Crisaborole and atopic dermatitis skin biomarkers: An intrapatient randomized trial

Sensitivity of clinician-assessed efficacy outcome measurement instruments in trials of topical therapies for atopic dermatitis: a systematic review and meta-analysis

The rising prevalence of atopic dermatitis (AD) in developing countries and its substantial socioeconomic impact have furthered research over the last two decades giving way to advances in its aetiopathogenesis and treatment. Topical therapies targeting newly identified AD signalling pathways are being developed. Numerous clinician-assessed disease severity outcome measurement instruments (OMIs) are available to evaluate the efficacy of investigational treatments in proof-of-concept (POC) trials for AD. However, little is known about the comparative sensitivity of these efficacy OMIs. We performed a systematic review and meta-analysis to compare the sensitivity of different OMIs in controlled trials of topical therapies for AD published between January 1, 2000 and April 7, 2020. Treatment effect size of OMIs reported at Week 4 was calculated with 95% Confidence Interval (CI). The sensitivity of OMIs was compared by pooling the standardized difference between means (Cohen's d and Cohen's h) for any two OMI-parameter combinations that were reported in ≥3 studies identified in our systematic review. Assessed parameters were difference between active and vehicle at Week 4 and change from baseline [CFB] and percentage change from baseline [%CFB] at Week 4. We identified a total of 15 studies with 3313 subjects examining 14 different OMIs were included in this quantitative meta-analysis. Continuous OMIs had a significantly higher treatment effect size vs. dichotomous OMIs (P = 0.006). Comparisons of Eczema Area and Severity Index (EASI), Investigator's Global Assessment (IGA), body surface area (BSA) and SCORing Atopic Dermatitis (SCORAD) for available parameters were performed and generally had a similar sensitivity, with BSA showing smaller overall effect size estimates. In conclusion, continuous OMIs used in topical clinical trials for AD had significantly higher treatment effect sizes when compared to dichotomous OMIs. Continuous OMIs could provide more power for POC trials with a small sample size in atopic dermatitis with topical therapies.

Transcriptomic Profiling of Tape-Strips From Moderate to Severe Atopic Dermatitis Patients Treated With Dupilumab

BACKGROUND

Tape-strips are a minimally invasive approach to characterize skin biomarkers in atopic dermatitis (AD). However, they have not yet been used for tracking gene expression changes with systemic treatment.

OBJECTIVE

The aim of the study was to evaluate gene expression changes and therapeutic response biomarkers in AD patients before and after dupilumab (interleukin 4Rα antibody) treatment using tape-strips to obtain epidermal tissue for analysis.

METHODS

Lesional and nonlesional tape-stripped skin was sampled from 18 AD patients before and after dupilumab treatment and from 17 healthy subjects and analyzed by RNA-seq.

RESULTS

At baseline, we detected 6745 and 4859 differentially expressed genes between lesional and nonlesional skin versus normal, respectively, whereas 841 and 977 genes were differentially expressed after treatment, respectively (fold change >1.5 and false discovery rate <0.05). Tape-strips captured significant modulation with dupilumab in key AD immune (eg, C-C motif chemokine ligand 13 [CCL13], CCL17, CCL18) and barrier (eg, periplakin, FA2H) biomarkers. Changes in biomarkers (CCL20, interleukin 34, FABP7) were also significantly correlated with clinical disease improvements (Eczema Area and Severity Index; R > 0.5 or R < -0.4, P < 0.05).

CONCLUSIONS

This real-life study represents the first comprehensive RNA-seq molecular profiling of tape-strips from moderate to severe AD patients after dupilumab therapy. Analysis of tape strip specimens detected significant gene expression changes in key AD biomarkers with dupilumab treatment, suggesting that this approach may be useful to monitor therapeutic responses in inflammatory skin diseases.

High-dimensional analysis defines multicytokine T-cell subsets and supports a role for IL-21 in atopic dermatitis

BACKGROUND

Flow cytometry is a well-accepted approach for immune profiling; however, its value is restricted by the limited number of markers that can be analyzed simultaneously. Mass cytometry/CyTOF offers broad-scale immune characterization integrating large number of parameters. While partial blood phenotyping was reported in atopic dermatitis (AD), patients' comprehensive profiling, critical for leveraging new targeted treatments, is not available. IL-21 may be involved in inflammatory skin diseases but its role in AD is not well established.

