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<b><i>Background and Objectives:</i></b> Gene mutations within the leptin-melanocortin signaling pathway lead to severe early-onset obesity. Recently, a phase 2 trial evaluated new pharmacological treatment options with the MC4R agonist <i>setmelanotide</i> in patients with mutations in the genes encoding proopiomelanocortin (POMC) and leptin receptor (LEPR). During treatment with <i>setmelanotide,</i> changes in skin pigmentation were observed, probably due to off-target effects on the closely related melanocortin 1 receptor (MC1R). Here, we describe in detail the findings of dermatological examinations and measurements of skin pigmentation during this treatment over time and discuss the impact of these changes on patient safety. <b><i>Methods:</i></b> In an investigator-initiated, phase 2, open-label pilot study, 2 patients with loss-of-function POMC gene mutations and 3 patients with loss-of-function variants in LEPR were treated with the MC4R agonist <i>setmelanotide</i>. Dermatological examination, dermoscopy, whole body photographic documentation, and spectrophotometric measurements were performed at screening visit and approximately every 3 months during the course of the study. <b><i>Results:</i></b> We report the results of a maximum treatment duration of 46 months. Skin pigmentation increased in all treated patients, as confirmed by spectrophotometry. During continuous treatment, the current results indicate that elevated tanning intensity levels may stabilize over time. Lips and nevi also darkened. In red-haired study participants, hair color changed to brown after initiation of <i>setmelanotide</i> treatment. <b><i>Discussion:</i></b> <i>Setmelanotide</i> treatment leads to skin tanning and occasionally hair color darkening in both POMC- and LEPR-deficient patients. No malignant skin changes were observed in the patients of this study. However, the results highlight the importance of regular skin examinations before and during MC4R agonist treatment.

Non-invasive sample collection methods could facilitate clinical research on hair diseases. In an exploratory experimental study on six male volunteers with untreated androgenetic alopecia (AGA), Hamilton-Norwood stage IIIv-IV, skin surface and infundibular protein as well as RNA extracts from plucked hair follicles were analyzed from frontal skin, vertex and clinically unaffected occiput. Slightly increased levels of inflammatory markers were only found in AGAaffected scalp skin and infundibulum, not in RNA from plucked hair follicles. RNA expression profiles point towards differential expression of genes involved in hair cycle regulation, hair keratin production, but also RNA methylation and ion channel regulation. | BACKGROUNDOur current concept of androgenetic alopecia (AGA) suggests that different factors including hormonal effects, ion channel regulation, vascularization, and prostaglandins contribute to the disease onset and progression. [1][2][3] Microinflammation has been postulated to be involved. [4,5] Yet, exploratory molecular work in patients is difficult.Clinical trials largely rely on macroscopic readouts. Inclusion of biomarkers usually requires skin biopsies, limiting the number of investigational sites and frequency of sampling. Non-invasive sample collection methods could help increase our understanding of hair growth regulation. | QUESTIONS ADDRESSEDIn this pilot study, we combined clinical diagnostics with a new method for non-invasive sampling of infundibular protein [6] and RNA microarray analysis of plucked hair follicles to investigate inflammatory processes in AGA-affected scalp skin. Additionally, we looked into gene expression to identify new markers of relevance in androgenetic alopecia. | EXPERIMENTAL DESIGNSix male volunteers with untreated AGA, Hamilton-Norwood stage IIIv-IV, were included. Investigational sites (frontotemporal area, vertex, clinically unaffected occiput) were assessed (Table S1) by phototrichogram analysis, sebum and pH determination, optical coherence tomography (OCT), ultrasonography, hair root plucking (trichogram, Figure S1) and mini-zone cyanoacrylate skin surface stripping (CSSS).[6] Seborrhoeic dermatitis was an exclusion criterion.RNA from about 30 hairs from each site was obtained by hair plucking and extraction performed using RNeasy kit (Qiagen, Hilden, Germany). For hybridization, Agilent Gene Expression Hybridization kit (Agilent Technologies Inc., Santa Clara, CA, USA) was used, andCy3-labelled fragmented cRNA hybridized overnight to Agilent WholeHuman Genome Oligo Microarrays 8 × 60 K V2 using Agilent's recommended hybridization chamber and oven. The Agilent FeatureExtraction software was used to read out and process the microarray image files. Data were normalized followed by correlation analysis and differential gene expression analysis (DGA). For further details concerning study plan, methods and the microarray data, please refer to the Appendix S1. | RESULTSConsistent with the clinical diagnosis, the total hair density was significantl...