Immune checkpoint inhibitor-related myositis and myocarditis in patients with cancer

Rheumatic complications in cancer patients treated with immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) have revolutionized anticancer therapy due to their long-term clinical benefits and immune boosting mechanisms. However, despite their consistent therapeutic effects, the use of ICIs is associated with a spectrum of adverse events due to their autoimmune and auto-inflammatory actions. These adverse events can affect any organ system, including the endocrine, neurologic, gastrointestinal, cardiac, skin, pulmonary, and musculoskeletal systems. Of the immune-related adverse events (irAEs), rheumatic complications are common and appear to be distinct from irAEs in other organs in terms of variability of onset time, capacity for persistence, and relationship with pre-existing autoimmune rheumatologic diseases. In this article, we review the mechanisms of the anti-cancer effects of ICIs, the irAEs of immuno-oncology drugs, and the general recommendations for managing irAEs. In particular, we focus on rheumatologic irAEs and discuss their prevalence, clinical characteristics, and management.

Neurological Immune Related Adverse Events Associated with Nivolumab, Ipilimumab, and Pembrolizumab Therapy-Review of the Literature and Future Outlook

Immune checkpoint inhibitor (ICI) therapy has revolutionized the management of various cancers with previously poor prognosis. Despite its great efficacy, the therapy is associated with a wide spectrum of immune-related adverse events (irAE) including neurological symptoms which can affect all parts of the central and peripheral nervous system. Even though these events are rare, they are of high relevance as the rate of residual symptoms or even fatal outcomes is remarkable. To provide a detailed overview of neurological adverse events associated with immune checkpoint-inhibitor therapy we conducted a literature search. While focusing on ipilimumab, nivolumab, and pembrolizumab therapy, all available case reports as well as larger case series and clinical trials have been considered. Eighty-two case reports about checkpoint-inhibitor therapy induced symptoms of the peripheral nervous system have been published, while only 43 case reports addressed central nervous system abnormalities. The frequency of immune checkpoint-inhibitor therapy inducing neurological adverse events is about 1% in larger studies. Especially neuromuscular adverse events exhibit distinct clinical and diagnostic characteristics. Additionally, several affected patients presented with overlap-syndromes, which means that symptoms and diagnostic findings indicating myositis, myasthenia gravis, and neuropathy were present in one individual patient at the same time. Thus, neurological and particularly neuromuscular adverse events of immune checkpoint-inhibitor therapy may constitute a new disease entity.

[Clinical Diagnosis and Treatment Recommendations for Cardiac Adverse Reactions Related to Immune Checkpoint Inhibitor]

Immunotherapy of malignant tumors has become a hot spot in the field of cancer research and treatment, bringing new hope to patients with advanced cancer. Activation of molecular programmer death protein-1 and T lymphocyte-associated antigen 4-related signaling pathways at the immunological checkpoint can inhibit T lymphocyte activation and thereby block the inflammatory response. Tumor cells achieve immune escape by activating the molecular pathways associated with immune checkpoints. The immune checkpoint inhibitor can wake up T lymphocytes and enhance the body's clearance of tumor cells. However, the role of immune checkpoint inhibitors is not specific to tumor cells, and it can cause side effects of multiple systems including the cardiovascular system while killing tumor cells. We will summarize the relevant cardiac side effects and give advice on how to manage it.

[Clinical Diagnosis and Treatment Recommendations for Adverse Reaction in the Nervous System Related to Immunocheckpoint Inhibitor]

Immune checkpoint inhibitors (ICIs) can cause adverse reactions in the nervous system, with the incidence rate ranging from 0.1% to 12%, and 80% occurring within the first 4 months of ICI application. It can cause lesions in various parts of the nervous system, including aseptic meningitis, meningoencephalitis, necrotizing encephalitis, brainstem encephalitis, transverse myelitis and other central nervous system diseases. It can also cause cranial peripheral neuropathy, multifocal radicular neuropathy, Guillain-Barre syndrome, spinal radicular neuropathy and myasthenia gravis, myopathy, etc. For these complications of the nervous system, diagnosis could be made by sufficient collection of disease manifestations combined with imaging, cerebrospinal fluid examinations, electro-encephalogram or electro myography to exclude infection or tumor progression. In the treatment of severe cases, ICIs should be discontinued and treated with high doses of glucocorticoid or gamma globulin with systemic support. After neurological adverse reactions, the prognosis of severe cases is poor.

