Erlotinib-induced hair repigmentation

Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers

Hair graying holds psychosocial importance and serves as an excellent model for studying human pigmentation and aging in an accessible miniorgan. Current evidence suggests that graying results from an interindividually varying mixture of cumulative oxidative and DNA damage, excessive mTORC1 activity, melanocyte senescence, and inadequate production of pigmentation-promoting factors in the hair matrix. Various regulators modulate this process, including genetic factors (DNA repair defects and IRF4 sequence variation, peripheral clock genes, P-cadherin signaling, neuromediators, HGF, KIT ligand secretion, and autophagic flux. This leads to reduced MITF- and tyrosinase-controlled melanogenesis, defective melanosome transfer to precortical matrix keratinocytes, and eventual depletion of hair follicle (HF) pigmentary unit (HFPU) melanocytes and their local progenitors. Graying becomes irreversible only when bulge melanocyte stem cells are also depleted, occurring later in this process. Distinct pigmentary microenvironments are created as the HF cycles: early anagen is the most conducive phase for melanocytic reintegration and activation, and only during anagen can the phenotype of hair graying and repigmentation manifest, whereas the HFPU disassembles during catagen. The temporary reversibility of graying is highlighted by several drugs and hormones that induce repigmentation, indicating potential target pathways. We advise caution in directly applying mouse model concepts, define major open questions, and discuss future human antigraying strategies.

A Comprehensive Review of Mammalian Pigmentation: Paving the Way for Innovative Hair Colour-Changing Cosmetics

The natural colour of hair shafts is formed at the bulb of hair follicles, and it is coupled to the hair growth cycle. Three critical processes must happen for efficient pigmentation: (1) melanosome biogenesis in neural crest-derived melanocytes, (2) the biochemical synthesis of melanins (melanogenesis) inside melanosomes, and (3) the transfer of melanin granules to surrounding pre-cortical keratinocytes for their incorporation into nascent hair fibres. All these steps are under complex genetic control. The array of natural hair colour shades are ascribed to polymorphisms in several pigmentary genes. A myriad of factors acting via autocrine, paracrine, and endocrine mechanisms also contributes for hair colour diversity. Given the enormous social and cosmetic importance attributed to hair colour, hair dyeing is today a common practice. Nonetheless, the adverse effects of the long-term usage of such cosmetic procedures demand the development of new methods for colour change. In this context, case reports of hair lightening, darkening and repigmentation as a side-effect of the therapeutic usage of many drugs substantiate the possibility to tune hair colour by interfering with the biology of follicular pigmentary units. By scrutinizing mammalian pigmentation, this review pinpoints key targetable processes for the development of innovative cosmetics that can safely change the hair colour from the inside out.

The biology of human hair greying

Hair greying (canities) is one of the earliest, most visible ageing-associated phenomena, whose modulation by genetic, psychoemotional, oxidative, senescence-associated, metabolic and nutritional factors has long attracted skin biologists, dermatologists, and industry. Greying is of profound psychological and commercial relevance in increasingly ageing populations. In addition, the onset and perpetuation of defective melanin production in the human anagen hair follicle pigmentary unit (HFPU) provides a superb model for interrogating the molecular mechanisms of ageing in a complex human mini-organ, and greying-associated defects in bulge melanocyte stem cells (MSCs) represent an intriguing system of neural crest-derived stem cell senescence. Here, we emphasize that human greying invariably begins with the gradual decline in melanogenesis, including reduced tyrosinase activity, defective melanosome transfer and apoptosis of HFPU melanocytes, and is thus a primary event of the anagen hair bulb, not the bulge. Eventually, the bulge MSC pool becomes depleted as well, at which stage greying becomes largely irreversible. There is still no universally accepted model of human hair greying, and the extent of genetic contributions to greying remains unclear. However, oxidative damage likely is a crucial driver of greying via its disruption of HFPU melanocyte survival, MSC maintenance, and of the enzymatic apparatus of melanogenesis itself. While neuroendocrine factors [e.g. alpha melanocyte-stimulating hormone (α-MSH), adrenocorticotropic hormone (ACTH), ß-endorphin, corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH)], and micropthalmia-associated transcription factor (MITF) are well-known regulators of human hair follicle melanocytes and melanogenesis, how exactly these and other factors [e.g. thyroid hormones, hepatocyte growth factor (HGF), P-cadherin, peripheral clock activity] modulate greying requires more detailed study. Other important open questions include how HFPU melanocytes age intrinsically, how psychoemotional stress impacts this process, and how current insights into the gerontobiology of the human HFPU can best be translated into retardation or reversal of greying.

