Thiopurines and non-melanoma skin cancer: partners in crime in inflammatory bowel diseases

[Risks of Cancer Associated with Therapeutic Drugs for Inflammatory Bowel Disease]

Crohn's disease and ulcerative colitis are lifelong chronic inflammatory conditions, with many patients requiring ongoing immunomodulatory drug therapy for maintenance treatment. Recent therapeutic goals in inflammatory bowel disease (IBD) are not only aimed at symptomatic remission but also at achieving mucosal healing to improve the natural course of the disease. In this context, therapeutic approaches are being applied in clinical settings that involve early and appropriate use of drugs, such as immunomodulators or biologics, that have the potential to induce healing of the inflamed intestine before irreversible intestinal damage occurs. All drugs that continuously control intestinal inflammation in IBD can heal the mucosa and potentially reduce the incidence of colitis-associated bowel cancer; however, the continuous use of immunosuppressants can potentially increase the risk of malignancies. The safety issues of the drugs used in clinical practice are partly confirmed during their development processes or shortly after initial marketing, but in other cases, they are estimated through post-marketing case reports or epidemiological studies, sometimes decades after drug approval. This review explores the risks associated with malignancies related to the treatment of IBD, focusing on drugs currently approved in Republic of Korea.

Risk of Cancer in Patients With Crohn's Disease 30 Years After Diagnosis (the IBSEN Study)

Background

Patients with Crohn's disease (CD) are most often diagnosed as young adults; therefore, long-term studies are needed to assess the risk of cancer over their lifetime. Thus, the aims of the present study were to determine the risk of cancer in a Norwegian population-based cohort (the Inflammatory Bowel South Eastern Norway [IBSEN] study), 30 years after diagnosis, and to assess whether patients with CD were at an increased risk of specific cancer types.

Methods

The IBSEN cohort prospectively included all incident patients diagnosed between 1990 and 1993. Data on cancer incidence were obtained from the Cancer Registry of Norway. Overall and cancer-specific hazard ratios (HRs) for CD patients compared with age- and sex-matched controls were modeled using Cox regression. Standardized incidence ratios (SIRs) were estimated compared to the general population.

Results

In total, the cohort included 237 patients with CD, and 36 of them were diagnosed with cancer. Compared to the general Norwegian population, patients with CD had an increased overall risk of cancer (HR = 1.56, 95% CI: 1.06-2.28), particularly male patients (HR = 1.85, 95% CI: 1.08-3.16). The incidence of lung cancer and nonmelanoma skin cancer was increased; however, the difference was not statistically significant (SIR = 2.29, 95% CI: 0.92-4.27 and SIR = 2.45, 95% CI: 0.67-5.37, respectively).

Conclusions

After 30 years of follow-up, the risk of all cancers in patients with CD was increased compared to the general population.

Cumulative thiopurine dosing and keratinocyte skin cancer in inflammatory bowel disease: a case-control study

BACKGROUND AND AIM

Patients with inflammatory bowel disease (IBD) treated with thiopurines are at increased risk of keratinocyte skin cancer (KSC). Most international guidelines recommend yearly dermatological screening of thiopurine-treated patients. Whether the association between the development of KSC and the use of thiopurines is dose-dependent remains unclear. The aim of this study was to investigate the association between the cumulative thiopurine dose and KSC development in patients with IBD which can be helpful to assist in further skin cancer risk stratification and personalization of screening recommendations in patients with IBD.

METHODS

We performed a single-center case-control study, including patients with IBD with and without a history of KSC (cases and controls, respectively). The primary outcome was the association of cumulative azathioprine, mercaptopurine and thioguanine dose with KSC development. Univariable and multivariable logistic regression analyses were performed, the latter corrected for age and smoking, known risk factors of KSC.