Tertiary lymphoid organs in the inflammatory myopathy associated with PD-1 inhibitors

BACKGROUND

Programmed cell death 1 inhibitors have revolutionized therapy for cancer by their outstanding effectiveness. However, they may cause adverse effects, among which inflammatory myopathy is one of the most disabling. To elucidate its mechanism, we analysed muscle biopsies and compared them with other inflammatory myopathies.

METHODS

Muscle biopsies from three patients with inflammatory myopathy after treatment with PD-1 inhibitors for cancer were subjected to immunohistochemical and ultrastructural analyses to localize CD8+ cytotoxic cells and markers of lymphoid follicles. For comparison, two cases of polymyositis and one of juvenile dermatomyositis were examined.

RESULTS

Nearly identical pathological features were observed in the three cases. In the island-like foci of inflammation, muscle fibers were undergoing degeneration. CD8+ cytotoxic T cells, macrophages, CD4+ cells, and B cells were observed in the foci. CD8+ cells were seen outside and inside the basal lamina of non-necrotic muscle fibers. Lymphoid follicle-like structures with CD21+ follicular dendritic cells were present. The blood vessels in the foci showed features consistent with the high endothelial venules, on which their markers, PNAd and CCL21, were expressed. In polymyositis, blood vessels stained only faintly for PNAd and CCL21, while in juvenile dermatomyositis, in which tertiary lymphoid follicle-like structure was reported in the past, they stained positively.

CONCLUSIONS

In inflammatory myopathy associated with PD-1 inhibitors, CD8+ cells appear to predominantly destruct muscle fibers. The presence of lymphoid follicle-like structures and expression of PNAd and CCL21 on the endothelial cells suggest the tertiary lymphoid organs are formed, and involved in the leakage of lymphocytes. Thus, in the three cases examined, formation of the tertiary lymphoid organs is likely to play an important role in genesis of the PD-1 myopathy.

Trouble at the junction: When myopathy and myasthenia overlap

Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1, DES, DNM2, GMPPB, MTM1, or PLEC and congenital myasthenic syndromes due to mutations in ALG2, ALG14, COL13A1, DOK7, DPAGT1, or GFPT1. Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co-occurrence of myasthenia gravis or Lambert-Eaton myasthenic syndrome with an immune-mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.

Neurologic Autoimmunity in the Era of Checkpoint Inhibitor Cancer Immunotherapy

Neurologic autoimmune disorders in the context of systemic cancer reflect antitumor immune responses against onconeural proteins that are autoantigens in the nervous system. These responses observe basic principles of cancer immunity and are highly pertinent to oncological practice since the introduction of immune checkpoint inhibitor cancer therapy. The patient's autoantibody profile is consistent with the antigenic composition of the underlying malignancy. A major determinant of the pathogenic outcome is the anatomic and subcellular location of the autoantigen. IgGs targeting plasma membrane proteins (eg, muscle acetylcholine receptor -IgG in patients with paraneoplastic myasthenia gravis) have pathogenic potential. However, IgGs specific for intracellular antigens (eg, antineuronal nuclear antibody 1 [anti-Hu] associated with sensory neuronopathy and small cell lung cancer) are surrogate markers for CD8⁺ T lymphocytes targeting peptides derived from nuclear or cytoplasmic proteins. In an inflammatory milieu, those peptides translocate to neural plasma membranes as major histocompatibility complex class I protein complexes. Paraneoplastic neurologic autoimmunity can affect any level of the neuraxis and may be mistaken for cancer progression. Importantly, these disorders generally respond favorably to early-initiated immunotherapy and cancer treatment. Small cell lung cancer and thymoma are commonly associated with neurologic autoimmunity, but in the context of checkpoint inhibitor therapy, other malignancy associations are increasingly recognized.

