Severe acute myositis and myocarditis on initiation of 6-weekly pembrolizumab post-COVID-19 mRNA vaccination.

We describe three cases of critical acute myositis with myocarditis occurring within 22 days of each other at a single institution, all within 1 month of receiving the initial cycle of the anti-PD-1 drug pembrolizumab. Analysis of T cell receptor repertoires from peripheral blood and tissues revealed a high degree of clonal expansion and public clones between cases, with several T cell clones expanded within the skeletal muscle putatively recognizing viral epitopes. All patients had recently received a COVID-19 mRNA booster vaccine prior to treatment and were positive for SARS-CoV2 Spike antibody. In conclusion, we report a series of unusually severe myositis and myocarditis following PD-1 blockade and the COVID-19 mRNA vaccination.

Effectiveness and safety of mycophenolate mofetil and rituximab combination therapy for immune idiopathic myopathies.

INTRODUCTION: Idiopathic inflammatory myopathies (IIM) represent a rare and heterogenous group diseases, and their treatment is not fully defined yet. According to previous small case series, the combination of mycophenolate mofetil (MMF) and rituximab (RTX) may be effective in controlling difficult-to-treat patients. Our aim was to further explore the efficacy and safety of this combined approach in patients with IIM. METHODS: Patients with IIM treated with the RTX/MMF combination in our Center were retrospectively identified. After the start of combination therapy, the efficacy was evaluated at 12 months (T12) according the 2016 ACR/EULAR response criteria for IIM. Cardiac imaging and pulmonary function tests were used to monitor disease activity in patients with myocarditis and interstitial lung disease, respectively. Adverse events were recorded over the follow-up period. RESULTS: Among the 20 patients (median age 61 years; 70% female) included in the study, anti-synthetase syndrome was the most prevalent IIM subgroup (60%). At treatment start, muscle, heart, and lung were the most commonly actively affected organs. After 12 months, a moderate or major response was observed in all patients, and creatine kinase was significantly decreased (p-value = 0.012). Cardiac imaging and enzymes monitoring showed a reduction of heart inflammation, while pulmonary function tests improved in patients with lung involvement. No severe side effects were observed. CONCLUSION: Our data show that combination of RTX and MMF is effective and safe in patients with severe and refractory IIM. Therefore, this combined treatment might represent a feasible approach for difficult-to-treat IIM cases.

Murine MHC-Deficient Nonobese Diabetic Mice Carrying Human HLA-DQ8 Develop Severe Myocarditis and Myositis in Response to Anti-PD-1 Immune Checkpoint Inhibitor Cancer Therapy.

Myocarditis has emerged as an immune-related adverse event of immune checkpoint inhibitor (ICI) cancer therapy associated with significant mortality. To ensure patients continue to safely benefit from life-saving cancer therapy, an understanding of fundamental immunological phenomena underlying ICI myocarditis is essential. We recently developed the NOD-cMHCI/II-/-.DQ8 mouse model that spontaneously develops myocarditis with lower mortality than observed in previous HLA-DQ8 NOD mouse strains. Our strain was rendered murine MHC class I and II deficient using CRISPR/Cas9 technology, making it a genetically clean platform for dissecting CD4+ T cell-mediated myocarditis in the absence of classically selected CD8+ T cells. These mice are highly susceptible to myocarditis and acute heart failure following anti-PD-1 ICI-induced treatment. Additionally, anti-PD-1 administration accelerates skeletal muscle myositis. Using histology, flow cytometry, adoptive transfers, and RNA sequencing analyses, we performed a thorough characterization of cardiac and skeletal muscle T cells, identifying shared and unique characteristics of both populations. Taken together, this report details a mouse model with features of a rare, but highly lethal clinical presentation of overlapping myocarditis and myositis following ICI therapy. This study sheds light on underlying immunological mechanisms in ICI myocarditis and provides the basis for further detailed analyses of diagnostic and therapeutic strategies.

Pembrolizumab-induced myocarditis with complete atrioventricular block and concomitant myositis in a metastatic bladder cancer patient: a case report and review of the literature.