Medication-Induced Repigmentation of Gray Hair: A Systematic Review

Hair graying is a common sign of aging resulting from complex regulation of melanogenesis. Currently, there is no medical treatment available for hair repigmentation. In this article we review the literature on medication-induced hair repigmentation, discuss the potential mechanisms of action, and review the quality of the literary data. To date, there have been 27 studies discussing medication-induced gray hair repigmentation, including 6 articles on gray hair repigmentation as a primary objective, notably with psoralen treatment or vitamin supplementation, and 21 reports on medication-induced gray hair repigmentation as an incidental finding. Medications noted in the literature include anti-inflammatory medications (thalidomide, lenalidomide, adalimumab, acitretin, etretinate, prednisone, cyclosporin, cisplatinum, interferon-α, and psoralen), stimulators of melanogenesis (latanoprost, erlotinib, imatinib, tamoxifen, and levodopa), vitamins (calcium pantothenate and para-amino benzoic acid), a medication that accumulates in tissues (clofazimine), and a medication with an undetermined mechanism (captopril). Diffuse repigmentation of gray hair can be induced by certain medications that inhibit inflammation or stimulate melanogenesis. There is also low-quality evidence that some vitamin B complex supplementation can promote gray hair darkening. While these compounds are not currently indicated for the treatment of gray hair, their mechanisms shed light on targets for future medications for hair repigmentation.

Dermatologic conditions in women receiving systemic cancer therapy

As advances in cancer therapies have improved cancer-related survival, novel therapeutics have also introduced a variety of dermatologic toxicities, and an increased number of patients are living with these sequalae. Women with cancer in particular experience a spectrum of dermatologic conditions that affect their skin, hair, nail, and mucosal surfaces. Studies have shown that these toxic effects can significantly affect quality of life and alter a woman's self-image, cultural identity, femininity, sexuality, and mental health. In severe instances, dermatologic toxicities may even disrupt cancer therapy and can therefore affect overall survival and treatment response. In this article, we review the dermatologic adverse effects from traditional chemotherapy, targeted therapy, immune checkpoint inhibitors, and endocrine therapy that disproportionately affect women. The timely diagnosis and management of these dermatologic conditions is crucial in the multidisciplinary care of women with cancer.

Histopathology of aging of the hair follicle

Hair follicles experience several changes with aging, the most noticeable of which is graying of the hair shaft due to loss of melanin. Additional changes in the diameter and length of the hair have contributed to the concept of senescent alopecia, which is different from androgenetic alopecia according to most. Graying happens in most individuals, although in different grades and starting at different ages. It is related to a decrease in the number and activity of the melanocytes of the hair bulb, which eventually completely disappear from the bulb of the white hair. Residual non-active melanocytes remain in the outer root sheath and in the bulge, which allows for repigmentation of the hair under certain stimuli or conditions.

Hair Repigmentation During Immunotherapy Treatment With an Anti-Programmed Cell Death 1 and Anti-Programmed Cell Death Ligand 1 Agent for Lung Cancer

Importance

New targeted therapies for cancer have been released in recent years, opening new horizons in the treatment of patients with cancer. However, their related adverse events (AE) are not fully characterized. Hair repigmentation (HR) is a nondescribed effect secondary to anti-programmed cell death 1 (anti-PD-1) and anti-programmed cell death ligand 1 (anti-PD-L1 ) therapy for treatment of lung cancer (LC), in opposition to the vitiligo reactions that develop during melanoma treatment.