[A case of myasthenia gravis and myositis induced by pembrolizumab]

A 77-year-old woman with lung adenocarcinoma noticed bilateral ptosis 7 weeks after a first pembrolizumab infusion. Her symptoms rapidly progressed to generalized manifestations including limb and neck weakness, dyspnea, and dysphasia within the following two weeks. We diagnosed him with pembrolizumab-related myasthenia gravis and myositis based on clinical symptoms, elevation of muscle enzymes and anti-acetylcholine receptor antibodies, repetitive nerve stimulation and muscle biopsy. We commenced combination immunotherapy, including intravenous and oral steroid therapy, immune absorption therapy and plasma exchange therapy with noninvasive positive-pressure ventilation and tracheotomy positive pressure ventilation. She had gradual symptoms improvement and discharged after 209 days in a hospital. In this case, anti-titin antibodies, one of anti-striational antibodies, was positive and correlated with severity of myasthenia gravis. With the development of immune checkpoint inhibitors for various malignancies, clinicians should closely monitor patients for important immune-related adverse events and coordinate on early treatment.

Immune checkpoint inhibition alters the inflammatory cell composition of human coronary artery atherosclerosis

BACKGROUND

Immune checkpoint inhibition (ICI) has emerged as a promising new approach to treat malignancy. Such therapies can result in autoimmune-related complications such as myocarditis and hepatitis. The impact of ICI on sites of preexisting chronic inflammation has been less clear. Atherosclerosis is a chronic vascular disease with a significant inflammatory component.

METHODS

To determine the effect of ICI on the inflammatory infiltrate in coronary artery atherosclerotic plaques, 11 patients who had recently been treated with ICI and subsequently underwent autopsy were matched with 11 cancer patients who had not received ICI treatment. The amount of CD3⁺ T-lymphocytes, CD8⁺ cytotoxic T-lymphocytes, and CD68⁺ macrophages and the ratios of the various cell types in the coronary artery atherosclerotic plaques were compared.

RESULTS

There was no significant difference in the absolute numbers of CD3⁺, CD8⁺, or CD68⁺ cells in the atherosclerotic plaques. In the plaques of the ICI-treated patients, there was a significant increase in the ratio of CD3⁺ cells to CD68⁺ cells (CD3/CD68) (P=.002) and a trend towards an increased CD8/CD68 ratio. The increased CD3/CD68 ratio in the ICI-treated patients resulted in 6 of the 11 patients having lymphocyte-predominate inflammation in contrast to the macrophage-predominate inflammation typically found in atherosclerotic plaques.

CONCLUSIONS

These findings indicate that ICI alters the inflammatory composition of human atherosclerotic plaque and, thus, may influence plaque progression and/or clinical coronary events.

SUMMARY

In cancer patients, treatment with immune checkpoint inhibition is associated with an altered inflammatory cell composition in coronary artery atherosclerotic plaques with an increased ratio of CD3⁺ T cells to CD68⁺ macrophages. Thus, immune checkpoint inhibition may influence plaque progression and/or clinical coronary events.

Pembrolizumab-related systemic myositis involving ocular and hindneck muscles resembling myasthenic gravis: a case report

Background

Pembrolizumab is an immune-checkpoints inhibitor that enhances the immune response against cancer cells and therefore is useful for the treatment of several carcinomas. However, pembrolizumab sometimes perturbs the immune system resulting in various autoimmune neurological complications. In this situation, autoimmune myositis due to pembrolizumab is a rare but not-negligible complication. Here, we report two cases of autoimmune myositis due to pembrolizumab, with systemic myositis involving levator palpebrae superioris, extraocular and hindneck muscles.

