Rheumatic immune-related adverse events associated with cancer immunotherapy: A nationwide multi-center cohort

Immune Checkpoint Inhibitor-Associated Remitting Seronegative Symmetrical Synovitis With Pitting Edema: Description of a New Entity by CanRIO

OBJECTIVE

Remitting seronegative symmetrical synovitis with pitting edema (RS3PE) is characterized by symmetrical synovitis with pitting edema and negative rheumatoid factor (RF). It has been described in a setting of malignancy, suggesting a paraneoplastic association. With the increasing use of immune checkpoint inhibitors (ICIs) for the treatment of cancers and emergence of immune-related adverse events (irAEs), our objective was to identify and describe cases of ICI-associated RS3PE (ICI-RS3PE) and compare them to non-ICI-RS3PE.

METHODS

The Canadian Research Group of Rheumatology in Immuno-Oncology (CanRIO) network is a collaboration of Canadian rheumatologists with experience in the management of patients with rheumatic irAEs (Rh-irAEs). Standardized data on adult patients with Rh-irAE have been collected as part of retrospective and prospective cohorts. In this study, detailed information on all cases of ICI-RS3PE from both cohorts were extracted and analyzed.

RESULTS

We identified 11 cases of ICI-RS3PE. The most frequently observed malignancy was nonsmall cell lung cancer (4 of 11), followed by malignant melanoma (2 of 11) and cutaneous squamous cell carcinoma (2 of 11). The median time to onset of ICI-RS3PE was 26 weeks from ICI start and 52 weeks from diagnosis of malignancy. Seven patients had stable cancer prior to onset of ICI-RS3PE, 3 had partial response, and 1 had complete response. All patients received glucocorticoids. Conventional synthetic disease-modifying antirheumatic drugs (csDMARD) were needed in 10 patients.

CONCLUSION

ICI-RS3PE may be an independent Rh-irAE, separate from paraneoplastic RS3PE. The symptoms of ICI-RS3PE responded well to glucocorticoids, but concomitant treatment with csDMARDs may be necessary.

Second-line therapies for steroid-refractory immune-related adverse events in patients treated with immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICI) induce adverse events (irAEs) that do not respond to steroids, i.e. steroid-refractory (sr) irAEs, and irAEs in which steroids cannot be tapered, i.e. steroid-dependent (sd) irAEs, in about 10% of cases. An evidence-based analysis of the effectiveness of second-line immunosuppressive agents with regard to irAE and tumor control is lacking.

METHODS

The international web-based Side Effect Registry Immuno-Oncology (SERIO; http://serio-registry.org) is a collaborative initiative with the Paul-Ehrlich-Institute to document rare, severe, complex or therapy-refractory immunotherapy-induced side effects. The registry was queried on August 1, 2023 for cases of irAEs which were treated with second-line therapies.

RESULTS

From a total of 1330 cases, 217 patients (16.3%) received 249 second-line therapies. A total of 19 different second-line therapies were employed, including TNF-alpha antagonists (46.5%), intravenous immunoglobulins (IVIG; 19.1%), mycophenolate mofetil (15.9%), and methotrexate (3.6%). Therapy choices were determined by the type of irAE. The time to onset of sr-/sd-irAEs after ICI initiation did not consistently differ from steroid-responsive irAEs. While 74.3% of sr-/sd-irAEs resolved and 13.1% had improved, 4.3% persisted, 3.9% resulted in permanent sequelae, and 4.3% in death with ongoing symptoms. Infliximab exhibited potential for earlier symptom improvement compared to mycophenolate mofetil or IVIG. Tumor response in patients with second-line treated sd-/sr-irAE was similar to patients with irAEs treated with steroids only.

CONCLUSION

Several second-line therapies are effective against sr-/sd-irAEs, the second-line therapies show no clear negative impact on tumor response, and infliximab shows potential for faster improvement of symptoms. However, prospective comparative data are needed.

The Utility of Laboratory Investigations for the Assessment and Management of Rheumatic Immune Related Adverse Events

Immune checkpoint inhibitors (ICIs) have greatly improved survival of several cancers with historically very poor prognosis. ICIs act by stimulating the patient's own immune system to fight cancer. Simultaneously, this immune activation can lead to immune-related adverse events (irAEs), including rheumatic manifestations (Rh-irAEs). Rh-irAEs mimic primary rheumatic diseases including arthritis, polymyalgia rheumatica, myositis, vasculitis, sarcoidosis, and sicca. This article summarizes the latest evidence regarding the utility of laboratory investigations in Rh-irAEs.

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.

Mimickers of Immune Checkpoint Inhibitor-induced Inflammatory Arthritis

The differential diagnosis of inflammatory arthritis as an immune-related adverse event can be challenging as patients with cancer can present with musculoskeletal symptoms that can mimic arthritis because of localized or generalized joint pain. In addition, immune checkpoint inhibitors can exacerbate joint conditions such as crystal-induced arthritis or osteoarthritis, or induce systemic disease that can affect the joints such as sarcoidosis. This distinction is important as the treatment of these conditions can be different from that of immune-related inflammatory arthritis.

Checkpoint inhibitor immunotherapy induced inflammatory arthritis secondary to Nivolumab and Ipilimumab: a pediatric first

BACKGROUND

Immune checkpoint inhibitors (ICIs) have expanded the arsenal of cancer therapeutics over the last decade but are associated with a spectrum of immune-related adverse events (irAEs), including inflammatory arthritis. While these complications are increasingly recognized in the adult population, no cases of inflammatory arthritis irAEs have been reported in the pediatric literature.

CASE PRESENTATION

A 14-year-old female with metastatic epithelioid mesothelioma was referred to the pediatric rheumatology clinic after developing progressive inflammatory joint pain in her bilateral shoulders, hips, and small joints of hands following the second cycle of Nivolumab and Ipilimumab. Initial examinations showed bilateral shoulder joint line tenderness, positive FABERs test bilaterally, tenderness over bilateral greater trochanters, and bilateral second PIP effusions. Her serological profile was notable for positive HLA-B27, positive anti-CCP, negative Rheumatoid Factor, and negative ANA. PET-CT scan performed for disease response following immunotherapy showed symmetric increased metabolic activity primarily involving the supraspinatus, gluteus medius and minimus, and semimembranosus tendon insertions. Her presentation was consistent with a grade 1 irAE that worsened to a grade 2 irAE despite NSAID therapy, prompting a short course of oral prednisolone. She achieved clinical remission of her mesothelioma following six cycles of Nivolumab and Ipilimumab and her inflammatory arthritis was controlled on Celebrex monotherapy.

