Reversal of UVA skin photosensitivity and DNA damage in kidney transplant recipients by replacing azathioprine

Outcomes in solid organ transplant recipients with a pretransplant diagnosis of melanoma

Melanoma causes significant morbidity in solid organ transplant recipients (SOTRs). Melanomas diagnosed before transplantation can recur with intensive immunosuppression, but outcomes have not been well studied. We evaluated 901 non-Hispanic White SOTRs with a pretransplant melanoma identified using linked transplant and cancer registry data in the United States. Most pretransplant melanomas were invasive (60.7%), and the median time from diagnosis to transplantation was 5.1 years. After transplantation, 41 SOTRs developed a new invasive melanoma, corresponding to 9-fold increased risk compared with the general population (standardized incidence ratio, 9.2; 95% confidence interval [CI], 6.6-12). Twenty-two SOTRs died from melanoma after transplantation, corresponding to 52-fold increased risk (standardized mortality ratio, 52; 95% CI, 33-79). Risk factors for posttransplant melanoma included age at transplantation (adjusted hazard ratio [HR], 2.86; 95% CI, 1.24-6.60; for age 55+ vs <55 years) and maintenance immunosuppression with cyclosporine/azathioprine (adjusted HR, 2.53; 95% CI, 1.08-5.90). Melanoma mortality was strongly elevated after a posttransplant melanoma diagnosis (HR, 35.6; 95% CI, 14.0-90.4; adjusted for cyclosporine/azathioprine maintenance therapy and calendar year of transplantation). In conclusion, SOTRs with a pretransplant melanoma are at risk of adverse melanoma-related outcomes after transplantation. These findings support thorough dermatologic evaluation prior to transplantation and frequent posttransplant surveillance.

Cutaneous squamous cell carcinoma of the eyelid in northern latitudes, a 25-year experience in Finland

PURPOSE

To evaluate the incidence, clinical features, diagnostic challenges, management and prognosis of cutaneous squamous cell carcinoma of the eyelid (ecSCC) in southern Finland, northern Europe, latitude 62° N.

METHODS

Patients were identified from the Finnish Cancer Registry and the Helsinki University Hospital databases during a 25-year period (1998-2022). Age, sex, location, clinical and histopathological diagnosis, treatment and outcome were retrieved.

RESULTS

Cutaneous squamous cell carcinoma of the eyelid (ecSCC) was diagnosed in 58 patients. The mean age-standardized incidence was 1.03 per 100 000. Median age at the time of histopathological diagnosis was 79 (range 55-93) years; sex ratio was 0.52. Clinical diagnosis in the referral was ecSCC in only three patients. The most frequent misdiagnosis (38%) was basal cell carcinoma (BCC). One or more of the known risk factors (smoking, history of extensive sun exposure, systemic immunosuppression and previous in situ cSCC/cSCC) were documented in 71% of the patients. More than one third (38%) of the patients developed in situ SCC elsewhere on the skin; one third (31%) of the patients had invasive cSCC elsewhere. During the median follow-up time of 24 months, three patients experienced local recurrence, four patients developed metastatic disease (median 19 months) and two patients died of metastatic ecSCC.

CONCLUSION

The estimated incidence of ecSCC in Finland (predominantly white Caucasian) was higher than in a previous study from Europe. Clinical diagnosis of ecSCC is difficult and often misdiagnosed as BCC. Immunosuppression as a risk factor should noticed. Recurrences of ecSCC, which may be lethal, were infrequent.

Emerging Concepts in Managing Malignancy in Kidney Transplant Patients

Cancer remains a significant cause of morbidity and mortality in kidney transplant recipients, due to long-term immunosuppression. Salient issues to consider in decreasing the burden of malignancy among kidney transplant recipients include pretransplant recipient evaluation, post-transplant screening and monitoring, and optimal treatment strategies for the kidney transplant recipients with cancer. In this review, we address cancer incidence and outcomes, approaches to cancer screening and monitoring pretransplant and post-transplant, as well as treatment strategies, immunosuppressive management, and multidisciplinary approaches in the kidney transplant recipients with cancer.

Reducing non-melanoma skin cancer risk in renal transplant recipients

With an increasing number of renal transplant recipients (RTRs) and improving patient survival, a higher incidence of non-melanoma skin cancer (NMSC) has been observed. NMSC in RTRs are often more numerous and biologically more aggressive than the general population, thus contributing towards an increase in morbidity and to a lesser degree, mortality. The resultant cumulative health and financial burden is a recognized concern. Proposed strategies in mitigating risks of developing NMSC and early therapeutic options thereof include tailored modification of immunosuppressants in conjunction with sun protection in all transplant patients. This review highlights the clinical and financial burden of transplant-associated skin cancers, carcinogenic mechanisms in association with immunosuppression, importance of skin cancer awareness campaign and integrated transplant skin clinic, and the potential role of chemoprotective agents. A scheme is proposed for primary and secondary prevention of NMSC based on the available evidence.

Parotid metastases of cutaneous squamous cell carcinoma in renal transplant recipients: Case series and literature review

Cutaneous squamous cell skin carcinoma (cSCC) is the most common skin cancer in renal transplant recipients (RTR). Metastatic potential of cSCC is significantly higher in RTR than in the general population. Parotid metastases (PM) of cSCC are rare, but their prognosis is poor. The present study aimed to investigate the frequency and characteristics of PM of cSCC in our renal transplant cohort. Among 1610 patients who received kidney allografts at our institution in the period from January 1999 to December 2019, 84 patients (5.2%) developed at least one cSCC. Three patients were identified to develop PM within 3 to 6 months after the occurrence of primary cSCC. All PM were discovered by clinical examination and in an advanced stage. Two of them died early after the diagnosis of PMs (after 4 months and 1 year, respectively). In conclusion, immunosuppression is one of the major risk factors for the development of cSCC and its metastases. It contributes to the poor survival of patients with PMs of the cSCC. Our experience emphasizes the need for the employment of the radiological tests in patients with primary high-risk cSCC to evaluate nonpalpable lymph node involvement.

The incidence of post-transplant malignancies in kidney transplant recipients treated with Rituximab

BACKGROUND

Rituximab has been proposed as induction therapy in kidney transplant recipients (KTRs) with preformed donor-specific antibodies (DSA) or a positive flow cross-match. We here evaluated whether adding rituximab was associated with a higher incidence of post-transplant malignancies (PTM) due to greater immunosuppression.

PATIENTS AND METHODS

Forty-eight HLA-sensitized KTRs received induction therapy with anti-thymocyte globulin (ATG) and rituximab because of preformed DSA or a positive flow cross-match (RTX group). They were compared with a control group of 154 patients receiving ATG alone.

