Immune-related adverse events (irAEs) with immune checkpoint inhibitors (ICIs) are occasionally associated with autoantibodies, but researchers didn’t know how frequently or whether these autoantibodies existed before ICI began. For a study, investigators sought to determine how often autoantibodies were positive in patients with organ-specific ICI-associated irAEs and how useful they were as pretreatment biomarkers.

They searched MEDLINE, Embase, and the Cochrane Library for all English-language peer-reviewed papers published in English between February 20, 2020, and included any publication describing patients with irAEs and reporting the results of any autoantibody analysis. About 3 reviewers extracted data separately, and one reviewer double-checked all data for correctness and reporting quality.

Around 515 publications were found. IrAEs associated with endocrine, rheumatic, gastrointestinal/hepatic and myositis/myasthenia/myocarditis were described in the majority of studies. Nearly half of patients with ICI-associated endocrinopathies had autoantibodies. More than half of the patients with cutaneous irAEs had anti-BP180 antibodies. Antibodies were found prevalent in patients with myositis/myasthenia/myocarditis, including striatal antibodies (49%), acetylcholine receptor antibodies (40%), and myositis-associated antibodies (27%). Only 11% of arthritis patients had rheumatoid factor or cyclic citrullinated peptide antibodies, while 30% of sicca patients had Sjögren antibodies. In patients with hepatitis (antinuclear antibody, 18%) and colitis, autoantibodies were also infrequent (perinuclear antineutrophil cytoplasmic antibody, 19%). Some cohort studies examining pre-ICI seropositivity indicated that autoantibodies may have a role as irAE biomarkers. Autoantibody positivity was more common in irAEs involving the endocrine system, skin, and muscle, but less common in irAEs affecting other organ systems. Autoantibody studies in pre-ICI therapy patients had shown conflicting results in terms of their efficacy as an irAE biomarker.