Risk of nonmelanoma skin cancer with azathioprine use

Immunosuppressive therapy management in cancer patients with autoimmune diseases treated with immune checkpoint inhibitors: A case series and systematic literature review

INTRODUCTION

Prescribing immune checkpoint inhibitors (ICIs) to cancer patients with an autoimmune disease (AID) is presumed safe when cautious adverse event management is applied. However, guidelines on immunosuppressant (IS) adaptations are limited and real-world evidence is scarce.

METHODS

Current practice of IS adaptations is described in a case series of AID patients treated with ICIs in a tertiary university hospital in Belgium (1/1/2016-31/12/2021). Patient, drug and disease-related data were documented using retrospective chart review. A systematic search of the PubMed database was performed to identify similar cases (1/1/2010-30/11/2022).

RESULTS

Sixteen patients were described in the case series (62% with active AID). Systemic IS were changed before ICI initiation in 5/9 patients. Four patients continued therapy, of which one achieved partial remission. Patients who had IS (partially) stopped before ICI start (n = 4) had AID flares in two cases; immune-related adverse events in three cases. In the systematic review, 37 cases were identified in 9 articles. Corticosteroids (n = 12) and non-selective IS (n = 27) were continued in, respectively, 66% and 68% of patients. Methotrexate was frequently discontinued (13/21). Biologicals, excluding tocilizumab and vedolizumab, were withheld during ICI treatment. Out of all patients with flares (n = 15), 47% had stopped IS therapy before ICI start and 53% had continued their AID drugs.

CONCLUSIONS

A detailed overview of IS management in patients with AID receiving ICI therapy is presented. Expanding the knowledge base germane to IS management with ICI therapy in the diverse population is essential to evaluate their mutual impact, thus advancing responsible patient care.

Cutaneous Lupus Erythematosus: Review and Considerations for Older Populations

Though more common earlier in life, increasing attention is being focused on the development of cutaneous lupus erythematosus (CLE) in patients with advancing age. Studies show that CLE is more common in older populations than previously thought, and all CLE subtypes are possible in this group. Just like patients in the third or fourth decade of life, CLE may appear alongside or independent of systemic lupus erythematosus. Older populations manifesting CLE for the first time seem to have a lower risk of progression to systemic disease than younger peers, and are more commonly White. CLE must be carefully distinguished from other skin conditions that have a predilection for presentation in older populations, including rosacea, lichen planus, and other autoimmune conditions such as dermatomyositis or pemphigus/pemphigoid. It is thought that most CLE in older populations is drug-induced, with drug-induced subacute cutaneous lupus erythematosus being the most common subtype. Management of CLE in older patients focuses on eliminating unnecessary medications known to induce CLE, and otherwise treatment proceeds similarly to that in younger patients, with a few special considerations.

Advances and controversies in studying sunscreen delivery and toxicity

This review critically evaluates the sunscreen delivery and toxicity field. We chose to focus on approved sunscreens in this review. Optimal sunscreen use prevents skin cancer and photoageing but there is an important knowledge gap in sunscreen/skin interactions. Sunscreen delivery is a key for efficacy, but studying sunscreen delivery is not straightforward. We review the strengths and weaknesses of in vitro, excised skin and clinical approaches. Understanding positive and negative sunscreen effects on skin homeostasis is also challenging. The results in this field, especially in vitro testing, are controversial and experimental design varies widely which further supports disparities between some findings. We hypothesize that bias towards showing sunscreen toxicity to increase impact could be problematic. We explore that perception through a detailed review of experimental design, especially in cell culture models. Our conclusion is that emerging, non- and minimally invasive technologies are enabling new approaches to volunteer studies that could significantly improve knowledge of sunscreen delivery and interactions.

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.

Malignancies in Patients with Antineutrophil Cytoplasmic Antibody-associated Vasculitis: A Population-based Cohort Study

OBJECTIVE

Patients with ANCA-associated vasculitides (AAV) exhibit higher rates of malignancy than the general population. We assessed whether the cancer risk is increased in a well-characterized population-based cohort of AAV in southern Sweden, followed for a median time of 8 years.

