International melanoma and non melanoma skin cancer mortality trends: is it time to refocus our attention?

We show how international melanoma crude mortality rates are decreasing, whereas those of nonmelanoma skin cancer (NMSC) are increasing. This reflects how our melanoma care has vastly progressed over the last decade but highlights a need for better prevention and NMSC therapeutics development, especially given our increasingly ageing population.

Cutaneous squamous cell carcinoma tumor accrual rates in immunosuppressed patients with autoimmune and inflammatory conditions: A retrospective cohort study

BACKGROUND

Immunosuppression is a known risk factor for the development of cutaneous squamous cell carcinoma (CSCC), especially in solid organ transplant recipients and chronic lymphocytic leukemia. However, this risk is less well defined in autoimmune and inflammatory conditions.

OBJECTIVE

Assess the impact that disease-type, duration of immunosuppression, and systemic medications have on CSCC accrual rates, defined as the number of CSCCs a patient develops per year, in autoimmune and inflammatory conditions.

METHODS

Retrospective review of 94 immunosuppressed (rheumatoid arthritis: 31[33.0%], inflammatory bowel disease: 17[18.1%], psoriasis: 11[11.7%], autoimmune other (AO): 24[25.5%], inflammatory other: 21[22.3%]) and 188 immunocompetent controls to identify all primary, invasive CSCCs diagnosed from 2010 to 2020.

RESULTS

Immunosuppressed patients had higher CSCC accrual rates than immunocompetent controls (0.44 ± 0.36): total cohort (0.82 ± 0.95, P < .01), rheumatoid arthritis (0.88 ± 1.10, P < .01), inflammatory bowel disease (0.94 ± 0.88, P < .01), psoriasis (1.06 ± 1.58, P < .01), AO (0.72 ± 0.56, P < .01), and inflammatory other (0.72 ± 0.61, P < .01). There was an association between increased tumor accrual rates and exposure to systemic medications including, immunomodulators, tumor necrosis factor-alpha inhibitors, non-tumor necrosis factor inhibitor biologics, and corticosteroids, but not with number of systemic medication class exposures or duration of immunosuppression.

LIMITATIONS

Retrospective, singlecenter study.

CONCLUSION

Patients with autoimmune and inflammatory conditions accrue CSCCs at higher rates than immunocompetent patients.

Driver gene combinations dictate cutaneous squamous cell carcinoma disease continuum progression

The molecular basis of disease progression from UV-induced precancerous actinic keratosis (AK) to malignant invasive cutaneous squamous cell carcinoma (cSCC) and potentially lethal metastatic disease remains unclear. DNA sequencing studies have revealed a massive mutational burden but have yet to illuminate mechanisms of disease progression. Here we perform RNAseq transcriptomic profiling of 110 patient samples representing normal sun-exposed skin, AK, primary and metastatic cSCC and reveal a disease continuum from a differentiated to a progenitor-like state. This is accompanied by the orchestrated suppression of master regulators of epidermal differentiation, dynamic modulation of the epidermal differentiation complex, remodelling of the immune landscape and an increase in the preponderance of tumour specific keratinocytes. Comparative systems analysis of human cSCC coupled with the generation of genetically engineered murine models reveal that combinatorial sequential inactivation of the tumour suppressor genes Tgfbr2, Trp53, and Notch1 coupled with activation of Ras signalling progressively drives cSCC progression along a differentiated to progenitor axis. Taken together we provide a comprehensive map of the cSCC disease continuum and reveal potentially actionable events that promote and accompany disease progression.

Immune Checkpoint Inhibitors in Solid Organ Transplant Recipients With Advanced Skin Cancers-Emerging Strategies for Clinical Management

Use of immune checkpoint inhibitors (ICIs) in solid organ transplant recipients (SOTRs) with advanced skin cancers presents a significant clinical management dilemma. SOTRs and other immunosuppressed patients have been routinely excluded from ICI clinical trials with good reason: immune checkpoints play an important role in self- and allograft-tolerance and risk of acute allograft rejection reported in retrospective studies affects 10% to 65% of cases. These reports also confirm that cutaneous squamous cell carcinoma and melanoma respond to ICI therapy, although response rates are generally lower than those observed in immunocompetent populations. Prospective trials are now of critical importance in further establishing ICI efficacy and safety. However, based on current knowledge, we recommend that ICIs should be offered to kidney transplant recipients with advanced cutaneous squamous cell carcinoma, melanoma, or Merkel cell carcinoma if surgery and/or radiotherapy have failed. For kidney transplant recipients, this should be first line ahead of chemotherapy and targeted therapies. In SOTRs, the use of ICIs should be carefully considered with the benefits of ICIs versus risks of allograft rejection weighed up on a case-by-case basis as part of shared decision-making with patients. In all cases, parallel management of immunosuppression may be key to ICI responsiveness. We recommend maintaining immunosuppression before ICI initiation with a dual immunosuppressive regimen combining mammalian target of rapamycin inhibitors and either corticosteroids or calcineurin inhibitors. Such modification of immunosuppression must be considered in the context of allograft risk (both rejection and also its subsequent treatment) and risk of tumor progression. Ultimately, a multidisciplinary approach should underpin all clinical decision-making in this challenging scenario.

Multimodal Transplant-clinic-based Skin Cancer Prevention Education for Organ Transplant Recipients: Feasibility Study

We studied the feasibility of transplant-clinic staff routinely providing primary prevention advice to lung transplant recipients at high risk of skin cancer.

Methods

Patients enrolled by a transplant-clinic study nurse completed baseline questionnaires and received sun-safety brochures. For the 12-mo intervention, transplant physicians were alerted to provide standard sun-protection advice (use of hat, long sleeves, and sunscreen outdoors) by sun-advice prompt cards attached to participants' medical charts at each clinic visit. Patients indicated receiving advice from their physician and from study personnel via an exit-card postclinic, and at final study clinics, they also reported their sun behaviors by questionnaire. Feasibility of the intervention was measured by patients' and clinic staff's study engagement; effectiveness was assessed by calculating odds ratios (ORs) for improved sun protection, using generalized estimating equations.

Results

Of 151 patients invited, 134 consented (89%), and 106 (79 %) (63% male, median age 56 y, 93% of European descent) completed the study. Odds of receiving sun advice from transplant physicians and study nurses rose after the intervention compared with baseline (ORs, 1.67; 95% confidence interval [CI], 0.96-2.96 and 3.56; 95% CI, 1.38-9.14, respectively). After 12 mo of regular transplant-clinic advice, odds of sunburn decreased (OR, 0.59; 95% CI, 0.13-2.60), and odds of applying sunscreen (OR, 1.93; 95% CI, 1.20-3.09) almost doubled.

Conclusions

Encouragement of primary prevention of skin cancer among organ transplant recipients by physicians and nurses during routine transplant-clinic visits is feasible and appears to be effective.