Case presentation

Case 1 was a 78-year-old man with advanced urinary cancer referred to the neurological ward presenting with bilateral ptosis, restriction of eye movements, dropped head and weakness in the lower extremities after pembrolizumab administration. His blood examination showed elevated serum levels of creatine kinase with positive anti-PM-Scl 75 and anti-signal recognition particle antibodies. Needle electromyography and MRI suggested systemic inflammatory myopathy. There were no findings to indicate myocardial involvement on electrocardiogram or echocardiogram. Administration of intravenous methylprednisolone following plasma exchange ameliorated creatine kinase levels and inhibited the progression of clinical symptoms. Case 2 was a 72-year-old female with lung cancer and multiple metastasis, including lymph nodes and brain. She presented with back pain, right-sided ptosis, weakness of her neck extensors and flexors and elevated serum creatine kinase after receiving pembrolizumab. Although myositis specific autoantibodies were negative, needle electromyography and MRI suggested systemic inflammatory myopathy and muscle biopsy indicated necrotizing myopathy. There were no signs indicating heart dysfunction and her electrocardiogram was normal. Clinical symptoms and serum creatine kinase levels were ameliorated after the administration of intravenous methylprednisolone.

Conclusions

Both cases showed atypical extensive inflammatory myositis including levator palpebrae superioris, extraocular and hindneck muscles, resembling myasthenia gravis (MG), but they did not have MG-related antibodies. Edrophonium test was negative and showed no daily fluctuation. Two previously reported cases also presented with systemic necrotizing systemic myositis involving extraocular and facial muscles caused by pembrolizumab. Idiopathic inflammatory myositis evolving levator palpebrae superioris and ocular muscles is quite rare; however, myositis due to immune-checkpoint inhibitors may preferentially involve these muscles. This case report will alert physicians to the possibility of systemic inflammatory myopathy evolving levator palpebrae superioris, extraocular and hindneck muscles mimicking MG due to pembrolizumab.

[A case of anti-titin antibody positive nivolumab-related necrotizing myopathy with myasthenia gravis]

A 53-year-old man suffering from squamous cell lung cancer presented with bilateral ptosis and bulbar palsy a month after initial treatment with the immune checkpoint inhibitor nivolumab. The symptoms showed worsening from midday, suggesting myasthenia gravis (MG), although anti-AChR antibody was negative. Although no muscle weakness was detected, the CK level was elevated to 5,255 IU/l, and MRI of the thigh revealed inflammation of the bilateral rectus femoris muscle. A muscle biopsy showed signs of necrotizing myopathy with expression of sarcolemmal HLA class I and accumulation of macrophages, CD4, CD8, and CD20-positive lymphocytes. Positivity for anti-titin antibody, one of the anti-striated muscle antibodies, was evident. The patient was diagnosed as having nivolumab-related necrotizing myopathy with myasthenia gravis, an immune-related adverse event (irAE). Treatment with prednisolone rapidly ameliorated the symptoms, and the serum CK level normalized. There have been several reports of nivolumab-related myositis with MG. On the basis of the muscle pathology and antibody data, we were able to clarify that necrotizing myopathy was related to the pathogenesis of this case.

How we treat neurological toxicity from immune checkpoint inhibitors

Neurological adverse events from immune checkpoint inhibition are increasingly recognised, especially with combination anti-cytotoxic T-lymphocyte antigen 4 (CTLA4) and anti-programmed death receptor 1 (anti-PD-1) therapies. Their presenting symptoms and signs are often subacute and highly variable, reflecting the numerous components of the nervous system. Given the risk of substantial morbidity and mortality, it is important to inform patients of symptoms that may be of concern, and to assess any suspected toxicity promptly. As with other immune-related adverse events, the cornerstone of management is administration of corticosteroids. Specialist neurology input is vital in this group of patients to guide appropriate investigations and tailor treatment strategies.

Susceptible loci associated with autoimmune disease as potential biomarkers for checkpoint inhibitor-induced immune-related adverse events

Unprecedented successes regarding cancer immunotherapy have been achieved, in which therapeutic agents are used to target immune cells rather than cancer cells. The most effective immunotherapy to date is the group of immune checkpoint inhibitors (CPI), targeting, for example, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) or programmed cell death protein (PD-1). TThe combination of these therapies (anti-PD-1 with anti-CTLA-4) induces high response rates, and seem to be increased further when applied in early-stage disease. However, combined CTLA-4 plus PD-1 blockade causes frequent high-grade immune-related adverse events (irAE). To date, research on biological mechanism of irAEs is scarce and no widely accepted biomarkers predicting onset of severe irAEs have been identified. The similarity of irAEs to autoimmune disorders fuels the hypothesis that irAEs may be linked to susceptible genetic loci related to various autoimmune diseases. In this review, we extensively searched for susceptible loci associated with various autoimmune diseases, and pooled them in groups most likely to be associated with CPI-induced irAEs. These sets could be used in future research on predicting irAEs and guide physicians in a more refined and personal manner.