METHODS

We studied T-cell polarization in the blood of 20 moderate-to-severe AD and 15 controls. Using CyTOF and an unsupervised analysis, we measured the frequencies and mean metal intensities of activated polar CD4⁺ /CD8⁺ T-cell subsets. Immunohistochemistry, immunofluorescence, and qRT-PCR were used to analyze skin samples.

RESULTS

Examining 24 surface, intracellular markers, and transcription factors, we identified six CD4⁺ and five CD8⁺ T-cell metaclusters. A CD4⁺ skin-homing IL-13⁺ monocytokine and a novel IL-13⁺ IL-21⁺ multicytokine metaclusters were increased in AD vs. controls (p < .01). While IL-13 signature characterized both clusters, levels were significantly higher in the IL-21⁺ group. Both clusters correlated with AD severity (r = 0.49, p = .029). Manual gating corroborated these results and identified additional multicytokine subsets in AD. Immunohistochemistry and immunofluorescence, validated by mRNA expression, displayed significantly increasedIL-21 counts and colocalization with IL-13/IL-4R in AD skin.

CONCLUSION

A multicytokine signature characterizes moderate-to-severe AD, possibly explaining partial therapeutic responses to one cytokine targeting, particularly in severe patients. Prominent IL-21 signature in blood and skin hints for a potential pathogenic role of IL-21 in AD.

From Emollients to Biologicals: Targeting Atopic Dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease and significantly impacts patients' lives, particularly in its severe forms. AD clinical presentation varies over the course of the disease, throughout different age groups, and across ethnicities. AD is characterized by a spectrum of clinical phenotypes as well as endotypes. Starting from the current description of AD pathogenesis, this review explores the rationale of approved AD therapies from emollients to biologicals and introduces novel promising drugs.

Efficacy and safety of crisaborole in patients with mild-to-moderate atopic dermatitis and other atopic comorbidities

Background: Crisaborole is a nonsteroidal anti-inflammatory phosphodiesterase 4 inhibitor that is approved for the treatment of patients with mild-to-moderate atopic dermatitis (AD); however, the efficacy and safety of crisaborole in patients with AD and other atopic comorbidities have not been investigated. Objective: This post hoc pooled analysis of the pivotal phase III studies (CrisADe CORE 1 and CORE 2) assessed the efficacy and safety of crisaborole versus vehicle in patients aged ≥ 2 years with mild-to-moderate AD and other atopic comorbidities. Methods: Patients with mild-to-moderate AD and a medical history of asthma, allergic rhinitis, or food allergies were identified. Efficacy assessments included the proportion of patients who achieved Investigator's Static Global Assessment (ISGA) success at day 29, ISGA clear or almost clear at day 29, and improvement in the Severity of Pruritus Scale score at week 4. Safety was assessed via treatment-emergent adverse events (TEAEs). Results: This analysis included 1522 patients (crisaborole, 1016; vehicle, 506); 26.2, 15.9, and 16.5% had a medical history of asthma, allergic rhinitis, and food allergies, respectively. The mean age was 12.2 years. A significantly greater proportion of patients treated with crisaborole achieved ISGA success at day 29 compared with patients treated with vehicle for most subgroups analyzed. Furthermore, a significantly greater proportion of patients treated with crisaborole achieved ISGA clear or almost clear at day 29 across all subgroups and demonstrated improvement in the Severity of Pruritus Scale score at week 4 versus patients treated with vehicle in most of the subgroups. Overall, most TEAEs were mild or moderate in severity; the most common treatment-related TEAE in patients with atopic comorbidities was application-site pain (crisaborole, 5.1%; vehicle, 1.7%). Conclusion: Crisaborole was efficacious and well tolerated in patients with mild-to-moderate AD and other atopic comorbidities, which suggested that crisaborole should be considered for the management of AD in this population. Clinical Trials NCT02118766 (CrisADe CORE 1) and NCT02118792 (CrisADe CORE 2), <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.clinicaltrials.gov">www.clinicaltrials.gov</ext-link>.