METHODS

With case record review, the outcomes and malignancy development in a cohort of 195 patients with AAV [granulomatosis with polyangiitis (GPA), microscopic polyangiitis, and eosinophilic GPA] diagnosed between 1997 and 2010 were assessed. The patients were followed until death or December 31, 2015. The age- and sex-standardized incidence ratios (SIR) were estimated using the Swedish population data as a reference.

RESULTS

During the observation period of about 1500 person-years, we found 60 cancers in 52 of the 195 patients. SIR (95% CI) was 2.8 (2.1-3.6) for cancers at all sites, 1.8 (1.3-2.5) for all cancers excluding squamous cell carcinoma (SCC), 12.9 (8.4-18.8) for SCC, 4.3 (1.4-10.0) for bladder cancer, and 7.0 (1.4-20.5) for pancreatic cancer. Cumulative doses of cyclophosphamide (CYC) < 10 g were not associated with higher incidence of cancers other than SCC (SIR 1.63, 95% CI 0.8-2.9).

CONCLUSION

In contrast to previous publications assessing malignancy risk in patients with AAV, we show in this population-based cohort of patients a persistent increased risk for overall malignancy, bladder cancer, and pancreatic cancer as well as a markedly increased risk for SCC. There was no increase in incidence of cancers other than SCC for those treated with < 10 g CYC.

Clinical and Genetic Factors Associated with Cutaneous Squamous Cell Carcinoma in Kidney and Heart Transplant Recipients

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) occurs with higher frequency and recurrence rates, increased morbidity and mortality, and more aggressive metastasis in kidney and heart transplant recipients compared to the general population but all transplant recipients do not develop cSCC. In addition, the phenotypic expression of cSCC among transplant recipients can vary between mild disease to extensive recurrent metastatic disease. These clinically observed differences in occurrence and severity of cSCC among transplant recipients suggest the possibility that an underlying genetic component might modify risk.

METHODS

We identified 88 white post-transplant cSCC cases (71 kidney and 17 heart) and 300 white post-transplant controls (265 kidney and 35 heart) using a DNA biobank linked with de-identified electronic medical records. Logistic regression was used to determine adjusted odds ratios (OR) for clinical characteristics and single nucleotide polymorphisms (SNP) associated with cSCC in both a candidate SNP and genome wide analysis.

RESULTS

Age (OR 1.08 [1.05-1.11], p<0.001) and azathioprine exposure (OR 8.64 [3.92-19.03], p<0.001) were significantly associated while gender, smoking tobacco use, dialysis duration and immunosuppression duration were not. Ten candidate SNPs previously associated with non-melanoma skin cancer in the general population were significantly associated with cSCC in transplant recipients. Genome wide association analysis implicated SNPs in genes previously associated with malignancy, CSMD1 (OR 3.14 [1.90-5.20]) and CACNA1D (OR 2.67 [1.73-4.10]).

CONCLUSIONS

This study shows an association of increasing age and azathioprine exposure with cSCC and confirms a genetic contribution for cSCC development in kidney and heart transplant recipients.

Glutathione transferases in the bioactivation of azathioprine

The prodrug azathioprine is primarily used for maintaining remission in inflammatory bowel disease, but approximately 30% of the patients suffer adverse side effects. The prodrug is activated by glutathione conjugation and release of 6-mercaptopurine, a reaction most efficiently catalyzed by glutathione transferase (GST) A2-2. Among five genotypes of GST A2-2, the variant A2*E has threefold-fourfold higher catalytic efficiency with azathioprine, suggesting that the expression of A2*E could boost 6-mercaptopurine release and adverse side effects in treated patients. Structure-activity studies of the GST A2-2 variants and homologous alpha class GSTs were made to delineate the determinants of high catalytic efficiency compared to other alpha class GSTs. Engineered chimeras identified GST peptide segments of importance, and replacing the corresponding regions in low-activity GSTs by these short segments produced chimeras with higher azathioprine activity. By contrast, H-site mutagenesis led to decreased azathioprine activity when active-site positions 208 and 213 in these favored segments were mutagenized. Alternative substitutions indicated that hydrophobic residues were favored. A pertinent question is whether variant A2*E represents the highest azathioprine activity achievable within the GST structural framework. This issue was addressed by mutagenesis of H-site residues assumed to interact with the substrate based on molecular modeling. The mutants with notably enhanced activities had small or polar residues in the mutated positions. The most active mutant L107G/L108D/F222H displayed a 70-fold enhanced catalytic efficiency with azathioprine. The determination of its structure by X-ray crystallography showed an expanded H-site, suggesting improved accommodation of the transition state for catalysis.