CONCLUSIONS

To our knowledge, this is the first pediatric case of ICI-induced inflammatory arthritis and enthesitis. This case highlights the importance of increasing awareness of diagnosis and management of irAEs in children.

Immune Checkpoint Inhibitors and Lupus Erythematosus

Immune checkpoint inhibitors (ICIs) are the standard of care for a growing number of malignancies. Unfortunately, they are associated with a broad range of unique toxicities that mimic the presentations of primary autoimmune conditions. These adverse events are termed immune-related adverse events (irAEs), of which ICI-lupus erythematosus (ICI-LE) constitutes a small percentage. Our review aims to describe the available literature on ICI-LE and ICI treatment for patients with pre-existing lupus. Most diagnoses of ICI-LE had findings of only cutaneous lupus; four diagnoses of ICI-LE had systemic lupus manifestations. Over 90% (27 of 29) of cases received anti-PD-1/PDL-1 monotherapy, 1 received combination therapy, and 1 received only anti-CTLA-4 treatment. About three-fourths (22 of 29 or 76%) of patients with ICI-lupus were managed with topical steroids, 13 (45%) received hydroxychloroquine, and 10 (34%) required oral corticosteroids. In our case series, none of the patients with pre-existing lupus receiving ICI therapy for cancer had a flare of their lupus, but few had de novo irAE manifestations, all of which were characterized as low-grade. The review of the literature yielded seven ICI-LE flares from a total of 27 patients with pre-existing lupus who received ICI. Most flares were manageable without need for ICI cessation.

Significantly Delayed Development of Polyarthritis with Active Tenosynovitis after Possible Temporary Neutropenic Immune-Related Adverse Events Caused by Atezolizumab Treatment: A Novel Case Report

Immune checkpoint inhibitors have drastically improved cancer treatment. However, they may induce immune-related adverse events (irAEs). Here, we report a case of significantly delayed rheumatic irAEs (Rh-irAEs) with prior possible temporary neutropenic irAEs in a patient with atezolizumab-treated non-small-cell lung cancer and its management. A man in his sixties received atezolizumab monotherapy as the sixth-line treatment. He experienced an infusion-related reaction (fever) during the first cycle. On day 22 of cycle 2, grade 4 neutropenia suddenly appeared, but it disappeared on the next day. Cycle 3 was initiated after seven days; the patient did not exhibit any symptoms for approximately 500 days. However, on day 534 (day 1 of cycle 21), the patient complained of pain in the shoulders, back, and wrists. On day 644, the shoulder and back pain worsened with obvious swelling of the fingers. We thus suspended treatment and consulted a rheumatologist. A diagnosis of polyarthritis with active tenosynovitis was made based on joint ultrasound and laboratory tests. Prednisolone 15 mg attenuated the symptoms, allowing suspension of analgesics; however, dose reduction from 15 mg/day was difficult because of symptom flares. Finally, iguratimod 25 mg twice daily was initiated on day 764; prednisolone was reduced to 10 mg without flares, and its dosage was slowly reduced to 5 mg/day. Although irAEs exhibit multisystem features, delayed development of polyarthritis with active tenosynovitis after possible temporary neutropenic irAEs is rare. Thus, irAEs need to be monitored for a long time in patients with suspected irAE development even if it appears transiently.

Advances of autoimmune rheumatic diseases related to malignant tumors

BACKGROUND

Malignant neoplasms are a well-recognized global public health concern, with significant impacts on human health and quality of life. The interplay between tumors and autoimmune rheumatic diseases is complex, and the resulting tumor-associated rheumatic diseases represent a rare and intricate group of conditions that occur in the context of malignant tumors. In addition, various rheumatic diseases can arise as a consequence of oncology treatment. These diseases present with intricate clinical manifestations and pathological features, often rendering them challenging to diagnose and impacting patients' quality of life. Despite this, they have yet to be fully recognized.

METHODS

This article presents a literature review of published original articles and review articles concerning paraneoplastic rheumatic syndromes and rheumatic diseases associated with cancer treatment. We conducted a comprehensive literature search in PubMed, Web of Science and Google Scholar databases, excluding duplicated and irrelevant studies. In cases of duplicated research, we selected articles with higher impact factors for the review.

RESULTS

This review focuses on the clinical features, diagnosis, and treatment of paraneoplastic rheumatic diseases, as well as the pathogenesis of these diseases. Additionally, we summarize the autoimmune rheumatic diseases associated with cancer treatment. Ultimately, the goal of this review is to enhance recognition and improve the management of autoimmune rheumatic diseases related to tumors.

Immune-related adverse effects of checkpoint immunotherapy and implications for the treatment of patients with cancer and autoimmune diseases

During the past decade, there has been a revolution in cancer therapeutics by the emergence of antibody-based immunotherapies that modulate immune responses against tumors. These therapies have offered treatment options to patients who are no longer responding to classic anti-cancer therapies. By blocking inhibitory signals mediated by surface receptors that are naturally upregulated during activation of antigen-presenting cells (APC) and T cells, predominantly PD-1 and its ligand PD-L1, as well as CTLA-4, such blocking agents have revolutionized cancer treatment. However, breaking these inhibitory signals cannot be selectively targeted to the tumor microenvironment (TME). Since the physiologic role of these inhibitory receptors, known as immune checkpoints (IC) is to maintain peripheral tolerance by preventing the activation of autoreactive immune cells, IC inhibitors (ICI) induce multiple types of immune-related adverse effects (irAEs). These irAEs, together with the natural properties of ICs as gatekeepers of self-tolerance, have precluded the use of ICI in patients with pre-existing autoimmune diseases (ADs). However, currently accumulating data indicates that ICI might be safely administered to such patients. In this review, we discuss mechanisms of well established and newly recognized irAEs and evolving knowledge from the application of ICI therapies in patients with cancer and pre-existing ADs.

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.

