS score change from baseline to week 4 was -2.78 (SD: 2.64) points in the 30 mg group, -3.04 (SD: 3.06) points in the 10 mg group and -3.21 (SD: 1.77) points in the placebo group; the difference between orvepitant and placebo was not statistically significant. No safety signal was detected. Adverse events related to orvepitant (asthenia, dizziness, dry mouth, hyperhidrosis) were all of mild or moderate severity.

CONCLUSIONS

Orvepitant was safe and well tolerated. No difference in NRS score between the orvepitant and placebo groups was observed at the week 4 primary endpoint. A number of explanations for this outcome are possible.

TRIAL REGISTRATION NUMBER

EudraCT2013-002763-25.

Hair eruption initiates and commensal skin microbiota aggravate adverse events of anti-EGFR therapy

Epidermal growth factor receptor (EGFR)-targeted anticancer therapy induces stigmatizing skin toxicities affecting patients' quality of life and therapy adherence. The lack of mechanistic details underlying these adverse events hampers their management. We found that EGFR/ERK signaling is required in LRIG1-positive stem cells during de novo hair eruption to secure barrier integrity and prevent the invasion of commensal microbiota and inflammatory skin disease. EGFR-deficient epidermis is permissive for microbiota outgrowth and displays an atopic-like TH2-dominated signature. The opening of the follicular ostia during hair eruption allows invasion of commensal microbiota into the hair follicle, initiating an additional TH1 and TH17 response culminating in chronic folliculitis. Restoration of epidermal ERK signaling via prophylactic FGF7 treatment or transgenic SOS expression rescues the barrier defect in the absence of EGFR, highlighting a therapeutic anchor point. These data reveal that commensal skin microbiota provoke atopic-like inflammatory skin diseases by invading into the follicular opening of erupting hair.

Proteomic and Phosphoproteomic Analysis Reveals that Neurokinin-1 Receptor (NK1R) Blockade with Aprepitant in Human Keratinocytes Activates a Distinct Subdomain of EGFR Signaling: Implications for the Anti-Pruritic Activity of NK1R Antagonists

Background: Epidermal growth factor receptor (EGFR) inhibitors can cause serious cutaneous toxicities, including pruritus and papulopustular acneiform skin eruptions. Increasingly, the neurokinin-1 receptor (NK1R) antagonist aprepitant is being utilized as an anti-pruritic agent in the treatment of EGFR-inhibitor induced pruritus. Aprepitant is believed to reduce itching by blocking NK1R on the surface of dermal mast cells. However, the effects of aprepitant on human keratinocytes remains unexplored. Methods: Herein, we examine the effects of aprepitant on EGFR stimulation in HaCaT cells using a phosphoproteomic approach including reverse phase protein arrays and Ingenuity Pathway Analysis. Changes in EGFR phosphorylation were visualized using Western blotting and the effect of EGF and aprepitant on the growth of HaCaT cells was determined using the WST-1 Cell Proliferation Assay System. Results: We found that aprepitant increased the phosphorylation of EGFR, as well as 10 of the 23 intracellular proteins phosphorylated by EGF. Analysis of phosphoproteomic data using Ingenuity Pathway Analysis software revealed that 5 of the top 10 pathways activated by EGF and aprepitant are shared. Conclusions: We propose that aprepitant produces its antipruritic effects by partially activating EGFR. Activation of EGFR by aprepitant was also seen in primary human keratinocytes. In addition to itch reduction through partial activation of shared EGFR pathways, aprepitant exerts a dose-dependent cytotoxicity to epithelial cells, which may contribute to its antitumor effects.

Differential Gene Expression in Erlotinib-Treated Fibroblasts

BACKGROUND

Therapies targeting the epidermal growth factor receptor (EGFR) result in a painful rash, the most common and debilitating toxicity among patients with non-small cell lung cancer (NSCLC) who take EGFR tyrosine kinase inhibitor (TKI) therapy; however, predicting the development and the severity of the rash is difficult.

OBJECTIVE

The aim of this study was to examine how erlotinib-an EGFR TKI that NSCLC patients take to stop or slow tumor growth-altered the transcriptome of dermal fibroblasts.

METHODS

Dermal fibroblasts (ATCC PCS-201-012) were seeded in cell culture flasks, grown under standard conditions, and transferred to cell culture dishes. Cells were treated once daily for 3 days with erlotinib 100 nM (n = 5), erlotinib 1 μM (n = 5), vehicle 1 μM (dimethyl sulfoxide) (n = 5), or no treatment (n = 5). Total RNA was extracted using a standard TRIzol method and hybridized using Affymetrix GeneChip Human Genome U133 Plus 2.0 arrays. Raw intensities generated from the arrays were normalized using a Robust Multiarray Average method and analyzed using analysis of variance in Limma R software. Differentially expressed genes were analyzed using Ingenuity Pathway Analysis to identify canonical or noncanonical signaling pathways enriched in this dataset.