Hepatocellular and extrahepatic cancer in patients with autoimmune hepatitis--a long-term follow-up study in 634 Swedish patients

OBJECTIVES

Cirrhosis is a well-known risk factor for hepatocellular cancer, but the true risk in autoimmune hepatitis (AIH) is scarcely studied. Other cancers may arise after prolonged use of immune-modulating drugs. The aim of this study was to investigate the cancer risk in a large cohort of AIH patients.

MATERIAL AND METHODS

Six hundred and thirty-four Swedish patients in a well-defined cohort were matched to the Cause of Death Registry and the Cancer Registry. Standard incidence ratios were calculated by relating the incidences in the cohort to an age-matched material from the Swedish background population.

RESULTS

A higher overall incidence of malignancies than the background population was found, counting from the date of diagnosis (standard incidence ratio (SIR) 2.08, 95% CI 1.68-2.55). The highest risk was found for hepatocellular carcinoma (HCC). We found 10 cases (4.0%) in 248 patients with cirrhosis, which gives an incidence rate of 0.3%. Standard incidence ratio for developing hepatobiliary cancer was 54.55 (95% CI 19.92-99.99). HCC only occurred in cirrhotic patients. There was also an increased risk for non-melanoma skin cancer (SIR 9.87, 95% CI 6.26-14.81).

CONCLUSION

A slightly enhanced risk for malignancies in general compared to the background population was found. The risk of hepatobiliary cancer was increased, but the annual risk over the observational period was well under the postulated 1.5% when surveillance in cirrhotic patients is considered to be cost-effective.

Malignancies in inflammatory bowel disease

Patients with inflammatory bowel diseases (IBDs) are at increased risk of colorectal cancer (CRC), but the risk varies between different studies and seems to be decreasing. The cumulative risk of CRC has been reported to be 1%, 2%, and 5% after 10, 20, and over 20 years of disease duration, respectively, in recent meta-analysis. Disease duration and grade of inflammation are the main driving forces of dysplasia and CRC development. Also, the risk of extraintestinal cancers is increased in IBD, where the degree of immunosuppression and its duration are the most important risk factors. Most important extraintestinal malignancies are lymphomas and non-melanoma skin cancers, both of which are increased in patients receiving thiopurines. Also, extraintestinal manifestations or concomitant diseases such as primary sclerosing cholangitis predispose IBD patients to malignancies such as cholangiocarcinoma. History of previous cancer increases the risk of developing either new or recurrent cancers and should be taken into account when choosing therapy and planning surveillance. Dysplasia and cancer screening and surveillance must be individualized according to patients' risk factors. Malignancies are the second most common cause of death after cardiovascular diseases in both genders in patients with IBD.

Risk of malignancies in patients with inflammatory bowel disease treated with thiopurines or anti-TNF alpha antibodies

PURPOSE

We aimed to analyse malignancy rates and predictors for the development of malignancies in a large German inflammatory bowel disease (IBD) cohort treated with thiopurines and/or anti-tumour necrosis factor (TNF) antibodies.

METHODS

De novo malignancies in 666 thiopurine-treated and/or anti-TNF-treated IBD patients were analysed. Patients (n = 262) were treated with thiopurines alone and never exposed to anti-TNF antibodies (TP group). In addition, patients (n = 404) were exposed to anti-TNF antibodies (TNF+ group) with no (7.4%), discontinued (80.4%) or continued (12.1%) thiopurine therapy.

RESULTS

In the TP group, 20 malignancies were observed in 18 patients compared with 8 malignancies in 7 patients in the TNF+ group (hazard ratio 4.15; 95% CI 1.82-9.44; p = 0.0007; univariate Cox regression). Moreover, 18.2% of all patients in the TP group ≥50 years of age developed a malignancy, compared with 3.8% of all patients <50 years of age (p = 0.0008). In the TNF+ group, 6.5% of all patients ≥50 years of age developed malignancies compared with 0.3% of all patients <50 years of age (p = 0.0007). In both groups combined, thiopurine treatment duration ≥4 years was associated with the risk for skin cancer (p = 0.0024) and lymphoma (p = 0.0005).