Immune-related Adverse Events Associated with Cancer Immunotherapy: A Review for the Practicing Rheumatologist

Immune checkpoint inhibitors have revolutionized cancer therapy by blocking inhibitory pathways of the immune system to fight cancer cells. Their use is often limited by the development of autoimmune toxicities, which can affect multiple organ systems and are referred to as immune-related adverse events (irAE). Among these are rheumatologic irAE, including inflammatory arthritis, myositis, vasculitis, and others. Rheumatologic irAE seem to be different from irAE in other organs and from traditional autoimmune diseases in that they can occur early or have delayed onset, and can persist chronically, even after cancer therapy is terminated. Because immune checkpoint inhibitors are increasingly used for many types of cancer, it is important for oncologists and rheumatologists to recognize and manage toxicities early. In this review, we discuss currently approved immune checkpoint inhibitors and their mechanisms of action and systemic toxicities, with a focus on the management and effect on further cancer therapy of rheumatic irAE.

[An autopsy case of nivolumab-induced myasthenia gravis and myositis]

An 84-year-old woman developed blepharoptosis, diplopia, weakness of extremities, and dysphagia with elevation of serum CK levels after treatment with nivolumab against renal cell carcinoma. 3 Hz repetitive stimulation showed waning in the trapezius muscle, leading to the diagnosis of myasthenia gravis. Laboratory examination showed that anti-acetylcholine receptor antibody was negative. We performed IVIg and steroid therapy. However, her symptoms did not improve, and she died of respiratory failure, although serum CK levels ameliorated to the normal range. The results of autopsy showed atrophy of muscle fibers and massive infiltration of inflammatory cells in the endomysium of the iliopsoas muscle and diaphragm, indicating occurrence of myositis. Immunohistochemical analysis showed that CD8-positive T cells mainly infiltrates in the endomysium with a small number of CD4-potive T cells. Here, we report an autopsy case of nivolumab-induced myasthenia gravis and myositis.

Cardiotoxicity of Immune Checkpoint Inhibitors

PURPOSE OF REVIEW

Immunotherapies, particularly immune checkpoint inhibitors (ICI), are revolutionary cancer therapies being increasingly applied to a broader range of cancers. Our understanding of the mechanism, epidemiology, diagnosis, and treatment of cardiotoxicity related to immunotherapies remains limited. We aim to synthesize the limited current literature on cardiotoxicity of ICIs and to share our opinions on the diagnosis and treatment of this condition.

RECENT FINDINGS

The incidence of ICI-associated myocarditis ranges from 0.1 to 1%. Patients with ICI-associated myocarditis often have a fulminant course with a case fatality rate of 25-50%. The diagnosis of this condition poses many challenges because independently a normal electrocardiogram, biomarkers, or a preserved left ventricular function do not rule out ICI-associated myocarditis. Endomyocardial biopsy should be pursued when clinical suspicion remains despite normal non-invasive tests. Data on optimal screening and surveillance tools are lacking. Cessation of ICIs, combined with high dose corticosteroids and other immunosuppressant approaches are the cornerstones of the treatment of ICI-associated myocarditis. This condition may recur when patients are re-challenged with these agents and the decision to resume ICIs should be made through a multidisciplinary discussion. Immunotherapies have changed the landscape of cancer treatment. Recognizing and managing cardiotoxicity related to ICIs is of critical importance. Our understanding of ICI-cardiotoxicity has improved, but large information gaps remain for further research. Due to the high case fatality rate, any type of cardiac symptoms or signs in a patient who has recently started an ICI should prompt consideration of ICI-cardiotoxicity.