RESULTS

We selected genes for investigation based on their potential role in wound healing (AQP3), rash development (CCL2), fibroblast activation (PALLD), cancer and cancer progression (GDF-15, SLC7A11, MMP12, and DIRAS3), and cell cycle control (CDC6). We were able to validate four of these genes by both Western blot analysis and quantitative polymerase chain reaction (MMP12, CCL2, CDC6, and SLC7A11).

DISCUSSION

If found predictive of rash in future studies using patient samples, our findings may help to identify those at risk for severe rash so that (a) the dose of EGFR TKI therapy may be adjusted; (b) additional treatments for the rash can be developed; and/or (c) precise, patient-centered interventions can be developed so that patients with cancer can better self-manage their rash and adhere to EGFR TKI treatment.

Bucillamine Prevents Afatinib-Mediated Inhibition of Epidermal Growth Factor Receptor Signaling

Molecular targeting therapies often cause characteristic adverse effects, such as skin rash during anti-epidermal growth factor receptor (EGFR) therapies, making treatment continuation difficult. In contrast, skin symptoms induced by EGFR inhibition are strongly correlated with the overall survival of the therapies. Therefore, controlling adverse effects not only facilitates treatment continuation but also increases clinical benefits. In this study, we proposed a novel strategy for reducing EGFR–tyrosine kinase inhibitor (TKI)-induced adverse effects in nontumorous organs by repositioning approved medicines using a zebrafish model. We developed a model system for evaluating chemical quenchers of afatinib, a clinically available irreversible EGFR-TKI, by scoring the inhibition of afatinib-induced hyperformation of lateral line neuromasts in zebrafish larvae. Bucillamine, an antirheumatic drug, was identified as an afatinib quencher in the zebrafish system and inhibited TKI activity in vitro. In addition, bucillamine restored EGFR autophosphorylation and downstream signaling in afatinib-treated A431 cells. Thus, topical bucillamine is a potential reliever of irreversible EGFR-TKI-induced skin rash. The zebrafish model can be applied to a screening for quenchers of other anti-EGFR-targeting therapies, including reversible TKIs and biologics.

Polymorphisms of NF-κB pathway genes influence adverse drug reactions of gefitinib in NSCLC patients

Gefitinib is a widely used targeted therapeutic drug in East Asian non-small cell lung cancer (NSCLC) patients. This research retrospectively investigated the relationship between the polymorphisms of genes involved in NF-κB pathways and gefitinib-related Adverse Drug Reactions (ADRs). From 2011 to 2016, 109 NSCLC patients were enrolled in this study. Thirty-two SNPs of 15 genes were genotyped with a Sequenom MassARRAY system. We collected 34 paired RNA samples before and after gefitinib administration for the detection of whole blood RNA expression of genes in NF-κB pathways (NFKBIA, NFKB1, NFKB2, RELA, RELB, and TNFAIP3). IKBKB rs2272733 (CC vs non-CC: OR = 0.256, 95% CI 0.087-0.753, P = 0.013) and IKBKE rs12142086 (CC vs non-CC: OR = 3.640, 95% CI 1.320-10.039, P = 0.013) were significantly associated with gefitinib-induced skin toxicity. IKBKE rs2151222 was associated with diarrhea with the odds ratio of non-TT vs TT as 0.162 (non-TT vs TT: 95% CI 0.034-0.775, P = 0.023). Furthermore, RELA rs11227247 was a predictor for hepatic toxicity (GG vs non-GG: OR = 0.212, 95% CI 0.062-0.726, P = 0.013). None of the gene expression levels after drug administration were determined to be significant predictors for adverse drug reactions by a logistics regression analysis. Polymorphisms of IKBKB, IKBKE, and RELA are potential biomarkers for predicting gefitinib-related ADRs. Further studies are needed to understand the underlying mechanisms for diagnostic and prophylactic therapy applications.

A protective Langerhans cell-keratinocyte axis that is dysfunctional in photosensitivity

Photosensitivity, or skin sensitivity to ultraviolet radiation (UVR), is a feature of lupus erythematosus and other autoimmune and dermatologic conditions, but the mechanistic underpinnings are poorly understood. We identify a Langerhans cell (LC)-keratinocyte axis that limits UVR-induced keratinocyte apoptosis and skin injury via keratinocyte epidermal growth factor receptor (EGFR) stimulation. We show that the absence of LCs in Langerin-diphtheria toxin subunit A (DTA) mice leads to photosensitivity and that, in vitro, mouse and human LCs can directly protect keratinocytes from UVR-induced apoptosis. LCs express EGFR ligands and a disintegrin and metalloprotease 17 (ADAM17), the metalloprotease that activates EGFR ligands. Deletion of ADAM17 from LCs leads to photosensitivity, and UVR induces LC ADAM17 activation and generation of soluble active EGFR ligands, suggesting that LCs protect by providing activated EGFR ligands to keratinocytes. Photosensitive systemic lupus erythematosus (SLE) models and human SLE skin show reduced epidermal EGFR phosphorylation and LC defects, and a topical EGFR ligand reduces photosensitivity. Together, our data establish a direct tissue-protective function for LCs, reveal a mechanistic basis for photosensitivity, and suggest EGFR stimulation as a treatment for photosensitivity in lupus erythematosus and potentially other autoimmune and dermatologic conditions.