Mena regulates nesprin-2 to control actin-nuclear lamina associations, trans-nuclear membrane signalling and gene expression

Interactions between cells and the extracellular matrix, mediated by integrin adhesion complexes, play key roles in fundamental cellular processes, including the sensing and transduction of mechanical cues. Here, we investigate systems-level changes in the integrin adhesome in patient-derived cutaneous squamous cell carcinoma cells and identify the actin regulatory protein Mena as a key node in the adhesion complex network. Mena is connected within a subnetwork of actin-binding proteins to the LINC complex component nesprin-2, with which it interacts and co-localises at the nuclear envelope. Moreover, Mena potentiates the interactions of nesprin-2 with the actin cytoskeleton and the nuclear lamina. CRISPR-mediated Mena depletion causes altered nuclear morphology, reduces tyrosine phosphorylation of the nuclear membrane protein emerin and downregulates expression of the immunomodulatory gene PTX3 via the recruitment of its enhancer to the nuclear periphery. We uncover an unexpected role for Mena at the nuclear membrane, where it controls nuclear architecture, chromatin repositioning and gene expression. Our findings identify an adhesion protein that regulates gene transcription via direct signalling across the nuclear envelope.

Topical treatment of actinic keratoses in organ transplant recipients: a feasibility study for SPOT (Squamous cell carcinoma Prevention in Organ transplant recipients using Topical treatments)

BACKGROUND

The risk of cutaneous squamous cell carcinoma (cSCC) is significantly increased in organ transplant recipients (OTRs). Clearance of actinic keratoses (AKs) is generally regarded as a surrogate biomarker for cSCC prevention. OTR-cSCC chemoprevention with topical AK treatments has not been investigated in randomized controlled trials (RCTs), although there is evidence that 5% 5-fluorouracil (5-FU) may be chemoprotective in immunocompetent patients.

OBJECTIVES

To assess the feasibility, activity and evaluation outcomes relevant to the design of a future phase III RCT of topical cSCC chemoprevention in OTRs.

METHODS

OTRs with 10 or more AKs in predefined areas were randomized 1 : 1 : 1 to topical 5-FU, 5% imiquimod (IMIQ) or sunscreen (sun-protective factor 30+) in a phase II, open-label RCT over 15 months. Feasibility outcomes included proportions of eligible OTRs randomized, completing treatment and willing to be re-treated. AK activity [AK clearance, new AK development, patient-centred outcomes (toxicity, health-related quality of life, HRQoL)] and evaluation methodology (clinical vs. photographic) were assessed.

RESULTS

Forty OTRs with 903 AKs were randomized. All feasibility outcomes were met (56% of eligible OTRs were randomized; 89% completed treatment; 81% were willing to be re-treated). AK activity analyses found 5-FU and IMIQ were superior to sunscreen for AK clearance and prevention of new AKs. 5-FU was more effective than IMIQ in AK clearance and prevention in exploratory analyses. Although toxicity was greater with 5-FU, HRQoL outcomes were similar.

CONCLUSIONS

Trials of topical AK treatments in OTRs for cSCC chemoprevention are feasible and AK activity results support further investigation of 5-FU-based treatments in future phase III trials. What is already known about this topic? Cutaneous squamous cell carcinoma (cSCC) is significantly more common in immunocompromised individuals including organ transplant recipients (OTRs) compared with immunocompetent populations. cSCC chemoprevention activity of sunscreen and 5-fluorouracil-based (5-FU) actinic keratosis (AK) treatments has been demonstrated in randomized controlled trials (RCTs) in immunocompetent populations but not in OTRs. AKs are cSCC precursors and their clearance and prevention are generally regarded as surrogate endpoint biomarkers for potential cSCC chemoprevention activity. What does this study add? SPOT (SCC Prevention in OTRs using Topical treatments) has confirmed that RCTs of OTR-cSCC chemoprevention with topical AK treatments are feasible. It also suggests that topical 5-FU may be superior to 5% imiquimod and sunscreen in AK clearance and prevention. Together with recent evidence from several RCTs in the general population, these data provide a compelling rationale for further studies of intervention with 5-FU-based topical chemoprevention approaches in OTR-cSCC prevention.

Clinicopathological characteristics of individuals with co-existing melanoma and chronic lymphocytic leukaemia: a multicentre cohort study

BACKGROUND

Individuals with a prior diagnosis of chronic lymphocytic leukaemia (CLL) have a higher risk of developing melanoma (MM) and exhibit poorer outcomes when compared to patients without CLL. However, there are limited data reporting the clinicopathological features of MM diagnosed in patients with CLL.

OBJECTIVES

To review clinicopathological characteristics of patients with co-existing diagnoses of MM and CLL.

METHODS

A retrospective review was undertaken for patients with co-existing diagnoses of MM and CLL between 2005-2015 in 11 centres in the UK and Ireland.

RESULTS

Overall, 46 cutaneous MM identified in 45 patients were included. In 28 (62.2%) patients, MM was diagnosed after an existing diagnosis of CLL. In this group, mean Breslow thickness was 2.7 mm (range = 0.2-25 mm). Ten (35.7%) tumors developed locoregional recurrence and 8 (28.6%) developed distant metastases. Melanoma-specific mortality was 5/28 (17.9%) and all-cause mortality was 13/28 (46.4%). In 17 patients, MM was diagnosed before CLL. In this group, mean BT was 2.9 mm (range = 0.4-14 mm), 5 (29.4%) developed locoregional recurrence and 3 (17.6%) distant metastases. Melanoma-specific mortality was 1/17 (5.8%) and all-cause mortality was 5/17 (29.4%) in this group.

CONCLUSIONS

To our knowledge, this is the first and largest cohort study to report clinicopathological data of co-existing melanoma and CLL in the UK and Ireland. Although the thickness of primary melanoma was not different before or after a CLL diagnosis, melanoma recurrence and melanoma-specific mortality appear to be more common in patients with a prior diagnosis of CLL.

Consensus-Based Recommendations on the Prevention of Squamous Cell Carcinoma in Solid Organ Transplant Recipients: A Delphi Consensus Statement

IMPORTANCE

There is a paucity of evidence to guide physicians regarding prevention strategies for cutaneous squamous cell carcinoma (CSCC) in solid organ transplant recipients (SOTRs).

OBJECTIVE

To examine the development and results of a Delphi process initiated to identify consensus-based medical management recommendations for prevention of CSCC in SOTRs.

EVIDENCE REVIEW

Dermatologists with more than 5 years' experience treating SOTRs were invited to participate. A novel actinic damage and skin cancer index (AD-SCI), consisting of 6 ordinal stages corresponding to an increasing burden of actinic damage and CSCC, was used to guide survey design. Three sequential web-based surveys were administered from January 1, 2019, to December 31, 2020. Pursuant to Delphi principles, respondents thoroughly reviewed all peer responses between rounds. Supplemental questions were also asked to better understand panelists' rationale for their responses.