Prevalence and Clinical Patterns of Ocular Complications Associated With Anti-PD-1/PD-L1 Anticancer Immunotherapy

PURPOSE

Immune checkpoint inhibitors (ICI) targeting the programmed cell death protein 1 (PD-1), or its ligand PD-L1, are the mainstay of metastatic cancer treatment. Patients receiving these treatments may develop immune-related adverse events (irAEs). This study aimed to estimate the prevalence and describe the clinical patterns of moderate-to-severe ocular irAEs-associated with anti-PD-(L)1 treatment.

DESIGN

Prospective case series.

METHODS

This study included patients recruited via (1) a single-center prospective cohort and (2) a national pharmacovigilance registry between June 2014 and March 2018, and focused on patients with moderate-to-severe ocular irAEs following anti-PD-(L)1. All patients underwent a comprehensive ophthalmologic assessment. The main outcome measure was the prevalence of moderate-to-severe ocular irAEs.

RESULTS

Of a total of 745 patients included in the prospective cohort, 3 developed moderate-to-severe ocular irAEs, providing a prevalence of 0.4% and an incidence of 0.7 per 1000 patient-months of treatment. An additional 5 cases of moderate-to-severe ocular irAEs were reported through the national registry. From these 8 patients, 5 presented with intraocular inflammation, 2 with ocular surface disease, and 1 with orbital myopathy. Five patients (62.5%) experienced additional extraophthalmologic irAEs. Ocular irAEs led to permanent discontinuation of anti-PD-(L)1 in 4 patients. Treatment by local and/or systemic corticosteroids allowed resolution or control of the ocular symptoms in 7 of 8 patients.

CONCLUSION

Although uncommon, anti-PD-(L)1-associated ocular complications may be sight-threatening and lead to discontinuation of anti-PD-(L)1 treatments. Patients complaining of eye problems while receiving ICI treatment should immediately be seen by an ophthalmologist.

Neuromuscular Weakness Syndromes from Immune Checkpoint Inhibitors: A Case Series and Literature Review

Immune checkpoint inhibitors (CPIs) (anti-cytotoxic T-lymphocyte antigen-4, anti-programmed death 1, and anti-programmed death-ligand 1) have transformed the landscape of cancer therapy. However, their increasing use has unleashed immune-related adverse events in various organs, among which neurologic ones, while rare, are increasingly being recognized and remain incompletely characterized. Herein, we report five patients with nonmelanoma cancers who developed weakness after receiving CPIs. The etiology was attributed to radiculoneuritis (one patient), myositis (one patient), Miller Fisher/myasthenia gravis (MG) (one patient), neuropathy/myositis/MG (one patient), and myositis/MG (one patient). Weakness developed after a median of two doses (range: 1–3) and 4 weeks (range: 3–10) from initiation of therapy. Two patients had severe manifestations without improvement while the other three experienced partial improvement despite discontinuation of the CPI (s) and initiation of immunosuppressive therapy. A review of literature identified 62 similar cases. This report highlights the challenges in the diagnosis and management of neurologic adverse events related to the use of CPIs. It also addresses the crucial need for early recognition, proper workup, and better biomarkers to help improve the outcomes of these adverse events.

Electrophysiological findings in immune checkpoint inhibitor-related peripheral neuropathy

OBJECTIVE

To report the electrodiagnostic features of immune checkpoint inhibitor (ICI)-related neuropathy.

METHODS

We retrospectively reviewed clinical presentations and electrodiagnostic features of 23 patients studied after receiving immune checkpoint inhibitors (ICIs). The presentations for electrodiagnostic evaluation included an acute neuropathy or neuromuscular junction disorder. We applied established electrodiagnostic criteria for polyneuropathy and acute demyelinating neuropathy.

RESULTS

We identified acute demyelinating neuropathy (13 cases), axonal sensory motor neuropathy (5), pure sensory neuropathy (4) and mononeuropathy (1). 13 patients had acute demyelinating neuropathy confirmed by demonstrating demyelination in 2 or more nerves; 3 additional patients had demyelination in only one nerve. Analysis of motor nerve conduction parameters revealed demyelination involving median and ulnar nerve distal motor latencies as well as median, ulnar and peroneal nerve conduction velocities. Conduction block was found in median, ulnar and peroneal nerves. The remaining one-third patients without demyelination had acute painful axonal neuropathy. Coexisting myopathic changes (6) and neuromuscular junction dysfunction (4) were also identified.