RESULTS

Thirty-nine of 202 (19.3%) patients developed PTM; the rate was similar in the RTX and no-RTX groups (14.6% vs. 20.8%, respectively, P = .3). The distributions of the types of cancer were similar between the two groups, with the majority being non-melanoma skin cancer (NMSC, n = 24). The risk factors for PTM were male gender, age, history of cancer, and azathioprine.

CONCLUSION

Our data do not indicate a higher rate of post-transplantation de novo malignancies after kidney transplantation in high-immunological risk patients who received induction therapy based on ATG and rituximab.

Continuous function of 80 primary renal allografts for 30-47 years with maintenance prednisone and azathioprine/mycophenolate mofetil therapy: A clinical mosaic of long-term successes

Eighty primary renal allograft recipients, 61 living-related and 19 deceased donor, transplanted from 1963 through 1984 had continuous graft function for 30-47 years. They were treated with three different early immunosuppression programs (1963-1970: thymectomy, splenectomy, high oral prednisone; 1971-1979: divided-dose intravenous methylprednisolone; and 1980-1984: antilymphocyte globulin) each with maintenance prednisone and azathioprine, and no calcineurin inhibitor. Long-term treatment often included the anti-platelet medication, dipyridamole. Although both recipient and donor ages were young (27.2 ± 9.5 and 33.1 ± 12.0 years, respectively), six recipients with a parent donor had >40-year success. At 35 years, death-censored graft survival was 85.3% and death with a functioning graft 84.2%; overall graft survival was 69.5% (Kaplan-Meier estimate). Biopsy-documented early acute cellular and highly probable antibody-mediated rejections were reversed with divided-dose intravenous methylprednisolone. Complications are detailed in an integrated timeline. Hypogammaglobulinemia identified after 20 years doubled the infection rate. An association between a monoclonal gammopathy of undetermined significance and non-plasma-cell malignancies was identified. Twenty-seven azathioprine-treated patients tested after 37 years had extremely low levels of T1/T2 B lymphocytes representing a "low immunosuppression state of allograft acceptance (LISAA)". The lifetime achievements of these patients following a single renal allograft and low-dose maintenance immunosuppression are remarkable. Their success evolved as a clinical mosaic.

Skin Cancer Development in Solid Organ Transplant Recipients in Switzerland (Swiss Transplant Cohort Study)

IMPORTANCE

Skin cancer, in particular squamous cell carcinoma, is the most frequent malignancy among solid organ transplant recipients with a higher incidence compared to the general population.

OBJECTIVE

To determine the skin cancer incidence in organ transplant recipients in Switzerland and to assess the impact of immunosuppressants and other risk factors.

DESIGN

Prospective cohort study of solid organ transplant recipients in Switzerland enrolled in the Swiss Transplant Cohort Study from 2008 to 2013.

PARTICIPANTS

2,192 solid organ transplant recipients.

MATERIALS AND METHODS

Occurrence of first and subsequent squamous cell carcinoma, basal cell carcinoma, melanoma and other skin cancers after transplantation extracted from the Swiss Transplant Cohort Study database and validated by medical record review. Incidence rates were calculated for skin cancer overall and subgroups. The effect of risk factors on the occurrence of first skin cancer and recurrent skin cancer was calculated by the Cox proportional hazard model.

RESULTS

In 2,192 organ transplant recipients, 136 (6.2%) developed 335 cases of skin cancer during a median follow-up of 32.4 months, with squamous cell carcinoma as the most frequent one. 79.4% of skin cancer patients were male. Risk factors for first and recurrent skin cancer were age at transplantation, male sex, skin cancer before transplantation and previous transplantation. For a first skin cancer, the number of immunosuppressive drugs was a risk factor as well.

CONCLUSIONS AND RELEVANCE

Skin cancer following solid organ transplantation in Switzerland is greatly increased with risk factors: age at transplantation, male sex, skin cancer before transplantation, previous transplantation and number of immunosuppressive drugs.

Association between Use of Hydrochlorothiazide and Risk of Keratinocyte Cancers in Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES

Keratinocyte cancers, which primarily comprise squamous cell carcinomas and basal cell carcinomas, represent a major concern and potential risk for kidney transplant recipients. Hydrochlorothiazide, a diuretic widely used to treat hypertension, has been implicated in skin photosensitivity reaction. Recent studies conducted in the general population have found that hydrochlorothiazide use is associated with a higher risk of keratinocyte cancer, especially squamous cell carcinomas. High-risk groups, however, including transplant recipients were excluded from these. Our aim was to investigate whether hydrochlorothiazide use was associated with keratinocyte cancer in kidney transplant recipients on immunosuppressive therapy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a single-center cohort of kidney (n=2155), combined kidney-pancreas (n=282), and pancreas (n=59) transplant recipients from the Données Informatisées VAlidées Transplantation (DIVAT) database transplanted between 2000 and 2017 in Nantes, France, we evaluated the association between hydrochlorothiazide exposure and keratinocyte cancers. Multivariable cause-specific, time-varying Cox models were used to estimate the relationship between hydrochlorothiazide exposure and the hazard of squamous cell carcinoma and basal cell carcinoma, with hydrochlorothiazide designated as the time-dependent variable.

RESULTS

Among the participants, 279 of 2496 (11%) were exposed to hydrochlorothiazide after the transplantation. Cumulative incidence rates of keratinocyte cancer by 10 and 15 years were 7% and 9% for squamous cell carcinomas, respectively, and 8% and 11% for basal cell carcinomas, respectively. We found a relationship between exposure to hydrochlorothiazide and the risk of squamous cell carcinomas (hazard ratio, 2.04; 95% confidence interval, 1.27 to 3.28). In contrast, we found no association between hydrochlorothiazide exposure and basal cell carcinomas (hazard ratio, 0.63; 95% confidence interval, 0.35 to 1.15).

CONCLUSIONS

In a single-center cohort of kidney, combined kidney-pancreas, and pancreas transplant recipients, exposure to hydrochlorothiazide was associated with a two-fold higher risk of squamous cell carcinoma and no higher risk of basal cell carcinoma.

Repeated Occurrences of Basal Cell Cancer in Patients With Inflammatory Bowel Disease Treated With Immunosuppressive Medications

INTRODUCTION

There are limited data on repeated basal cell cancer (BCC) occurrences among patients with inflammatory bowel disease (IBD), especially the impact of continuing immunosuppressive medications.

METHODS

We conducted a retrospective cohort study of 54,919 patients with IBD followed in the Veterans Affairs Healthcare System. We identified patients who had an incident BCC after their IBD diagnosis. We defined patients' exposure based on their IBD medications use as follows: (i) only aminosalicylate (5-ASA) use, (ii) only active thiopurine (TP) use, (iii) past TP use (discontinued >6 months ago) and no antitumor necrosis factor (TNF) use, (iv) anti-TNF use after previous TP use, (v) only anti-TNF use, and (vi) active anti-TNF and TP use. The outcome of interest was the repeated occurrence of BCC. Adjusted and unadjusted hazard ratios with 95% confidence intervals were used to estimate the risk of repeated BCC occurrence.