BACKGROUND: The cardiovascular system is among the least systems affected by immune-related adverse events. We report a rare life-threatening case of pembrolizumab-induced myocarditis with complete atrioventricular block and concomitant myositis in a metastatic bladder cancer patient. CASE PRESENTATION: An 82-year-old Caucasian female with invasive urothelial carcinoma, started on first-line pembrolizumab, was admitted four days after receiving her second dose for severe asthenia, diffuse muscle aches, neck pain, and lethargy. In the emergency department, she had several episodes of bradycardia reaching 40 beats per minute associated with general discomfort and fatigue. Electrocardiography showed a third-degree atrioventricular heart block, while the patient remained normotensive. Cardiac damage parameters were altered with elevated levels of creatine phosphokinase of 8930 U/L, suggestive of immune checkpoint inhibitor-induced myositis, and troponin T of 1.060 ng/mL. Transthoracic echocardiography showed a preserved ejection fraction. Pembrolizumab-induced myocarditis was suspected. Therefore, treatment was initiated with high-dose glucocorticoids for 5 days, followed by a long oral steroid taper. A pacemaker was also implanted. Treatment resulted in the resolution of heart block and a decrease in creatine phosphokinase to the normal range. CONCLUSION: Life-threatening cardiac adverse events in the form of myocarditis may occur with pembrolizumab use, warranting vigilant cardiac monitoring. Troponin monitoring in high-risk patients, along with baseline echocardiography may help identify this complication promptly to prevent life-threatening consequences.

A 25-Year-Old Military Recruit with Isolated Myositis Following Routine Chemoprophylaxis with Intramuscular Benzathine Penicillin G.

BACKGROUND Myositis is an inflammatory myopathy that can be caused by a variety of drugs, diseases, and toxins. The U.S. military uses chemoprophylaxis with intramuscular penicillin G to prevent group A streptococcal infection. We present a case of penicillin G-induced myositis, a rare cause of drug-induced myositis with limited discussion in the medical literature. CASE REPORT A 25-year-old man with no pertinent medical history presented to the Emergency Department with right hip and leg pain after receiving a single dose of intramuscular penicillin G as part of standard prophylaxis for group A streptococcal infection during basic military training. He reported pain and leg weakness that was exacerbated by physical exertion and weight bearing but had no systemic symptoms, such as fevers or chills. Initial radiographs of the hip were normal; however, subsequent magnetic resonance imaging of the hip revealed intramuscular edema and features consistent with myositis of the right proximal thigh and hip musculature. He was admitted for isolated right gluteal myositis, attributed to his preceding local penicillin injection. He recovered with symptomatic care over the following 2 weeks, with return to baseline function. CONCLUSIONS This case highlights a rare complication of intramuscular penicillin G as a cause of acute isolated myositis. It serves to inform physicians of this rare complication and to recommend the consideration of intramuscular penicillin G as a causative etiology in individuals presenting with myositis and recent penicillin G exposure.

Safety and tolerability of intravenous immunoglobulin in patients with active dermatomyositis: results from the randomised, placebo-controlled ProDERM study.