CONCLUSIONS

Our findings suggest that, while immune-mediated motor nerve demyelination is the primary underlying mechanism of ICI-related neuropathy, axonal painful neuropathy can also be an important presentation. Early recognition and effective intervention may reduce morbidity and permanent disability.

SIGNIFICANCE

Electrophysiological studies might be useful in the evaluation of ICI-related neuropathy.

Immune-mediated necrotising myopathy: A critical review of current concepts

Immune-mediated necrotising myopathy (IMNM) is a relatively recently described form of idiopathic inflammatory myopathy (IIM) that is characterised by progressive proximal weakness and few extra-muscular manifestations. Prominent myonecrosis, muscle fibre regeneration and a relative paucity of intramuscular lymphocytes are seen histologically. Immunological mechanisms are believed to underpin the pathogenesis, and intense immunotherapy is frequently required. Disease is often severe and neuromuscular recovery may be poor. Recently there has been an impressive international research effort to understand and characterise this emerging condition, although much remains unknown. Significant advances in the field include the discovery of specific autoantibodies, increased understanding of the risk factors, clinical characteristics and treatment options owing to a wealth of observational studies, and the development of novel classification criteria. Herein we review the current evidence regarding the pathophysiology, clinical presentation, histological features and serological profiles associated with this condition. Diagnostic approaches are discussed, including the role of muscle MRI and antibodies targeting 3‑hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and signal-recognition peptide (SRP), and a review of current treatment recommendations is provided.

PD1 pathway in immune-mediated myopathies: Pathogenesis of dysfunctional T cells revisited

Objective

To investigate the relevance of dysfunctional T cells in immune-mediated myopathies. We analyzed T-cell exhaustion and senescence, in the context of programmed cell death protein 1 (PD1)-related immunity in skeletal muscle biopsies from patients with immune-mediated necrotizing myopathy (IMNM), sporadic inclusion body myositis (sIBM), and myositis induced by immune checkpoint inhibitors (irMyositis).

Methods

Skeletal muscle biopsies from 12 patients with IMNM, 7 patients with sIBM, and 8 patients with irMyositis were analyzed by immunostaining and immunofluorescence as well as by quantitative PCR. Eight biopsies from nondisease participants served as controls.

Results

CD3⁺CD8⁺ T cells in biopsies from IMNM, sIBM, and irMyositis were largely PD1-positive, while CD68⁺ macrophages were sparsely positive to the ligand of programmed cell death protein 1 (PD-L1). The sarcolemma of myofibers was PD-L2⁺ and was colocalized with major histocompatibility complex (MHC) class I. CD68⁺ macrophages were colocalized with PD-L2. Senescent T cells were strongly enriched in skeletal muscle of sIBM, revealing a distinct immunologic signature. Biopsies from patients with irMyositis showed mild signs of senescence and exhaustion.

Conclusion

Persistent exposure to antigens in IMNMs and sIBM may lead to T-cell exhaustion, a process controlled by the PD1 receptor and its cognate ligands PD-L1/PD-L2. To our knowledge, these data are the first evidence of presence of dysfunctional T cells and relevance of the PD1 pathway in IMNM, sIBM, and irMyositis. These findings may guide the way to a novel understanding of the immune pathogenesis of immune-mediated myopathies.

Inflammatory myopathy associated with PD-1 inhibitors

OBJECTIVE

To characterize the inflammatory myopathy associated with programmed cell death 1 inhibitors (PD-1 myopathy).

METHODS

We studied 19 Japanese patients with PD-1 myopathy (13 men and 6 women, mean age 70 years), who were referred to Keio University. As control groups, we used 68 patients with anti-signal recognition particle antibodies, 51 patients with anti-aminoacyl transfer RNA synthetase antibodies and 460 healthy subjects.