RESULTS

A total of 518 patients developed BCC after their IBD diagnosis. The numbers of repeated BCC occurrences per 100 person-years were 12.8 (5-ASA use only), 34.5 (active TP use), 19.3 (past TP use and no anti-TNF use), 25.4 (anti-TNF use after previous TP use), 17.8 (only anti-TNF use), and 22.4 (active anti-TNF and TP use). Compared with 5-ASA use alone, only active TP use was associated with an increased risk for repeated BCC occurrence (adjusted hazard ratio 1.65, 95% confidence interval 1.24-2.19; P = 0.0005). However, the increased risk was no longer present for other exposure categories.

DISCUSSION

Among IBD patients who developed an incident BCC while taking a TP and continued it, there was an increased risk of repeated BCC occurrences.

Cutaneous Squamous Cell Carcinoma: From Biology to Therapy

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and its incidence continues to rise. Although CSCC usually display a benign clinical behavior, it can be both locally invasive and metastatic. The signaling pathways involved in CSCC development have given rise to targetable molecules in recent decades. In addition, the high mutational burden and increased risk of CSCC in patients under immunosuppression were part of the rationale for developing the immunotherapy for CSCC that has changed the therapeutic landscape. This review focuses on the molecular basis of CSCC and the current biology-based approaches of targeted therapies and immune checkpoint inhibitors. Another purpose of this review is to explore the landscape of drugs that may induce or contribute to the development of CSCC. Beginning with the pathogenetic basis of these drug-induced CSCCs, we move on to consider potential therapeutic opportunities for overcoming this adverse effect.

Variation in Nonmelanoma Skin Cancer Incidence by Treatment Modality Among Patients Receiving Multiple Kidney Transplants

Importance

Existing data suggest that nonmelanoma skin cancer (NMSC) is more common in renal transplant recipients than in maintenance dialysis patients. However, whether the risk of NMSC varies as the treatment modality for end-stage kidney disease (ESKD) changes between dialysis and transplantation is not well described.

Objective

To determine whether the incidence of NMSC is attenuated during periods of graft loss with a return to dialysis in those who receive multiple kidney transplants.

Design, Setting, and Participants

Retrospective analysis of data from recipients of kidney transplants from the Irish National Kidney Transplant Service database, linked with the Irish Cancer Registry, from 1994 to 2014. All analysis took place between January 10, 2018 and March 31, 2018. Standardized incidence ratios (SIRs) were calculated for NMSC incidence in comparison with the general population using Irish census data as the denominator. Incidence of NMSC was calculated with modality of treatment for ESKD varying over time; incidence rates and rate ratios associated with dialysis intervals were calculated using Poisson regression; and disease was defined according to International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes for cancer diagnosis.

Exposures

Kidney transplantation.

Main Outcomes and Measures

Incidence rates per 1000 patient-years and incident rate ratios of NMSC after kidney transplant.

Results

Data from the records of 3821 deceased or living donor kidney transplant recipients were assessed; 2399 (62.8%) male and 1422 (37.2%) female recipients; mean (SD) age at time of first data recorded, 41.9 (16.0) years. A total of 3433 recipients were included who had a functioning transplant on January 1, 1994, or received a transplant after that date up to December 31, 2014: 3215 received 1 transplant, 522 a second kidney transplant, and 84 had 3 or more kidney transplants. Periods of treatment with a functioning transplant were associated with a higher incidence of NMSC diagnosis than periods of graft failure: adjusted incidence rate ratio (aIRR), 2.19 (95% CI, 1.56-3.07), P < .001. The aIRRs of NMSC fell from 41.7 (95% CI, 39.38-44.15) per 1000 patient-years in the first transplant to 19.29 (95% CI, 13.41-27.76) in the dialysis period following the first allograft failure. Incidence similarly rose and fell following each subsequent consecutive transplant.

Conclusions and Relevance

In recipients of multiple kidney transplants, while the incidence of NMSC fell during periods defined by transplant failure, there was residual elevated risk. While ascertainment bias may have contributed to the observed trends, the stagnant incidence of invasive cancer overall highlights the need for continued cancer surveillance during graft failure.

The frequency of photosensitizing drug dispensings in Austria and Germany: a correlation with their photosensitizing potential based on published literature

Background

Drug‐induced photosensitivity refers to the development of cutaneous adverse events due to interaction between a pharmaceutical compound and sunlight. Although photosensitivity is a very commonly listed side‐effect of systemic drugs, reliable data on its actual incidence are lacking so far.

Objectives

A possible approach to evaluate the real‐life extent of drug‐induced photosensitivity would be an analysis of the frequency of exposure to a given photosensitizing drug combined with an indicator of its photosensitizing potential. This could serve as a basis for developing a pharmaceutical ‘heatmap’ of photosensitivity.

Methods

The present study investigated the number of reimbursed dispensed packages of potentially photosensitizing drugs in Germany (DE) and Austria (AT) between 2010 and 2017 based on nationwide health insurance‐based databases. In addition, an indicator for the photosensitizing potential was established for each drug based on the number of reports on photosensitivity in the literature.

Results

This analysis includes means of 632 826 944 (+/−14 894 918) drug dispensings per year in DE and 113 270 754 (+/−1 964 690) in AT. Out of these, the mean percentage of drugs that enlist photosensitivity as a potential side‐effect was 49.5% (±0.7) in DE and 48.2% (±1.2) in AT. When plotting the number of reimbursed dispensed packages vs. the number of reports on photosensitivity, two categories of drugs show high numbers for both parameters, that is diuretics and non‐steroidal anti‐inflammatory drugs (NSAIDs).

Conclusions

Diuretics and NSAIDs appear to be responsible for the greatest part of exposure to photosensitizing drugs with potential implication on public health.

Mortality Associated With Development of Squamous Cell Cancer in Patients With Inflammatory Bowel Diseases Receiving Treatment With Thiopurines

BACKGROUND & AIMS

Treatment with thiopurines is associated with an increased risk of squamous cell carcinoma of the skin (SCC) in patients with inflammatory bowel diseases (IBD). We studied outcomes of patients with IBD who developed SCC while receiving thiopurine therapy.

METHODS

We conducted a retrospective cohort study of 54,919 patients with IBD followed in the nationwide Veterans Affairs Healthcare System from January 1, 2000, through May 23, 2018. From this cohort, we created a sub-cohort of patients with an incident diagnosis of SCC, confirmed by review of patients' medical records; we identified those who had received treatment with thiopurines (exposed group) vs those treated with mesalamine and no prior exposure to thiopurines or tumor necrosis factor antagonists (unexposed group). The primary outcome was death associated with SCC (SCC mortality). We collected data on baseline demographic features, exposure to ultraviolet light, Charlson comorbidity index, smoking status, and environmental exposures. Follow up began at the time of incident SCC diagnosis and ended at death or last recorded date in the health system. Cause-specific hazard models were used to estimate the adjusted and unadjusted hazard ratio (HRs), with 95% CIs, for SCC mortality.