CONCLUSIONS

Our data demonstrate an increased risk for the development of malignancies in IBD patients treated with thiopurines in comparison with patients treated with anti-TNF antibodies with or without thiopurines.

Drug therapies and the risk of malignancy in Crohn's disease: results from the TREAT™ Registry

OBJECTIVES

We assessed potential associations between malignancy and antitumor necrosis factor therapy in patients with Crohn's disease (CD), as this relationship is currently poorly defined.

METHODS

Utilizing data from the Crohn's Therapy, Resource, Evaluation, and Assessment Tool (TREAT™) Registry, a prospective cohort study examining long-term outcomes of CD treatments in community and academic settings, influences of baseline patient/disease characteristics and medications were assessed by survival analysis and multivariate models. Standardized incidence ratios and exact 95 % confidence intervals were determined as the ratio of events observed (TREAT) vs. expected (general population of USA).

RESULTS

As of 23 February 2010, 6,273 CD patients (infliximab during registry=3,420 (during or within 1 year before registry=3,764); other-treatments-only: 2,509), were enrolled and, on average, had been followed for 5.2/7.6 years, respectively, for all/currently active patients. Crude cancer incidences were similar between infliximab- and other-treatments-only-exposed patients. Multivariate Cox regression analysis demonstrated that baseline age (hazard ratio (HR)=1.59/10 years; P<0.001), disease duration (HR=1.64/10 years; P=0.012), and smoking (HR=1.38; P=0.045) but neither immunosuppressive therapy alone (HR=1.43; P=0.11), infliximab therapy alone (HR=0.59; P=0.16), nor their combination (HR=1.22, P=0.34) were independently associated with the risk of malignancy. When compared with the general population, no significant increase in incidence was observed in any malignancy category. In an exposure-based analysis, use of immunosuppressants alone (odds ratio=4.19) or in combination with infliximab (3.33) seemed to be associated with a numerically, but not significantly, greater risk of malignancy than did treatment with infliximab alone (1.96) relative to treatment with neither.

CONCLUSIONS

In the TREAT Registry, age, disease duration, and smoking were independently associated with increased risk of malignancy. Although results for immunosuppressant use were equivocal, no significant association between malignancy and infliximab was observed.

Melatonin's protective effect against UV radiation: a systematic review of clinical and experimental studies

BACKGROUND

Ultraviolet (UV) radiation is the main etiologic factor for skin cancer. The endogenous hormone melatonin has been proposed to have protective effects against sunlight.

AIM

The aim of this review was to evaluate melatonin's protective effects against UV radiation and to clarify the cellular mechanisms behind this effect.

METHOD

Medline, Embase and Cinahl were searched up to January 2013 to identify studies evaluating melatonin's protective effect against UV radiation (UVR)-induced skin erythema in humans and damage on a cellular level.

RESULTS

Four human studies have investigated melatonin's protective effect on UVR-induced skin damage. Melatonin was shown to have protective effects when applied before UVR, but no effect if applied after exposure. A total of 16 experimental studies evaluated melatonin's protective effect against UVR-induced damage to cellular structures and pathways.

DISCUSSION/CONCLUSION

The protection against UVR-induced skin damage was conducted by melatonin acting directly as an antioxidant, and indirectly by regulating gene expression and inducing a DNA stabilizing effect. As these results were obtained using artificial UVR and without investigating possible side effects, studies using natural sunlight and evaluating possible side effects of topical melatonin administration are warranted.

Review article: dermatological complications of immunosuppressive and anti-TNF therapy in inflammatory bowel disease

BACKGROUND

With the expanding list of medications available to treat patients with inflammatory bowel disease (IBD), it is important to recognise adverse events, including those involving the skin. Dermatological adverse events may be confused with extra-intestinal manifestations of IBD.

AIM

To review drug-related dermatological manifestations associated with immunosuppressive and anti-tumour necrosis factor (anti-TNF) therapy.

METHODS

The literature was searched on PubMed for dermatological adverse events in IBD.