BACKGROUND: Dermatomyositis is an idiopathic inflammatory myopathy characterised by rashes and progressive muscle weakness. The recent ProDERM (Progress in DERMatomyositis) study is the first large randomised, placebo-controlled trial to establish the efficacy and safety of intravenous immunoglobulin (IVIg) in adult patients with dermatomyositis. Objectives of this analysis were to closely examine the safety and tolerability of IVIg in patients from the ProDERM study. METHODS: ProDERM was a double-blind, randomised, placebo-controlled, multicentre, phase 3 study. In the first period (weeks 0-16), adults with active dermatomyositis received 2.0 g/kg IVIg (Octagam 10%; Octapharma AG) or placebo every 4 weeks. In the open-label extension period (weeks 16-40), all patients received IVIg for 6 additional cycles; dose reduction (1.0 g/kg) was permitted if patients were stable. Treatment-emergent adverse events (TEAEs) were documented. RESULTS: The 95 patients enrolled were randomised to receive IVIg (N = 47) or placebo (N = 48) in the first period, with 5 switching from placebo to IVIg. Overall, 664 IVIg infusion cycles were administered. During the first period, 113 TEAEs were possibly/probably related to treatment in 30/52 patients (57.7%) receiving IVIg and 38 in 11 patients (22.9%) on placebo. Eight patients discontinued therapy due to IVIg-related TEAEs. Eight thromboembolic events (TEEs) occurred in six patients on IVIg; six in five patients were deemed possibly/probably related to IVIg. Patients with TEEs exhibited more baseline TEE risk factors than those without TEEs (2.4-15.2-fold higher). Lowering infusion rate reduced the rate of TEEs, and none occurred at the lower IVIg dose. No haemolytic transfusion reactions or deaths occurred. CONCLUSIONS: Results from this study demonstrate that IVIg has a favourable safety profile for treatment of adult dermatomyositis patients and provides evidence that will help to inform treatment choice for these patients. Dermatomyositis patients receiving high-dose IVIg should be monitored for TEEs, and a low rate of infusion should be used to minimise TEE risk, particularly in those with pre-existing risk factors. TRIAL REGISTRATION: ProDERM study (NCT02728752).

Atezolizumab-induced myositis in a patient with small-cell lung cancer.

OBJECTIVE: Myositis, an inflammatory disease affecting muscles, is a rare and potentially fatal immune-related adverse event associated with immune checkpoint inhibitors. There are limited data on its clinical features and management. CASE PRESENTATION: Atezolizumab, in combination with etoposide and carboplatin, was initiated in the patient diagnosed with metastatic small-cell lung cancer. After four cycles, maintenance atezolizumab was initiated. At the third visit of the maintenance therapy, the patient reported weakness, edema, and tightness in the muscles that had progressed over the course of a week. Mild solid-food dysphagia was also observed. Neutrophilic leukocytosis with elevated creatine phosphokinase (9234 U/L), erythrocyte sedimentation rate (111 mm/h), and transaminase levels were observed. A diagnosis of myositis was considered based on clinical findings. Atezolizumab was omitted and an oral 0.5 mg/kg/day dose of methylprednisolone was administered. The myositis resolved within 10 days. During the treatment of myositis, the patient underwent prophylactic cranial irradiation. The steroid dose was tapered off within 35 days and then atezolizumab was restarted. CONCLUSION: The literature contains only a few case reports about atezolizumab-induced myositis, highlighting the challenges in defining its clinical features and management. Prompt diagnosis and treatment are crucial to prevent severe complications, such as myocarditis or respiratory muscle paralysis.

Thrombotic microangiopathy in a patient with anti-signal recognition particle antibody-positive immune-mediated necrotizing myopathy.

We describe the case of a 61-year-old woman with anti-signal recognition particle (SRP) antibody-positive immune-mediated necrotizing myopathy (IMNM) who exhibited biopsy-confirmed thrombotic microangiopathy (TMA). The patient developed proximal-dominant muscle weakness and was diagnosed with anti-SRP antibody-positive IMNM based on muscle biopsy results and serological examination. A high-dose corticosteroid prescription was initiated, followed by intravenous methylprednisolone and intravenous immunoglobulin therapy (IVIg). The patient showed IVIg-induced hemolytic anemia with preserved ADAMTS13 activity. Transient oral tacrolimus administration was initiated. Approximately 8 weeks after admission, the serum creatinine levels gradually increased. Renal histological examination revealed TMA, including ischemic changes in the renal tubules, stenosis, and occlusion of the interlobular arteries with fibrinoid necrosis of the afferent arteriolar walls. The arteriolar walls demonstrated an accumulation of C1q and C3c. Myofiber damage in patients with IMNM accounts for the activation of the classical pathway of the complement cascade in the sarcolemma due to antibody deposition. Additionally, a membrane attack complex is observed on capillaries in the muscle tissues of patients with anti-SRP antibody-positive IMNM. Although drug-induced pathomechanisms, such as IVIg and tacrolimus, can trigger the development of TMA, we suggest that the presence of serum anti-SRP antibodies would be implicated in complement-associated kidney vascular damage.