RESULTS

We identified 467 patients with incident SCC and included 449 patients (161 exposed and 288 unexposed) in our final analysis. Eleven patients from complications of SCC (8 in the exposed group and 3 in the unexposed group). The estimated 5- and 10-year cumulative mortality values were 2.9% and 2.9% in the exposed group and 0.4% and 0.9% in the unexposed group, respectively. The unadjusted and adjusted cause-specific HRs for SCC mortality associated with exposure were 7.0 (95% CI, 1.8-28.0; P = .006) and 8.0 (95% CI, 2.0-32.8; P = .004), respectively.

CONCLUSIONS

Although the cause-specific mortality is relatively low, patients with IBD exposed to thiopurines who develop SCC have an increased risk of SCC-associated death compared to patients exposed to only mesalamine.

Brief Report: Cutaneous Melanoma Risk Among People With HIV in the United States and Canada

BACKGROUND

Cutaneous melanoma incidence may be modestly elevated in people with HIV (PWH) vs. people without HIV. However, little is known about the relationship of immunosuppression, HIV replication, and antiretroviral therapy (ART) with melanoma risk.

METHODS

PWH of white race in the North American AIDS Cohort Collaboration on Research and Design were included. A standardized incidence ratio was calculated comparing risk with the white general population, standardizing by age, sex, and calendar period. Associations between melanoma incidence and current, lagged, and cumulative measures of CD4 count, HIV RNA level, and ART use were estimated with Cox regression, adjusting for established risk factors such as age and annual residential ultraviolet B (UVB) exposure.

RESULTS

Eighty melanomas were diagnosed among 33,934 white PWH (incidence = 40.75 per 100,000 person-years). Incidence was not elevated compared with the general population [standardized incidence ratio = 1.15, 95% confidence interval (95% CI) = 0.91 to 1.43]. Higher melanoma incidence was associated with older age [adjusted hazard ratio (aHR) per decade increase = 1.50, 95% CI = 1.20 to 1.89] and higher UVB exposure (aHR for exposure ≥35 vs. <35 mW/m = 1.62, 95% CI = 0.99 to 2.65). Current, lagged, and cumulative CD4 and HIV RNA were not associated with melanoma incidence. Melanoma incidence was higher among people ART-treated for a larger proportion of time in the previous 720 days (aHR per 10% increase = 1.16, 95% CI = 1.03 to 1.30).

CONCLUSIONS

These results suggest that HIV-induced immune dysfunction does not influence melanoma development. The association between ART and melanoma risk may be due to increased skin surveillance among PWH engaged in clinical care. Associations with age and UVB confirmed those established in the general population.

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.

Dissecting the Multiplicity of Immune Effects of Immunosuppressive Drugs to Better Predict the Risk of de novo Malignancies in Solid Organ Transplant Patients

De novo malignancies constitute an emerging cause of morbidity after solid organ transplant (SOT), significantly affecting the long-term survival of transplant recipients. Pharmacologic immunosuppression may functionally impair the immunosurveillance in these patients, thereby increasing the risk of cancer development. Nevertheless, the multiplicity and heterogeneity of the immune effects induced by immunosuppressive drugs limit the current possibilities to reliably predict the risk of de novo malignancy in SOT patients. Therefore, there is the pressing need to better characterize the immune dysfunctions induced by the different immunosuppressive regimens administered to prevent allograft rejection to tailor more precisely the therapeutic schedule and decrease the risk of de novo malignancies. We herein highlight the impact exerted by different classes of immunosuppressants on the most relevant immune cells, with a particular focus on the effects on dendritic cells (DCs), the main regulators of the balance between immunosurveillance and tolerance.

Drug and chemical induced photosensitivity from a clinical perspective

Drug photosensitivity is a relatively common occurrence and a range of mechanisms may be involved. Some of these mechanisms will be discussed, including the most common, that of drug phototoxicity. Different types of photosensitivity are addressed with respect to clinical presentation, mechanisms and additionally the contribution to our understanding through clinically directed investigations and regulatory requirements. Repeated controlled therapeutic use of drug phototoxicity, with psoralen-UVA (PUVA) photochemotherapy and photodynamic therapy (PDT) will also be discussed. Finally, the potential for drug-induced photocarcinogenesis will also be covered.

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.

Cutaneous complications of immunosuppression in 812 transplant recipients: a 40-year single center experience

BACKGROUND

As a consequence of the improvement in survival after solid organ transplantation, to visit transplant recipients with neoplastic and non-neoplastic skin disorders due to immunosuppressive treatment has become common for dermatologists.

METHODS

Our endpoints were: 1) to investigate the most common skin diseases in a population of transplant recipients; 2) their associations with the type of immunosuppressant or transplant received; and 3) to compare our single center 40-year experience with the literature data. We retrospectively analyzed the clinical details of the adult patients transplanted in the years 1974-2014, visited for consultation at the Unit of Dermatology of our hospital.

RESULTS

Pathologic conditions were observed in more than 3/4 of 812 adults during the follow-up (mean 12.1 years): nonmelanoma skin cancers or actinic keratoses were seen in 44.0% (N.=357) of patients, non-neoplastic events in 55.2% (N.=448). Heart transplant had the statistically significant highest rate of NMSC and AK (52.6%, P=0.0352). Patients receiving cyclosporine A developed at least one non-melanoma skin cancer or actinic keratosis in 57.7% of cases (P=0.0001), while tacrolimus showed a lower risk (33%, P=0.0001).

CONCLUSIONS

As transplant recipients are susceptible to skin changes, especially after immunosuppressant treatments, a dermatological follow-up should be scheduled for each patient.

Comprehensive review of post-organ transplant hematologic cancers

A higher risk for a variety of cancers is among the major complications of posttransplantation immunosuppression. In this part of a continuing series on cancers posttransplantation, this review focuses on the hematologic cancers after solid organ transplantation. Posttransplantation lymphoproliferative disorders (PTLDs), which comprise the great majority of hematologic cancers, represent a spectrum of conditions that include, but are not limited to, the Hodgkin and non-Hodgkin lymphomas. The oncogenic Epstein-Barr virus is a key pathogenic driver in many PTLD cases, through known and unknown mechanisms. The other hematologic cancers include leukemias and plasma cell neoplasms (multiple myeloma and plasmacytoma). Clinical features vary across malignancies and location. Preventive screening strategies have been attempted mainly for PTLDs. Treatments include the chemotherapy regimens for the specific cancers, but also include reduction of immunosuppression, rituximab, and other therapies.