RESULTS

We included 50 cases and 150 controls, predominantly white population. Age and current azathioprine use were univariably significantly associated with KSC development. In multivariable logistic regression analyses, age at inclusion remained significantly associated. Cumulative doses of thiopurines (separate or combined) or duration of thiopurine use did not impact KSC risk, also after correcting for age and smoking.

CONCLUSION

Cumulative thiopurine dose and duration did not show an association with KSC development. Future KSC risk stratification, based on all available KSC risk factors, may aid in selecting individuals who can benefit most from dermatologic screening programs.

Incidence of cancer in patients with ulcerative colitis 30 years after diagnosis (the IBSEN study)

OBJECTIVES

Patients with ulcerative colitis (UC) have shown an increased risk for colorectal cancer, hepatobiliary, hematologic, and skin cancers, but updated long-term data is needed. This study aimed to estimate the risk of cancer in patients with UC compared to the general Norwegian population, in a population-based cohort (the IBSEN study), 30 years after diagnosis; and to identify possible risk factors associated with cancer.

METHODS

The IBSEN cohort prospectively included all incident patients between 1990 and 1993. Cancer incidence data were obtained from the Cancer Registry of Norway. The overall and cancer-specific hazard ratios (HR) were modelled using Cox regression. Standardized incidence ratios were estimated compared to the general population.

RESULTS

In total, the cohort included 519 patients, and 83 cases were diagnosed with cancer. There was no statistically significant difference in the overall cancer risk (HR = 1.01, 95% CI: [0.79-1.29]) and colorectal cancer risk (HR = 1.37, 95% CI: [0.75-2.47]) between patients and controls. The incidence of biliary tract cancer was higher than expected (SIR = 9.84, 95%CI: [3.19-20.15]), especially when UC patients suffered from primary sclerosing cholangitis. Male UC patients were also more at risk of being diagnosed with hematologic malignancies (HR = 3.48, 95% CI: [1.55-7.82]). Being prescribed thiopurines was associated with a higher risk of cancer (HR = 2.03, 95% CI: [1.02-4.01]).

CONCLUSIONS

At 30 years after diagnosis, the risk of all cancer in patients with UC was not significantly increased compared with the general population. However, the risks of biliary tract cancer and hematologic cancers were increased, particularly in male patients.

The evolving role of JAK inhibitors in the treatment of inflammatory bowel disease

INTRODUCTION

Janus Kinase inhibitors (JAKi) are a new class of oral therapies for the treatment of moderate-severe ulcerative colitis with additional potential for the treatment of moderate-severe Crohn's disease. In contrast to biologic therapies JAKi provide the opportunity for non-immunogenic once or twice daily oral therapies.

AREAS COVERED

Janus Kinase inhibitors for the treatment of ulcerative colitis and Crohn's disease based on mechanism of action, pharmacokinetics, clinical trial and real-world data regarding safety and efficacy; focusing on regulatory approvals in the U.S. and Europe.

EXPERT OPINION

Janus Kinase inhibitors are considered among the 'advanced therapies' for IBD and are approved for the treatment of moderate to severe ulcerative colitis in adults with pending approvals for Crohn's disease in the U.S. JAKi offer non-immunogenic, oral options for patient not responding to other conventional agents but, have been 'restricted' by the FDA to patients with inadequate response to TNF blockers. JAKi offer rapidly acting oral alternatives to biologic agents for moderate-severe ulcerative colitis where the risks of cardiovascular and thrombotic events noted in rheumatoid arthritis have not been observed in IBD clinical trials. Nevertheless, monitoring of infections (primarily herpes zoster) and risk factors for cardiovascular and thrombotic complications is appropriate.

Classic drugs in the time of new drugs: real-world, long-term outcomes of thiopurine monotherapy in 1016 patients with inflammatory bowel disease

BACKGROUND

Thiopurines remain recommended as maintenance therapy in patients with inflammatory bowel disease (IBD). Despite their widespread use, long-term effectiveness data are sparse and safety is an increasingly debated topic which thwarts proper delineation in the current IBD treatment algorithm.