RESULTS

Present thiopurine exposure was associated with a 5.9-fold [95% confidence interval (CI), 2.1-16.4] increased risk of developing non-melanoma skin cancer (NMSC). The peak incidence is highest in Caucasians over the age of 65 years with crude incidence rates of 4.0 and 5.7/1000 patient-years for present and previous use. In anti-TNF-exposed subjects, drug-induced lupus was reported in 1% of the cases and a psoriatic rash in up to 3% of the cases. Anti-TNF monotherapy increases the risk of NMSC ~2-fold to a rate of 0.5 cases per 1000 person-years. Cutaneous lymphomas have been rarely reported in subjects on thiopurine or anti-TNF drug monotherapy. Combination therapy seems to have an additive effect on the risk of developing NMSC and lymphoma.

CONCLUSIONS

Physicians need to be aware of the wide spectrum of dermatological complications of immunosuppressive and anti-TNF therapy in IBD, especially psoriasis and non-melanoma skin cancer. Vigilance and regular screening for non-melanoma skin cancer is recommended. Case discussions between gastroenterologists and dermatologists should be undertaken to best manage dermatological adverse events.

Mortality and cancer in pediatric-onset inflammatory bowel disease: a population-based study

OBJECTIVES

Although the incidence of pediatric inflammatory bowel disease (IBD) continues to rise in Northern France, the risks of death and cancer in this population have not been characterized.

METHODS

All patients <17 years, recorded in EPIMAD registry, and diagnosed between 1988 and 2004 with Crohn's disease (CD) or ulcerative colitis (UC) were included. The observed incidences of death and cancer were compared with those expected in the regional general population obtained by French Statistical Institute (INSEE) and the cancer Registry from Lille. Comparisons were performed using Fisher's exact test and were expressed using the standardized mortality ratios (SMRs) and standardized incidence ratios.

RESULTS

A total of 698 patients (538 with CD and 160 with UC) were identified; 360 (52%) were men, the median age at IBD diagnosis was 14 years (12-16) and the median follow-up time was 11.5 years (7-15). During follow-up, the mortality rate was 0.84% (6/698) and did not differ from that in the reference population (SMR=1.4 (0.5-3.0); P=0.27). After a median follow-up of 15 years (10-17), 1.3% of patients (9/698) had a cancer: colon (n=2), biliary tract (cholangiocarcinoma; n=1), uterine cervix (n=1), prepuce (n=1), skin (basal cell carcinoma (n=2), hematological (acute leukemia; n=1), and small bowel carcinoid (n=1). There was a significantly increased risk of cancer regardless of gender and age (standardized incidence ratio=3.0 (1.3-5.9); P<0.02). Four out of nine patients who developed a cancer had received immunosuppressants or anti-tumor necrosis factor-α therapy (including combination therapy in three patients).

CONCLUSIONS

In this large pediatric population-based IBD cohort, mortality did not differ from that of the general population but there was a significant threefold increased risk of neoplasia.

Health supervision in the management of children and adolescents with IBD: NASPGHAN recommendations

Ulcerative colitis (UC) and Crohn disease (CD), collectively referred to as inflammatory bowel disease (IBD), are chronic inflammatory disorders that can affect the gastrointestinal tract of children and adults. Like other autoimmune processes, the cause(s) of these disorders remain unknown but likely involves some interplay between genetic vulnerability and environmental factors. Children, in particular with UC or CD, can present to their primary care providers with similar symptoms, including abdominal pain, diarrhea, weight loss, and bloody stool. Although UC and CD are more predominant in adults, epidemiologic studies have demonstrated that a significant percentage of these patients were diagnosed during childhood. The chronic nature of the inflammatory process observed in these children and the waxing and waning nature of their clinical symptoms can be especially disruptive to their physical, social, and academic development. As such, physicians caring for children must consider these diseases when evaluating patients with compatible symptoms. Recent research efforts have made available a variety of more specific and effective pharmacologic agents and improved endoscopic and radiologic assessment tools to assist clinicians in the diagnosis and interval assessment of their patients with IBD; however, as the level of complexity of these interventions has increased, so too has the need for practitioners to become familiar with a wider array of treatments and the risks and benefits of particular diagnostic testing. Nonetheless, in most cases, and especially when frequent visits to subspecialty referral centers are not geographically feasible, primary care providers can be active participants in the management of their pediatric patients with IBD. The goal of this article is to educate and assist pediatricians and adult gastroenterology physicians caring for children with IBD, and in doing so, help to develop more collaborative care plans between primary care and subspecialty providers.