EGFR Controls Hair Shaft Differentiation in a p53-Independent Manner

Epidermal growth factor receptor (EGFR) signaling controls skin development and homeostasis in mice and humans, and its deficiency causes severe skin inflammation, which might affect epidermal stem cell behavior. Here, we describe the inflammation-independent effects of EGFR deficiency during skin morphogenesis and in adult hair follicle stem cells. Expression and alternative splicing analysis of RNA sequencing data from interfollicular epidermis and outer root sheath indicate that EGFR controls genes involved in epidermal differentiation and also in centrosome function, DNA damage, cell cycle, and apoptosis. Genetic experiments employing p53 deletion in EGFR-deficient epidermis reveal that EGFR signaling exhibits p53-dependent functions in proliferative epidermal compartments, as well as p53-independent functions in differentiated hair shaft keratinocytes. Loss of EGFR leads to absence of LEF1 protein specifically in the innermost epithelial hair layers, resulting in disorganization of medulla cells. Thus, our results uncover important spatial and temporal features of cell-autonomous EGFR functions in the epidermis.

Preventive effect of Diallyl Trisulfide on cutaneous toxicities induced by EGFR inhibitor

Cutaneous toxicities are the commonest side effects in patients with cancer treated using epidermal growth factor receptor inhibitors such as erlotinib. For patients with such toxicities, there is a lack of safe, effective pharmacological agents. Here we established a skin toxicity model and investigated the preventive and therapeutic effect of Diallyl Trisulfide (DATS) in vivo. The mouse skin toxicities model was established through continuous administration of erlotinib for 49 days. Meanwhile, the mice in the experimental group underwent DATS treatment for 49 days. Hematoxylin and eosin (HE) staining and oil red O staining of back and limb skin was performed to determine whether DATS aqueous extract can reverse the skin toxicities caused by erlotinib. Compared with the erlotinib group, the incidence of rash in the DATS group was lower. In addition, in the DATS group, the degree of skin redness and herpes was mild, the body weight was stable, and the activity was favorable. By comparing the HE and oil red O staining results for the mouse skin, the degree of keratin hyperplasia was determined to be lower in the experimental group than in the erlotinib group, and the number of purulent neutrophils decreased. The number of follicles was relatively less. The release of TNF-α, IL-6 and other inflammatory factors was reduced by DATS. Erlotinib hydrochloride can cause severe skin toxicities, and DATS prevents skin toxicities, its mechanism may be related to DATS reduced erlotinib-induced inflammatory injury.

Linking tyrosine kinase inhibitor-mediated inflammation with normal epithelial cell homeostasis and tumor therapeutic responses

Receptor tyrosine kinases (RTKs) bearing oncogenic mutations in EGFR, ALK and ROS1 occur in a significant subset of lung adenocarcinomas. Tyrosine kinase inhibitors (TKIs) targeting tumor cells dependent on these oncogenic RTKs yield tumor shrinkage, but also a variety of adverse events. Skin toxicities, hematological deficiencies, nausea, vomiting, diarrhea, and headache are among the most common, with more acute and often fatal side effects such as liver failure and interstitial lung disease (ILD) occurring less frequently. In normal epithelia, RTKs regulate tissue homeostasis. For example, EGFR maintains keratinocyte homeostasis while MET regulates processes associated with tissue remodeling. Previous studies suggest that the acneiform rash occurring in response to EGFR inhibition is a part of an inflammatory response driven by pronounced cytokine and chemokine release and recruitment of distinct immune cell populations. Mechanistically, blockade of EGFR causes a Type I interferon (IFN) response within keratinocytes and in carcinoma cells driven by this RTK. This innate immune response within the tumor microenvironment (TME) involves increased antigen presentation and effector T cell recruitment that may participate in therapy response. This TKI-mediated release of inflammatory suppression represents a novel tumor cell vulnerability that may be exploited by combining TKIs with immune-oncology (IO) agents that rely on T-cell inflammation for efficacy. However, early clinical data indicate that combination therapies enhance the frequency and magnitude of the more acute adverse events, especially pneumonitis, hepatitis, and pulmonary fibrosis. Further preclinical studies to understand TKI mediated inflammation and crosstalk between normal epithelial cells, cancer cells, and the TME are necessary to improve treatment regimens for patients with RTK-driven carcinomas.