Long-term Change in the Risk of Skin Cancer After Organ Transplantation: A Population-Based Nationwide Cohort Study

Importance

The high risk of skin cancer after organ transplantation is a major clinical challenge and well documented, but reports on temporal trends in the risk of posttransplant cutaneous squamous cell carcinoma (SCC) are few and appear contradictory.

Objective

To study temporal trends for the risk of skin cancer, particularly SCC, after organ transplantation.

Design, Setting, and Participants

Population-based, nationwide, prospective cohort study of 8026 patients receiving a kidney, heart, lung, or liver transplant in Norway from 1968 through 2012 using patient data linked to a national cancer registry. The study was conducted in a large organ transplantation center that serves the entire Norwegian population of approximately 5.2 million.

Exposures

Receiving a solid organ transplant owing to late-stage organ failure, followed by long-term immunosuppressive treatment according to graft-specific treatment protocols.

Main Outcomes and Measures

Occurrence of first posttransplant SCC, melanoma, or Kaposi sarcoma of the skin. Risk of skin cancer was analyzed using standardized incidence ratios (SIRs) and, for SCC, multivariable Poisson regression analysis of SIR ratios, adjusting for 5-year time period of transplantation, different follow-up time, age, sex, and type of organ.

Results

The study cohort included 8026 organ transplant recipients, 5224 men (65.1%), with a mean age at transplantation of 48.5 years. Median follow-up time was 6.7 years per recipient; total follow-up time, 69 590 person-years. The overall SIRs for SCC, melanoma, and Kaposi sarcoma were 51.9 (95% CI, 48.4-55.5), 2.4 (95% CI, 1.9-3.0), and 54.9 (95% CI, 27.4-98.2), respectively. In those who underwent transplantation in the 1983-1987 period, the unadjusted SIR for SCC was 102.7 (95%, 85.8-122.1), declining to 21.6 (95% CI, 16.8-27.0) in those who underwent transplantation in the 2003-2007 period. Adjusting for different follow-up times and background population risks, as well as age, graft organ, and sex, a decline in the SIR for SCC was found, with SIR peaking in patients who underwent transplantation in the 1983-1987 period and later declining to less than half in patients who underwent transplantation in the 1998-2002, 2003-2007, and 2008-2012 periods, with the relative SIRs being 0.42 (95% CI, 0.32-0.55), 0.31 (95% CI, 0.22-0.42), and 0.44 (95% CI, 0.30-0.66), respectively.

Conclusions and Relevance

The risk of SCC after organ transplantation has declined significantly since the mid-1980s in Norway. Less aggressive and more individualized immunosuppressive treatment and close clinical follow-up may explain the decline. Still, the risk of SCC in organ transplant recipients remains much higher than in the general population and should be of continuous concern for dermatologists, transplant physicians, and patients.

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.

Risk of Second Malignancies in Solid Organ Transplant Recipients Who Develop Keratinocyte Cancers

Solid organ transplant recipients have increased risk for developing keratinocyte cancers, including cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), in part as a result of immunosuppressive medications administered to prevent graft rejection. In the general population, keratinocyte cancers are associated with increased risks of subsequent malignancy, however, the risk in organ transplant populations has not been evaluated. We addressed this question by linking the U.S. Scientific Registry of Transplant Recipients, which includes data on keratinocyte cancer occurrence, with 15 state cancer registries. Risk of developing malignancies after keratinocyte cancer was assessed among 118,440 Caucasian solid organ transplant recipients using multivariate Cox regression models. Cutaneous SCC occurrence (n = 6,169) was associated with 1.44-fold increased risk [95% confidence interval (CI), 1.31-1.59] for developing later malignancies. Risks were particularly elevated for non-cutaneous SCC, including those of the oral cavity/pharynx (HR, 5.60; 95% CI, 4.18-7.50) and lung (HR, 1.66; 95% CI, 1.16-2.31). Cutaneous SCC was also associated with increased risk of human papillomavirus-related cancers, including anal cancer (HR, 2.77; 95% CI, 1.29-5.96) and female genital cancers (HR, 3.43; 95% CI, 1.44-8.19). In contrast, BCC (n = 3,669) was not associated with overall risk of later malignancy (HR, 0.98; 95% CI, 0.87-1.12), including any SCC. Our results suggest that transplant recipients with cutaneous SCC, but not BCC, have an increased risk of developing other SCC. These findings somewhat differ from those for the general population and suggest a shared etiology for cutaneous SCC and other SCC in the setting of immunosuppression. Cutaneous SCC occurrence after transplantation could serve as a marker for elevated malignancy risk. Cancer Res; 77(15); 4196-203. ©2017 AACR.

Non-melanoma skin cancer in Portuguese kidney transplant recipients - incidence and risk factors

BACKGROUND

Cancer is currently among the three leading causes of death after solid organ transplantation and its incidence is increasing. Non-melanoma skin cancer - squamous cell carcinoma and basal cell carcinoma - is the most common malignancy found in kidney transplant recipients (KTRs). The incidence of non-melanoma skin cancer in KTRs has not been extensively studied in Portugal.

OBJECTIVES

To determine the incidence of non-melanoma skin cancer in KTRs from the largest Portuguese kidney transplant unit; and to study risk factors for non-melanoma skin cancer.

METHODS

Retrospective analysis of clinical records of KTRs referred for the first time for a dermatology consultation between 2004 and 2013. A case-control study was performed on KTRs with and without non-melanoma skin cancer.

RESULTS

We included 288 KTRs with a median age at transplantation of 47 years, a male gender predominance (66%) and a median transplant duration of 3.67 years. One fourth (n=71) of KTRs developed 131 non-melanoma skin cancers, including 69 (53%) squamous cell carcinomas and 62 (47%) basal cell carcinomas (ratio squamous cell carcinoma: basal cell carcinoma 1.11), with a mean of 1.85 neoplasms per patient. Forty percent of invasive squamous cell carcinomas involved at least two clinical or histological high-risk features. The following factors were associated with a higher risk of non-melanoma skin cancer: an older age at transplantation and at the first consultation, a longer transplant duration and the presence of actinic keratosis. KTRs treated with azathioprine were 2.85 times more likely to develop non-melanoma skin cancer (p=0.01).

CONCLUSION

Non-melanoma skin cancer was a common reason for dermatology consultation in Portuguese KTRs. It is imperative for KTRs to have access to specialized dermatology consultation for early referral and treatment of skin malignancies.

