Scleroderma Induced by Pembrolizumab: A Case Series

Scleroderma-like Lesions in a Patient Undergoing Combined Pembrolizumab and Routine Chemotherapy: A Case Report and Literature Review

Triple-negative breast cancer (TNBC) represents a challenging malignancy with limited treatment options and a poor prognosis. Adjuvant therapies, including chemotherapy and immune checkpoint inhibitors (ICI), are commonly employed following breast conservation surgery. However, these treatments can lead to various adverse effects, including cutaneous complications and connective tissue disorders. Here, we present the case of a 54-year-old woman with TNBC who developed morphea, a form of localized scleroderma, following adjuvant chemotherapy and pembrolizumab administration. This case highlights the rarity of drug-induced morphea and emphasizes the importance of recognizing and managing such adverse events in breast cancer patients. We discuss the clinical characteristics, diagnostic challenges, and treatment considerations associated with drug-induced scleroderma-like lesions, as well as the potential mechanisms underlying their development. Furthermore, we review the literature on the incidence, clinical features, and outcomes of scleroderma-like lesions induced by chemotherapy and ICIs. This case underscores the need for increased awareness of immune-related adverse events in patients receiving immunotherapy, as well as the importance of individualized treatment approaches to optimize patient care and outcomes.

The Use of Biologic Agents for the Treatment of Cutaneous Immune-Related Adverse Events from Immune Checkpoint Inhibitors: A Review of Reported Cases

Cutaneous immune-related adverse events encompass a spectrum of dermatological manifestations, including lichenoid reactions, psoriasiform eruptions, eczematous dermatitis, immunobullous disorders, granulomatous reactions, pruritus, vitiligo, and severe cutaneous adverse reactions such as Stevens-Johnson syndrome. The conventional approach to treating high-grade or refractory cutaneous immune-related adverse events has involved high-dose systemic corticosteroids. However, their use is limited owing to the potential disruption of antitumor responses and associated complications. To address this, corticosteroid-sparing targeted immunomodulators have been explored as therapeutic alternatives. Biologic agents, commonly employed for non-cutaneous immune-related adverse events such as colitis, are increasingly recognized for their efficacy in treating various patterns of cutaneous immune-related adverse events, including psoriasiform, immunobullous, and Stevens-Johnson syndrome-like reactions. This review consolidates findings from the English-language literature, highlighting the use of biologic agents in managing diverse cutaneous immune-related adverse event patterns, also encompassing maculopapular, eczematous, and lichenoid eruptions, pruritus, and transient acantholytic dermatosis (Grover disease). Despite the established efficacy of these agents, further research is necessary to explore their long-term effects on antitumor responses.

De novo Connective Tissue Disorders as Immune-related Adverse Events

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment through blocking immunoregulatory pathways, resulting in augmented antitumor responses. However, ICIs can cause inflammatory autoimmune toxicities, known as immune-related adverse events (irAEs). Common rheumatic irAEs include inflammatory arthritis, polymyalgia rheumatica-like symptoms, and myositis. Fewer cases of de novo connective tissue disease as irAEs have been described and have mainly presented with cutaneous manifestations of systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). Treatments include glucocorticoids and steroid-sparing agents such as hydroxychloroquine, mycophenolate mofetil, and methotrexate with improvement of symptoms. In this review, the authors discuss immune-related SLE and SSc and their management.

Immune Checkpoint Inhibitor-Associated Systemic Sclerosis in the Treatment of a Small Cell Lung Cancer Patient with Durvalumab: A Case Report

As one of the key cancer treatment measures, immune-checkpoint inhibitors (ICIs) have revolutionized the treatment landscape of various cancers, including malignancies previously thought to be untreatable. Immune checkpoint inhibitors work by targeting the dysfunctional immune system, to enhance cancer-cell killing by CD8-positive T cells. Despite the beneficial effects of ICIs, these treatments are also linked to a novel class of side effects, termed immune-related adverse events (irAEs). Immune-related adverse events can affect multiple organ systems, such as endocrine, neurological, gastroenteric, dermatologic, ocular, hepatic, renal, and rheumatic ones. While variable in severity, irAEs can be associated with significant morbidity, mortality, cessation of ICI treatment and can be potentially life-threatening sometimes. Among varieties of irAEs, dermatological manifestations are frequently reported, since they can be easily observed. Here, we present a case of a 74-year-old patient with widespread fibrosis of skin, eventually diagnosed as diffuse cutaneous systemic sclerosis after the treatment with durvalumab for small cell lung cancer (SCLC). Prompt recognition and treatment of immune-checkpoint inhibitors-associated systemic sclerosis may help enhance tolerance to ICIs and ensure better performance in treating tumors.

Immune Checkpoint Inhibitors and Scleroderma: Data from the European Pharmacovigilance Database

BACKGROUND

Immune checkpoint inhibitors (ICIs) can be commonly associated with the occurrence of immune-related adverse drug reactions (irADRs), which can involve any tissue and organ. ICI-induced skin toxicities are common irADRs and they can be a consequence of a rheumatologic ADR, such as in the case of scleroderma. A recent literature review reported that scleroderma and scleroderma mimics represent a group of disorders with significant morbidity that have been described during ICIs' use.

OBJECTIVE AND METHODS

Considering the clinical significance of scleroderma cases, the present study aimed to analyze the occurrence of these events in patients receiving ICIs by describing data from individual case safety reports (ICSRs) retrieved from the European spontaneous reporting system, EudraVigilance (EV).

RESULTS

Until February 2023, 70 ICSRs with at least one ICI as the suspected drug and at least one preferred term (PT) related to scleroderma cases were retrieved from the EV. Pembrolizumab was reported as suspected in 41 ICSRs, nivolumab in 25 ICSRs, ipilimumab in 8 ICSRs and atezolizumab in 3 ICSRs. Patients who experienced scleroderma cases were adults, and no differences were found in terms of sex distribution. Scleroderma cases were mainly classified as serious, while the outcome was mainly reported as favorable. The most reported PTs were scleroderma and morphea.

CONCLUSIONS

Considering the seriousness of ICI-induced scleroderma cases and the recent marketing authorization of some ICIs, we believe that further high-quality clinical studies should be conducted on this topic to better estimate the impact of these events in patients with cancer.