Pembrolizumab-induced peripheral nervous system damage: A combination of myositis/ myasthenia overlap syndrome and motor axonal polyneuropathy.

Introduction - Immune-checkpoint inhibitors (ICI) are effective drugs in cancer treatment that block immune checkpoints and stimulate an attack on cancer cells. However, various side effects were reported with ICIs. Peripheral nervous system (PNS) side effects are three times more frequent than those in the central nervous system.
Case report - A 63-year-old male patient was admitted to our department with a 10-day history of dyspnea, diplopia, and generalized weakness. He had a diagnosis of non-small cell lung cancer, which was treated with pembrolizumab. His neurological symptoms appeared one week after the second course of pembrolizumab, and gradually worsened. His neurological examination showed nasal speech, bilateral ptosis, tongue and neck flexor weakness, prominent asymmetrical upper limb weakness, and mild lower limb weakness. Deep tendon reflexes and sensory examination were normal. He had an elevated creatine kinase level (4430 U/L). Needle electromyography (EMG) showed a myopathic pattern, and single fiber EMG demonstrated an increased jitter in the right frontal muscle. Pembrolizumab treatment was discontinued, and intravenous methylprednisolone followed by intravenous immunoglobulin (IVIg) were initiated. His symptoms gradually improved. However, his weakness began to worsen after a month, and repeated nerve conduction studies showed a predominantly motor axonal polyneuropathy. Thereafter, the patient was treated with IVIg infusions (0.4 g/every two weeks) to maintain his motor function.
Conclusion - Our case showed that ICIs could simultaneously or sequentially cause damage in multiple domains of the PNS. Early recognition of these adverse events is essential since the outcome is favorable with rapid cessation of the causative ICI and administration of immune-modulator treatment.

 

Unveiling the Rare Complication: Statin-Induced Immune-Mediated Necrotizing Myopathy.

BACKGROUND Statin-induced necrotizing autoimmune myopathy is an exceptionally rare yet severe complication of statin therapy that may develop in individuals at any time during their exposure to statins. The development of proximal muscle weakness, muscle pain, and elevated creatine kinase (CK) levels in patients while taking statins should prompt clinical consideration of statin-induced myopathy. The pathophysiology arises from the production of auto-antibodies, which target the 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) enzyme, leading to the aggressive breakdown of myofibrils. CASE REPORT Here, we present a case of a 59-year-old woman with a medical history of dyslipidemia who developed anti-HMG-CoA reductase antibodies after taking atorvastatin. She came to the emergency department with complaints of severe proximal muscle weakness. The laboratory workup showed an elevated CK level up to 12 000 IU/L. Despite discontinuing atorvastatin, the patient's elevated CK levels persisted. The patient underwent a muscle biopsy, demonstrating myofibril necrosis. Serological analysis showed anti-HMG-CoA reductase antibodies in the patient's serum, which led to the diagnosis of immune-mediated necrotizing myopathy due to statins. The patient's statin therapy was promptly discontinued, and she was treated with a high dose of IV corticosteroids. After the patient's discharge, brief discontinuation of the corticosteroids resulted in CK elevation and a return of symptoms. This led to the second re-admission and restarting of corticosteroids until stabilization and discharge. CONCLUSIONS This case represents an important reminder for clinicians to recognize the possibility of statin-induced immune-mediated necrotizing myopathy in patients presenting with proximal muscle weakness while taking a statin, notwithstanding the rarity of this condition.

A first-in-human, open-label, dose-escalation and dose-expansion phase I study to evaluate the safety, tolerability, pharmacokinetics/pharmacodynamics, and antitumor activity of QL1604, a humanized anti-PD-1 mAb, in patients with advanced or metastatic solid tumors.