A phase 2b, randomized, double-blind, multicenter, vehicle-controlled study to assess the efficacy and safety of two crisaborole regimens in Japanese patients aged 2 years and older with mild-to-moderate atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritus, xerosis, and eczematous lesions. In Japan, treatment options, such as topical corticosteroids and tacrolimus, are associated with efficacy and safety concerns. Crisaborole ointment, 2%, is a topical non‐steroidal anti‐inflammatory agent approved in several countries for the treatment of mild‐to‐moderate AD. This phase 2b, randomized, double‐blind study (NCT03954158) assessed the efficacy and safety of two crisaborole regimens versus vehicle in the treatment of Japanese patients aged ≥2 years with mild‐to‐moderate AD. Each patient was assigned to one of two age cohorts (≥12 or 2–11 years) and randomized to crisaborole once daily (QD) or twice daily (BID). All patients had two target lesions that were each randomly assigned to crisaborole or vehicle at baseline and treated for 2 weeks. The primary endpoint was change from baseline in total sign score (TSS) in crisaborole‐ or vehicle‐treated target lesions on day 15, and secondary endpoints included change from baseline in Investigator’s Static Global Assessment (ISGA) and pruritic assessments (Cohort 1: peak pruritus numeric rating scale [NRS]; Cohort 2: Itch Severity Scale Self‐Report and Caregiver‐Reported Itch Severity NRS) and incidence of treatment‐emergent adverse events (TEAEs). This study comprised 81 patients (Cohort 1: n = 41; Cohort 2: n = 40). Crisaborole‐treated lesions showed statistically significant reductions in TSS versus vehicle‐treated lesions at day 15 (p < 0.01), and numerically larger decreases in TSS were observed with crisaborole BID versus crisaborole QD in both cohorts. Furthermore, crisaborole‐treated lesions generally demonstrated greater decreases in ISGA, peak pruritus NRS, Itch Severity Scale, and Caregiver‐Reported Itch Severity NRS versus vehicle‐treated lesions irrespective of regimen or cohort. Overall, TEAEs were mild; the most frequently reported TEAEs was application site irritation. In summary, both crisaborole regimens, particularly crisaborole BID, demonstrated efficacy and were well tolerated.

New and Emerging Systemic Treatments for Atopic Dermatitis

Atopic dermatitis (AD) is a prevalent inflammatory skin condition that, depending on its severity, can cause enormous morbidity. Corticosteroids and systemic immunosuppression, traditionally standard of care for difficult-to-treat disease, have many undesirable side effects. The desire for targeted treatments along with an improved understanding of the pathophysiology of AD has spurred the development of novel treatments. In this article, we review promising new treatments and discuss how their targets—IL-13, IL-31, OX40 (CD134), and the Janus kinase family of proteins—participate in the pathogenesis of AD. We review the published phase II and III data for dupilumab, tralokinumab, lebrikizumab, nemolizumab, anti-OX40 antibody, baricitinib, abrocitinib, and upadacitinib. The introduction of new agents may offer new options, but it remains to be seen how narrow-acting agents, like single interleukin inhibitors, will compare in safety and efficacy to broad-acting agents such as JAK inhibitors.

Atopic dermatitis: Role of the skin barrier, environment, microbiome, and therapeutic agents

Atopic dermatitis (AD) is a chronic, inflammatory skin disorder characterized by eczematous and pruritic skin lesions. In recent decades, the prevalence of AD has increased worldwide, most notably in developing countries. The enormous progress in our understanding of the complex composition and functions of the epidermal barrier allows for a deeper appreciation of the active role that the skin barrier plays in the initiation and maintenance of skin inflammation. The epidermis forms a physical, chemical, immunological, neuro-sensory, and microbial barrier between the internal and external environment. Not only lesional, but also non-lesional areas of AD skin display many morphological, biochemical and functional differences compared with healthy skin. Supporting this notion, genetic defects affecting structural proteins of the skin barrier, including filaggrin, contribute to an increased risk of AD. There is evidence to suggest that natural environmental allergens and man-made pollutants are associated with an increased likelihood of developing AD. A compromised epidermal barrier predisposes the skin to increased permeability of these compounds. Numerous topical and systemic therapies for AD are currently available or in development; while anti-inflammatory therapy is central to the treatment of AD, some existing and novel therapies also appear to exert beneficial effects on skin barrier function. Further research on the skin barrier, particularly addressing epidermal differentiation and inflammation, lipid metabolism, and the role of bacterial communities for skin barrier function, will likely expand our understanding of the complex etiology of AD and lead to identification of novel targets and the development of new therapies.