Immune checkpoint inhibitor-induced cutaneous toxicities: a review of histopathologic and clinical features

Immune checkpoint inhibitors (ICIs) represent an emerging treatment option for a variety of cancer types. Through inhibition of programmed cell death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), and/or cytotoxic lymphocyte-associated antigen-4 (CTLA-4), ICIs activate the host's immune system causing a heightened anti-tumor response. However, off-target effects of ICIs can result in numerous different immune-related cutaneous adverse events (irCAEs). Beyond impacting quality of life, irCAEs can lead to dose limitations or discontinuation of anti-cancer therapies. Correct diagnosis is necessary for expedient and appropriate management. Skin biopsies are often performed to increase diagnostic accuracy and guide clinical management. An extensive literature review was performed using the PubMed database to identify the reported clinical and histopathologic features of irCAEs. This comprehensive review primarily details the histopathologic features of various irCAEs reported to date. Clinical presentation and immunopathogenesis are also discussed in relation to histopathology.

Rheumatologic immune checkpoint inhibitor-related adverse events

PURPOSE OF REVIEW

Immune check point inhibitors (ICIs) are a unique class of cancer treatments that harness the body's innate antitumor response. Although these medications have transformed oncology care, they also lead to generalized immune activation that can result in toxicities across a spectrum of organ systems called immune-related adverse events. This article reviews the most common rheumatologic immune-related adverse events and their management.

RECENT FINDINGS

Inflammatory arthritis, polymyalgia rheumatic, sicca symptoms, systemic sclerosis, myositis, and vasculitis have all been reported as ICI adverse events. Treatment includes nonsteroidal anti-inflammatory drugs, glucocorticoids, traditional DMARDs, and biologics.

SUMMARY

Rheumatologists have an important role in the management of patients with rheumatologic immune-related adverse events. Working with our oncology colleagues, we can help manage rheumatologic immune-related adverse events while optimally preserving ICI's antitumor effects.

Rheumatic Immune-Related Adverse Events due to Immune Checkpoint Inhibitors—A 2023 Update

With the aging of the population, malignancies are becoming common complications in patients with rheumatoid arthritis (RA), particularly in elderly patients. Such malignancies often interfere with RA treatment. Among several therapeutic agents, immune checkpoint inhibitors (ICIs) which antagonize immunological brakes on T lymphocytes have emerged as a promising treatment option for a variety of malignancies. In parallel, evidence has accumulated that ICIs are associated with numerous immune-related adverse events (irAEs), such as hypophysitis, myocarditis, pneumonitis, and colitis. Moreover, ICIs not only exacerbate pre-existing autoimmune diseases, but also cause de novo rheumatic disease–like symptoms, such as arthritis, myositis, and vasculitis, which are currently termed rheumatic irAEs. Rheumatic irAEs differ from classical rheumatic diseases in multiple aspects, and treatment should be individualized based on the severity. Close collaboration with oncologists is critical for preventing irreversible organ damage. This review summarizes the current evidence regarding the mechanisms and management of rheumatic irAEs with focus on arthritis, myositis, and vasculitis. Based on these findings, potential therapeutic strategies against rheumatic irAEs are discussed.

Immune Checkpoint Inhibitor Related Rheumatological Complications: Cooperation between Rheumatologists and Oncologists

In cancer, immune checkpoint inhibitors (ICIs) improve patient survival but may lead to severe immune-related adverse events (irAEs). Rheumatic irAEs are a distinct entity that are much more common in a real-life than in clinical trial reports due to their unspecific symptoms and them being a rare cause of hospitalization. This review focuses on an interdisciplinary approach to the management of rheumatic irAEs, including cooperation between oncologists, rheumatologists, and immunologists. We discuss the immunological background of rheumatic irAEs, as well as their unique clinical characteristics, differentiation from other irAEs, and treatment strategies. Importantly, steroids are not the basis of therapy, and nonsteroidal anti-inflammatory drugs should be administered in the front line with other antirheumatic agents. We also address whether patients with pre-existing rheumatic autoimmune diseases can receive ICIs and how antirheumatic agents can interfere with ICIs. Interestingly, there is a preclinical rationale for combining ICIs with immunosuppressants, particularly tumor necrosis factor α and interleukin 6 inhibitors. Regardless of the data, the mainstay in managing irAEs is interdisciplinary cooperation between oncologists and other medical specialties.

Rheumatological adverse events secondary to immune checkpoint inhibitors

The first experiences with a group of drugs called immune checkpoint inhibitors for the treatment of cancer were described in 2010. They are currently used in many tumours, with successful survival outcomes but a new profile of adverse events. This new spectrum of immune-mediated toxicities includes an exaggerated inflammatory response of T lymphocyte and the development of autoimmune diseases or similar pathologies. Of these, of particular note are the rheumatological toxicities. This review aims to alert internists and rheumatologists to their recognition and clinical management.

Checkpoint Inhibitor-Associated Scleroderma and Scleroderma Mimics

Immune checkpoint inhibitors (ICI) are the standard of care for various malignancies and have been associated with a wide spectrum of complications that are phenotypically akin to primary autoimmune diseases. While the literature on these toxicities is growing, there is a paucity of data regarding ICI-associated scleroderma which can carry significant morbidity and limit the ability to continue effective ICI therapy. Our review aimed to analyze the current literature on ICI-associated systemic scleroderma (ICI-SSc) and key scleroderma mimics. Cases of ICI-SSc had notable differences from primary SSc, such as fewer vascular features and less seropositivity (such as scleroderma-specific antibodies and antinuclear antibodies). We found that patients with a diagnosis of SSc prior to the start of ICI can also experience flares of pre-existing disease after ICI treatment used for their cancer. Regarding scleroderma mimics, several cases of ICI-eosinophilic fasciitis have also been described with variable clinical presentations and courses. We found no cases of scleroderma mimics: ICI-scleromyxedema or ICI-scleroedema. There is a critical need for multi-institutional efforts to collaborate on developing a patient database and conducting robust, prospective research on ICI-scleroderma. This will ultimately facilitate more effective clinical evaluations and management for ICI-scleroderma.