Background: QL1604 is a humanized immunoglobulin G4 monoclonal antibody against programmed cell death protein 1. This first-in-human, open-label phase I study aimed to investigate the safety and tolerability and to identify the recommended doses of QL1604 for future studies. Pharmacokinetics/pharmacodynamics (PK/PD) and preliminary antitumor activity were also assessed. Methods: Patients with advanced or metastatic solid tumors who failed or had no standard therapies available were recruited. In the dose-escalation phase, patients were treated with QL1604 at 0.3 mg/kg, 1 mg/kg, 3 mg/kg, and 10 mg/kg intravenously once every 2 weeks (Q2W) in an accelerated titration with a traditional 3 + 3 design, followed by a dose-expansion phase at 3 mg/kg Q2W, 3 mg/kg once every 3 weeks (Q3W), 10 mg/kg Q2W and a fixed dose of 200 mg Q3W. Dose-limiting toxicities (DLTs) were assessed during the first 28 days after the first dose of study drug. Adverse events (AEs) were graded per National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0, and antitumor activity of QL1604 was evaluated by investigators on the basis of Response Evaluation Criteria in Solid Tumors version 1.1. Results: A total of 35 patients with advanced or metastatic solid tumors were enrolled. DLTs were reported in one patient at the dose level of 3 mg/kg Q2W (grade 3 immune-mediated myositis and myasthenia gravis), and maximum tolerated dose was not reached. The most frequent treatment-related AEs (≥10%) were fatigue (37.1%), anemia (22.9%), increased blood thyroid-stimulating hormone (17.1%), increased aspartate aminotransferase (AST) (17.1%), increased alanine aminotransferase (ALT) (14.3%), decreased white blood cell (WBC) count (11.4%), rash (14.3%), and pruritus (14.3%). AEs leading to discontinuation of QL1604 occurred in three of the 35 patients (8.6%). Partial responses (PRs) occurred in seven patients, resulting in an objective response rate of 20.0% (7/35). Single dose of QL1604 exhibited a dose-dependent increase in the exposure ranging from 0.3 mg/kg to 10 mg/kg. Mean receptor occupancy (RO) for QL1604 at the dose of 3 mg/kg (Q2W and Q3W) and 200 mg (Q3W) was greater than 80% during cycle 1 after one infusion. Conclusion: QL1604 monotherapy exhibited favorable safety, PK, and signal of antitumor activity in patients with advanced or metastatic solid tumors, and the results supported further clinical studies of QL1604. On the basis of the safety, PK, and RO data, the recommended dosage for further clinical trials is 3 mg/kg or a fixed dose of 200 mg given every 3 weeks. Clinical Trial Registration: https://classic.clinicaltrials.gov/ct2/show/NCT05649761?term=QL1604&draw=2&rank=1, identifier NCT05649761.

Sintilimab-induced inflammatory myopathy in a patient with esophageal cancer: a case report.

The use of immune checkpoint inhibitors (ICIs) has shown remarkable efficacy in the treatment of various malignancies, significantly reshaping cancer treatment. However, as a result of the widespread use of ICIs, several immune-related adverse events (iRAEs) have emerged, some of which can be rare and potentially fatal. In this paper, we reported the earliest case of Sintilimab used in the treatment of esophageal cancer with severe inflammatory myopathy (involving the cardiac, respiratory, and skeletal muscles)in China. This patient was an elderly female who presented to our institution with progressive limb weakness and ptosis. Prior to the onset of symptoms, the patient had undergone a radical esophagectomy for esophageal cancer, experienced several cycles of of radiotherapy and chemotherapy, as well as two doses of Sintilimab treatment. Shortly after initiating immunotherapy, the patient developed symptoms including bilateral ptosis, limb weakness, and difficulty swallowing and breathing. The levels of creatine kinase and troponin I in the patient's blood were significantly elevated, and positive results were observed for anti-skeletal and anti-cardiac muscle antibodies, indicating that the patient might be developing ICIs-related inflammatory myopathy. Fortunately, the patient responded well to treatment including corticosteroids, plasmapheresis, intravenous immunoglobulin, and other supportive therapies. Here, we discuss the incidence, mechanisms, and management strategies of fatal iRAEs. Early detection and timely intervention may be critical in reducing the incidence and mortality rates of iRAEs and improving patient outcomes.

Thymus alterations and susceptibility to immune checkpoint inhibitor myocarditis.