Highly potent activation of Nrf2 by topical tricyclic bis(cyano enone): implications for protection against UV radiation during thiopurine therapy

Chronic treatment with azathioprine, a highly effective anti-inflammatory and immunosuppressive agent, profoundly increases the risk for development of unusually aggressive cutaneous squamous cell carcinoma. Its ultimate metabolite, 6-thioguanine (6-TG) nucleotide, is incorporated in DNA of skin cells, and upon exposure to UVA radiation, causes oxidative stress, followed by damage of DNA and associated proteins. The acetylenic tricyclic bis(cyano enone) TBE-31 is a strong inhibitor of inflammation and a potent inducer of the Keap1/Nrf2/ARE pathway, which orchestrates the expression of a large network of cytoprotective genes. We now report that long-term (five days per week for four weeks) topical daily applications of small (200 nmol) quantities of TBE-31 cause a robust systemic induction of the Keap1/Nrf2/ARE pathway and decreases the 6-TG incorporation in DNA of skin, blood, and liver of azathioprine-treated mice, indicating extraordinary bioavailability and efficacy. In addition, TBE-31, at nanomolar concentrations, protects cells with 6-TG in their genomic DNA against oxidative stress caused by UVA radiation through induction of the Keap1/Nrf2/ARE pathway. At the same 6-TG DNA levels, Keap1-knockout cells, in which the pathway is constitutively upregulated, are highly resistant to UVA radiation-induced oxidative stress. The protective effects of both the Keap1-knockout genotype and TBE-31 are completely lost in the absence of transcription factor Nrf2. Our findings suggest that compounds of this kind are excellent candidates for mechanism-based chemoprotective agents against conditions in which oxidative stress and inflammation underlie disease pathogenesis. Moreover, their potential skin patch incorporation for transdermal delivery is an exciting possibility.

Increased risk for nonmelanoma skin cancers in patients who receive thiopurines for inflammatory bowel disease

BACKGROUND & AIMS

Patients with inflammatory bowel disease (IBD) who have been exposed to thiopurines might have an increased risk of skin cancer. We assessed this risk among patients in France.

METHODS

We performed a prospective observational cohort study of 19,486 patients with IBD, enrolled from May 2004 to June 2005, who were followed up until December 31, 2007. The incidence of nonmelanoma skin cancer (NMSC) in the general population, used for reference, was determined from the French Network of Cancer Registries.

RESULTS

Before the age of 50 years, the crude incidence rates of NMSC among patients currently receiving or who previously received thiopurines were 0.66/1000 and 0.38/1000 patient-years, respectively; these values were 2.59/1000 and 1.96/1000 patient-years for the age group of 50 to 65 years and 4.04/1000 and 5.70/1000 patient-years for patients older than 65 years. Among patients who had never received thiopurines, the incidence of NMSC was zero before the age of 50 years, 0.60/1000 for the ages of 50 to 65 years, and 0.84/1000 for those older than 65 years. A multivariate Cox regression model stratified by propensity score quintiles showed that ongoing thiopurine treatment (hazard ratio [HR], 5.9; 95% confidence interval [CI], 2.1-16.4; P = .0006) and past thiopurine exposure (HR, 3.9; 95% CI, 1.3-12.1; P = .02) were risk factors for NMSC. They also identified age per 1-year increase as a risk factor for NMSC (HR, 1.08; 95% CI, 1.05-1.11; P < .0001).

CONCLUSIONS

Ongoing and past exposure to thiopurines significantly increases the risk of NMSC in patients with IBD, even before the age of 50 years. These patients should be protected against UV radiation and receive lifelong dermatologic screening.