Evaluation of risk in chronic cutaneous inflammatory conditions for malignant transformation

Skin carcinomas are the most common form of cancer, and every year thousands of people die from skin cancer-related malignancies. Chronic inflammation is linked to the development and progression of cancer in multiple organ systems - about 20% of all human cancers are a result of chronic inflammation - skin included. While acute inflammation under normal circumstances is a mechanism for host defence and tissue regeneration following insult by trauma or infection by pathogens, over the long term it can drive oncogenic transformation of epithelial cells and promote cancer development, growth and metastasis. Therefore, inflammatory conditions may put individuals at a higher risk to developing skin malignancies. Many skin conditions are characterized by chronic inflammatory processes. These conditions may be particularly susceptible to malignant transformation and predispose patients to develop skin malignancies. As more pathophysiology of chronic inflammatory skin conditions is unveiled, we find that many of these conditions are characterized by immune dysregulation and signalling that result in chronic activation and upregulation of pro-inflammatory chemokines and cytokines, leading to downstream processes that further exacerbate inflammatory processes and cause abnormal cell growth and apoptosis. Here, we review the major chronic cutaneous inflammatory diseases that may have an increased risk of skin malignancies, including atopic dermatitis, psoriasis, discoid lupus erythematosus, lichen planus, hidradenitis suppurativa, prurigo nodularis, lichen sclerosus, systemic sclerosis and morphea, chronic leg ulcers, seborrheic keratoses and basal cell carcinoma. We evaluate the evidence for increased incidence and prevalence, the risk factors associated, the populations at heightened risk and the best management practices.

Cutaneous manifestations associated with immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that block key mediators of tumor-mediated immune evasion. The frequency of its use has increased rapidly and has extended to numerous cancers. ICIs target immune checkpoint molecules, such as programmed cell death protein 1 (PD-1), PD ligand 1 (PD-L1), and T cell activation, including cytotoxic T-lymphocyte-associated protein-4 (CTLA-4). However, ICI-driven alterations in the immune system can induce various immune-related adverse events (irAEs) that affect multiple organs. Among these, cutaneous irAEs are the most common and often the first to develop. Skin manifestations are characterized by a wide range of phenotypes, including maculopapular rash, psoriasiform eruption, lichen planus-like eruption, pruritus, vitiligo-like depigmentation, bullous diseases, alopecia, and Stevens-Johnson syndrome/toxic epidermal necrolysis. In terms of pathogenesis, the mechanism of cutaneous irAEs remains unclear. Still, several hypotheses have been proposed, including activation of T cells against common antigens in normal tissues and tumor cells, increased release of proinflammatory cytokines associated with immune-related effects in specific tissues/organs, association with specific human leukocyte antigen variants and organ-specific irAEs, and acceleration of concurrent medication-induced drug eruptions. Based on recent literature, this review provides an overview of each ICI-induced skin manifestation and epidemiology and focuses on the mechanisms underlying cutaneous irAEs.

Palmar Fasciitis and Polyarthritis Syndrome Associated with Lung Adenocarcinoma

Palmar fasciitis and polyarthritis syndrome (PFPAS) is a rare paraneoplastic rheumatic disease with characteristic features. We herein report a 77-year-old man with lung adenocarcinoma and contralateral pulmonary metastasis receiving chemotherapy who presented with progressive symmetrical flexion contractures associated with palmar fascial thickening and arthritis of both hands and shoulders. He was diagnosed with PFPAS as paraneoplastic manifestations. Salazosulfapyridine was not effective, but 15 mg/day of oral prednisolone improved his symptoms. Physicians should consider PFPAS and rule out malignancy in patients with arthritis in the extremities and flexion contractures associated with palmar fascial thickening.

Co-Inhibitory Molecules – Their Role in Health and Autoimmunity; Highlighted by Immune Related Adverse Events

Immune checkpoint receptors are key players in regulating the immune response. They are responsible for both generating an immune response sufficient to kill invading pathogens, balancing the same response, and protecting against tissue destruction or the development of autoimmune events. The central role of the co-inhibitory receptors also referred to as inhibitory immune checkpoints, including PD-1 and CTLA-4 has become especially evident with the cancer treatments targeting these receptors. Blocking these pathways enhances the immune activity, resulting in both an increased chance of cancer clearance, at the same time induction of immune-related adverse events (irAE). Some of these irAE progress into actual autoimmune diseases with autoantibodies and symptoms, undistinguished from the naturally occurring diseases. This review will take advantage of the lessons learned from immune checkpoint blockade and relate this knowledge to our understanding of the same pathways in naturally occurring autoimmune diseases, mainly focusing on rheumatic diseases.

Cutaneous adverse events of immune checkpoint inhibitor therapy: incidence and types of reactive dermatoses

BACKGROUND

Dermatoses are common and potentially serious complications of programmed cell death receptor PD-1 immune checkpoint inhibitor (anti-PD-1 ICI) therapy. Understanding their incidence is necessary to support clinical awareness, diagnosis, and management.

OBJECTIVE

To examine the incidence and odds of reported non-cancerous dermatoses in the setting of anti-PD-1 ICI therapy.

METHODS

Cross-sectional study of anti-PD-1 (pembrolizumab or nivolumab) treated patients at a tertiary healthcare institution. Selected dermatologic events following immunotherapy were identified in the electronic medical record. Comparator arm were patients that developed these same dermatoses without receiving anti-PD-1 ICI therapy.

RESULTS

There were 13.7% (254/1857) patients that developed one of 28 dermatoses. Compared with the general population, patients treated with anti-PD-1 had a greater risk for development of mucositis (OR 65.7, 95% CI 35.0-123.3), xerostomia (OR 11.9, 95% CI 8.4-16.8), pruritus (11.3, 95% CI 8.9-14.3), and lichen planus/lichenoid dermatitis (OR 10.7, 95% CI 5.6-20.7).

CONCLUSIONS

We report the frequency of dermatoses encountered in the setting of ICI therapy, both common (pruritus, rash, vitiligo) and uncommon (scleroderma, urticaria).

