A case of myositis with dropped head syndrome and anti-titin antibody positivity induced by pembrolizumab

Pembrolizumab-induced Myopathy with Anti-striated Muscle Antibodies Successfully Treated by Plasma Exchange

A 70-year-old woman with advanced endometrial cancer developed right ptosis and muscle weakness in the right quadriceps after pembrolizumab administration. Serum creatine kinase (CK) levels were elevated, and anti-striated muscle antibodies were positive. On magnetic resonance imaging, the right vastus lateral muscle showed an abnormal signal. She was diagnosed with pembrolizumab-induced myopathy. We initiated plasma exchange (PE), and the ptosis immediately resolved. We then introduced oral corticosteroids, which improved her muscle weakness. We were able to rapidly diagnose her with ocular symptoms and serum CK level elevation. The early initiation of PE might prevent the exacerbation of pembrolizumab-induced myopathy.

Nivolumab-induced Myositis and Myocarditis with Positive Anti-titin Antibody and Anti-voltage-gated Potassium Channel Kv1.4 Antibody

Immune checkpoint inhibitors (ICIs) are complicated by immune-related adverse events (irAEs), such as myositis, myocarditis, and myasthenia gravis (MG). Anti-titin antibody and anti-voltage-gated potassium channel Kv1.4 antibody are anti-striated antibodies that are frequently detected in MG patients with myositis and/or myocarditis. However, the clinical relationship between positive anti-striated antibodies and irAEs of ICIs remains unknown. We herein report a case of nivolumab-induced myositis and myocarditis with positive anti-titin antibody and anti-voltage-gated potassium channel Kv1.4 antibody in a patient with non-small-cell lung cancer. We also review reported cases of positive anti-striated antibodies related to irAEs of ICIs.

Dropped head syndrome: a rare adverse drug reaction identified in the FDA adverse event reporting system and review of case reports in the literature

BACKGROUND

Dropped head syndrome (DHS) is a relatively rare disease, and its potential relationship with drug exposure has been postulated but is poorly understood.

RESEARCH DESIGN AND METHODS

This retrospective study evaluated the adverse event reports of DHS in the FDA adverse event reporting system （FAERS) between 1 January 2004, to 31 March 2021. Empirical Bayes Geometric Means (EBGM) and the lower 95% one-sided CI of EBGM were calculated to identify disproportionate reporting of DHS associated with drugs. In addition, published case reports were identified in the PubMed, Embase and Cochrane Library up to 5 August 2021.

RESULTS

There were 193 reports of DHS in the FAERS, in which nervous system agents were most frequently reported, followed by antineoplastic and immunomodulating agents. Pramipexole, ropinirole, levodopa, pregabalin, rotigotine, cisplatin, imatinib and botulinum toxin showed disproportionality signal based each on more than 5 cases. Ten published DHS case reports were identified in the literature.

CONCLUSION

Our study provides a more explicit profile on the occurrences and characteristics of DHS associated with drugs by analyzing the FAERS data and indicates that exposure of certain drug showed disproportionality signal with the increased DHS risk, which suggests the importance of further clinical and observational investigations.

Incidence and Distinct Features of Immune Checkpoint Inhibitor-Related Myositis From Idiopathic Inflammatory Myositis: A Single-Center Experience With Systematic Literature Review and Meta-Analysis

Immune checkpoint inhibitor (ICI)-related myositis is a rare, potentially fatal condition that warrants further studies. Its incidence, clinical features, and prognosis remain poorly understood. To address these gaps, we conducted a systematic review and meta-analysis to evaluate the risk of myositis associated with ICI for solid tumors by analyzing phase III randomized controlled trials of anti-programmed death-1/ligand-1 (PD-1/PD-L1) and anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4). To complement this analysis with clinical data, we evaluated published ICI case reports along with cases from our institutional registry. This registry comprised 422 patients treated with ICIs alone or in combination from September 2014 to June 2021. The analysis revealed an incidence of ICI-related myositis in 6,838 patients in 18 randomized controlled trials of 0.38% (odds ratio 1.96; 95% confidence interval 1.02–3.75) for patients receiving ICIs compared with controls. Detailed analysis of 88 cases from the literature search and our registry showed that myositis induced by PD-1 inhibitors was more frequent than that induced by anti-CTLA-4 agents, revealing a clinically diverse trend including myasthenia gravis and myocarditis. Importantly, having ptosis at the time of onset was significantly associated with the development of concomitant myocarditis (odds ratio 3.81; 95% CI 1.48–9.83), which is associated with poor prognosis. Regarding treatment, most patients received glucocorticoids, and some received immunosuppressants. Our study revealed the incidence of ICI-mediated myositis and the clinical features of myocarditis, highlighting the need for recognition and early intervention.