Pembrolizumab-induced psoriatic arthritis treated with disease-modifying anti-rheumatic drugs in a patient with gastric cancer: A case report

BACKGROUND

Immune checkpoint inhibitor (ICI)-induced rheumatic immune-related adverse events (irAEs) have been infrequently reported, and the treatment of severe or refractory arthritis as irAEs has not been established yet.

CASE SUMMARY

The patient was a 67-year-old man with a history of well-controlled foot psoriasis who presented with polyarthralgia. He had received pembrolizumab for metastatic gastric adenocarcinoma 2 mo previously. Physical examination revealed erythematous swelling in the distal interphalangeal joints, left shoulder, and both knees. He had plaque psoriasis with psoriatic nail dystrophy and dactylitis in the distal joints of the fingers and toes. Inflammatory markers including C-reactive protein and erythrocyte sedimentation rate were elevated but rheumatoid factor and anticyclic citrullinated peptide antibody were negative. The patient was diagnosed with psoriatic arthritis (PsA) and started on methylprednisolone 1 mg/kg/day after pembrolizumab discontinuation. However, despite 1 wk of methylprednisolone treatment, PsA worsened; hence, leflunomide and methotrexate were started. After 4 wk of steroid treatment, PsA worsened and improved repeatedly with steroid tapering. Therefore, the therapy was intensified to include etanercept, a tumor necrosis factor inhibitor, which ultimately resulted in adequate PsA control.

CONCLUSION

This is the first report of ICI-induced PsA in a gastric cancer patient. Some rheumatic irAEs with refractory severe arthritis may require disease-modifying anti-rheumatic drugs and long-term management.

Musculoskeletal immune-related adverse events in 927 patients treated with immune checkpoint inhibitors for solid cancer

OBJECTIVE

The prevalence of the musculoskeletal immune-related adverse events (irAEs) is probably underestimated, as most studies report only severe side effects. Our aim was to describe and characterize all musculoskeletal irAEs in a large cohort of patients treated with immune checkpoint inhibitors (ICI).

METHODS

We conducted a retrospective study among patients who received ICI from 07/27/2014 to 05/08/2020 at the medical oncology department of the Institut Paoli-Calmettes, Marseille, France. All medical files were systemically reviewed by a rheumatologist who collected clinical features, time of occurrence, treatment regimen, irAEs management, course and outcomes. We also assessed tumor response 3 months after introduction of ICI, according to severity and treatments used to manage musculoskeletal irAEs.

RESULTS

Among 927 patients treated with ICI for a solid tumor, 118 patients (12.7%) presented a musculoskeletal irAE. Their median age was 66.5, 61% were male, and they mainly had a lung (57.6%) or urological cancer (27.1%). The most frequently involved ICI was an anti PD-1. Arthralgias and myalgias were the most frequent musculoskeletal irAEs (9.8%) and inflammatory rheumatic features were reported in 36 patients (3.9%) with elevated acute phase reactants and negative immunological markers. The median time of onset was 2 months (IC 95% 1.8; 2.7). Tumor response at 3 months did not differ according to musculoskeletal irAE severity, type of manifestation (arthralgias/myalgias versus inflammatory rheumatic features), pain patterns (mechanical versus inflammatory) or irAE treatments.

CONCLUSION

Musculoskeletal irAEs in this large cohort of patients treated with ICI were frequent (12.7%), mostly mild and well tolerated.

Rare immune-related adverse events in patients with melanoma: incidence, spectrum, and clinical presentations

Immune-related adverse events (irAEs) are side effects of immune checkpoint inhibitor therapy (ICI). While common irAEs have been well characterized, there are more limited data on rare immune related adverse events (RirAEs) due to low incidence. Lack of characterization of these entities has led to difficulties in accurate diagnosis and management. Here, we conducted a multi-institution analysis of all patients with stage III/IV melanoma who developed RirAEs after being treated with ICIs (anti-PD-1/L1, anti-CTLA-4, and combination PD-1/CTLA-4 blockade) at three institutions (Vanderbilt University Medical Center, Massachusetts General Hospital, and Melanoma Institute of Australia). RirAEs were defined as those occurring in approximately <1% of patients treated with anti-PD-1 or <2% with combination. Of 2834 patients who received ICIs, 82 developed RirAEs and were more common with combination PD-1/CTLA-4 blockade (4.6%) vs. anti-PD-1/L1 agents (2.8%). Overall median time from ICI start to RirAE was 86 days (interquartile range 42-235 days) with significantly earlier onset in combination therapy (p < 0.001). The spectrum of RirAEs spanned across several organ systems. Most RirAEs were grade 2 (57 [41.3%]) and grade 3 (40 [29.0%]) with relatively few grade 4 (11 [8.0%]) or 5 (5 [3.6%]) events. Steroid re-escalation (21.4%) or additional immunosuppression (13.8%) were commonly required. RirAE recurrence occurred in 22.6% with ICI rechallenge; 37.1% had new irAEs with rechallenge. In conclusion, RirAEs associated with ICIs in melanoma patients occurred, in aggregate, in 2-5% of patients treated with anti-PD-1-based therapy. Steroid re-escalation and alternative immunosuppression use were frequently required but fatal irAEs were fairly uncommon.

Treatment of rheumatic adverse events of cancer immunotherapy

Immune checkpoint inhibitors (ICIs), used to treat many advanced cancers, activate the immune system to elicit an antitumor response. ICIs can also cause immune-related adverse events (irAEs) when nontumor tissues are affected by excess inflammation and autoimmunity. Rheumatic irAEs include inflammatory arthritis, myositis, sicca syndrome, polymyalgia rheumatica, and several other rare phenotypes. Treating rheumatic irAEs requires balancing the desire to decrease off-target inflammation while not negatively impacting the antitumor immune response. In this review, treatment recommendations for rheumatic irAEs have been discussed. Pathogenesis of rheumatic irAEs has been briefly reviewed. Knowledge about the effects of corticosteroids and steroid-sparing agents on tumor responses has been detailed to give context for treatment decisions. Recommendations ultimately depend not only on the clinical presentation and severity of the irAE but also on the goals of cancer treatment. Finally, how to safely use ICI therapy in patients with preexisting autoimmune diseases is considered.