Objective

To describe a new adverse event occurring during anti-PD-1/anti-PD-L1 therapy for LC.

Design, Setting, and Participants

A case series from a descriptive observation of 14 patients with HR after anti-PD-1/anti-PD-L1 treatment, recruited between September and December, 2016, who were followed up to detect whether they developed cutaneous AE at the time HR was detected. The patients had all been treated in the dermatology department at Hospital Universitari Germans Trias i Pujol, Badalona, Spain.

Main Outcomes and Measures

Clinical observation of HR during anti-PD-1/anti-PD-L1 therapy for LC, proved by comparing old pictures provided by the patients and recent pictures taken during the follow-up.

Results

Fourteen patients (13 men and 1 woman; mean age, 64.9 years) receiving anti-PD-1 or anti-PD-L1 therapy for non-small-cell lung cancer (NSCLC) presented hair repigmentation during follow-up. This hair repigmentation consisted in a diffuse darkening of the hair in 13 of 14 patients, or in black patches between white hairs in 1. Thirteen of 14 patients presented a good clinical response to the treatment, with at least stable disease, and only 1 had to stop the therapy after only 4 cycles of treatment owing to a life-threatening progression of the disease.

Conclusions and Relevance

We present to our knowledge the first report of hair repigmentation owing to anti-PD-1/anti-PD-L1 therapy for lung cancer in a series of 14 patients. Hair repigmentation may be a good response marker in patients receiving anti-PD1/anti-PD-L1 therapy for LC.

Pigmentary changes in patients treated with targeted anticancer agents: A systematic review and meta-analysis

BACKGROUND

The discovery of signaling networks that drive oncogenic processes has led to the development of targeted anticancer agents. The burden of pigmentary adverse events from these drugs is unknown.

OBJECTIVE

To conduct a systematic review and meta-analysis of published clinical trials and determine the incidence and risk of development of targeted therapy-induced pigmentary changes.

METHODS

A comprehensive search was conducted to identify studies reporting targeted therapy-induced pigmentary changes. The incidence and relative risk were calculated. Case reports and series were reviewed to understand clinical characteristics.

RESULTS

A total of 8052 patients from 36 clinical trials were included. The calculated overall incidences of targeted cancer therapy-induced all-grade pigmentary changes in the skin and hair were 17.7% (95% confidence interval [CI], 11.9-25.4) and 21.5% (95% CI, 14.9-30.1), respectively. The relative risk of all-grade pigmentary changes of skin and hair were 93.7 (95% CI, 5.86-1497.164) and 20.1 (95% CI, 8.35-48.248). Across 53 case reports/series (N = 75 patients), epidermal growth factor receptor and breakpoint cluster region-abelson inhibitors were the most common offending agents.

LIMITATIONS

Potential under-reporting and variability in oncologists reporting these events.

CONCLUSION

There is a significant risk of development of pigmentary changes during treatment with targeted anticancer therapies. Appropriate counseling and management are critical to minimize psychosocial impairment and deterioration in quality of life.

Epidermal growth factor receptor inhibitors: a review of cutaneous adverse events and management

Epidermal growth factor inhibitors (EGFRI), the first targeted cancer therapy, are currently an essential treatment for many advance-stage epithelial cancers. These agents have the superior ability to target cancers cells and better safety profile compared to conventional chemotherapies. However, cutaneous adverse events are common due to the interference of epidermal growth factor receptor (EGFR) signaling in the skin. Cutaneous toxicities lead to poor compliance, drug cessation, and psychosocial discomfort. This paper summarizes the current knowledge concerning the presentation and management of skin toxicity from EGFRI. The common dermatologic adverse events are papulopustules and xerosis. Less common findings are paronychia, regulatory abnormalities of hair growth, maculopapular rash, mucositis, and postinflammatory hyperpigmentation. Radiation enhances EGFRI rash due to synergistic toxicity. There is a positive correlation between the occurrence and severity of cutaneous adverse effects and tumor response. To date, prophylactic systemic tetracycline and tetracycline class antibiotics have proven to be the most effective treatment regime.