Immune checkpoint inhibitors (ICI) have transformed the therapeutic landscape in oncology. However, ICI can induce uncommon life-threatening autoimmune T-cell-mediated myotoxicities, including myocarditis and myositis. The thymus plays a critical role in T cell maturation. Here we demonstrate that thymic alterations are associated with increased incidence and severity of ICI myotoxicities. First, using the international pharmacovigilance database VigiBase, the Assistance Publique Hôpitaux de Paris-Sorbonne University data warehouse (Paris, France) and a meta-analysis of clinical trials, we show that ICI treatment of thymic epithelial tumors (TET, and particularly thymoma) was more frequently associated with ICI myotoxicities than other ICI-treated cancers. Second, in an international ICI myocarditis registry, we established that myocarditis occurred earlier after ICI initiation in patients with TET (including active or prior history of TET) compared to other cancers and was more severe in terms of life-threatening arrythmias and concurrent myositis, leading to respiratory muscle failure and death. Lastly, we show that presence of anti-acetylcholine-receptor antibodies (a biological proxy of thymic-associated autoimmunity) was more prevalent in patients with ICI myocarditis than in ICI-treated control patients. Altogether, our results highlight that thymic alterations are associated with incidence and seriousness of ICI myotoxicities. Clinico-radio-biological workup evaluating the thymus may help in predicting ICI myotoxicities.

Anti-Kv1.4 Antibody-positive Nivolumab-induced Myasthenia Gravis and Myositis Presenting with Bilateral Ptosis and Demonstrating Different Pathophysiologies.

Nivolumab blocks inhibitors of T-cell activation and restores antitumor immunity but promotes T-cell activity in host tissues by blocking inhibition of the T-cell function, resulting in immune-related adverse effects. We herein report an 80-year-old man presenting with nivolumab-related myasthenia gravis with anti-muscular voltage-gated potassium channel-complex (Kv1.4) antibodies. On day 29 after nivolumab administration, he simultaneously developed rapidly progressing right ptosis and left facial paralysis. Nivolumab administration was discontinued. He subsequently presented with bulbar paralysis, dyspnea, and muscle weakness and received intravenous immunoglobulin, methylprednisolone, and plasma exchange. The severity of nivolumab-related myasthenia gravis with anti-Kv1.4 antibodies presented with diverse clinical findings.

[A case of atezolizumab- and bevacizumab-induced myositis showing high intensity in the pterygoid muscles, soft palate, and tongue on STIR-MRI].

A 61-year-old woman was treated with atezolizumab plus bevacizumab for hepatocellular carcinoma with peritoneal dissemination. Blood tests revealed elevated creatine kinase (CK) that peaked at 2,657 U/l. After two cycles of atezolizumab plus bevacizumab combination therapy, she complained of progressive dysarthria and dysphagia. Needle electromyography showed myopathic changes. Initial MRI showed high signal intensity in the orbicularis oris muscle, soft palate, tongue, pterygoid muscles, and paravertebral muscles on STIR images. Myositis-specific autoantibodies were not detected. Based on these findings, the patient was diagnosed with immune checkpoint inhibitor-associated myositis. The clinical symptoms improved after administration of oral prednisone, and follow-up MRI showed reduced extent of areas of high signal intensity and almost complete resolution of signal abnormality in the paravertebral muscles. The CK level normalized after 1 months of oral steroid administration. MRI of the head and neck, including the tongue and soft palate, may be useful in diagnosis and for evaluating therapeutic efficiency in cases of bulbar symptoms that occur following the introduction of immune checkpoint inhibitors.

Immune checkpoint inhibitors induced side effects of the peripheral nervous system.