Biomarkers in atopic dermatitis-a review on behalf of the International Eczema Council

Atopic dermatitis (AD) is a common yet complex skin disease, posing a therapeutic challenge with increasingly recognized different phenotypes among variable patient populations. Because therapeutic response may vary on the basis of heterogeneous clinical and molecular phenotypes, a shift toward precision medicine approaches may improve AD management. Herein, we will consider biomarkers as potential instruments in the toolbox of precision medicine in AD and will review the process of biomarker development and validation, the opinion of AD experts on the use of biomarkers, types of biomarkers, encompassing biomarkers that may improve AD diagnosis, biomarkers reflecting disease severity, and those potentially predicting AD development, concomitant atopic diseases, or therapeutic response, and current practice of biomarkers in AD. We found that chemokine C-C motif ligand 17/thymus and activation-regulated chemokine, a chemoattractant of TH2 cells, has currently the greatest evidence for robust correlation with AD clinical severity, at both baseline and during therapy, by using the recommendations, assessment, development, and evaluation approach. Although the potential of biomarkers in AD is yet to be fully elucidated, due to the complexity of the disease, a comprehensive approach taking into account both clinical and reliable, AD-specific biomarker evaluations would further facilitate AD research and improve patient management.

Mouse models of atopic dermatitis: a critical reappraisal

Mouse models for atopic dermatitis (AD) are an indispensable preclinical research tool for testing new candidate AD therapeutics and for interrogating AD pathobiology in vivo. In this Viewpoint, we delineate why, unfortunately, none of the currently available so-called "AD" mouse models satisfactorily reflect the clinical complexity of human AD, but imitate more "allergic" or "irriant" contact dermatitis conditions. This limits the predictive value of AD models for clinical outcomes of new tested candidate AD therapeutics and the instructiveness of mouse models for human AD pathophysiology research. Here, we propose to initiate a rational debate on the minimal criteria that a mouse model should meet in order to be considered relevant for human AD. We suggest that valid AD models should at least meet the following criteria: (a) an AD-like epidermal barrier defect with reduced filaggrin expression along with hyperproliferation, hyperplasia; (b) increased epidermal expression of thymic stromal lymphopoietin (TSLP), periostin and/or chemokines such as TARC (CCL17); (c) a characteristic dermal immune cell infiltrate with overexpression of some key cytokines such as IL-4, IL-13, IL-31 and IL-33; (d) distinctive "neurodermatitis" features (sensory skin hyperinnervation, defective beta-adrenergic signalling, neurogenic skin inflammation and triggering or aggravation of AD-like skin lesions by perceived stress); and (e) response of experimentally induced skin lesions to standard AD therapy. Finally, we delineate why humanized AD mouse models (human skin xenotransplants on SCID mice) offer a particularly promising preclinical research alternative to the currently available "AD" mouse models.

Early transcriptional changes after UVB treatment in atopic dermatitis include inverse regulation of IL-36γ and IL-37

Phototherapy with narrow-band Ultraviolet B (nb-UVB) is a major therapeutic option in atopic dermatitis (AD), yet knowledge of the early molecular responses to this treatment is lacking. The objective of this study was to map the early transcriptional changes in AD skin in response to nb-UVB treatment. Adult patients (n = 16) with AD were included in the study and scored with validated scoring tools. AD skin was irradiated with local nb-UVB on day 0, 2 and 4. Skin biopsies were taken before and after treatment (day 0 and 7) and analysed for genome-wide modulation of transcription. When examining the early response after three local UVB treatments, gene expression analysis revealed 77 significantly modulated transcripts (30 down- and 47 upregulated). Among them were transcripts related to the inflammatory response, melanin synthesis, keratinization and epidermal structure. Interestingly, the pro-inflammatory cytokine IL-36γ was reduced after treatment, while the anti-inflammatory cytokine IL-37 increased after treatment with nb-UVB. There was also a modulation of several other mediators involved in inflammation, among them defensins and S100 proteins. This is the first study of early transcriptomic changes in AD skin in response to nb-UVB. We reveal robust modulation of a small group of inflammatory and anti-inflammatory targets, including the IL-1 family members IL36γ and IL-37, which is evident before any detectable changes in skin morphology or immune cell infiltrates. These findings provide important clues to the molecular mechanisms behind the treatment response and shed light on new potential treatment targets.