Drug-induced scleroderma-like lesion

Drug-induced scleroderma-like lesion is a condition in which administration of a drug induces skin sclerotic lesions similar to systemic sclerosis or morphea. The clinical manifestations of drug-induced scleroderma-like lesion can be divided into two types: scleroderma-like lesions and morphea-like plaques. A wide variety of drugs can cause drug-induced scleroderma-like lesion. Bleomycin, _L-tryptophan, vinyl chloride, and phytonadione (vitamin K₁) have been reported, but in recent years, cases due to chemotherapeutic agents, such as taxane-based agents, gemcitabine, and tegafur-uracil, and immune checkpoint inhibitors have increased. Drug-induced scleroderma-like lesion differs from systemic sclerosis in that it does not include Raynaud's phenomenon, nail-fold capillary abnormality, organ involvement, such as reflux esophagitis, interstitial pneumonia, renal crisis, or anti-nuclear Abs. On the other hand, there are reports of cases in which Raynaud's phenomenon, positive conversion of anti-nuclear Abs, and development of skin sclerosis from the fingers developed after initiation of the drug. Whether the skin sclerosis improves after discontinuation of the drug depends on the patient. In patients with severe skin sclerosis, functional impairment, such as flexion contracture of the fingers, may occur, and systemic therapy, such as steroids, may be necessary. When treating patients with skin sclerosis, it is important to keep in mind the possibility that the sclerotic lesion may be induced by a drug.

Treatment Equity in the Immunotherapy Era: Options for Patients with Both Autoimmune Disease and GU Cancers

Numerous immunotherapeutic agents, such as immune checkpoint inhibitors (ICIs), have been approved for the treatment of genitourinary (GU) malignancies. While ICIs have improved treatment outcomes and expanded treatment options, they can cause immune-related adverse events (irAEs). The scope of irAEs is broad, and this paper aims to review the rheumatologic side effects associated with immunotherapy drugs approved for bladder cancer and renal cell carcinoma. IrAEs are graded by the common terminology criteria for adverse events (CTCAE), which ranges from 1 to 5. The management of irAEs includes corticosteroids or other immunosuppressive therapies, and it may require discontinuation of immunotherapy. Several real world experience studies suggest that most patients with pre-existing autoimmune diseases treated with ICI did not have to discontinue treatment due to immune-mediated side effects. While data suggest autoimmune side effects are manageable, patients with pre-existing autoimmune diseases are often excluded from immunotherapy clinical trials. Better understanding of these irAEs will improve its safety and expand its use in those with underlying autoimmune disease.

Diagnostic Dilemma of Paraneoplastic Rheumatic Disorders: Case Series and Narrative Review

Paraneoplastic rheumatic disorder (RD) is a disorder that may present before, concurrent with, or after the diagnosis of malignancy. Paraneoplastic RDs are a clinical expression of occult cancer that is not directly related to a tumor or metastasis and manifests as rheumatoid symptoms. The RD is determined by the organ system affected by articular, muscular, cutaneous, vascular, or miscellaneous symptoms. Each case is challenging to diagnose because cancer may present with similar symptoms as a common rheumatic disorder. Of note, the majority of cases have minimal responsiveness or no responsiveness to standard rheumatoid treatment. Therefore, it is imperative to recognize and treat the underlying cancer accordingly. Herein, we present four different diagnostic dilemma cases of RD: case #1 - leukocytoclastic vasculitis and C3 glomerulopathy, case #2 - scleroderma, case #3 - Raynaud’s syndrome and possible lupus-like syndrome, and case #4 - inflammatory myositis. Institutional IRB approval was obtained for this case series. We will discuss and review the literature on each topic. In addition, we will mention a review of paraneoplastic rheumatoid arthritis. As rheumatic disease is associated with the use of immune checkpoint inhibitors (ICIs) for cancer treatment, we will briefly discuss some of the most common rheumatic presentations in the setting of these drugs. This case review aims to inform clinicians about the atypical presentation of paraneoplastic RD and to highlight the need for interdisciplinary management between rheumatologists, oncologists, and primary care practitioners.

Atezolizumab-induced scleroderma: a rare complication

Few cases of programmed death-ligand 1 inhibitor-induced scleroderma have been reported and their clinical features remain unpublished. Optimal management is, therefore, unknown and an autoantibody association has yet to be identified. We present the case of a female in her 60s who developed skin thickening after starting atezolizumab for metastatic non-small cell lung cancer. Skin biopsy 7 months after symptom onset showed histological changes consistent with scleroderma. Anti-PM/SCL-75 antibody was positive. Atezolizumab was discontinued and treatment was started with mycophenolate mofetil. After 5 months, she experienced mild improvement in skin thickening. Earlier identification of this complication may limit morbidity in this disease process, which otherwise has limited treatment options. In suspected cases, obtaining scleroderma-associated autoantibodies may help with earlier diagnosis.

New-onset systemic sclerosis and scleroderma renal crisis under docetaxel

Systemic sclerosis is a rare systemic autoimmune disease characterized by microvascular impairment and fibrosis of the skin and other organs with poor outcomes. Toxic causes may be involved. We reported the case of a 59-year-old woman who developed an acute systemic sclerosis after two doses of adjuvant chemotherapy by docetaxel and cyclophosphamide for a localized hormone receptor + human epithelial receptor 2-breast cancer. Docetaxel is a major chemotherapy drug used in the treatment of breast, lung, and prostate cancers, among others. Scleroderma-like skin-induced changes (morphea) have been already described for taxanes. Here, we report for the first time a case of severe lung and kidney flare with thrombotic microangiopathy after steroids for acute interstitial lung disease probably induced by anti-RNA polymerase III + systemic sclerosis after docetaxel.

Cutaneous adverse events caused by immune checkpoint inhibitors

IMPORTANCE

Immune checkpoint inhibitors (ICIs) have emerged as active therapies for a variety of cancers. Cutaneous toxicities are common immune-related adverse events and patients will often be referred to dermatologists for evaluation.

OBSERVATIONS

Cutaneous adverse events to ICIs can have a variety of clinical presentations. Among the more common are eczematous, morbilliform, and lichenoid dermatoses, as well as vitiligo and pruritus. Less common adverse events include psoriasiform dermatoses, bullous disorders, and severe cutaneous adverse reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms. Because of the immunologic mechanism of ICIs, there are also a variety of rheumatologic adverse reactions with cutaneous manifestations, such as scleroderma, dermatomyositis, cutaneous lupus erythematosus, and various vasculitides. These cutaneous reactions often respond to topical or systemic steroids, although specific toxicities may have alternative treatments available.

CONCLUSIONS AND RELEVANCE

As they become more widely prescribed, dermatologists will see an increasing number of patients with cutaneous adverse events caused by ICI therapies. Accurately diagnosing and treating these toxicities is paramount to achieving the most favorable outcomes for patients.