Oral azathioprine leads to higher incorporation of 6-thioguanine in DNA of skin than liver: the protective role of the Keap1/Nrf2/ARE pathway

Azathioprine is a widely used anti-inflammatory, immunosuppressive, and anticancer agent. However, chronic treatment with this drug is associated with a profoundly increased risk (in certain cases by more than 100-fold) of developing squamous cell carcinoma of the skin. Incorporation of its ultimate metabolite, thio-dGTP, in DNA results in partial substitution of guanine with 6-thioguanine which, combined with exposure to UVA radiation, creates a source of synergistic mutagenic damage to DNA. We now report that oral treatment with azathioprine leads to a much greater incorporation of 6-thioguanine in DNA of mouse skin than liver. These higher levels of 6-thioguanine, together with the fact that the skin is constantly exposed to UV radiation from the sun, may be responsible, at least in part, for the increased susceptibility of this organ to tumor development. Genetic upregulation of the Keap1/Nrf2/ARE pathway, a major cellular regulator of the expression of a network of cytoprotective genes, reduces the incorporation of 6-thioguanine in DNA of both skin and liver following treatment with azathioprine. Similarly, pharmacologic activation of the pathway by the potent inducer sulforaphane results in lower 6-thioguanine incorporation in DNA and protects 6-thioguanine-treated cells against oxidative stress following exposure to UVA radiation. Protection is accompanied by increased levels of glutathione and induction of multidrug resistance-associated protein 4, an organic anion efflux pump that also exports nucleoside monophosphate analogues. Our findings suggest that activation of the Keap1/Nrf2/ARE pathway could reduce the risk for skin cancer in patients receiving long-term azathioprine therapy.

Facial basal cell carcinoma in a young patient with Crohn disease

A 26-year-old man with Crohn disease developed a 10-mm-diameter facial basal cell carcinoma. He was referred to our department, and the tumor was excised with a clear margin. The wound was closed by primary closure, and he made an uneventful postoperative recovery with a satisfactory cosmetic result. Although the increased risk of nonmelanoma skin cancer in immunosuppressed solid organ transplant patients is well known, the association with inflammatory bowel disease remains unclear. There are few articles in the literature on this topic, and the authors believe this to be the first documented case of facial basal cell carcinoma occurring in the context of Crohn disease. Of particular interest is the very young age at presentation.

Nonmelanoma skin cancer in inflammatory bowel disease: a review

At least 1 million new cases of nonmelanoma skin cancer (NMSC) are diagnosed in the United States each year and the incidence is increasing. A higher incidence of NMSC in organ transplant recipients on immunosuppression has been documented for some time, and recent studies indicate that patients with inflammatory bowel disease (IBD), particularly those treated with immunosuppressive medications, might also be at higher risk for this condition. In this review we summarize recent data evaluating the associations between immunomodulators, antitumor necrosis factor-α biologic agents and NMSC in patients with IBD and other autoimmune conditions such as rheumatoid arthritis. We also offer recommendations for prevention of NMSC in these populations.

6-Thioguanine and S⁶-methylthioguanine are mutagenic in human cells

Thiopurines are effective immunosuppressants and anticancer agents. However, the long-term use of thiopurines was found to be associated with a significantly increased risk of various types of cancer. To date, the specific mechanism(s) underlying the carcinogenicity associated with thiopurine treatment remain(s) unclear. Herein, we constructed duplex pTGFP-Hha10 shuttle vectors carrying a 6-thioguanine ((S)G) or S⁶-methylthioguanine (S⁶mG) at a unique site and allowed the vectors to propagate in three different human cell lines. Analysis of the replication products revealed that although neither thionucleoside blocked considerably DNA replication in any of the human cell lines, both (S)G and S⁶mG were mutagenic, resulting in G→A mutation at frequencies of ~8% and ~39%, respectively. Consistent with what was found from our previous study in E. coli cells, our data demonstrated that the mutagenic properties of (S)G and S⁶mG provided significant evidence for mutation induction as a potential carcinogenic mechanism associated with chronic thiopurine intervention.