Use of a bDMARD or tsDMARD for the management of inflammatory arthritis under checkpoint inhibitors: an observational study

OBJECTIVE

There is limited experience regarding the use of biological disease-modifying antirheumatic drug (bDMARD) and JAK inhibitor (JAKi) for the management of immune checkpoint inhibitors (ICI)-induced inflammatory arthritis. We aimed to assess their efficacy and safety in this setting.

METHODS

Using the Club Rhumatismes and Inflammation French network, we conducted a multicentre, retrospective, observational study of patients with cancer diagnosed with inflammatory arthritis under ICI(s) and treated with bDMARD or JAKi. Clinical data were collected using a standardised case report form.

RESULTS

Twenty patients (60% men, median age 69.5 years) were included, with rheumatoid arthritis (RA)-like (n=16), polymyalgia rheumatica-like (n=2) or psoriatic arthritis-like (n=2) clinical presentation. Two patients had pre-existing RA. 90% were treated with glucocorticoids as first-line therapy and 60% received methotrexate prior to bDMARD or JAKi. Anti-interleukin-6 receptor (IL-6R) therapy was used in 13/20 patients (65%), leading to clinical improvement in 11/13 patients (85%), but one patient experienced intestinal perforation and cancer progression was noticed in 6/13 patients (46%). Tumour necrosis factor inhibitors were used in 5/20 patients (25%), with improvement in 4/5 patients (80%) and cancer progression was observed in 3/5 patients (60%). Two infections (diverticulitis and pneumonitis) were reported. Anakinra, baricitinib and ustekinumab were each used in one patient. Median duration of the bDMARD or JAKi was 17 weeks.

CONCLUSION

Anti-IL-6R therapy is currently the most common strategy in patients with ICI-induced inflammatory arthritis and insufficient response to glucocorticoids and methotrexate, leading to improvement in &gt;80%. Overall, cancer progression occurred in about half of patients and whether the bDMARD/JAKi impacted the tumour response remains to be determined.

Immune Checkpoint Inhibitor-Associated Myositis: A Distinct Form of Inflammatory Myopathy

ABSTRACT

Research on the relationship between inflammatory myopathy and malignancy has grown considerably within the last century. Now, the burgeoning field of inflammatory myopathy has yet another player in the mix: immune checkpoint inhibitor-associated myositis (ICI myositis). Immune checkpoint inhibitor-associated myositis is indicated by clinical diagnosis of inflammatory myopathy after initiation of immune checkpoint inhibitor for cancer management. Current literature reflects low prevalence but high mortality associated with ICI myositis, especially when involving myasthenia gravis and myocarditis. Immune checkpoint inhibitor-associated myositis tends to have muscle pain along with weakness, infrequent presentation with dermatitis, or interstitial lung disease and is typically seronegative with scattered, endomysial inflammatory infiltrates on biopsy. The differential diagnosis of ICI myositis includes myasthenia gravis and other neurological immune-related adverse events. Therapeutic approach involves high doses of corticosteroids with a choice of steroid-sparing immunomodulating agent(s) that is primarily driven by expert opinion due to lack of robust research to support one agent over another. There is wide variation in the inclusion criteria for ICI myositis used in previous studies. We review previously used inclusion criteria and suggest an expertise-based classification criterion to provide a standardized definition and allow comparability between studies. There is a critical need for prospective translational and clinical studies that elucidate the pathophysiology of ICI myositis in order to improve evaluation and management of these patients.

Systemic Sclerosis Association with Malignancy

The association of systemic sclerosis (SSc) and cancer is well known from several decades suggesting common genetic and environmental risk factors involved in the development of both diseases. Immunosuppressive drugs widely used in SSc may increase the risk of cancer occurrence and different SSc clinical and serological features identify patients at major risk to develop malignancy. In this context, among serological features, presence of anti-RNA polymerase III and anti-topoisomerase I autoantibodies seems to increase cancer frequency in SSc patients (particularly lung and breast cancers). Lung fibrosis and a long standing SSc pulmonary involvement have been largely proposed as lung cancer risk factors, and the exposure to cyclophosphamide and an upper gastrointestinal involvement have been traditionally linked to bladder and oesophagus cancers, respectively. Furthermore, immune checkpoint inhibitors used for cancer therapy can induce immune-related adverse events, which are more frequent and severe in patients with pre-existing autoimmune diseases such as SSc. The strong association between SSc and cancer occurrence steers clinicians to carefully survey SSc patients performing periodical malignancy screening. In the present review, the most relevant bilateral relationships between SSc and cancer will be addressed.

The effects of glucocorticoids and immunosuppressants on cancer outcomes in checkpoint inhibitor therapy

The emergence of checkpoint inhibitors has created a paradigm shift for the treatment of various malignancies. However, although these therapies are associated with improved survival rates, they also carry the risk of immune-related adverse events (irAEs). Moderate to severe irAEs are typically treated with glucocorticoids, sometimes with the addition of immunosuppressants as steroid-sparing therapy. However, it is unclear how glucocorticoids and immunosuppressants may impact cancer survival and the efficacy of immune checkpoint therapy on cancer. In this narrative review, we discuss the effects of glucocorticoids and immunosuppressants including methotrexate, hydroxychloroquine, azathioprine, mycophenolate mofetil, tumor-necrosis factor (TNF)-inhibitors, interleukin-6 inhibitors, interleukin-1 inhibitors, abatacept, rituximab, and Janus kinase inhibitors (JAKi) on cancer-specific outcomes in the setting of immune checkpoint inhibitor use.

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.

Clinical Patterns and Follow-Up of Inflammatory Arthritis and Other Immune-Related Adverse Events Induced by Checkpoint Inhibitors. A Multicenter Study

Objectives

To describe different clinical patterns of rheumatic immune-related adverse events (irAEs) induced by immune checkpoint inhibitors (ICI) and their rheumatic and oncologic outcomes.

Methods

We classified clinical syndromes according to five different categories: non-inflammatory arthralgias (NIA), rheumatoid arthritis (RA)-like, psoriatic arthritis (PsA)-like, polymyalgia rheumatica (PMR)-like, and a miscellaneous group of patients with other syndromes. We conducted a baseline visit and then follow-up in order to determine their clinical pattern, treatment response, and outcome.