FINDINGS

The Delphi panel comprised 48 dermatologists. Respondents represented 13 countries, with 27 (56%) from the US. Twenty-nine respondents (60%) were Mohs surgeons. Consensus was reached with 80% or higher concordance among respondents when presented with a statement, question, or management strategy pertaining to prevention of CSCC in SOTRs. A near-consensus category of 70% to less than 80% concordance was also defined. The AD-SCI stage-based recommendations were established if consensus or near-consensus was achieved. The panel was able to make recommendations for 5 of 6 AD-SCI stages. Key recommendations include the following: cryotherapy for scattered actinic keratosis (AK); field therapy for AK when grouped in 1 anatomical area, unless AKs are thick in which case field therapy and cryotherapy were recommended; combination lesion directed and field therapy with fluorouracil for field cancerized skin; and initiation of acitretin therapy and discussion of immunosuppression reduction or modification for patients who develop multiple skin cancers at a high rate (10 CSCCs per year) or develop high-risk CSCC (defined by a tumor with approximately ≥20% risk of nodal metastasis). No consensus recommendation was achieved for SOTRs with a first low risk CSCC.

CONCLUSIONS AND RELEVANCE

Physicians may consider implementation of panel recommendations for prevention of CSCC in SOTRs while awaiting high-level-of-evidence data. Additional clinical trials are needed in areas where consensus was not reached.

A summary of the updated report on the incidence and epidemiological trends of keratinocyte cancers in the United Kingdom 2013-2018

Skin cancer is the commonest cancer in the UK. Skin cancer referrals via the two-week wait (urgent suspected cancer) pathway outnumber any other suspected malignancy.^{1, 2} The commonest skin cancers are keratinocyte cancers (KCs) which represents Basal Cell Carcinomas (BCC) and Cutaneous Squamous Cell Carcinomas (cSCC). Accurate KC incidence reporting is crucial for healthcare planning.

The Genomic Landscape of Actinic Keratosis

Actinic keratoses (AKs) are lesions of epidermal keratinocyte dysplasia and are precursors for invasive cutaneous squamous cell carcinoma (cSCC). Identifying the specific genomic alterations driving the progression from normal skin to skin with AK to skin with invasive cSCC is challenging because of the massive UVR-induced mutational burden characteristic at all stages of this progression. In this study, we report the largest AK whole-exome sequencing study to date and perform a mutational signature and candidate driver gene analysis on these lesions. We demonstrate in 37 AKs from both immunosuppressed and immunocompetent patients that there are significant similarities between AKs and cSCC in terms of mutational burden, copy number alterations, mutational signatures, and patterns of driver gene mutations. We identify 44 significantly mutated AK driver genes and confirm that these genes are similarly altered in cSCC. We identify azathioprine mutational signature in all AKs from patients exposed to the drug, providing further evidence for its role in keratinocyte carcinogenesis. cSCCs differ from AKs in having higher levels of intrasample heterogeneity. Alterations in signaling pathways also differ, with immune-related signaling and TGFβ signaling significantly more mutated in cSCC. Integrating our findings with independent gene expression datasets confirms that dysregulated TGFβ signaling may represent an important event in AK‒cSCC progression.

Clinically relevant aberrant Filip1l DNA methylation detected in a murine model of cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinomas (cSCC) are among the most common and highly mutated human malignancies. Understanding the impact of DNA methylation in cSCC may provide avenues for new therapeutic strategies.

METHODS

We used reduced-representation bisulfite sequencing for DNA methylation analysis of murine cSCC. Differential methylation was assessed at the CpG level using limma. Next, we compared with human cSCC Infinium HumanMethylation BeadArray data. Genes were considered to be of major relevance when they featured at least one significantly differentially methylated CpGs (RRBS) / probes (Infinium) with at least a 30% difference between tumour vs. control in both a murine gene and its human orthologue. The human EPIC Infinium data were used to distinguish two cSCC subtypes, stem-cell-like and keratinocyte-like tumours.

FINDINGS

We found increased average methylation in mouse cSCC (by 12.8%, p = 0.0011) as well as in stem-cell like (by 3.1%, p=0.002), but not keratinocyte-like (0.2%, p = 0.98), human cSCC. Comparison of differentially methylated genes revealed striking similarities between human and mouse cSCC. Locus specific methylation changes in mouse cSCC often occurred in regions of potential regulatory function, including enhancers and promoters. A key differentially methylated region was located in a potential enhancer of the tumour suppressor gene Filip1l and its expression was reduced in mouse tumours. Moreover, the FILIP1L locus showed hypermethylation in human cSCC and lower expression in human cSCC cell lines.

INTERPRETATION

Deregulation of DNA methylation is an important feature of murine and human cSCC that likely contributes to silencing of tumour suppressor genes, as shown for Filip1l.

FUNDING

British Skin Foundation, Cancer Research UK.

Sulfoxythiocarbamate S-4 inhibits HSP90 in human cutaneous squamous cell carcinoma cells

Cancer cells rely heavily on molecular chaperones, such as heat shock protein 90 (HSP90), and their co-chaperones. The development of HSP90 inhibitors is an attractive therapeutic approach that has the potential to affect multiple hallmarks of cancer. Such approach is particularly needed for tumors that carry large mutational burdens, including cutaneous squamous cell carcinomas (cSCC). We previously identified sulfoxythiocarbamate S-4 as an HSP90 inhibitor. In this study, we investigated the mechanism(s) by which S-4 compromises the viability of human cSCC cells. S-4 inhibits HSP90 and causes depletion of its clients HER2, a tyrosine kinase oncoprotein, and Bcl-2, an anti-apoptotic protein. The decrease in Bcl-2 is accompanied by cytochrome c release from mitochondria into the cytoplasm, suggesting apoptosis. In the surviving cells, depletion of the HSP90 clients cyclin D and CDK4 by S-4 prevents phosphorylation of the retinoblastoma protein Rb and the release of transcription factor E2F, inhibiting G1-S cell cycle progression and cell division. These findings illustrate the comprehensive effectiveness of S-4 and encourage future development of compounds of this type for cancer prevention and treatment.

A 10-year review of surgical management of dermatofibrosarcoma protuberans

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a rare skin cancer. Standard treatment in the UK is either wide local excision (WLE) or Mohs micrographic surgery (MMS). It is unclear which approach has the lower recurrence rate.

OBJECTIVES

We undertook a retrospective comparative review of surgical management of DFSP in the UK National Health Service in order to define (i) current surgical practice for primary and recurrent DFSP, (ii) local recurrence rates for primary DFSP and (iii) survival outcomes for DFSP.

METHODS

A retrospective clinical case-note review of patients with histologically confirmed DFSP (January 2004 to December 2013) who have undergone surgical treatment.

RESULTS

The surgical management of 483 primary and 64 recurrent DFSP in 11 plastic surgery and 15 dermatology departments was analysed. Almost 75% of primary DFSP (n = 362) were treated with WLE and 20% (n = 97) with MMS. For recurrent DFSP, 69% (n = 44) and 23% (n = 15) of patients underwent WLE and MMS, respectively. Recurrent primary DFSP occurred in six patients after WLE and none after MMS. The median follow-up time was 25·5 months (interquartile range 6·8-45·1) for new and 19·8 (IQR 4·5-44·5) for recurrent DFSP [Correction added on 1 Feb 2021, after first online publication: 4.8 years (interquartile range 3.5-5.8) was incorrect], with eight reported deaths during the follow-up analysis period (one confirmed to be DFSP related).