Immunosuppressive Medications and Squamous Cell Skin Carcinoma: Nested Case-Control Study Within the Skin Cancer after Organ Transplant (SCOT) Cohort

Organ transplant recipients (OTRs) have a substantially elevated risk of squamous cell skin carcinoma (SCSC), largely attributed to immunosuppressive medications used to prevent graft rejection, although data to support the role of newer drugs in SCSC risk are sparse. We investigated the association between immunosuppressive medications and SCSC risk among cardiac and renal transplant recipients in the SCOT cohort study. Incident cases were ascertained through medical record review after self-report of skin biopsy (n = 170). Controls without SCSC (n = 324) were matched to cases on sex, age, race, transplant year, hospital, donor type, organ transplanted, and time between transplantation and interview. Conditional logistic regression was used to evaluate the association between specific medications and SCSC. Users of the antimetabolite azathioprine were more than twice as likely to develop SCSC (odds ratio [OR] = 2.67, 95% confidence interval [CI] 1.23-5.76). In contrast, the newer antimetabolite preparations (i.e., mycophenolic acid [MPA]) were associated with lower SCSC risk (OR = 0.45, 95% CI 0.29-0.69). This inverse association between MPA and SCSC persisted among OTRs with no history of azathioprine use, even after adjustment for simultaneous use of the calcineurin inhibitor tacrolimus (OR = 0.52, 95% CI 0.32-0.84). Our data suggest that the increased risk of SCSC historically associated with azathioprine is not seen in OTRs prescribed newer regimens, including MPA and tacrolimus.

High azathioprine dose and lip cancer risk in liver, heart, and lung transplant recipients: A population-based cohort study

BACKGROUND

Iatrogenic immunosuppression is a risk factor for lip cancer but the determinants are unknown.

OBJECTIVE

We sought to quantify the association between the type, dose, and duration of iatrogenic immunosuppression and lip cancer risk in solid organ transplant recipients.

METHODS

We conducted a population-based cohort study of all adult Australian liver, heart, and lung transplant recipients from 1984 to 2006 (n = 4141). We abstracted longitudinal data from medical records and ascertained incident lip cancer (n = 58) and deaths (n = 1434) by linkage with national registries. We estimated multivariable hazard ratios (HR) for lip cancer using the Fine and Gray proportional subdistribution hazards model, accounting for death as a competing risk.

RESULTS

Lip cancer risk (n = 58) increased with high mean daily dose of azathioprine (HR 2.28, 95% confidence interval [CI] 1.18-4.38), longer duration of immunosuppression (HR 9.86, 95% CI 2.10-46.3), increasing year of age at transplantation (HR 1.14, 95% CI 1.04-1.25), earlier transplantation era (HR 8.73, 95% CI 1.11-68.7), and history of smoking (HR 2.71, 95% CI 1.09-6.70).

LIMITATIONS

Data on potential confounders such as personal solar ultraviolet radiation exposure were not available.

CONCLUSION

Higher doses of azathioprine increase lip cancer risk, with implications for managing immunosuppressed populations and our understanding of the relationship between solar ultraviolet radiation and lip cancer.

Post-transplantation malignancies: here today, gone tomorrow?

From the early days of transplantation onwards, increased cancer development in transplant recipients, who require immunosuppression to avoid graft rejection, has been recognized. Registry data indicate that approximately 10-30% of deaths are attributed to post-transplant malignancy, with an upward trend in this incidence as more patients have been exposed to chronic lifelong immunosuppression. In this Review, the overall incidence and most frequent types of cancer encountered are summarized, along with information about which transplant recipients are at the greatest risk of malignancy. Reasons for why differences exist in susceptibility to cancer in this patient population are examined, and approaches that might improve our understanding of the options available for reducing the incidence of this adverse effect of immunosuppression are described. Whether anti-rejection drugs have been successful in diminishing overall immunosuppressive burden, and consequently show any promise for decreasing post-transplant malignancies is also discussed. The topic shifts to one class of conventional anti-rejection drugs, the mammalian target of rapamycin (mTOR) inhibitors, which paradoxically have both immunosuppressive and anti-neoplastic properties. The complex activities of mTOR are reviewed in order to provide context for how these seemingly opposing effects are possible, and the latest clinical data on use of mTOR inhibitors in the clinic are discussed. The current and future perspectives on how best to normalize these unacceptably high rates of post-transplantation malignancies are highlighted.

Ingenol Mebutate Signals via PKC/MEK/ERK in Keratinocytes and Induces Interleukin Decoy Receptors IL1R2 and IL13RA2

Squamous cell carcinoma (SCC) is the second most common human skin cancer and the second leading cause of skin cancer-related death. Recently, a new compound, ingenol mebutate, was approved for treatment of actinic keratosis, a precursor of SCC. As the mechanism of action is poorly understood, we have further investigated the mechanism of ingenol mebutate-induced cell death. We elucidate direct effects of ingenol mebutate on primary keratinocytes, patient-derived SCC cells, and a SCC cell line. Transcriptional profiling followed by pathway analysis was performed on ingenol mebutate-treated primary keratinocytes and patient-derived SCC cells to find key mediators and identify the mechanism of action. Activation of the resulting pathways was confirmed in cells and human skin explants and supported by a phosphorylation screen of treated primary cells. The necessity of these pathways was demonstrated by inhibition of certain pathway components. Ingenol mebutate inhibited viability and proliferation of all keratinocyte-derived cells in a biphasic manner. Transcriptional profiling identified the involvement of PKC/MEK/ERK signaling in the mechanism of action and inhibition of this signaling pathway rescued ingenol mebutate-induced cell death after treatment with 100 nmol/L ingenol mebutate, the optimal concentration for the first peak of response. We found the interleukin decoy receptors IL1R2 and IL13RA2 induced by ingenol mebutate in a PKC/MEK/ERK-dependent manner. Furthermore, siRNA knockdown of IL1R2 and IL13RA2 partially rescued ingenol mebutate-treated cells. In conclusion, we have shown that ingenol mebutate-induced cell death is mediated through the PKCδ/MEK/ERK pathway, and we have functionally linked the downstream induction of IL1R2 and IL13RA2 expression to the reduced viability of ingenol mebutate-treated cells.

Skin changes following organ transplantation: an interdisciplinary challenge

BACKGROUND

The immunosuppressants used in transplantation medicine significantly elevate the incidence of neoplasia, particularly in the skin. The cumulative incidence of non-melanocytic skin cancer (NMSC) in renal transplant recipients was 20.5% in a study carried out in German centers. Data on more than 35 000 renal transplant recipients in the USA document a cumulative NMSC incidence of over 7% after 3 years of immunosuppression.

METHOD

The authors selectively review publications obtained by a PubMed search to discuss the incidence of, and major risk factors for, skin tumors and infectious diseases of the skin in immunosuppressed patients.