Epidemiology and treatment of peripheral neuropathy in systemic sclerosis

OBJECTIVE

The epidemiology and treatment of peripheral neuropathy in systemic sclerosis (SSc) is poorly understood. The objectives of this study were to evaluate the incidence, prevalence, risk factors, and treatments of peripheral neuropathy in SSc.

METHODS

A systematic review of Medline, Embase and CINAHL databases for literature reporting peripheral neuropathy in SSc was performed. Studies evaluating incidence, prevalence, risk factors, and treatments were synthesized. Meta-analysis using a random effects model was used to evaluate the prevalence of peripheral neuropathy.

RESULTS

113 studies reported 949 subjects with at least one type of peripheral neuropathy out of 2143 SSc patients studied. The mean age was 48.5 years. The mean time between SSc onset and detection of peripheral neuropathy was 8.85 years. The pooled prevalence of neuropathy was 27.4% (95%CI 22.4% - 32.7%). Risk factors for peripheral neuropathy in SSc included advanced diffuse disease, anticentromere antibodies, calcinosis cutis, ischemia of the vasa nervosum, iron deficiency anemia, metoclopramide, pembrolizumab, silicosis and uremia. There were 73 subjects with successful treatments (n=36 restoring sensation, n=37 restoring motor or sensorimotor function). Treatments included decompression surgery, prednisone, cyclophosphamide, carbamazepine, transcutaneous electrical nerve stimulation, tricyclic antidepressants and IVIG.

CONCLUSION

All-cause peripheral neuropathy is not uncommon in SSc. Compression neuropathies can be treated with decompression surgery. Observational data reporting immunosuppressive and anticonvulsants to treat peripheral neuropathy in SSc is limited and conflicting. This data provides the signal of effect to justify RCT to evaluate the efficacy of these interventions.

[Rheumatic immune adverse events related to immune checkpoint inhibitors-(IrAEs related to ICI)]

New anti-cancer therapeutics have been developed in the recent years and dramatically change prognosis and patient management. Either used alone or in combination, immune checkpoint inhibitors (ICI), such as anti-CTLA-4 and anti-PD1/PD-(L)1, act by removing T-cell inhibition to enhance their antitumor response. This change in therapeutic targets leads to a break in immune-tolerance and a unique toxicity profile resulting in immune complications. These side effects, called Immune-Related Adverse Events (IrAEs), can affect all organs, with a wide range of clinical and biological presentations and severity. Various rheumatic and musculoskeletal manifestations have been reported in the literature, ranging from mild arthralgia, polymyalgia rheumatica, to genuine serodefined rheumatoid arthritis and myositis. Tolerance studies suggest some correlations between IrAEs occurrence and tumor response. Assessment of patient musculoskeletal status prior to the start of the ICI is warranted. Management of rheumatic IrAEs does not usually request ICI discontinuation, exception for myositis or very severe forms where it should be discussed. Treatment relies on non-steroidal anti-inflammatory drugs (NSAIDs) or low dose glucocortioids (<20mg per day). Dose should be adjusted according to severity. The use of disease modifying anti-rheumatic drugs (DMARDs), either conventional and/or biological should be very cautious and result from a shared decision between oncologist and rheumatologist to best manage dysimmunitary complications without hampering the antitumor efficacy of ICI.

Generalized morphoea in the setting of combined immune checkpoint inhibitor therapy for metastatic melanoma: A case report

RATIONALE

Immune checkpoint inhibition has dramatically altered the therapeutic landscape in the treatment of a range of locally advanced and metastatic skin cancers. In particular, the treatment of metastatic melanoma with combined anti-programmed cell death protein 1 (anti-PD1) and anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA4) antagonists has resulted in median 5-year survival rates of over 50%. However, combined immune checkpoint inhibitor therapy frequently results in the development of immune-related adverse events (irAE) which can be severe and life-threatening. While the typical irAEs, namely colitis, thyroiditis, and hepatitis are well recognized, cutaneous irAEs are varied and can be difficult to accurately diagnose.

PATIENT CONCERNS

A 61-year-old female with metastatic melanoma presented with widespread indurated, waxy skin changes, and weight loss following combined anti-PD1 and anti-CTLA4 immunotherapy.

DIAGNOSES

Generalized morphea in the setting of combined immunotherapy.

INTERVENTIONS

Dexamethasone pulse therapy (100 mg i.v. over 3 days) was combined with topical therapy (clobetasone propionate ointment) and physiotherapy. Four cycles of dexamethasone pulse therapy, at 4 weekly intervals, led to an improvement in the skin changes, accompanied by increased mobility. However, the changes did not resolve completely.

OUTCOME

Staging examinations revealed progressive melanoma brain metastases and despite 2 further cycles of combined anti-PD1 and anti-CTLA4 immunotherapy followed by 1.5 cycles of Fotemustine, the patient died 22 months after the development of the scleroderma-like skin changes.

LESSONS

Cutaneous irAEs are varied in nature and severity. Sclerotic skin changes are rare, but unlike cutaneous irAEs related to immune checkpoint inhibitor therapy, they are often refractory to standard treatment with systemic corticosteroids. Clinicians should be aware of immunotherapy-related scleroderma to prompt dermatological evaluation to facilitate early recognition and initiate treatment. Administration of systemic immunosuppression should be carefully balanced against the risk of promoting melanoma progression.

A Review of Cancer Immunotherapy Toxicity: Immune Checkpoint Inhibitors

Cancer immunotherapy, which leverages features of the immune system to target neoplastic cells, has revolutionized the treatment of cancer. The use of these therapies has rapidly expanded in the past two decades. Immune checkpoint inhibitors represent one drug class within immunotherapy with its first agent FDA-approved in 2011. Immune checkpoint inhibitors act by disrupting inhibitory signals from neoplastic cells to immune effector cells, allowing activated T-cells to target these neoplastic cells. Unique adverse effects associated with immune checkpoint inhibitors are termed immune-related adverse effects (irAEs) and are usually immunostimulatory in nature. Almost all organ systems may be affected by irAEs including the dermatologic, gastrointestinal, pulmonary, endocrine, and cardiovascular systems. These effects range from mild to life-threatening, and their onset can be delayed several weeks or months. For mild irAEs, symptomatic care is usually sufficient. For higher grade irAEs, discontinuation of therapy and initiation of immunosuppressive therapy may be necessary. The management of patients with irAEs involves multidisciplinary care coordination with respect to the long-term goals the individual patient. Clinicians must be aware of the unique and sometimes fatal toxicologic profiles associated with immunotherapies to ensure prompt diagnosis and appropriate management.