Results

We included 73 patients (64% male) with a mean age of 66.1 ± 11.6 years. Main underlying diagnosis was lung carcinoma in 29 (39%) patients, melanoma in 20 (27%), and renal-urothelial cancer in 11 (15%). Main ICI included Pembrolizumab in 24 (32%), Nivolumab 17 (23%), and Atezolizumab 7 (9 %). Seventeen out of seventy-three patients had an underlying rheumatic disease before ICI treatment. Fourteen patients developed other irAEs before or simultaneously with rheumatic syndromes. Main rheumatic irAEs included: RA-like in 31 (42.4%), NIA in 19 (26.0%), PMR-like in 10 (13.7%), and PsA-like in 5 (6.8%), among others. Median time from ICI to irAEs was 5 months (IQR 3–9). Those patients who received combined therapy, had a trend for an earlier presentation than those who received monotherapy (4.3 months IQR 1.85–17 vs. 6 months IQR 3–9.25, p = NS). Mean follow-up time was 14.0 ± 10.8 (SD, months). At the last visit, 47 % were taking glucocorticoids and 11% DMARD therapy. At the last visit, 13 (17.8%) patients remained with persistent arthritis, 19 (26%) had intermittent flares, and 39 (53.4%) had a self-limited pattern. Only in 15.1% of patients ICI therapy was discontinued.

Conclusions

We described different patterns according to treatment and irAEs. Combined ICI therapy had an earlier onset of symptoms. Patients who presented as RA-like, had a higher risk of persistent arthritis. After a mean follow-up of more than 1 year, one-fifth of the patients remained with persistent arthritis and 11% required DMARD therapy.

Monitoring and Management of the Patient with Immune Checkpoint Inhibitor-Induced Inflammatory Arthritis: Current Perspectives

In this review, we draw from observational studies, treatment guidelines and our own clinical experience to describe approaches to monitoring and management of immune checkpoint inhibitor (ICI)-induced inflammatory arthritis, including polymyalgia rheumatica. This condition occurs in about 4% of ICI-treated cancer patients and can persist for a year or longer. Mild arthritis can generally be managed with non-steroidal anti-inflammatory drugs, intraarticular steroids injections and/or low dose corticosteroids. Higher grade arthritis should be brought under control with corticosteroids, but early introduction of a steroid-sparing agent is recommended to minimize steroid toxicity. In order to assess the effectiveness of any arthritis treatment, tender and swollen joint counts and patient reported measures of physical function, such as the health assessment questionnaire, should be obtained at each visit. Referral to a rheumatologist is recommended for patients with high grade arthritis to help guide the use of disease-modifying antirheumatic drugs.

Immune-checkpoint inhibitors: long-term implications of toxicity

The development of immune-checkpoint inhibitors (ICIs) has heralded a new era in cancer treatment, enabling the possibility of long-term survival in patients with metastatic disease, and providing new therapeutic indications in earlier-stage settings. As such, characterizing the long-term implications of receiving ICIs has grown in importance. An abundance of evidence exists describing the acute clinical toxicities of these agents, although chronic effects have not been as well catalogued. Nonetheless, emerging evidence indicates that persistent toxicities might be more common than initially suggested. While generally low-grade, these chronic sequelae can affect the endocrine, rheumatological, pulmonary, neurological and other organ systems. Fatal toxicities also comprise a diverse set of clinical manifestations and can occur in 0.4-1.2% of patients. This risk is a particularly relevant consideration in light of the possibility of long-term survival. Finally, the effects of immune-checkpoint blockade on a diverse range of immune processes, including atherosclerosis, heart failure, neuroinflammation, obesity and hypertension, have not been characterized but remain an important area of research with potential relevance to cancer survivors. In this Review, we describe the current evidence for chronic immune toxicities and the long-term implications of these effects for patients receiving ICIs.

Predictors of Rheumatic Immune-Related Adverse Events and De Novo Inflammatory Arthritis After Immune Checkpoint Inhibitor Treatment for Cancer

OBJECTIVE

To identify predictors of rheumatic immune-related adverse events (irAEs) following immune checkpoint inhibitor (ICI) treatment for cancer.

METHODS

We performed a case-control study to predict the occurrence of rheumatic irAEs in cancer patients who initiated ICI treatment at Mass General Brigham and the Dana-Farber Cancer Institute between 2011 and 2020. We screened for the presence of rheumatic irAEs by reviewing the medical records of patients evaluated by rheumatologists or those prescribed nonglucocorticoid immunomodulatory drugs after the time of ICI initiation (baseline). Review of medical records confirmed the presence of rheumatic irAEs and the indications necessitating immunomodulatory drug treatment. Controls were defined as patients who did not experience rheumatic irAEs, did not have preexisting rheumatic disease, did not have a clinical evaluation by a rheumatologist after ICI treatment, did not receive an immunomodulatory drug after ICI, did not receive systemic glucocorticoids after ICI, and survived at least 6 months after the initial ICI treatment. We used logistic regression to estimate the odds ratios (ORs) (with 95% confidence intervals [95% CIs]) for the risk of a rheumatic irAE in the presence of various baseline predictors.

RESULTS

A total of 8,028 ICI recipients were identified (mean age 65.5 years, 43.1% female, 31.8% with lung cancer). After ICI initiation, 404 patients (5.0%) were evaluated by rheumatologists, and 475 patients (5.9%) received an immunomodulatory drug to treat any irAEs. There were 226 confirmed rheumatic irAE cases (2.8%) and 118 de novo inflammatory arthritis cases (1.5%). Rheumatic diseases (either preexisting rheumatic diseases or rheumatic irAEs) were a common indication for immunomodulatory drug use (27.9%). Baseline predictors of rheumatic irAEs included melanoma (multivariable OR 4.06 [95% CI 2.54-6.51]) and genitourinary (GU) cancer (OR 2.22 [95% CI 1.39-3.54]), both relative to patients with lung cancer; combination ICI treatment (OR 2.35 [95% CI 1.48-3.74]), relative to patients receiving programmed death 1 inhibitor monotherapy; autoimmune disease (OR 2.04 [95% CI 1.45-2.85]) and recent glucocorticoid use (OR 2.13 [95% CI 1.51-2.98]), relative to patients not receiving a glucocorticoid, compared to the 2,312 controls without rheumatic irAEs. Predictors of de novo inflammatory arthritis were similar to those of rheumatic irAEs.