RESULTS

The main risk factors for skin tumors are age at the time of transplantation, light skin color, previous and present exposure to sunlight, and the type and duration of immunosuppressive treatment. Squamous-cell carcinoma (SCC) is the most common kind of skin tumor in immunosuppressed patients. Human herpesvirus 8 and Merkel-cell polyoma virus also cause neoplasia more often in immunosuppressed patients than in the general population. Surgical excision is the treatment of choice. Actinic keratosis markedly elevates the risk that SCC will arise in the same skin area (odds ratio 18.36, 95% confidence interval 3.03-111). Patients with multiple actinic keratoses can be treated with photodynamic therapy or with acitretin. To lower the skin cancer risk, organ transplant recipients should apply medical screening agents with a sun protection factor of at least 50 to exposed skin areas every day. 55% to 97% of organ transplant recipients have skin infections; these are treated according to their respective types.

CONCLUSION

Squamous-cell carcinoma of the skin adds to the morbidity and mortality of transplant recipients and is therefore among the major oncological challenges in this patient group. Structured concepts for interdisciplinary care enable risk-adapted treatment.

Immune profiling and cancer post transplantation

Half of all long-term (> 10 year) australian kidney transplant recipients (KTR) will develop squamous cell carcinoma (SCC) or solid organ cancer (SOC), making cancer the leading cause of death with a functioning graft. At least 30% of KTR with a history of SCC or SOC will develop a subsequent SCC or SOC lesion. Pharmacological immunosuppression is a major contributor of the increased risk of cancer for KTR, with the cancer lesions themselves further adding to systemic immunosuppression and could explain, in part, these phenomena. Immune profiling includes; measuring immunosuppressive drug levels and pharmacokinetics, enumerating leucocytes and leucocyte subsets as well as testing leucocyte function in either an antigen specific or non-specific manner. Outputs can vary from assay to assay according to methods used. In this review we define the rationale behind post-transplant immune monitoring assays and focus on assays that associate and/or have the ability to predict cancer and rejection in the KTR. We find that immune monitoring can identify those KTR of developing multiple SCC lesions and provide evidence they may benefit from pharmacological immunosuppressive drug dose reductions. In these KTR risk of rejection needs to be assessed to determine if reduction of immunosuppression will not harm the graft.

Skin cancer in solid organ transplant recipients: are mTOR inhibitors a game changer?

While immunosuppressive agents are necessary to prevent the rejection of transplanted organs, and are a great medical success story for protecting against early allograft loss, graft and patient survival over the long term are diminished by side effects from these same drugs. One striking long-term side effect is a high rate of skin cancer development. The skin cancers that develop in transplant recipients tend to be numerous, as well as particularly aggressive, and are therefore a major contributor to morbidity and mortality in transplant recipients. An apparent reason for the high incidence of skin cancer likely relates to suppression of immune surveillance mechanisms, but other more direct effects of certain immunosuppressive drugs are also bound to contribute to cancers of UV-exposed skin. However, over the past few years, evidence has emerged to suggest that one class of immunosuppressants, mammalian target of rapamycin (mTOR) inhibitors, could potentially inhibit skin tumour formation through a number of mechanisms that are still being studied intensively today. Therefore, in light of the high skin cancer incidence in transplant recipients, it follows that clinical trials have been conducted to determine if mTOR inhibitors can significantly reduce these post-transplant skin malignancies. Here, the problem of post-transplant skin cancer will be briefly reviewed, along with the possible mechanisms contributing to this problem, followed by an overview of the relevant clinical trial results using mTOR inhibitors.

Risk of merkel cell carcinoma after solid organ transplantation

BACKGROUND

Solid organ transplant recipients have elevated risks of virus-related cancers, in part because of long-term immunosuppression. Merkel cell carcinoma (MCC) is an aggressive skin cancer recently found to have a viral origin, but little is known regarding the occurrence of MCC after transplant.

METHODS

We linked the US Scientific Registry of Transplant Recipients with data from 15 population-based cancer registries to ascertain MCC occurrence among 189498 solid organ transplant recipients from 1987 to 2009. Risks for MCC following transplantation were compared with the general population using standardized incidence ratios, and Poisson regression was used to compare incidence rates according to key patient and transplant characteristics. All statistical tests were two-sided.

RESULTS

After solid organ transplantation, overall risk of MCC was increased 23.8-fold (95% confidence interval = 19.6 to 28.7, n = 110). Adjusted risks were highest among older recipients, increased with time since transplantation, and varied by organ type (all P ≤ .007). Azathioprine, cyclosporine, and mTOR inhibitors given for maintenance immunosuppression increased risk, and non-Hispanic white recipients on cyclosporine and azathioprine experienced increasing MCC risk with lower latitude of residence (ie, higher ultraviolet radiation exposure, P = .012).

CONCLUSIONS

MCC risk is sharply elevated after solid organ transplant, likely resulting from long-term immunosuppression. Immunosuppressive medications may act synergistically with ultraviolet radiation to increase risk.

Skin cancer evaluation in transplant patients: a physician opinion survey with recommendations

BACKGROUND

Non-melanoma skin cancer is the most common malignancy in transplant patients. However, routine skin cancer evaluation is currently not the standard of care.

OBJECTIVE

To investigate the current barriers among transplant physicians to skin cancer screening in their patients. To provide recommendations for appropriate routine skin surveillance.

METHODS

A web-based survey was conducted among Baylor, Dallas transplant physicians. Thirty-seven of 46 responses were received, and 13 physicians (28%) were classified as "high screeners."

RESULTS

The univariate analysis revealed three main barriers including the perception of difficulty in seeing a dermatologist (p = 0.017), skin cancer evaluation is not an important aspect of transplant care (p = 0.038), and thirdly, the belief that there is insufficient evidence to warrant universal skin cancer screening in transplant patients (p = 0.013). The fully adjusted multivariable analysis resulted in two significant conclusions; the most important predictor was the perceived lack of medical evidence for skin cancer screening.

LIMITATIONS

The small sample size and all responses being from the same institution in Texas.

CONCLUSION

The dermatologic evidence for regular skin cancer screening in transplant patients needs dissemination to our transplant colleagues. This is a significant practice gap which can be appropriately closed by integrating dermatologists into the transplant team.

Risk of melanoma and non-melanoma skin cancer in ulcerative colitis patients treated with thiopurines: a nationwide retrospective cohort

OBJECTIVES

There are limited data on the risk of non-melanoma skin cancer (NMSC) and melanoma skin cancer (MSC) among thiopurine-treated patients with ulcerative colitis (UC). Our aim was to investigate the risk while on, by cumulative years, and after stopping thiopurine therapy.

METHODS

Nationwide data were obtained from the Veterans Affairs (VA) health-care system during 2001-2011. We performed a retrospective cohort study evaluating patients with UC. Cox regression was used to investigate the association between thiopurines use and time to NMSC while adjusting for demographics, ultraviolet radiation exposure, and VA visiting frequency. A matched nested case-control study was conducted to investigate the association between thiopurine use and MSC.