What's the Price? Toxicities of Targeted Therapies in Breast Cancer Care

Agents with mechanisms novel to breast cancer care have been approved to treat breast cancer. These agents include drugs that target cyclin-dependent kinases, phosphoinositide 3-kinase PI3KCA gene mutations, PARP, checkpoint regulation, and novel antibody-drug conjugates. However, these novel approaches bring a risk of toxicities quite different from those of conventional cytotoxic chemotherapy. Here, we review these agents and discuss related adverse events, with particular attention to endocrine, pulmonary, and dermatologic toxicities. Endocrine toxicities associated with novel cancer therapies for breast cancer are distinct and often present with symptoms related to the specific hormonal deficiencies and rarely hormonal excess. Given the complex and sometimes irreversible nature of these toxicities, once recognized, transdisciplinary management with an endocrinologist experienced with managing drug-related toxicities is encouraged. Drug-related pneumonitis is a serious concern with new targeted therapies. Presentation may not be easily distinguished, and a multidisciplinary team approach can optimize patient care. Heightened awareness is crucial for early detection and treatment. Management should follow recommendations provided by the National Cancer Institute Common Terminology Criteria for Adverse Events and agent-specific guidelines. Cutaneous toxicities from anticancer therapies represent a common and often poorly characterized challenge for patients with breast cancer. Although our understanding of dermatologic effects from novel therapies continues to improve, the breadth of toxicities spans all dermatologic conditions. Targeted therapies offer effective and often novel therapeutic strategies for patients with breast cancer but also bring new adverse event profiles. In this era, it will be important both to closely follow monitoring recommendations and to remain vigilant for emerging toxicities.

Nivolumab-induced plaque morphea in a malign melanoma patient

BACKGROUND

Nivolumab is one of the targeted cancer therapy agent that acts to increase the immune responses by inhibition of antiprogrammed-death-receptor 1, which is one of the check points of the immune response. Nivolumab can be used to treat malign melanoma, lung, renal, head and neck, colorectal, hepatocellular cancers, and special cases of Hodgkin lymphoma.

AIMS

We aimed to report a rarer cutaneous side effect of nivolumab because of the increasing uses of this agent in various cancer treatments.

METHODS

We present a 48-year-old female, metastatic melanoma patient who developed plaque morphea lesion without any systemic involvement during nivolumab treatment. Plaque lesion responded well to use of topical corticosteroid and calcipotriol.

RESULTS

Numerous cutaneous side effects associated with nivolumab have been reported in the literature. The most common cutaneous side effects are maculopapular rash, pruritus, and vitiligo. Morphea and disorders from this spectrum reported due to PD-1 inhibitors in the literature are; morphea, sclerodermoid changes, eosinophilic fasciitis, and lichen sclerosis.

CONCLUSION

Patients who are treated by PD-1 inhibitors may be examined carefully in terms of morphea and scleroderma-like conditions although they are not as common as other cutaneous side effects.

Cancer risk in systemic sclerosis: identifying risk and managing high-risk patients

Introduction: Systemic sclerosis (SSc) is associated with a heightened cancer risk compared to the general population. Several pathways including immune system upregulation, cumulative inflammation, environmental factors, and genetic predisposition contribute to the development of both cancer and autoimmunity. Areas covered: This paper provides an overview of studies investigating the relationship between SSc and various types of cancer with a special focus on the identification of patients at higher risk for malignancy development. The demographic, serological, clinical, and disease-related characteristics of SSc individuals who are diagnosed with cancer over the course of their disease are discussed to provide a practical guidance for relevant screening strategies. Expert opinion: Several studies have identified subgroups of SSc patients at higher cancer risk based on the immunological profile (anti-RNAPol III positivity), diffuse disease type, and older age at SSc onset. Additionally, a close temporal association between SSc and cancer onset in certain antibody subsets raises the question as to whether more aggressive screening strategies should be considered. Currently, there are no published studies investigating the cost-effectiveness, efficacy, and safety of a targeted cancer-detection program. Screening procedures should at least follow recommendations for the general population with a special focus on patients at higher risk and specific cancer types.

Cutaneous Immune-Related Adverse Events (irAEs) to Immune Checkpoint Inhibitors: A Dermatology Perspective on Management [Formula: see text]

Immune checkpoint inhibitors have proven to be efficacious for a broad spectrum of solid organ malignancies. These monoclonal antibodies lead to cytotoxic T-cell activation and subsequent elimination of cancer cells. However, they can also lead to immune intolerance and immune-related adverse event (irAEs) that are new and specific to these therapies. Cutaneous irAEs are the most common, arising in up to 34% of patients on PD-1 inhibitors and 43% to 45% on CTLA-4 inhibitors. The most common skin manifestations include maculopapular eruption, pruritus, and vitiligo-like lesions. A grading system has been proposed, which guides management of cutaneous manifestations based on the percent body surface area (BSA) involved. Cutaneous irAEs may prompt clinicians to reduce drug doses, add systemic steroids to the regiment, and/or discontinue lifesaving immunotherapy. Thus, the goal is for early identification and concurrent management to minimize treatment interruptions. We emphasize here that the severity of the reaction should not be graded based on BSA involvement alone, but rather on the nature of the primary cutaneous pathology. For instance, maculopapular eruptions rarely affect <30% BSA and can often be managed conservatively with skin-directed therapies, while Stevens-Johnson syndrome (SJS) affecting even 5% BSA should be managed aggressively and the immunotherapy should be discontinued at once. There is limited literature available on the management of the cutaneous irAEs and most studies present anecdotal evidence. We review the management strategies and provide recommendations for psoriatic, immunobullous, maculopapular, lichenoid, acantholytic eruptions, vitiligo, alopecias, vasculitides, SJS/toxic epidermal necrolysis, and other related skin toxicities.

Cancer and Scleroderma

Individuals with scleroderma have an increased risk of cancer compared with the general population. This heightened risk may be from chronic inflammation and tissue damage, malignant transformation provoked by immunosuppressive therapies, or a common inciting factor. In unique subsets of patients with scleroderma, there is a close temporal relationship between the onset of cancer and scleroderma, suggesting cancer-induced autoimmunity. This article discusses the potential mechanistic links between cancer and scleroderma, the serologic and clinical risk factors associated with increased cancer risk in patients with scleroderma, and implications for cancer screening.