CONCLUSIONS

WLE was the most common surgical modality used to treat DFSP across the UK. The local recurrence rate was very low, occurring only after WLE. Although a prospective randomized controlled trial may provide more definitive outcomes, in the absence of a clearly superior surgical modality, treatment decisions should be based on patient preference, clinical expertise and cost.

Treatment approaches in immunosuppressed patients with advanced cutaneous squamous cell carcinoma

Immunosuppression, both iatrogenic and disease-related, is associated with a greatly increased incidence of cutaneous SCC (cSCC) and with aggressive cSCC and worse disease outcomes. Consequently, rapid access to skin cancer services and prudent surgical choices, such as circumferential margin assessment, is essential when treating advanced cSCC in an immunosuppressed patient. For high-risk cancers and control of cSCC multiplicity, additional strategies should be actively considered within the multidisciplinary clinical care team. These include minimization or revision of immunosuppressive medications, systemic chemoprevention (including retinoids, nicotinamide, capecitabine) and adjuvant therapies such as radiotherapy. Unfortunately, there is a relative paucity of good evidence for many of these treatments in the immunosuppressed. Systemic treatments for metastatic cSCC are often contraindicated in organ transplant recipients, notably checkpoint inhibitor immunotherapy. There are also toxicity concerns with some conventional chemotherapies and EGFR inhibitors. Until recently, clinical trials have largely excluded immunosuppressed individuals. Development of more effective treatment for advanced cSCC in this high-risk group and prospective clinical trials are now research priorities.

A feasibility study of microwave therapy for precancerous actinic keratosis

BACKGROUND

Actinic keratosis (AK) is a common premalignant skin lesion that can progress to cutaneous squamous cell carcinoma (cSCC). Microwave therapy is an established cancer treatment and has been used for plantar viral warts.

OBJECTIVES

To evaluate the efficacy and feasibility of microwave as a treatment for AK.

METHODS

Stage I was a dose-setting study, in which seven participants had the dielectric properties of 12 thick and 22 thin AKs assessed for optimization of the microwave dose used for treatment in Stage II. Stage II was a randomized, internally controlled trial evaluating 179 AKs in 11 patients (93 treated, 86 untreated controls) on the scalp/forehead or dorsal hand. Participants received one treatment initially and a repeat treatment to unresolved AKs at week 4. The response was assessed at six visits over 4 months. The primary outcome was partial or complete resolution of the treated AKs.

RESULTS

A significantly higher proportion of treated AK areas responded than untreated (90% vs. 15%; P < 0·001). Thin AKs were more responsive than thick AKs. The site did not affect efficacy. Pain was severe, but brief (80% reported pain lasting 'a few seconds only'). Adverse effects were minimal (erythema, n = 6; flaking, n = 3; itch, n = 3). All participants who would chose microwave therapy over their current treatment cited the shorter discomfort period.

CONCLUSIONS

Microwave therapy is a portable, safe and effective treatment for AK. An easy-to-deliver, acceptable therapy for AK is attractive as a prevention strategy. While these results are promising, a larger randomized controlled trial is needed against an effective comparator to confirm clinical efficacy and patient acceptability. What is already known about this topic? Actinic keratoses (AKs) are common precancerous skin lesions. Successful treatment of AK can prevent cutaneous squamous cell carcinoma (cSCC). Most topical therapies for AK require repeated application over weeks and drive local skin inflammation, leading to poor compliance. An easy-to-deliver and effective treatment for AK, suitable for use in primary care, could reduce cSCC. What does this study add? Microwave therapy is a feasible, effective treatment for AK. Ninety per cent of treated AKs showed full or partial resolution at 120 days post-treatment. Microwave therapy was painful, but the pain was short-lived (seconds) and this short discomfort period was cited as the main reason that microwave was preferred to their current treatment.

Nationwide Incidence of Metastatic Cutaneous Squamous Cell Carcinoma in England

Importance

Cutaneous squamous cell carcinoma (cSCC) is the most common skin cancer with metastatic potential, but epidemiologic data are poor. Changes to the National Cancer Registration and Analysis Service (NCRAS) in England have allowed more accurate data analysis of primary and metastatic cSCC since 2013.

Objective

To assess the national incidence of cSCC and metastatic cSCC (mcSCC) in England from 2013 through 2015.

Design, Setting, and Participants

This national population-based study identified a cohort of patients with cSCC and mcSCC in England from January 1, 2013, through December 31, 2015. Patients were identified using diagnostic codes derived from pathology reports in the NCRAS. Data were analyzed from March 1, 2017, through March 1, 2018.

Main Outcomes and Measures

Incidence rates across sex and risk factors for cSCC were derived from the NCRAS data. Risk of occurrence of mcSCC among the population with cSCC was assessed with Cox proportional hazards regression analysis to determine indicators of mcSCC.

Results

Among the 76 977 patients with first primary cSCC in 2013 through 2015 (62.7% male; median age, 80 years [interquartile range, 72-86 years]), the age-standardized rates for the first registered cSCC in England from 2013 through 2015 were 77.3 per 100 000 person-years (PY) (95% CI, 76.6-78.0) in male patients and 34.1 per 100 000 PY (95% CI, 33.7-34.5) in female patients. Increased primary cSCC tumor count was observed in older, white male patients in lower deprivation quintiles. After a maximum follow-up of 36 months, cumulative incidence of mcSCC developed in 1.1% of women and 2.4% of men with a primary cSCC. Significant increases in the risk of metastasis with adjusted hazard rates of approximately 2.00 were observed in patients who were aged 80 to 89 years (hazard ratio [HR], 1.23; 95% CI, 1.07-1.43), 90 years or older (HR, 1.35; 95% CI, 1.09-1.66), male (HR, 1.79; 95% CI, 1.52-2.10), immunosuppressed (HR, 1.99; 95% CI, 1.64-2.42), and in higher deprivation quintiles (HR for highest quintile, 1.64; 95% CI, 1.35-2.00). Primary cSCC located on the ear (HR, 1.70; 95% CI, 1.42-2.03) and lip (HR, 1.85; 95% CI, 1.29-2.63) were at highest risk of metastasis.

Conclusions and Relevance

This study presents the first national study of the incidence of mcSCC. With limited health care resources and an aging population, accurate epidemiologic data are essential for informing future health care planning, identifying high-risk patients, and evaluating skin cancer prevention policies.

The Identification of Potential Therapeutic Targets for Cutaneous Squamous Cell Carcinoma

We performed a small interfering RNA screen to identify targets for cutaneous squamous cell carcinoma (cSCC) therapy in the ubiquitin/ubiquitin-like system. We provide evidence for selective anti-cSCC activity of knockdown of the E3 ubiquitin ligase MARCH4, the ATPase p97/VCP, the deubiquitinating enzyme USP8, the cullin-RING ligase (CRL) 4 substrate receptor CDT2/DTL, and components of the anaphase-promoting complex/cyclosome (APC/C). Specifically attenuating CRL4^CDT2 by CDT2 knockdown can be more potent in killing cSCC cells than targeting CRLs or CRL4s in general by RBX1 or DDB1 depletion. Suppression of the APC/C or forced APC/C activation by targeting its repressor EMI1 are both potential therapeutic approaches. We observed that cSCC cells can be selectively killed by small-molecule inhibitors of USP8 (DUBs-IN-3/compound 22c) and the NEDD8 E1 activating enzyme/CRLs (MLN4924/pevonedistat). A substantial proportion of cSCC cell lines are very highly MLN4924-sensitive. Pathways that respond to defects in proteostasis are involved in the anti-cSCC activity of p97 suppression. Targeting USP8 can reduce the expression of growth factor receptors that participate in cSCC development. EMI1 and CDT2 depletion can selectively cause DNA re-replication and DNA damage in cSCC cells.