RESULTS

We included 14,527 patients with UC in the analysis, with a median follow-up of 8.1 years. A total of 3,346 (23%) patients used thiopurines for a median duration of 1.6 years. We identified 421 NMSC and 45 MSC cases. The adjusted hazard ratios of developing NMSC while on and after stopping thiopurines were 2.1 (P<0.0001) and 0.7 (P=0.07), respectively, as compared with unexposed patients. The incidence rate of NMSC among those who never used thiopurines was 3.7 compared with 5.8, 7.9, 8.3, 7.8, and 13.6 per 1,000 person-years for the 1st, 2nd, 3th, 4th, and 5th year of thiopurine use, respectively. No statistically significant association was observed between thiopurine use and MSC, odds ratio 0.8 (P=0.6).

CONCLUSIONS

In this predominantly white male nationwide cohort, there was a twofold increase in the risk of NMSC while on thiopurines. The incidence rate of NMSC significantly increased with subsequent years of cumulative exposure to thiopurines. Stopping thiopurines reduced the risk of NMSC to pre-exposure levels irrespective of the prior exposure duration.

Protein oxidation and DNA repair inhibition by 6-thioguanine and UVA radiation

Damage to skin DNA by solar UV is largely unavoidable, and an optimal cellular response to it requires the coordinated operation of proteins in numerous pathways. A fully functional DNA repair proteome for removing harmful DNA lesions is a prerequisite for an appropriate DNA damage response. Genetically determined failure to repair UV-induced DNA damage is associated with skin photosensitivity and increased skin cancer risk. Patients treated with immunosuppressant/anti-inflammatory thiopurines are also photosensitive and have high rates of sun-related skin cancer. Their DNA contains the base analog 6-thioguanine (6-TG), which acts as a UVA photosensitizer to generate reactive oxygen species (ROS), predominantly singlet oxygen ((1)O2). ROS damage both DNA and proteins. Here we show that UVA irradiation of cultured human cells containing DNA 6-TG causes significant protein oxidation and damages components of the DNA repair proteome, including the Ku, OGG-1, MYH, and RPA proteins. Assays of DNA repair in intact cells or in cell extracts indicate that this protein damage compromises DNA break rejoining and base and nucleotide excision repair. As these experimental conditions simulate those in the skin of patients taking thiopurines, our findings suggest a mechanism whereby UVA in sunlight may contribute to skin carcinogenesis in immunosuppressed patients.

The oncogene ATF3 is potentiated by cyclosporine A and ultraviolet light A

Cutaneous squamous cell carcinoma (SCC) represents the most important cutaneous complication following organ transplantation. It develops mostly on sun-exposed areas. A recent study showed the role of activating transcription factor 3 (ATF3) in SCC development following treatment with calcineurin inhibitors. It has been reported that ATF3, which may act as an oncogene, is under negative calcineurin/nuclear factor of activated T cells (NFAT) control and is upregulated by calcineurin inhibitors. Still, these findings do not fully explain the preferential appearance of SCC on chronically sun-damaged skin. We analyzed the influence of UV radiation on ATF3 expression and its potential role in SCC development. We found that ATF3 is a specifically induced AP1 member in SCC of transplanted patients. Its expression was strongly potentiated by combination of cyclosporine A and UVA treatment. UVA induced ATF3 expression through reactive oxygen species-mediated nuclear factor erythroid 2-related factor 2 (NRF2) activation independently of calcineurin/NFAT inhibition. Activated NRF2 directly binds to ATF3 promoter, thus inducing its expression. These results demonstrate two mechanisms that independently induce and, when combined together, potentiate the expression of ATF3, which may then force SCC development. Taking into account the previously defined role of ATF3 in the SCC development, these findings may provide an explanation and a mechanism for the frequently observed burden on SCCs on sun-exposed areas of the skin in organ transplant recipients treated by calcineurin inhibitors.

[Phototherapy and carcinogenesis]

Phototherapy successfully uses the short-term effects of ultraviolet light against inflammation and proliferation. For its long-term effects, however, ultraviolet light was recently classified as a carcinogen. The wave spectrum employed in phototherapy has various carcinogenic effects in experimental systems, most notably DNA mutations in keratinocytes. Clinically, PUVA increases the risk for squamous cell carcinoma of the skin, especially after following 350 or more phototherapy sessions over a lifetime. Melanoma and genital skin cancer are not increased by PUVA alone. Previous UV damage, immunosuppression and other systemic treatments increase cutaneous carcinogenesis through PUVA. In contrast, broad-band UVB, narrow-band UVB and UVA1 have not yet been linked to cutaneous carcinogenesis, but will need careful follow-up in larger studies. Phototherapy remains a safe treatment modality, provided that the indication is well-founded, previous exposure and co-carcinogens are considered, and short and dose-intensive treatment protocols are favored, PUVA is chosen as second-line treatment that should not be used for more than a lifetime total of 250-300 phototherapy sessions.

Photosensitizing medications and photocarcinogenesis

Photosensitivity is an exaggerated or abnormal response to ultraviolet (UV) or visible light exposure. Many current medications are known photosensitizers; however, the effects of the sensitization can be subclinical and go unnoticed by the person affected. While some of these drugs are used for short and defined periods, others are used indefinitely for the treatment of chronic disease. The question of whether either of these practices translates into an increased risk of skin cancer is an important one. Numerous medications have real, distinct and well-elucidated mechanisms that potentiate the development of skin cancer, while with some medications the mechanism for the observed carcinogenesis remains unclear. In this article we will discuss the clinical, mechanistic and epidemiological evidence supporting photochemical genotoxicity and carcinogenesis.

Skin cancer in organ transplant recipients

Organ transplant recipients (OTR) are at a significantly increased risk for developing a wide variety of skin cancers, particularly epithelial skin cancer, Merkel cell carcinoma and Kaposi's sarcoma. Melanoma, skin adnexal neoplasm and cutaneous lymphomas are also more common in OTR and may differ in their clinicopathologic presentation from tumors in immunocompetent patients. The accuracy of clinical diagnosis of suspected premalignant and malignant skin lesions in OTR is modest. Therefore, histopathological diagnosis is an essential element for the diagnostic workup of skin cancers and, in addition, provides important information on prognosis. Squamous cell carcinoma and intraepithelial neoplasias (actinic keratosis, squamous cell carcinoma in situ or Bowen's disease) are the most common forms of skin cancer in OTR. The risk of Merkel cell carcinoma and Kaposi's sarcoma is dramatically increased in OTR. Merkel cell carcinoma shows a highly aggressive course. Kaposi's sarcoma tends to spread to extracutaneous sites. Primary cutaneous lymphomas developing after organ transplantation are rare. The spectrum of cutaneous B cell lymphomas in OTR, in particular, differs significantly from that of the general population, with a predominance of Epstein-Barr virus-driven posttransplant lymphoproliferative disorder. This review discusses the clinical and histopathological aspects of skin cancers in OTR, the impact of dermatopathological analysis on prognosis and the understanding of the pathogenesis of these neoplasms.