Rheumatic immune-related adverse events induced by immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) block the major inhibitory pathways in T cells, resulting in an augmented antitumor response. Immune‐related adverse events (irAEs) are a new class of side effects caused by ICIs and tend to be more prevalent in patients with preexisting autoantibodies and autoimmune diseases. The rheumatic subset of irAEs mainly includes arthralgia, arthritis, myalgia, myositis, vasculitis, sicca syndrome, scleroderma and systemic lupus erythematosus. The most common classification system for AEs, the Common Terminology Criteria for Adverse Events, is of limited use for irAEs, especially rheumatic irAEs. Therapy with glucocorticoid and temporary or permanent discontinuation of ICIs are the cornerstones of irAE treatment, and can be complemented with immunosuppressants (e.g., methotrexate), biologic agents (e.g., tumor necrosis factor inhibitors and interleukin‐6 receptor antagonists), intravenous immunoglobin and plasma exchange. Thus, the evaluation and treatment of rheumatic irAEs require multidisciplinary cooperation among physicians. Here, we review the most prevalent ICI‐associated rheumatic irAEs.

Sicca syndrome following immune checkpoint inhibition

The recent approval of Immunologic checkpoint inhibitors as an effective therapeutic strategy against cancer came at the cost of toxicities mediated by an excessive activation of immune system against health tissues, including among others musculoskeletal and sicca complaints.The latter occur in the context of an entity reminiscent of Sjogren's syndrome, with distinct characteristics such as abrupt onset, male predominance, lower prevalence of autoantibodies and response to steroids.

Risk of scleroderma according to the type of immune checkpoint inhibitors

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are associated with immune-related adverse events (irAEs). Among them, ICIs-induced systemic sclerosis (SSc) is poorly known.

METHODS

To better characterize this irAE, our comprehensive approach combined the description of ICIs-induced scleroderma cases, the systematic review of the literature and the analysis of VigiBase, the WHO pharmacovigilance database.

RESULTS

We identified two cases with underlying limited cutaneous SSc who presented a dramatic increase in the skin thickening following pembrolizumab, associated with scleroderma renal crisis in one case. In the literature, four cases of scleroderma and four cases of morphea have been reported with pembrolizumab or nivolumab. None following ipilimumab, atezolizumab or durvalumab were retrieved. Skin changes appeared or worsened more quickly with pembrolizumab than nivolumab, and had different patterns between both drugs. Patients with generalized skin changes required high-dose prednisone to improve skin thickening. Among the 2527 scleroderma cases identified in VigiBase, 35 were associated with ICIs. Nivolumab and pembrolizumab showed a disproportionality in scleroderma reporting. No disproportionality was found for ipilimumab, atezolizumab or durvalumab.

CONCLUSION

The risk of scleroderma or fibrosis extension in SSc patients should be considered when initiating anti-PD-1 agents. It suggests the role of PD-1/PD-L1 interaction in the pathophysiology of SSc.

Dermatomyositis in a patient undergoing nivolumab therapy for metastatic melanoma: a case report and review of the literature

Checkpoint inhibitor immunotherapy is a transformative treatment for advanced malignancies, but can be associated with numerous immune-related adverse events (irAEs). The majority of irAEs include those that closely resemble known cutaneous and neurocutaneous autoimmune or autoinflammatory diseases, such as scleroderma, psoriasis, and dermatomyositis. We present the case of a 63-year-old man with metastatic melanoma undergoing treatment with nivolumab who developed significant motor weakness, paresthesias of both hands, swollen fingers, and a pruritic rash over the face, chest, and upper back after two cycles. Creatine kinase was elevated. Electromyography revealed a myopathic pattern, muscle biopsy of the deltoid revealed an inflammatory myopathy, and skin biopsy showed interface dermatitis. There were no detectable autoantibodies except positive antinuclear antibody. He was diagnosed with immunotherapy-induced dermatomyositis, nivolumab was held, and he was treated with oral prednisone and intravenous immunoglobulin with overall improvement in myopathic and cutaneous symptoms. Dermatomyositis is an inflammatory myopathy with a characteristic dermatologic presentation that can occur spontaneously, as a paraneoplastic phenomenon, or as a drug reaction. This is the second known case of nivolumab-induced dermatomyositis. A review of the literature revealed seven total cases of immunotherapy-induced dermatomyositis. Functionally disabling autoimmune adverse effects of this severity would frequently persuade providers to discontinue immunotherapy in patients with metastatic disease.

Rheumatic Manifestations in Patients Treated with Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that activate the immune system, aiming at enhancing antitumor immunity. Their clinical efficacy is well-documented, but the side effects associated with their use are still under investigation. These drugs cause several immune-related adverse events (ir-AEs), some of which stand within the field of rheumatology. Herein, we present a literature review performed in an effort to evaluate all publicly available clinical data regarding rheumatic manifestations associated with ICIs. The most common musculoskeletal ir-AEs are inflammatory arthritis, polymyalgia rheumatica and myositis. Non-musculoskeletal rheumatic manifestations are less frequent, with the most prominent being sicca, vasculitides and sarcoidosis. Cases of systemic lupus erythematosus or scleroderma are extremely rare. The majority of musculoskeletal ir-AEs are of mild/moderate severity and can be managed with steroids with no need for ICI discontinuation. In severe cases, more intense immunosuppressive therapy and permanent ICI discontinuation may be employed. Oncologists should periodically screen patients receiving ICIs for new-onset inflammatory musculoskeletal complaints and seek a rheumatology consultation in cases of persisting symptoms.

EULAR points to consider for the diagnosis and management of rheumatic immune-related adverse events due to cancer immunotherapy with checkpoint inhibitors

Background

Rheumatic and musculoskeletal immune-related adverse events (irAEs) are observed in about 10% of patients with cancer receiving checkpoint inhibitors (CPIs). Given the recent emergence of these events and the lack of guidance for rheumatologists addressing them, a European League Against Rheumatism task force was convened to harmonise expert opinion regarding their identification and management.

Methods

First, the group formulated research questions for a systematic literature review. Then, based on literature and using a consensus procedure, 4 overarching principles and 10 points to consider were developed.