Aggressive Squamous Cell Carcinoma in Organ Transplant Recipients

Importance

Squamous cell carcinoma (SCC) is the most frequent malignant neoplasm found in solid organ transplant recipients and is associated with a more aggressive disease course and higher risk of metastasis and death than in the general population.

Objectives

To report the clinicopathologic features of and identify factors associated with aggressive SCC in solid organ transplant recipients.

Methods

This retrospective multicentric case series included 51 patients who underwent solid organ transplantation and were found to have aggressive SCC, defined by nodal or distant metastasis or death by local progression of primary SCC. Standard questionnaires were completed by the researchers between July 18, 2005, and January 1, 2015. Data were analyzed between February 22, 2016, and July 12, 2016.

Results

Of the 51 participants, 43 were men and 8 were women, with a median age of 51 years (range, 19-71 years) at time of transplantation and 62 years (range, 36-77 years) at time of diagnosis of aggressive SCC. The distribution of aggressive SCC was preferentially on the face (34 [67%]) and scalp (6 [12%]), followed by the upper extremities (6 [12%]). A total of 21 tumors (41%) were poorly differentiated, with a median tumor diameter of 18.0 mm (range, 4.0-64.0 mm) and median tumor depth of 6.2 mm (range, 1.0-20.0 mm). Perineural invasion was present in 20 patients (39%), while 23 (45%) showed a local recurrence. The 5-year overall survival rate was 23%, while 5-year disease-specific survival was 30.5%.

Conclusions and Relevance

Results of this case series suggest that anatomical site, differentiation, tumor diameter, tumor depth, and perineural invasion are important risk factors in aggressive SCC in solid organ transplant recipients.

Epidemiology of basal and cutaneous squamous cell carcinoma in the U.K. 2013-15: a cohort study

BACKGROUND

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), together known as keratinocyte cancers (KCs), are the commonest cancer in white ethnic populations. Recent improvements to registry data collection in England has allowed more accurate analysis of the epidemiology of BCC and cSCC and for the first time we are able to provide an accurate (representative) tumour burden for KC in the U.K.

OBJECTIVES

To estimate the incidence of BCC and cSCC in the U.K.

METHODS

A cohort of patients with KCs between 2013 and 2015 were identified using linkage to diagnostic codes derived from pathology reports collected into the national cancer registry. Data from England's cancer registry were combined with data from Scotland, Northern Ireland and Wales. European age-standardized incidence rates (EASRs) of the first BCC and cSCC per patient per annum (PPPA) were calculated.

RESULTS

In the U.K, the EASR of the first BCC and cSCC PPPA in 2013-15 were 285 and 77 per 100 000 person years, respectively (211 120 KCs total in 2015). The mean annual percentage increase was 5% between 2013 and 2015 for both BCC and cSCC. By counting the first KC PPPA, we include an additional 51% KCs compared with the previous reporting technique which counts only the first BCC and cSCC in a patient's lifetime, yet it represents a probable underestimation of 5-11% of the true tumour count.

CONCLUSIONS

Based on an improved methodology, a more representative incidence of KC is presented, which is essential to healthcare planning and will lead to improved understanding of the epidemiology of KC. What's already known about this topic? Keratinocyte cancers (KCs) are the most common cancers affecting white ethnic populations. The incidence of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) is increasing worldwide including the U.K., most commonly in elderly male Caucasian patients. These cancers are traditionally substantially underreported and frequently excluded from national cancer statistics. What does this study add? Using improved data collection methods in England and validated tumour-reporting techniques, we report the most accurate BCC and cSCC incidence data for the U.K. ever published. Identifying the first BCC and cSCC per patient per annum, the incidence of BCC and cSCC in the U.K. (excluding Wales) was 285 and 77 per 100 000 person years, respectively, between 2013 and 2015, with more than 210 000 KCs in the U.K. in 2015.

A Unique Panel of Patient-Derived Cutaneous Squamous Cell Carcinoma Cell Lines Provides a Preclinical Pathway for Therapeutic Testing

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) incidence continues to rise with increasing morbidity and mortality, with limited treatment options for advanced disease. Future improvements in targeted therapy will rely on advances in genomic/transcriptomic understanding and the use of model systems for basic research. We describe here the panel of 16 primary and metastatic cSCC cell lines developed and characterised over the past three decades in our laboratory in order to provide such a resource for future preclinical research and drug screening.

METHODS

Primary keratinocytes were isolated from cSCC tumours and metastases, and cell lines were established. These were characterised using short tandem repeat (STR) profiling and genotyped by whole exome sequencing. Multiple in vitro assays were performed to document their morphology, growth characteristics, migration and invasion characteristics, and in vivo xenograft growth.

RESULTS

STR profiles of the cSCC lines allow the confirmation of their unique identity. Phylogenetic trees derived from exome sequence analysis of the matched primary and metastatic lines provide insight into the genetic basis of disease progression. The results of in vivo and in vitro analyses allow researchers to select suitable cell lines for specific experimentation.

CONCLUSIONS

There are few well-characterised cSCC lines available for widespread preclinical experimentation and drug screening. The described cSCC cell line panel provides a critical tool for in vitro and in vivo experimentation.

Keratinocyte Carcinomas: Current Concepts and Future Research Priorities

Cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC) are keratinocyte carcinomas, the most frequently diagnosed cancers in fair-skinned populations. Ultraviolet radiation (UVR) is the main driving carcinogen for these tumors, but immunosuppression, pigmentary factors, and aging are also risk factors. Scientific discoveries have improved the understanding of the role of human papillomaviruses (HPV) in cSCC as well as the skin microbiome and a compromised immune system in the development of both cSCC and BCC. Genomic analyses have uncovered genetic risk variants, high-risk susceptibility genes, and somatic events that underlie common pathways important in keratinocyte carcinoma tumorigenesis and tumor characteristics that have enabled development of prediction models for early identification of high-risk individuals. Advances in chemoprevention in high-risk individuals and progress in targeted and immune-based treatment approaches have the potential to decrease the morbidity and mortality associated with these tumors. As the incidence and prevalence of keratinocyte carcinoma continue to increase, strategies for prevention, including effective sun-protective behavior, educational interventions, and reduction of tanning bed access and usage, are essential. Gaps in our knowledge requiring additional research to reduce the high morbidity and costs associated with keratinocyte carcinoma include better understanding of factors leading to more aggressive tumors, the roles of microbiome and HPV infection, prediction of response to therapies including immune checkpoint blockade, and how to tailor both prevention and treatment to individual risk factors and needs.

