IL-6

Tocilizumab (IL-6 receptor blockade) has a biologically plausible rationale in idiopathic inflammatory myopathies (IIM) given IL-6’s links to systemic inflammation, acute-phase responses, and immune–muscle cross-talk, but the best controlled data in classic refractory dermatomyositis/polymyositis are negative: in a 24-week phase IIb randomized, placebo-controlled trial, tocilizumab was safe and well tolerated yet did not improve the Total Improvement Score or secondary endpoints versus placebo. That said, “IIM” is not one disease, and smaller phenotype-enriched data suggest potential signal in select subsets—most notably refractory immune-mediated necrotizing myopathy (IMNM), where an 11-patient study reported clinically meaningful responses in a majority, with higher baseline IL-6 measures in responders (hypothesis-generating, not definitive). For IIM-associated ILD, evidence for tocilizumab is limited (case-based/real-world signals), but contemporary ILD guidance recognizes it as an option when ILD progresses despite first-line therapy (conditional, low-certainty context). Clinically, tocilizumab may be considered as an adjunct/third-line in carefully selected refractory phenotypes (particularly IMNM or progressive IIM-ILD) while weighing predictable risks—serious infection, cytopenias, transaminitis, hyperlipidemia, and rare GI perforation—with standard monitoring.