DRM02, a novel phosphodiesterase-4 inhibitor with cutaneous anti-inflammatory activity

Chronic inflammatory skin disorders are frequently associated with impaired skin barrier function. Selective phosphodiesterase-4 (PDE4) inhibition constitutes an effective therapeutic strategy for the treatment of inflammatory skin diseases. We now report the pharmacological anti-inflammatory profile of DRM02, a novel pyrazolylbenzothiazole derivative with selective in vitro inhibitory activity toward PDE4 isoforms A, B and D. DRM02 treatment of cultured primary human and mouse epidermal keratinocytes interfered with pro-inflammatory cytokine production elicited by interleukin-1α and tumor necrosis factor-α. Similarly, DRM02 inhibited the production of pro-inflammatory cytokines by human peripheral blood mononuclear cells ex vivo and cultured THP-1 monocyte-like cells, with IC₅₀ values of 0.6-14 µM. These anti-inflammatory properties of DRM02 were associated with dose-dependent repression of nuclear factor-κB (NF-κB) transcriptional activity. In skin inflammation in vivo mouse models, topically applied DRM02 inhibited the acute response to phorbol ester and induced Th2-type contact hypersensitivity reactivity. Further, DRM02 also decreased cutaneous clinical changes and expression of Th17 immune pathway cytokines in a mouse model of psoriasis evoked by repeated topical imiquimod application. Thus, the overall pharmacological profiling of the PDE4 inhibitor DRM02 has revealed its potential as a topical therapy for inflammatory skin disorders and restoration of skin homeostasis.

Predictors of Systemic Exposure to Topical Crisaborole: A Nonlinear Regression Analysis

Crisaborole ointment, 2%, is a nonsteroidal phosphodiesterase 4 inhibitor for the treatment of mild to moderate atopic dermatitis. Results from 2 randomized, double-blind, vehicle-controlled phase 3 studies showed that twice-daily crisaborole in children and adults with mild to moderate atopic dermatitis was efficacious and well tolerated. Initial pharmacokinetics (PK) studies of crisaborole indicated absorption with measurable systemic levels of crisaborole. The current analysis was conducted to correlate steady-state systemic exposure parameters with ointment dose and identify covariates impacting PK parameters in healthy participants and patients with atopic dermatitis or psoriasis. A nonlinear regression analysis was conducted using ointment dose and noncompartmental PK parameters at steady state (area under the curve [AUC_ss ] and maximum concentration [C_max,ss ]). PK data were available from 244 participants across 6 clinical studies (AUC_ss , N = 239; C_max,ss , N = 241). Disease condition had the greatest impact on slope in both models, corresponding to 2.5-fold higher AUC_ss and C_max,ss values at a given ointment dose in patients with atopic dermatitis or psoriasis relative to healthy participants. Disease severity, race/ethnicity, and sex had marginal effects on AUC_ss and C_max,ss . Systemic exposures were similar across age groups ≥2 years of age when the same percentage of body surface area (%BSA) was treated. Predictive performance plots for AUC_ss and C_max,ss for different age groups demonstrated that the models adequately describe the observed data. Model predictions indicated that systemic exposure to crisaborole in pediatric patients (2-17 years) is unlikely to exceed systemic exposure in adults (≥18 years), even at the highest possible ointment dose corresponding to a %BSA of 90.

Skin Barrier Abnormalities and Immune Dysfunction in Atopic Dermatitis

Atopic dermatitis (AD) is a common and relapsing skin disease that is characterized by skin barrier dysfunction, inflammation, and chronic pruritus. While AD was previously thought to occur primarily in children, increasing evidence suggests that AD is more common in adults than previously assumed. Accumulating evidence from experimental, genetic, and clinical studies indicates that AD expression is a precondition for the later development of other atopic diseases, such as asthma, food allergies, and allergic rhinitis. Although the exact mechanisms of the disease pathogenesis remain unclear, it is evident that both cutaneous barrier dysfunction and immune dysregulation are critical etiologies of AD pathology. This review explores recent findings on AD and the possible underlying mechanisms involved in its pathogenesis, which is characterized by dysregulation of immunological and skin barrier integrity and function, supporting the idea that AD is a systemic disease. These findings provide further insights for therapeutic developments aiming to repair the skin barrier and decrease inflammation.