Investigation into the use of histone deacetylase inhibitor MS-275 as a topical agent for the prevention and treatment of cutaneous squamous cell carcinoma in an SKH-1 hairless mouse model

Cutaneous squamous cell carcinomas are a common form of highly mutated keratinocyte skin cancers that are of particular concern in immunocompromised patients. Here we report on the efficacy of topically applied MS-275, a clinically used histone deacetylase inhibitor, for the treatment and management of this disease. At 2 mg/kg, MS-275 significantly decreased tumor burden in an SKH-1 hairless mouse model of UVB radiation-induced skin carcinogenesis. MS-275 was cell permeable as a topical formulation and induced histone acetylation changes in mouse tumor tissue. MS-275 was also effective at inhibiting the proliferation of patient derived cutaneous squamous cell carcinoma lines and was particularly potent toward cells isolated from a regional metastasis on an immunocompromised individual. Our findings support the use of alternative routes of administration for histone deacetylase inhibitors in the treatment of high-risk squamous cell carcinoma which may ultimately lead to more precise delivery and reduced systemic toxicity.

The genomic landscape of cutaneous SCC reveals drivers and a novel azathioprine associated mutational signature

Cutaneous squamous cell carcinoma (cSCC) has a high tumour mutational burden (50 mutations per megabase DNA pair). Here, we combine whole-exome analyses from 40 primary cSCC tumours, comprising 20 well-differentiated and 20 moderately/poorly differentiated tumours, with accompanying clinical data from a longitudinal study of immunosuppressed and immunocompetent patients and integrate this analysis with independent gene expression studies. We identify commonly mutated genes, copy number changes and altered pathways and processes. Comparisons with tumour differentiation status suggest events which may drive disease progression. Mutational signature analysis reveals the presence of a novel signature (signature 32), whose incidence correlates with chronic exposure to the immunosuppressive drug azathioprine. Characterisation of a panel of 15 cSCC tumour-derived cell lines reveals that they accurately reflect the mutational signatures and genomic alterations of primary tumours and provide a valuable resource for the validation of tumour drivers and therapeutic targets.

The Role of Human Papillomaviruses and Polyomaviruses in BRAF-Inhibitor Induced Cutaneous Squamous Cell Carcinoma and Benign Squamoproliferative Lesions

Background: Human papillomavirus (HPV) has long been proposed as a cofactor in the pathogenesis of cutaneous squamous cell carcinoma (cSCC). More recently, the striking clinico-pathological features of cSCCs that complicate treatment of metastatic melanoma with inhibitors targeting BRAF mutations (BRAFi) has prompted speculation concerning a pathogenic role for oncogenic viruses. Here, we investigate HPV and human polyomaviruses (HPyV) and correlate with clinical, histologic, and genetic features in BRAFi-associated cSCC.

Materials and Methods: Patients receiving BRAFi treatment were recruited at Barts Health NHS Trust. HPV DNA was detected in microdissected frozen samples using reverse line probe technology and degenerate and nested PCR. HPV immunohistochemistry was performed in a subset of samples. Quantitative PCR was performed to determine the presence and viral load of HPyVs with affinity for the skin (HPyV6, HPyV7, HPyV9, MCPyV, and TSPyV). These data were correlated with previous genetic mutational analysis of H, K and NRAS, NOTCH1/2, TP53, CDKN2A, CARD11, CREBBP, TGFBR1/2. Chromosomal aberrations were profiled using single nucleotide polymorphism (SNP) arrays.

Results: Forty-five skin lesions from seven patients treated with single agent vemurafenib in 2012–2013 were analyzed: 12 cSCC, 19 viral warts (VW), 2 actinic keratosis (AK), 5 verrucous keratosis/other squamoproliferative (VK/SP) lesions, one melanocytic lesion and 6 normal skin samples. Significant histologic features of viral infection were seen in 10/12 (83%) cSCC. HPV DNA was detected in 18/19 (95%) VW/SP, 9/12 (75%) cSCC, 4/5 (80%) SP, and 3/6 (50%) normal skin samples and in 1/12 cases assessed by immunohistochemistry. HPyV was co-detected in 22/30 (73%) of samples, usually at low viral load, with MCPyV and HPyV7 the most common. SNP arrays confirmed low levels of chromosomal abnormality and there was no significant correlation between HPV or HPyV detection and individual gene mutations or overall mutational burden.

Conclusion: Despite supportive clinicopathologic evidence, the role for HPV and HPyV infection in the pathogenesis of BRAFi-induced squamoproliferative lesions remains uncertain. Synergistic oncogenic mechanisms are plausible although speculative. Nonetheless, with the prospect of a significant increase in the adjuvant use of these drugs, further research is justified and may provide insight into the pathogenesis of other BRAFi-associated malignancies.

Patient preferences for topical treatment of actinic keratoses: a discrete-choice experiment

BACKGROUND

The treatment of actinic keratosis (AK) is a potentially effective strategy for the prevention of cutaneous squamous cell carcinoma (cSCC). However, the patient perspective on potential benefits of AK treatment in terms of skin cancer reduction has received little attention to date.

OBJECTIVES

(i) To investigate patient preferences for topical treatments for AK using a discrete-choice experiment (DCE); (ii) to evaluate patient willingness to trade between clinical benefit and medical burden.

METHODS

The DCE was conducted as part of a study to establish the feasibility of a phase III randomized controlled trial evaluating the prevention of cSCC using currently available topical interventions. Preferences were elicited by asking patients to make a series of choices between treatment alternatives with different hypothetical combinations of attribute levels. Willingness to trade between treatment attributes was estimated using a flexible-choice model that allows for the heterogeneity of patient preferences.

RESULTS

A total of 109 patients with AK completed the DCE. The majority of patients who expressed valid preferences were willing to accept some reduction in both prophylactic and cosmetic efficacy to reduce the burden of the treatment regimen, the severity of skin reaction and other adverse effects. Patients may reject treatment if the perceived therapeutic benefit is outweighed by the subjective burden of treatment.

CONCLUSIONS

Evidence of significant variation in the perceived utility of treatments across patients highlights the importance of taking individual patient preferences into account to improve AK treatment acceptability and adherence.

The widespread use of topical antimicrobials enriches for resistance in Staphylococcus aureus isolated from patients with atopic dermatitis

BACKGROUND

Carriage rates of Staphylococcus aureus on affected skin in atopic dermatitis (AD) are approximately 70%. Increasing disease severity during flares and overall disease severity correlate with increased burden of S. aureus. Treatment in AD therefore often targets S. aureus with topical and systemic antimicrobials.

OBJECTIVES

To determine whether antimicrobial sensitivities and genetic determinants of resistance differed in S. aureus isolates from the skin of children with AD and healthy child nasal carriers.

METHODS

In this case-control study, we compared S. aureus isolates from children with AD (n = 50) attending a hospital dermatology department against nasal carriage isolates from children without skin disease (n = 49) attending a hospital emergency department for noninfective conditions. Using whole genome sequencing we generated a phylogenetic framework for the isolates based on variation in the core genome, then compared antimicrobial resistance phenotypes and genotypes between disease groups.