CONCLUSION

We identified novel predictors of rheumatic irAE development in cancer patients, including baseline presence of melanoma, baseline presence of GU tract cancer, preexisting autoimmune disease, receiving or having received combination ICI treatment, and receiving or having received glucocorticoids. The proportion of cancer patients experiencing rheumatic irAEs may be even higher than was reported in the present study, since we used stringent criteria to identify cases of rheumatic irAEs. Our findings could be used to identify cancer patients at risk of developing rheumatic irAEs and de novo inflammatory arthritis and may help further elucidate the pathogenesis of rheumatic irAEs in patients with cancer who are receiving ICI treatment.

Potential therapies for immune-related adverse events associated with immune checkpoint inhibition: from monoclonal antibodies to kinase inhibition

The therapeutic benefits of immune checkpoint inhibitors (ICIs), which enable antitumor immune responses, can be tempered by unwanted immune-related adverse events (irAEs). Treatment recommendations stratified by irAE phenotype and immunohistopathological findings have only recently been proposed and are often based on those used in primary autoimmune diseases, including targeting of specific proinflammatory cytokines with monoclonal antibodies. Increasing evidence supports the use of such antibody-based strategies as effective steroid-sparing treatments, although the therapies themselves may be associated with additional drug toxicities and reduced ICI efficacy. Kinases are key contributors to the adaptive and innate responses that drive primary autoimmune diseases and irAEs. The janus kinase/signal transducer and activator of transcription, Bruton’s tyrosine kinase, and mitogen-activated protein kinase-interacting serine/threonine protein kinases 1 and 2 pathways are also critical to tumor progression and have important roles in cells of the tumor microenvironment. Herein, we review the histopathological, biological, and clinical evidence to support specific monoclonal antibodies and kinase inhibition as management strategies for irAEs.

Cancer incidence in primary Sjögren's syndrome: Data from the French hospitalization database

The relationship between cancer and primary Sjögren's syndrome (pSS) is uncertain. While the increased risk of hematological malignancies is well-known, data on the comparative incidence of solid neoplasms is conflicting. This study aimed to explore the associations between cancer and pSS. This nationwide population-based retrospective study from the French health insurance database (PMSI) evaluated patients hospitalized with new-onset pSS from 2011 to 2018 against age- and sex-matched hospitalized controls (1:10). The incidence of hematological malignancies and solid neoplasms was compared between the two groups. Mortality and multiple cancer incidence were also evaluated. Adjusted Hazard Ratios (aHR) calculations included confounding factors, such as low socioeconomic status. Among 25,661 hospitalized patients with pSS versus 252,543 matched patients (median follow-up of 3.96 years), we observed a higher incidence rate of lymphomas (aHR, 1.97 [95% CI, 1.59-2.43]), Waldenström macroglobulinemia (aHR, 10.8 [6.5-18.0]), and leukemia (aHR, 1.61 [1.1-2.4]). Thyroid cancer incidence was higher (aHR, 1.7 [1.1-2.8]), whereas bladder and breast cancer incidences were lower (aHR, 0.58 [0.37-0.89] and 0.60 [0.49-0.74], respectively). pSS patients with breast cancer exhibited a lower mortality rate. A limitation was that the database only encompasses hospitalized patients, and immunological and histological details are not listed. We confirmed the increased risk of hematological malignancies and thyroid cancers among patients with pSS. The lower risk of breast cancer suggests a role of hormonal factors and raises questions of the concept of immune surveillance within breast tissue. Epidemiological and translational studies are required to elucidate the relationships between pSS and cancer.

PD-1/PD-L1 blockade: Prospectives for immunotherapy in cancer and autoimmunity

Immune checkpoint blockade therapy (ICBT) has become a successful cancer treatment approach in the field of cancer immunotherapy. Blockade of programmed death 1 (PD-1) and programmed death-ligand 1 (PD-L1) with monoclonal antibodies have been known as successful examples of cancer immunotherapy in recent years. Although ICBT has been shown to be beneficial in cancers, such benefits have only been seen in a portion of cancer patients. In this regard, enhancing the therapeutic effects of inhibiting PD-1 and PD-L1 and reducing the side effects of this approach can be considered as a potential approach in a successful ICBT. In this review, we have highlighted new viewpoints regarding improving the therapeutic effect of PD-1 and PD-L1 blockades in cancer therapy. Besides, their expression levels as a biomarker with prognostic value, their role in intestinal microbiota modulation, combination therapy, and immune-related side effects (irAEs) have been discussed.

Autoimmunity and cancer

In many autoimmune rheumatic diseases, there is an increased risk of cancer compared to the general population. The link between autoimmunity and cancer is dynamic and bidirectional. Recent advances in terms of knowledge of biology, epidemiology, and long-term outcomes for the autoimmune rheumatic diseases have revealed several new connections between these two entities. Data suggest that chronic inflammation from the rheumatic diseases or their therapies may contribute to the onset and promotion of cancer. Conversely, antitumor immune responses may become cross-reactive with self-tissues resulting in the development of autoimmunity. In this review, we discuss about the potential mechanisms that link autoimmune rheumatic diseases and cancer and the association of malignancies with common autoimmune disorders. The increased incidence of malignancy in autoimmune rheumatic diseases has been largely described, although the biology underpinning this relationship should be further investigated. The development of evidence-based cancer screening recommendations in patients with autoimmune rheumatic diseases is complex due to the heterogeneity of clinical rheumatic phenotypes, cancer sites at risk and exposure to anti-neoplastic and anti-rheumatic treatment. In order to lay the foundation of risk stratification and targeted cancer screening, larger longitudinal cohort studies that provide a more detailed framework of the links between cancer and autoimmunity are urgently needed.

Prevalence, therapy and tumour response in patients with rheumatic immune-related adverse events following immune checkpoint inhibitor therapy: a single-centre analysis

Background:

Immune checkpoint inhibitors (ICIs) improved cancer therapy by inducing a higher immune system activity. This effect can cause rheumatic immune-related adverse events (rh-irAEs), which have not yet been extensively studied.

