ABSTRACT
Objective:
To investigate the clinical features and
treatment status of immune-related
myositis (IRM) caused by
immune checkpoint inhibitors (ICIs) in order to improve the
diagnosis and
treatment rate of the
disease.
Methods:
Two cases of IRM combined with the
diagnosis and
treatment were described and the
literature about IRM in the past 10 years was reviewed, and the clinical data of 59
patients were analyzed.
Results:
IRM was more common in
males, with a total of 47 (79.7%). IRM usually occurred after 45 days of medication or after two doses. The clinical manifestations were mainly
myalgia and
muscle weakness, which were more common in the
limbs. The initial symptoms were ptosis and
diplopia. Fifty
patients (84.7%) had
serum creatine kinase (CK) levels higher than twice the upper limit of normal (UNL). In immunological examinations, 18
patients were found to be positive for anti-rhabdoid
muscle antibody (AsM-Ab), while most of the myositisspecific
antibodies (MSAs) and
myositis-associated
antibodies (MAAs) were negative. Thirty-four
patients (75.6%) had abnormal EMG, and most
patients showed myogenic
injury.
Muscle magnetic resonance imaging (MRI) showed
muscle edema and
inflammation in 8
patients.
Muscle biopsies from 18 (45.0%)
patients showed varying degrees of necrotic myofibers. Fifty-seven
patients (96.6%) discontinued ICIs after developing IRM, 54(91.5%) received cortico-
steroids, and 20(33.9%) received other
treatments including intravenous immuno-
globulin (
IVIG),
plasma exchange.
Conclusion:
IRM can occur in the early stage of ICIs
treatment. Electro-
myography,
muscle MRI and
muscle biopsy in suspicious cases can improve the
diagnosis rate of the
disease. Early use of corticoteroid,
IVIG and other
immunotherapy can effectively alleviate the
disease.