RESULTS

In regard to muscle-disease severity, 10 patients showed a mild form of disease and 9 patients showed a severe form. Non-small cell lung cancer was the most common underlying cancer. PD-1 inhibitor consisted of 11 nivolumab and 8 pembrolizumab. PD-1 myopathy occurred 29 days on average after the first administration of PD-1 inhibitor. The initial manifestation of muscle weakness was ptosis in 10 patients, 15 patients had ptosis, 13 diplopia, 8 facial muscle weakness, 10 bulbar symptoms, 13 limb weakness, 14 neck weakness, 4 cardiac involvement, 6 respiratory involvement and 16 myalgia. Ocular, facial, cardiac and respiratory involvement and myalgia were more frequently observed than controls. Serum creatine kinase was increased to 5247 IU/L on average. Autoantibodies related to inflammatory myopathy were negative, while anti-striational antibodies were found in 13 (68%) patients. HLA-C*12:02 alleles were more frequently detected than healthy controls. Muscle pathology was characterized by multifocal necrotic myofibers with endomysial inflammation and expression of MHC class I. Immunosuppressive therapy with corticosteroids was generally effective for muscle weakness.

CONCLUSIONS

Based on our clinical, histological and immunological findings, PD-1 myopathy is a discrete subset of inflammatory myopathy.

Safety and Tolerability of Immune Checkpoint Inhibitors (PD-1 and PD-L1) in Cancer

Immunotherapy has emerged in recent years and has revolutionized the treatment of cancer. Immune checkpoint inhibitors, including anti-cytotoxic T lymphocyte antigen-4 (CTLA-4), anti-programmed cell death-1 (PD-1) and anti-programmed cell death ligand-1 (PD-L1) agents, are the first of this new generation of treatments. Anti-PD-1/PD-L1 agents target immune cells by blocking the PD-1/PD-L1 pathway. This blockade leads to enhancement of the immune system and therefore restores the tumour-induced immune deficiency selectively in the tumour microenvironment. However, this shift in the balance of the immune system can also produce adverse effects that involve multiple organs. The pattern of toxicity is different from traditional chemotherapy agents or targeted therapy, and there is still little experience in recognizing and managing it. Thus, toxicity constitutes a real clinical management challenge and any new alteration should be suspected of being treatment-related. The most common toxicities occur in the skin, gastrointestinal tract, lungs, and endocrine, musculoskeletal, renal, nervous, haematologic, cardiovascular and ocular systems. Immune-mediated toxic effects are usually manageable, but toxicities may sometimes lead to treatment withdrawal, and even fulminant and fatal events can occur. Oncologists need to collaborate with internists, clinical immunologists and other specialists to understand, manage and prevent toxicity derived from immunotherapy. This review focuses on the mechanisms of toxicity of anti-PD-1/PD-L1 agents, and its diagnosis and management.

Immunotherapy Toxicity

The development of immunotherapy to target cancer has led to improved treatment of many types of malignancy. The immune checkpoint inhibitors are a class of medications that block cell signaling and allow the immune system to recognize and attack cancer cells. CTLA-4, PD-1, and PD-L1 inhibitors have been approved as treatment options in many different types of localized and advanced malignancies. Immune checkpoint inhibitors can be associated with unique side effects known as immune-related adverse events. Side effects most commonly occur in the skin, gastrointestinal tract, lung, and endocrine glands but can affect other organ systems as well.

[What's new in internal medicine?]

What's new in internal medicine will be dedicated to three topics: i) inflammatory myopathies constituting a heterogenous group of diseases whose clinical manifestations, immunological abnormalities, treatment response and outcomes vary widely; ii) alterations of gut microbiota contributing to the occurrence or development of a range of conditions, including autoimmune diseases for which further work is necessary to understand the correlation of dysbiosis with these diseases; iii) the reciprocal relationship between obesity, metabolic syndrome, atherosclerosis and autoimmune diseases. New data concerning systemic sclerosis, cutaneous vasculitis, adult Still's disease, autoantibodies anti DFS70, Epstein Barr virus and autoimmune diseases were also highlighted.