Methods:

We analysed 437 patients between 2014 and 2019, treated with ipilimumab (anti-CTLA-4) and/or nivolumab (anti-PD-1) or pembrolizumab (anti-PD-1) at the Clinic for Internal Medicine III, Oncology, Haematology and Rheumatology at the University Hospital Bonn, Germany.

Results:

Of the 437 patients 60% were males. Patients were mainly treated for melanoma, lung cancer, head and neck tumour and urothelial carcinoma. At least one immune-related adverse event (irAE) was observed in 163 patients (37.3%), including rh-irAE. Most common side effects were rash, colitis and hepatitis. We identified 19 patients (4.3%) with a minimum of one rh-irAE due to ICI therapy; three of those had a pre-existing rheumatic disease. Arthralgia developed most frequently in eight patients (42.1%). Other rh-irAEs were: arthritis (n = 7; distinguished in rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis and undifferentiated arthritis), myalgia (n = 2) and myositis (n = 3). Most rh-irAEs were classified as moderately severe (Common Terminology Criteria of Adverse Events grade 2: 68.4%). Median time between starting ICI therapy and the occurrence of rh-irAE was 109 days (interquartile range 40–420 days). Fifteen patients (78.9%) were treated with glucocorticosteroids. In four cases additional therapy with methotrexate or tocilizumab was required. Even though patients benefited from ICI treatment, therapy had to be discontinued in six of the participants due to rh-irAE. Interestingly, patients with rh-irAE had a significantly higher tumour response compared with patients without rh-irAE (94.4% versus 43.5%; p < 0.0001).

Conclusion:

Rh-irAEs occur under ICI therapy, especially in patients with higher tumour response. However, they are not the most frequent irAE after ICI exposure: 9.3% of all irAEs were rheumatic (20 rh-irAE cases in 19 patients of a total of 215 irAE cases in 163 patients).

Fatal Adverse Events Associated With Immune Checkpoint Inhibitors in Non-small Cell Lung Cancer: A Systematic Review and Meta-Analysis

Background: Immune checkpoint inhibitors (ICIs) have previously been reported to have a promising potential in terms of the improvement of outcomes in non–small cell lung cancer (NSCLC). Fatal adverse events (FAEs) of ICIs are relatively uncommon, and the incidence and risk in NSCLC remain unclear. In the present study, we conducted a systematic review and meta-analysis to evaluate the risk of FAEs in NSCLC patients administered with ICIs.

Methods: Potentially relevant studies were identified in PubMed, EMBASE, and Cochrane library database from inception to September 16, 2020. The systematic review and meta-analysis included randomized controlled trials that reported treatment-related FAEs in NSCLC. The pooled incidence and risk ratios (RRs) were calculated to evaluate prospective risk.

Results: Twenty clinical trials that included a total of 13,483 patients were selected for the meta-analysis. The overall incidence of FAEs was 0.65% [95% confidence interval (CI) = 0.31–1.07, I² = 50.2%] in ICI monotherapy, 1.17% (95% CI = 0.74–1.69, I² = 56.3%) in chemotherapy, and 2.01% (95% CI = 1.42–2.69, I² = 5.9%) in the combination therapy (ICI and chemotherapy). ICI monotherapy was associated with lower incidence of FAEs caused by blood system disorders (RR = 0.23, 95% CI = 0.07–0.73, P = 0.013, I² = 0%) and infectious diseases (RR = 0.29, 95% CI = 0.13–0.63, P = 0.002, I² = 0%). The incidence of pneumonitis significantly increased in immunotherapy (RR = 5.72, 95% CI = 1.14–28.80, P = 0.03, I² = 0%).

Conclusions: The results of the present study demonstrate that ICI monotherapy decreases the risk of FAEs, whereas the combined regimens with chemotherapy have the opposite tendency as compared to conventional chemotherapy. While the patients who received chemotherapy suffered the risks of death mainly from myelosuppression and infection, those who received immunotherapy were mainly threatened by immune-related pneumonitis.

Preexisting autoimmune disease and immune-related adverse events associated with anti-PD-1 cancer immunotherapy: a national case series from the Canadian Research Group of Rheumatology in Immuno-Oncology

BACKGROUND

Limited data are available on the safety and efficacy of immune checkpoint inhibitors (ICI) in patients with preexisting autoimmune diseases (PAD).

METHODS

Retrospective study of patients with PAD referred for rheumatologic evaluation prior to starting or during immunotherapy between January 2013 and July 2019 from 10 academic sites across Canada. Data were extracted by chart review using a standardized form.

RESULTS

Twenty-seven patients with PAD on ICI therapy were identified. The most common PADs were rheumatoid arthritis (30%), psoriasis/psoriatic arthritis (30%), inflammatory bowel disease (IBD, 15%) and axial spondyloarthritis (11%), and the most frequently observed cancers were lung cancer and melanoma. All patients received anti-PD-1 therapies, and 2 received additional sequential anti-CTLA-4 therapy. PAD exacerbations occurred in 52% over a median (IQR) follow-up of 11.0 (6.0-17.5) months, with 14% being severe, 57% requiring corticosteroids, 50% requiring immunosuppression and 14% requiring ICI discontinuation. Flares were generally more frequent and severe in patients who previously required more intensive immunosuppression (i.e., biologics). Flares occurred despite background immunosuppression at the time of ICI initiation. In patients with preexisting psoriasis, IBD and axial spondyloarthritis, rheumatic immune-related adverse events (irAEs), mostly polyarthritis and tenosynovitis, were frequently observed. Tumor progression was not associated with exposure to immunosuppressive drugs before or after ICI initiation and was numerically less frequent in patients with irAEs.

CONCLUSION

PAD exacerbations in the context of ICI treatment are common, although generally mild, and occur despite background immunosuppression. Exacerbations are more frequent and severe in patients on more intensive immunosuppressive therapies pre-immunotherapy.

Musculoskeletal immune-related adverse events with the use of checkpoint inhibitors in malignancy

BACKGROUND

Immunotherapy has revolutionised the treatment of many malignancies. Along with their success, there have been inflammatory and immune-related adverse events (irAE). There is a paucity of literature describing the Australian experience of rheumatic irAE.

AIMS

To describe and characterise the Royal North Shore Hospital and Westmead Hospital cohort with rheumatic irAE.