RESULTS

Staphylococcus aureus from cases and controls had on average similar numbers of phenotypic resistances per isolate. Case isolates differed in their resistance patterns, with fusidic acid resistance (Fus^R ) being significantly more frequent in AD (P = 0·009). The genetic basis of Fus^R also differentiated the populations, with chromosomal mutations in fusA predominating in AD (P = 0·049). Analysis revealed that Fus^R evolved multiple times and via multiple mechanism in the population. Carriage of plasmid-derived qac genes, which have been associated with reduced susceptibility to antiseptics, was eight times more frequent in AD (P = 0·016).

CONCLUSIONS

The results suggest that strong selective pressure drives the emergence and maintenance of specific resistances in AD.

Human papillomavirus and posttransplantation cutaneous squamous cell carcinoma: A multicenter, prospective cohort study

Organ transplant recipients (OTRs) have a 100-fold increased risk of cutaneous squamous cell carcinoma (cSCC). We prospectively evaluated the association between β genus human papillomaviruses (βPV) and keratinocyte carcinoma in OTRs. Two OTR cohorts without cSCC were assembled: cohort 1 was transplanted in 2003-2006 (n = 274) and cohort 2 was transplanted in 1986-2002 (n = 352). Participants were followed until death or cessation of follow-up in 2016. βPV infection was assessed in eyebrow hair by using polymerase chain reaction-based methods. βPV IgG seroresponses were determined with multiplex serology. A competing risk model with delayed entry was used to estimate cumulative incidence of histologically proven cSCC and the effect of βPV by using a multivariable Cox regression model. Results are reported as adjusted hazard ratios (HRs). OTRs with 5 or more different βPV types in eyebrow hair had 1.7 times the risk of cSCC vs OTRs with 0 to 4 different types (HR 1.7, 95% confidence interval 1.1-2.6). A similar risk was seen with high βPV loads (HR 1.8, 95% confidence interval 1.2-2.8). No significant associations were seen between serum antibodies and cSCC or between βPV and basal cell carcinoma. The diversity and load of βPV types in eyebrow hair are associated with cSCC risk in OTRs, providing evidence that βPV is associated with cSCC carcinogenesis and may present a target for future preventive strategies.

Preclinical comparison of proteasome and ubiquitin E1 enzyme inhibitors in cutaneous squamous cell carcinoma: the identification of mechanisms of differential sensitivity

Proteasome inhibitors have distinct properties and the biochemical consequences of suppressing ubiquitin E1 enzymes and the proteasome differ. We compared the effects of the proteasome inhibitors bortezomib, ixazomib and carfilzomib and the ubiquitin E1 enzyme inhibitor MLN7243/TAK-243 on cell viability and cell death in normal keratinocytes and cutaneous squamous cell carcinoma (cSCC) cell lines. The effects of both a pulse of treatment and more extended incubation were investigated. This is relevant to directly-delivered therapy (topical treatment/intratumoral injection) where the time of exposure can be controlled and a short exposure may better reflect systemically-delivered inhibitor pharmacokinetics. These agents can selectively kill cSCC cells but there are variations in the pattern of cSCC cell line sensitivity/resistance. Variations in the responses to proteasome inhibitors are associated with differences in the specificity of the inhibitors for the three proteolytic activities of the proteasome. There is greater selectivity for killing cSCC cells compared to normal keratinocytes with a pulse of proteasome inhibitor treatment than with a more extended exposure. We provide evidence that c-MYC-dependent NOXA upregulation confers susceptibility to a short incubation with proteasome inhibitors by priming cSCC cells for rapid BAK-dependent death. We observed that bortezomib-resistant cSCC cells can be sensitive to MLN7243-induced death. Low expression of the ubiquitin E1 UBA1/UBE1 participates in conferring susceptibility to MLN7243 by increasing sensitivity to MLN7243-mediated attenuation of ubiquitination. This study supports further investigation of the potential of proteasome and ubiquitin E1 inhibition for cSCC therapy. Direct delivery of inhibitors could facilitate adequate exposure of skin cancers.

Reduced SMAD2/3 activation independently predicts increased depth of human cutaneous squamous cell carcinoma

The incidence of cutaneous squamous cell carcinoma (cSCC) is rising. Whilst the majority are cured surgically, aggressive metastatic cSCC carry a poor prognosis. Inactivating mutations in transforming growth factor beta (TGF-β) receptors have been identified amongst genetic drivers of sporadic tumours and murine models of cSCC, suggesting a tumour suppressor function for TGF-β in normal skin. However, paradoxically, TGF-β acts as a tumour promoter in some murine model systems. Few studies have analysed the role of TGF-β/activin signalling in human normal skin, hyper-proliferative skin disorders and cSCC. Antibodies recognising phospho-SMAD proteins which are activated during canonical TGF-β/activin signalling were validated for use in immunohistochemistry. A tissue microarray comprising FFPE lesional and perilesional tissue from human primary invasive cSCC (n=238), cSCC in-situ (n=2) and keratocanthoma (n=9) were analysed in comparison with tissues from normal human scalp (n=10). Phosphorylated SMAD2 and SMAD3 were detected in normal interfollicular epidermal keratinocytes and were also highly localised to inner root sheath, matrix cells and Keratin 15 positive cells. Lesional cSCC tissue had significantly reduced activated SMAD2/3 compared to perilesional tissue, consistent with a tumour suppressor role for SMAD2/3 activators in cSCC. Increased cSCC tumour thickness inversely correlated with the presence of phospho-SMADs in tumour tissue suggesting that a reduction in canonical TGF-β/activin signalling may be associated with disease progression.

Targeting the CoREST complex with dual histone deacetylase and demethylase inhibitors

Here we report corin, a synthetic hybrid agent derived from the class I HDAC inhibitor (entinostat) and an LSD1 inhibitor (tranylcypromine analog). Enzymologic analysis reveals that corin potently targets the CoREST complex and shows more sustained inhibition of CoREST complex HDAC activity compared with entinostat. Cell-based experiments demonstrate that corin exhibits a superior anti-proliferative profile against several melanoma lines and cutaneous squamous cell carcinoma lines compared to its parent monofunctional inhibitors but is less toxic to melanocytes and keratinocytes. CoREST knockdown, gene expression, and ChIP studies suggest that corin's favorable pharmacologic effects may rely on an intact CoREST complex. Corin was also effective in slowing tumor growth in a melanoma mouse xenograft model. These studies highlight the promise of a new class of two-pronged hybrid agents that may show preferential targeting of particular epigenetic regulatory complexes and offer unique therapeutic opportunities.

Genomic analysis of atypical fibroxanthoma

Atypical fibroxanthoma (AFX), is a rare type of skin cancer affecting older individuals with sun damaged skin. Since there is limited genomic information about AFX, our study seeks to improve the understanding of AFX through whole-exome and RNA sequencing of 8 matched tumor-normal samples. AFX is a highly mutated malignancy with recurrent mutations in a number of genes, including COL11A1, ERBB4, CSMD3, and FAT1. The majority of mutations identified were UV signature (C>T in dipyrimidines). We observed deletion of chromosomal segments on chr9p and chr13q, including tumor suppressor genes such as KANK1 and CDKN2A, but no gene fusions were found. Gene expression profiling revealed several biological pathways that are upregulated in AFX, including tumor associated macrophage response, GPCR signaling, and epithelial to mesenchymal transition (EMT). To further investigate the presence of EMT in AFX, we conducted a gene expression meta-analysis that incorporated RNA-seq data from dermal fibroblasts and keratinocytes. Ours is the first study to employ high throughput sequencing for molecular profiling of AFX. These data provide valuable insights to inform models of carcinogenesis and additional research towards tumor-directed therapy.