Results

The overarching principles defined the role of rheumatologists in the management of irAEs, highlighting the shared decision-making process between patients, oncologists and rheumatologists. The points to consider inform rheumatologists on the wide spectrum of musculoskeletal irAEs, not fulfilling usual classification criteria of rheumatic diseases, and their differential diagnoses. Early referral and facilitated access to rheumatologist are recommended, to document the target organ inflammation. Regarding therapeutic, three treatment escalations were defined: (1) local/systemic glucocorticoids if symptoms are not controlled by symptomatic treatment, then tapered to the lowest efficient dose, (2) conventional synthetic disease-modifying antirheumatic drugs, in case of inadequate response to glucocorticoids or for steroid sparing and (3) biological disease-modifying antirheumatic drugs, for severe or refractory irAEs. A warning has been made on severe myositis, a life-threatening situation, requiring high dose of glucocorticoids and close monitoring. For patients with pre-existing rheumatic disease, baseline immunosuppressive regimen should be kept at the lowest efficient dose before starting immunotherapies.

Conclusion

These statements provide guidance on diagnosis and management of rheumatic irAEs and aim to support future international collaborations.

Cutaneous adverse reactions to anti-PD-1 treatment-A systematic review

The use of the humanized monoclonal anti-programmed cell death 1 antibodies pembrolizumab and nivolumab as potent anticancer therapies is rapidly increasing. However, since their approval, numerous cases of cutaneous reactions have been reported. Cutaneous adverse reactions to these agents have yet to be fully characterized and range from nonspecific eruptions to recognizable skin manifestations, which may be localized and vary from mild to life threatening. This systematic review article provides an overview of the various adverse cutaneous reactions to pembrolizumab and nivolumab therapy and offers suggestions for their management.

Clinical characteristics of rheumatic syndromes associated with checkpoint inhibitors therapy

Compared with conventional cancer therapies, the spectrum of toxicities observed with checkpoint inhibitors is unique and can affect any organ system. Arthralgia and myalgia were by far the most commonly reported rheumatic immune-related adverse events in clinical trials, and there is now a growing number of case series and reports describing clinical features of de novo rheumatic immune-related adverse events, which will be the focus of this review. Some patients develop genuine classic rheumatic and musculoskeletal diseases, but a number of rheumatic immune-related adverse events mimic rheumatic and musculoskeletal diseases with atypical features, mainly polymyalgia rheumatica, rheumatoid arthritis and myositis, as well as several systemic conditions, including sicca syndrome, vasculitis, sarcoidosis, systemic sclerosis and lupus.

Management of rheumatic complications of ICI therapy: a rheumatology viewpoint

Since immune checkpoint inhibitors became the standard of care for an increasing number of indications, more patients have been exposed to these drugs and physicians are more challenged with the management of a unique spectrum of immune-related adverse events (irAEs) associated with immune checkpoint inhibitors. Those irAEs of autoimmune or autoinflammatory origin, or both, can involve any organ or tissue, but most commonly affect the dermatological, gastrointestinal and endocrine systems. Rheumatic/systemic irAEs seem to be less frequent (although underreporting in clinical trials is probable), but information on their management is highly relevant given that they can persist longer than other irAEs. Their management consists of anti-inflammatory treatment including glucocorticoids, synthetic and biologic immunomodulatory/immunosuppressive drugs, symptomatic therapies as well as holding or, rarely, discontinuation of immune checkpoint inhibitors. Here, we summarize the management of rheumatic/systemic irAEs based on data from clinical trials but mainly from published case reports and series, contextualize them and propose perspectives for their treatment.

The relationships between cancer and autoimmune rheumatic diseases

Links between autoimmune rheumatic diseases and cancer continue to be elucidated. In this review, we explore this complex, bidirectional relationship. First, the increased risk of cancer across the breadth of the autoimmune rheumatic diseases is described. The magnitude of risk and types of tumors seen can differ by the type of autoimmune disease, timing of disease course, and even clinical and laboratory features within a particular autoimmune disease, suggesting that targeted cancer screening strategies can be considered. Multiple mechanisms linking autoimmune rheumatic diseases and cancer are discussed, including the development of autoimmunity in the context of naturally occurring anti-tumor immune responses and malignancy arising in the context of inflammation and damage from autoimmunity. Immunosuppression for rheumatic disease can increase risk for certain types of cancers. Finally, immune checkpoint inhibitors, a type of cancer immunotherapy, which cause a variety of inflammatory syndromes of importance to rheumatologists, are reviewed.

Management of immune checkpoint inhibitor-related adverse events: A review of case reports

Immune checkpoint inhibitors represent a major breakthrough in cancer therapy. Immune‐related adverse events (irAEs) may occur during treatment due to their unique mechanism of action. Management of irAEs is based on clinical experience because it is not easy to conduct prospective trials to evaluate the best treatment strategy. Using a combination of search terms in the PubMed and Embase databases, we reviewed all cases in the English language citing toxicities associated with either pembrolizumab, nivolumab, ipilimumab, atezolizumab, tremelimumab, durvalumab, avelumab or any combination of these agents published before 20 May 2019. A total of 128 reports with 239 cases were included in the study. Here, we summarize the spectrum of toxicities, safety in special patients, rechallenging after irAEs and agents used for treatment of irAEs in those reports.

Diagnosis and Management of Rare Immune-Related Adverse Events

Oncologic treatment is being revolutionized by a burgeoning number of immune checkpoint inhibitors (ICPis). To date, seven ICPis have received Food and Drug Administration approval, targeting cytotoxic T-lymphocyte antigen, programmed cell death, or programmed cell death ligand. Adverse events associated with checkpoint inhibition have been described in the literature. Guidelines exist for the most common of these, but as the use of ICPis becomes more common, the number of patients presenting with rare events will increase. This article reviews the diagnosis and management of rare ocular, hematological, luminal gastrointestinal, and rheumatological toxicities arising from ICPi treatment. KEY POINTS: As the use of immune checkpoint inhibitors (ICPis) becomes more common, the number of rare immune-related adverse events (irAEs) will increase. A high level of suspicion is required to identify and treat these toxicities. Although it can be difficult to definitively attribute rare irAEs to ICPis, a temporal and mechanistic relationship and the absence of other etiologies should make the treating physician suspicious for a rare irAE. Certain rare irAEs, such as celiac disease, do not require treatment with glucocorticoids. Thus, differentiating this irAE from other gastrointestinal irAEs has important implications for treatment.