AIMS

To document effectiveness and safety of thiopurine monotherapy in patients with IBD, using the population-based IBD South-Limburg (IBDSL) cohort METHODS: All patients starting thiopurine monotherapy as maintenance between 1991 and 2014 were included. Therapy was defined as effective if there was no escalation to biologicals, no course of corticosteroids, no surgery and no hospitalisation for active disease during treatment. Long-term effectiveness was assessed by adjusting for differences in follow-up using Kaplan-Meier analyses. Mid- to long-term safety regarding cancer incidence and clinically relevant liver disease was documented.

RESULTS

In total, 1016 patients (643 Crohn's disease [CD]; 373 ulcerative colitis [UC]) received thiopurine monotherapy at a median of 15.2 (Q1-Q3 4.2-48.5) months after diagnosis. During follow-up, effectiveness rates at 1, 5 and 10 years were 64%, 45%, 32%, respectively, in CD and and 66%, 41%, 36%, respectively in UC. No statistically significant differences in effectiveness were observed after stratification for era of initiation (pre-biological vs biological, CD: p = 0.56; UC: p = 0.43). Sixteen non-melanoma skin cancers (incidence rate [IR] 3.33/1000 PY), five lymphomas (IR 1.04/1000 PY) and one urinary tract cancer (IR 0.21/1000 PY) were recorded. Two cases of portal hypertension were identified.

CONCLUSION

In real-world practice, thiopurine monotherapy remains effective, safe and durable for patients with CD or UC, including in the era of biologics.

The Thiopurine Tale: An Unexpected Journey

Exactly 70 years ago [1951] mercaptopurine was discovered by Gertrude Elion as a novel treatment option for acute leukaemia. A total of three thiopurines (also thioguanine [1950] and azathioprine [1957]) were developed over time. These immunosuppressive drugs were also successfully introduced a few decades later to prevent rejection of transplanted organs and to treat several autoimmune diseases. For her discovery of thiopurines and other antimetabolite drugs, in 1988 Elion was rewarded, together with George Hitchings and James Black, with the Nobel Prize in Physiology or Medicine. Important steps have been made in recent years to unravel its metabolism, mode of action and pharmacogenetics. Today thiopurine [based] therapy remains an essential immunosuppressive approach in treating patients with inflammatory bowel disease.

Risk of non-melanoma skin cancer with biological therapy in common inflammatory diseases: a systemic review and meta-analysis

BACKGROUND

Most previous studies compared the risk for non-melanoma skin cancer (NMSC) in biologic-treated common inflammatory diseases with the general population. Whether the increased NMSC risk is caused by the disease itself, the biologics, or both remains unknown.

METHODS

We systematically searched PubMed, Embase, Medline, Web of Science, and Cochrane Library from inception to May 2021. Studies were included if they assessed the risk of NMSC for rheumatoid arthritis (RA), inflammatory bowel disease (IBD), or psoriasis patients treated with biologics compared with patients not receiving biologics. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using the fixed- or random-effects model.

RESULTS

The current meta-analysis included 12 studies. Compared with patients with the inflammatory disease without biologics, patients receiving biological therapy were associated with an increased risk for NMSC (RR 1.25, 95% CI 1.14 to 1.37), especially in patients with RA (RR 1.24, 95% CI 1.13 to 1.36) and psoriasis (RR 1.28, 95% CI 1.07 to 1.52), but not in patients with IBD (RR 1.49, 95% CI 0.46 to 4.91). The risks for squamous cell skin cancer and basal cell skin cancer were both increased for patients receiving biologics. However, the risk of NMSC did not increase in patients treated with biologics less than 2 years.

CONCLUSIONS

Current evidence suggests that increased risk of NMSC was identified in RA and psoriasis treated with biologics compared with patients not receiving biologics, but not in patients with IBD. The inner cause for the increased risk of NMSC in IBD patients should be further discussed.