We identified 9 patients receiving anti-PD-1 or PD-L1 inhibitors consulting for either muscle weakness, asthenia, myasthenic-like syndrome or other muscle related-symptoms, along with biopsy-proven inflammatory myopathy.One had concomitant myocarditis.
We discuss current evidence regarding the role of molecular mimicry, somatic DNA tumor mutations, and the PD-1/PD-L1 pathway in the association between cancer and myositis.
Further, we investigated 23 muscle biopsy specimens from patients with polymyositis (PM), inclusion body myositis (IBM), dermatomyositis (DM), and nonmyopathic controls for B7-H1 expression by immunohistochemistry: B7-H1 was expressed in PM, IBM, and DM specimens but not in noninflammatory and nonmyopathic controls.