PURPOSE OF REVIEW: This review highlights recent knowledge on the diagnosis and treatment of immune checkpoint inhibitor-induced neurological side effects (irNAE) focussing on the neuromuscular system. RECENT FINDINGS: irNAEs mainly resemble sporadic neuromuscular autoimmune diseases and paraneoplastic neurological syndromes. However, neurological symptoms may be unspecific (muscle weakness, fatigue) in the oncological setting and carry the risk of misdiagnosis and delayed therapeutic intervention. The role of disease-specific neuromuscular autoantibodies in the diagnosis is controversial as preexisting autoantibodies may otherwise be present before immune checkpoint inhibitor (ICI) treatment without clinical symptoms and may not develop in case of irNAE manifestation. A new necrotising form of myositis (irMyositis) has been described presenting with facial weakness and ptosis mimicking myasthenia gravis. It comes along with a high rate of severe myocarditis accounting for a triad overlap syndrome (myasthenia/myositis/myocarditis). The role of modern biologicals in the treatment of irNAEs has to be determined. SUMMARY: irNAEs are rare but carry the risk of permanent morbidity and mortality. Early suspicion and diagnosis are key to prevent neurological sequelae. Beyond interruption of ICI administration, treatment corresponds to sporadic autoimmune diseases. The myasthenia/myositis/myocarditis overlap syndrome deserves special attention as it carries the highest risk of mortality. The role of neurotoxic pretreatment regimens, preexisting subclinical neurological autoimmune diseases and the risk of ICI-re-challenge after irNAEs has to be further investigated.

Improved outcomes with early immunosuppression in patients with immune-checkpoint inhibitor induced myasthenia gravis, myocarditis and myositis: a case series.

PURPOSE: Myasthenia gravis (MG) is a rare but life-threatening complication of immune-checkpoint inhibitor (ICI) therapy and often co-presents with myositis and myocarditis. Previous case series of ICI-related MG have reported high mortality rates. We present a series of ten patients from a tertiary oncology centre outlining outcomes of an early multi-modal immunosuppression strategy. METHODS: We reviewed The Christie Hospital database of immunotherapy-related toxicity from 2017 to 2020. Symptom severity was assessed using the Myasthenia Gravis Foundation of America (MGFA) classification. RESULTS: Ten patients with ICI-related MG were identified. All patients presented following 1 (n = 4) or 2 (n = 6) cycles of ICI. Symptom progression was rapid with a median of 3 days from onset of symptoms to admission. Concomitant myositis and myocarditis were observed in nine patients. AChR or MuSK autoantibodies were positive in six patients. All patients received urgent treatment with intravenous methylprednisolone (IVMP) and eight received intravenous immunoglobulin (IVIG). A single patient died from myasthenia-related symptoms; the remaining 9 patients were successfully discharged. CONCLUSION: In our cohort, we demonstrate good outcomes associated with early intensive immunosuppressive treatment with IVIG and IVMP. An agreed national treatment protocol or clinical discussion forum would be beneficial.

Gefitinib-induced Myositis: A Novel Case Report.

Chemotherapy-induced myositis is a severe adverse event caused by chemotherapeutic agents such as immune checkpoint inhibitors (ICIs) or cytotoxic agents. We experienced a patient with gefitinib-induced myositis with symptoms of muscle cramps and stiffness in the limbs, and reported the treatment process. A 70-year-old woman received four courses of carboplatin (CBDCA)+pemetrexed (PEM)+gefitinib (intravenous CBDCA area under the curve (AUC) 5 and PEM 500 mg/m2, every 3 weeks, and oral gefitinib 250 mg daily), for epidermal growth factor receptor (EGFR) mutation-positive stage IV lung cancer treatment; followed by seven courses of PEM+gefitinib, and continued gefitinib monotherapy thereafter. Myositis occurred 5 months after the initiation of gefitinib monotherapy. She developed strong limb cramps despite regular oral administration of 400 mg acetaminophen three times a day and complained of pain on a numeric rating scale of 10/10. Her creatine kinase (CK) was elevated from the second course of CBDCA+PEM+gefitinib but was stable at grade 1-2 thereafter. However, the muscle symptoms disappeared with CK normalization within a few days of gefitinib discontinuation due to disease progression. The Naranjo Adverse Drug Reaction Scale score was 6, suggesting a probable association. Osimertinib (an EGFR tyrosine kinase inhibitor)-induced myositis has been reported, but similar events were first observed with gefitinib in this case. Consequently, when treating with gefitinib, myositis, including the CK variation, should be monitored and appropriately managed with multidirectional treatment.