Safety, Effectiveness, and Pharmacokinetics of Crisaborole in Infants Aged 3 to < 24 Months with Mild-to-Moderate Atopic Dermatitis: A Phase IV Open-Label Study (CrisADe CARE 1)

Background

Crisaborole ointment, 2%, is a nonsteroidal phosphodiesterase 4 inhibitor for the treatment of mild-to-moderate atopic dermatitis (AD).

Objectives

The aim of this study was to evaluate the safety, effectiveness, and pharmacokinetics (PK) of crisaborole in infants aged 3 to < 24 months with mild-to-moderate AD in an open-label study.

Methods

Infants (3 to < 24 months) with Investigator’s Static Global Assessment (ISGA) of mild (2) or moderate (3) and percentage of treatable body surface area (%BSA) ≥ 5 received crisaborole twice daily for 28 days; a cohort with moderate AD per ISGA and %BSA ≥ 35 were included in a PK analysis. Endpoints included safety (primary), efficacy, and PK (exploratory).

Results

Included were 137 infants total (mean age [SD], 13.6 months [6.42]), with 21 in the PK cohort (12.7 months [6.58]). Treatment-emergent adverse events (TEAEs) were reported for 88 (64.2%) patients (98.9% rated as mild/moderate). TEAEs were considered treatment-related for 22 patients (16.1%); most frequently reported were application site pain (3.6%), application site discomfort (2.9%), and erythema (2.9%). ISGA clear/almost clear with ≥ 2-grade improvement at day 29 was achieved by 30.2% of patients. From baseline to day 29, mean percentage change in Eczema Area and Severity Index score was − 57.5%, and mean change in Patient-Oriented Eczema Measure total score was − 8.5. Crisaborole systemic exposures in infants were characterized and, based on nonlinear regression analysis, were comparable with that in patients aged ≥ 2 years.

Conclusions

In this open-label study, crisaborole was well tolerated and effective in infants (3 to < 24 months) with mild-to-moderate AD with systemic exposures similar to patients aged ≥ 2 years.

Clinical Trial Registration

NCT03356977.

Electronic supplementary material

The online version of this article (10.1007/s40257-020-00510-6) contains supplementary material, which is available to authorized users.

Plain Language Summary

Atopic dermatitis (AD) is a skin disease that causes inflamed and itchy skin. Crisaborole is an ointment that is approved to treat patients aged 2 years and older with mild-to-moderate AD. This clinical trial studied crisaborole in infants with mild-to-moderate AD who were 3 to under 24 months old. These infants were treated with crisaborole twice a day for 28 days. The trial studied crisaborole’s safety, effectiveness, and absorption into the bloodstream. In total, 137 infants were treated. Although side effects of some sort occurred in about two-thirds of patients, only 1 in 6 patients experienced side effects that were attributed to crisaborole. When these side effects did occur, these were mainly pain, discomfort, or redness where crisaborole was applied. Fewer than 1 in 25 patients experienced each side effect where crisaborole was applied. The doctors saw improvement in the AD symptoms of some patients at day 29 of the study compared to the beginning of the study. Crisaborole blood-level measurements in this age group were consistent with those seen in patients aged 2 years and older. Overall, crisaborole was considered well tolerated and effective in infants (3 to under 24 months old) with mild-to-moderate AD.

Video abstract

Review-Current Concepts in Inflammatory Skin Diseases Evolved by Transcriptome Analysis: In-Depth Analysis of Atopic Dermatitis and Psoriasis

During the last decades, high-throughput assessment of gene expression in patient tissues using microarray technology or RNA-Seq took center stage in clinical research. Insights into the diversity and frequency of transcripts in healthy and diseased conditions provide valuable information on the cellular status in the respective tissues. Growing with the technique, the bioinformatic analysis toolkit reveals biologically relevant pathways which assist in understanding basic pathophysiological mechanisms. Conventional classification systems of inflammatory skin diseases rely on descriptive assessments by pathologists. In contrast to this, molecular profiling may uncover previously unknown disease classifying features. Thereby, treatments and prognostics of patients may be improved. Furthermore, disease models in basic research in comparison to the human disease can be directly validated. The aim of this article is not only to provide the reader with information on the opportunities of these techniques, but to outline potential pitfalls and technical limitations as well. Major published findings are briefly discussed to provide a broad overview on the current findings in transcriptomics in inflammatory skin diseases.