METHODS

This case series reports on 17 patients with advanced cancer treated at two sites in Sydney, Australia who were referred for rheumatological evaluation from 2013 to 2016. Data were collected retrospectively and inspected for clinical signs, duration of immunotherapy prior to onset of symptoms, management strategies and cancer outcomes.

RESULTS

Patients presented with arthralgias, myalgias, periarticular and systemic symptoms. Onset of rheumatological symptoms was variable, with a median of 4 months (range 0.2-24) for monotherapy and 5.05 months (range 0.2-6.9) for combination. The predominant findings were of tenosynovitis (23%) and large joint involvement (65%). All patients were seronegative for RF and anti-CCP. Most patients responded well to non-steroidal anti-inflammatory drugs or low-dose prednisone (59%) and remained on immunotherapy (77%). The majority (76%) of patients experienced concomitant irAE in other organ systems. Sixty-five percent of patients had complete response of their malignancy to immunotherapy.

CONCLUSION

Rheumatic irAE are heterogenous clinical entities, which require further evaluation into classification, patient susceptibility and response. From our study, there was no clear clinical pattern. The present case series supports that rheumatic irAE may be associated with tumour response. However, there is still limited experience in rheumatic irAE management and outcomes.

Immune Checkpoint Inhibitor-Associated Scleroderma-Like Syndrome: A Report of a Pembrolizumab-Induced "Eosinophilic Fasciitis-Like" Case and a Review of the Literature

Immune checkpoint inhibitors are a promising new therapeutic strategy in oncology that aims to eliminate cancer cells by enhancing patients' immune response against tumor antigens. Despite their beneficial effects, immune checkpoint inhibitors are also responsible for a plethora of autoimmune manifestations, known as immune-related adverse events. We present a case of eosinophilic fasciitis-like disorder in an 81-year-old patient treated with the programmed death cell protein 1 inhibitor pembrolizumab for non-small-cell lung cancer. The patient developed characteristic indurated skin lesions in his limbs after 1½ years of treatment with pembrolizumab and a typical “groove sign.” Raynaud’s syndrome was absent. A full-thickness biopsy confirmed the clinical diagnosis of an “EF-like” condition. Neither peripheral eosinophilia nor eosinophilic infiltrates in the skin biopsy were found. His symptoms improved after a 2.5-month CPI discontinuation and treatment with 16 mg of methylprednisolone slowly tapered to a dose of 4 mg. Eosinophilic fasciitis is a rare immune-related adverse event of CPI treatment; our literature search identified only 12 cases that fulfill the criteria of EF in patients receiving CPIs.

Modulating the wayward T cell: New horizons with immune checkpoint inhibitor treatments in autoimmunity, transplant, and cancer

The T-cell response is regulated by the balance between costimulatory and coinhibitory signals. Immune checkpoints are essential for efficient T-cell activation, but also for maintaining self-tolerance and protecting tissues from damage caused by the immune system, and for providing protective immunity. Modulating immune checkpoints can serve diametric goals, such that blocking a coinhibitory molecule can unleash anti-cancer immunity whereas stimulating the same molecule can reduce an over-reaction in autoimmune disease. The purpose of this review is to examine the regulation of T-cell costimulation and coinhibition, which is central to the processes underpinning autoimmunity, transplant rejection and immune evasion in cancer. We will focus on the immunomodulation agents that regulate these unwanted over- and under-reactions. The use of such agents has led to control of symptoms and slowing of progression in patients with rheumatoid arthritis, reduced rejection rates in transplant patients, and prolonged survival in patients with cancer. The management of immune checkpoint inhibitor treatment in certain challenging patient populations, including patients with pre-existing autoimmune conditions or transplant patients who develop cancer, as well as the management of immune-related adverse events in patients receiving antitumor therapy, is examined. Finally, the future of immune checkpoint inhibitors, including examples of emerging targets that are currently in development, as well as recent insights gained using new molecular techniques, is discussed. T-cell costimulation and coinhibition play vital roles in these diverse therapeutic areas. Targeting immune checkpoints continues to be a powerful avenue for the development of agents suitable for treating autoimmune diseases and cancers and for improving transplant outcomes. Enhanced collaboration between therapy area specialists to share learnings across disciplines will improve our understanding of the opposing effects of treatments for autoimmune disease/transplant rejection versus cancer on immune checkpoints, which has the potential to lead to improved patient outcomes.

Immune checkpoint inhibitor-induced musculoskeletal manifestations

Immune checkpoint inhibitors (ICI) associate with a wide range of immune-related adverse events (Ir-AE), including musculoskeletal manifestations. We aimed at identifying all studies reporting musculoskeletal Ir-AE. An electronic (Medline, Scopus and Web of Science) search was performed using two sets of key words. The first set consisted of: arthritis, musculoskeletal, polymyalgia rheumatica and myositis. The second set consisted of: anti-PD-1, anti-PD-L1, anti-CTLA-4, ipilimumab, tremelimumab, pembrolizumab, nivolumab, atezolizumab, avelumab and durvalumab. We identified 3 prospective studies, 17 retrospective studies and 4 case series reporting 363 patients in total. Combined data from all three prospective studies provide a prevalence rate of 6.13%. Most patients were males (59.68%) and the vast majority (73%) were on programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) inhibitors. Most studies report a median time of ≤ 12 weeks from first ICI administration to symptom onset. The main clinical phenotypes reported were: (a) inflammatory arthritis (57.57%), (b) myositis (14.04%) and (c) polymyalgia rheumatica (PMR) (12.12%). A total of 256 patients required steroids (70.52%) and 67 patients (18.45%) were treated with DMARDs. Positive auto-antibodies and family history of any autoimmune disease were present in 18.48% and 19.04% of cases, respectively. Only a few patients (19%) had to discontinue treatment due to musculoskeletal Ir-AE. Two prospective studies show that significantly more patients with musculoskeletal Ir-AE exhibit a favorable oncologic response compared to patients not exhibiting such manifestations whereas retrospective studies show that 77.22% of patients with musculoskeletal Ir-AE have a good tumor response. One out of 15 patients treated with ICI will develop musculoskeletal Ir-AE; in most cases the severity of these manifestations is mild/moderate and usually ICI may be continued. Rheumatologists should familiarize with this new clinical entity and develop relevant therapeutic algorithms.