Critical Review of Preclinical Approaches to Evaluate the Potential of Immunosuppressive Drugs to Influence Human Neoplasia

Many immunosuppressive drugs are associated with an increased risk of B-cell lymphoma, squamous cell carcinoma, and Kaposi sarcoma. Thirteen immunosuppressive drugs have been tested in 2-year carcinogenicity studies (abatacept; azathioprine; busulfan; cyclophosphamide; cyclosporine; dexamethasone; everolimus; leflunomide; methotrexate; mycophenolate mofetil; prednisone; sirolimus; and tacrolimus) and in additional models including neonatal and genetically modified mice; chemical, viral, ultraviolet, and ionizing radiation co-carcinogenesis, and in models with transplanted tumor cells. The purpose of this review is to outline the mechanisms by which immunosuppressive drugs can influence neoplasia, to summarize the available preclinical data on the 13 drugs, and to critically review the performance of the models. A combination of primary tumor and metastasis assays conducted with transplanted cells may provide the highest value for hazard identification and can be applied on a case-by-case basis. However, for both small molecules and therapeutic proteins, determining the relative risk to patients from preclinical data remains problematic. Classifying immunosuppressive drugs based on their mechanism of action and hazard identification from preclinical studies and a prospective pharmacovigilance program to monitor carcinogenic risk may be a feasible way to manage patient safety during the clinical development program and postmarketing.

Overall and cause-specific mortality in Crohn's disease: a meta-analysis of population-based studies

BACKGROUND

An overview of mortality risk among unselected patients with Crohn's disease (CD) is lacking. We therefore performed a systematic review and meta-analysis of population-based studies on overall and cause-specific mortality in CD.

METHODS

MEDLINE (January 1965 to February 2008), abstracts from international conferences and reference lists of selected articles were searched systematically. All articles fulfilling the predefined inclusion criteria were scrutinized for data on population size, time of follow-up, gender, age, and observed to expected deaths. STATA meta-analysis software was used to calculate overall and cause-specific pooled standardized mortality ratios (SMR, observed/expected).

RESULTS

Nine studies were included with overall SMRs ranging from 0.72-3.2, resulting in a significantly increased pooled SMR of 1.39 (95% confidence interval [CI]: 1.30-1.49). Regarding cause-specific mortality, a significantly increased risk of death from cancer (SMR 1.50, 95% CI: 1.18-1.92), in particular of pulmonary cancer (SMR 2.72, 95% CI: 1.35-5.45), as well as chronic obstructive pulmonary disease (SMR 2.55, 95% CI: 1.19-5.47), gastrointestinal diseases (SMR 6.76, 95% CI: 4.37-10.45), and genitourinary diseases (SMR 3.28, 95% CI: 1.69-6.35) was observed.

CONCLUSIONS

Among unselected patients with CD, overall mortality was slightly but significantly higher than in the general population-primarily explained by deaths from gastrointestinal, respiratory, and genitourinary diseases. Notably, mortality from colorectal cancer was not increased.

Mutagenicity and potential carcinogenicity of thiopurine treatment in patients with inflammatory bowel disease

The thiopurines azathioprine and 6-mercaptopurine (6-MP) are effective immune modulators and cytotoxic agents extensively used in the treatment of autoimmune diseases, graft rejection, and cancer. There is compelling epidemiologic evidence that thiopurine treatment increases the risk for a variety of tumors by mechanisms that are unclear. We investigated the in vivo mutagenicity of long-term thiopurine treatment by determining the frequency and spectra of somatic mutation events at the hypoxanthine phosphoribosyltransferase (HPRT) locus in peripheral T lymphocytes as well as the prevalence of mutant clonal proliferation in a cross-sectional analysis of data from 119 children and adults with inflammatory bowel disease (IBD). ANOVA and regression were performed to assess relationships among the frequency and spectra of HPRT mutations with disease, duration of illness, duration of treatment, and total therapeutic dose of azathioprine and 6-MP. We observed a significant increase in the frequency of somatic mutations in 56 subjects treated with thiopurines for IBD compared with 63 subjects not treated with thiopurines. This increase was related to both total dose (P < 0.001) and duration of treatment (P < 0.001). Comparative mutation spectra analysis of 1,020 mutant isolates revealed a significant increase in the proportion of all transitions (P < 0.001), particularly G:C to A:T transitions (P < 0.001). Combined analyses of two signatures for mutant clonality, HPRT mutation, and T-cell receptor beta CDR3 region unique gene sequence also showed a significant thiopurine-dependent increase in mutant cell clonal proliferation (P < 0.001). These findings provide in vivo evidence for mutation induction as a potential carcinogenic mechanism associated with chronic thiopurine intervention.