The pathogenesis of cutaneous squamous cell carcinoma in organ transplant recipients

The pathogenesis of keratinocyte carcinoma following organ transplantation is multifactorial, and recent evidence suggests a complex and often synergistic interplay between the carcinogenic effects of ultraviolet radiation, compromised immune surveillance, direct pro- and anticarcinogenic effects of drugs, oncogenic viruses (in particular, beta-genus human papillomaviruses) and host genetic susceptibility factors. We present an overview of those factors for which there is currently the most convincing evidence and highlight important gaps in our knowledge. In particular, a clear understanding of the interdependence and relative contributions of these co-factors is currently lacking, yet has important implications for rational development of clinically relevant biomarkers and targeted strategies for treatment and prevention of post-transplant keratinocyte cancers.

The Microevolution and Epidemiology of Staphylococcus aureus Colonization during Atopic Eczema Disease Flare

Staphylococcus aureus is an opportunistic pathogen and variable component of the human microbiota. A characteristic of atopic eczema (AE) is colonization by S. aureus, with exacerbations associated with an increased bacterial burden of the organism. Despite this, the origins and genetic diversity of S. aureus colonizing individual patients during AE disease flares is poorly understood. To examine the microevolution of S. aureus colonization, we deep sequenced S. aureus populations from nine children with moderate to severe AE and 18 non-atopic children asymptomatically carrying S. aureus nasally. Colonization by clonal S. aureus populations was observed in both AE patients and control participants, with all but one of the individuals carrying colonies belonging to a single sequence type. Phylogenetic analysis showed that disease flares were associated with the clonal expansion of the S. aureus population, occurring over a period of weeks to months. There was a significant difference in the genetic backgrounds of S. aureus colonizing AE cases versus controls (Fisher exact test, P = 0.03). Examination of intra-host genetic heterogeneity of the colonizing S. aureus populations identified evidence of within-host selection in the AE patients, with AE variants being potentially selectively advantageous for intracellular persistence and treatment resistance.

Whole-Exome Sequencing Validates a Preclinical Mouse Model for the Prevention and Treatment of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinomas (cSCC) are among the most common and highly mutated human malignancies. Solar UV radiation is the major factor in the etiology of cSCC. Whole-exome sequencing of 18 microdissected tumor samples (cases) derived from SKH-1 hairless mice that had been chronically exposed to solar-simulated UV (SSUV) radiation showed a median point mutation (SNP) rate of 155 per Mb. The majority (78.6%) of the SNPs are C.G>T.A transitions, a characteristic UVR-induced mutational signature. Direct comparison with human cSCC cases showed high overlap in terms of both frequency and type of SNP mutations. Mutations in Trp53 were detected in 15 of 18 (83%) cases, with 20 of 21 SNP mutations located in the protein DNA-binding domain. Strikingly, multiple nonsynonymous SNP mutations in genes encoding Notch family members (Notch1-4) were present in 10 of 18 (55%) cases. The histopathologic spectrum of the mouse cSCC that develops in this model resembles very closely the spectrum of human cSCC. We conclude that the mouse SSUV cSCCs accurately represent the histopathologic and mutational spectra of the most prevalent tumor suppressors of human cSCC, validating the use of this preclinical model for the prevention and treatment of human cSCC. Cancer Prev Res; 10(1); 67-75. ©2016 AACR.

Inactivation of TGFβ receptors in stem cells drives cutaneous squamous cell carcinoma

Melanoma patients treated with oncogenic BRAF inhibitors can develop cutaneous squamous cell carcinoma (cSCC) within weeks of treatment, driven by paradoxical RAS/RAF/MAPK pathway activation. Here we identify frequent TGFBR1 and TGFBR2 mutations in human vemurafenib-induced skin lesions and in sporadic cSCC. Functional analysis reveals these mutations ablate canonical TGFβ Smad signalling, which is localized to bulge stem cells in both normal human and murine skin. MAPK pathway hyperactivation (through Braf(V600E) or Kras(G12D) knockin) and TGFβ signalling ablation (through Tgfbr1 deletion) in LGR5(+ve) stem cells enables rapid cSCC development in the mouse. Mutation of Tp53 (which is commonly mutated in sporadic cSCC) coupled with Tgfbr1 deletion in LGR5(+ve) cells also results in cSCC development. These findings indicate that LGR5(+ve) stem cells may act as cells of origin for cSCC, and that RAS/RAF/MAPK pathway hyperactivation or Tp53 mutation, coupled with loss of TGFβ signalling, are driving events of skin tumorigenesis.

The Promise of Genomics and the Development of Targeted Therapies for Cutaneous Squamous Cell Carcinoma

Targeted therapies for melanoma and basal cell carcinoma have evolved from deciphering the molecular mechanisms involved in their tumorigenesis. Mutations in BRAF have led to clinical use of BRAF-inhibitors in advanced melanoma, and mutations in Hedgehog signaling to smoothened inhibitors in basal cell carcinoma. The development of tumor resistance to these treatments is leading to many new drug development initiatives and the exploration of multiple signalling pathways. Cutaneous squamous cell carcinoma continues to rise steeply in incidence with very limited therapeutic options for locally advanced or metastatic disease. New genetic technologies find significant levels of mutation in Notch gene family as well as other already recognized gene mutations, such as TP53. The mutational burden in cutaneous squamous cell carcinoma is massive, challenging the identification of driver genes and inhibiting translation from genomics to the clinic. Clinical experience with targeted therapies, such as epidermal growth factor receptor inhibitors, or immune modulatory drugs suggests that these agents may be of benefit to patients, while a more complete understanding of the mechanisms behind squamous cell carcinogenesis awaits further progress.

Actinic keratoses, actinic field change and associations with squamous cell carcinoma in renal transplant recipients in Manchester, UK

While actinic keratoses (AKs) have a known association with cutaneous squamous cell carcinoma (SCC), the relation of actinic field change to SCC has not been quantified. This study investigated the presence of field change and AKs in renal transplant recipients (RTRs) and estimated SCC risk. In May 2010 to October 2011, a dermatologist examined 452 white RTRs (mean age 53 years) at two hospitals in Manchester, UK, counting AKs and recording field change presence by body site and SCCs arising during the study period. Of the participants 130 (29%) had AKs at examination. In 60 (13%) RTR patients with AKs but no field change, 4 (7%) developed SCCs, compared with 15 (21%) of the 70 (15%) with AKs and field change. SCCs developed directly within field change areas in 11/15 (73%) RTRs. This study confirms that RTRs with widespread confluent actinic skin damage are at very high risk of SCC and should be monitored closely.