OBJECTIVES: Immune checkpoint inhibitors (ICIs) have revolutionised cancer therapy but often cause immune-related adverse events (irAEs), including ICI-induced arthritis. Managing these rheumatic irAEs (R-irAEs) frequently requires prolonged glucocorticoid (GC) use, potentially compromising cancer outcomes. This study evaluates the use of conventional synthetic disease-modifying anti-rheumatic drugs (cs-DMARDs) and biologic DMARDs (b-DMARDs) as steroid-sparing agents in ICI-induced arthritis, focusing on their safety and efficacy. METHODS: We retrospectively analysed patients with ICI-induced arthritis treated at our centre (January 2019-January 2024). Demographic, oncologic, and treatment data were collected. Patients were grouped into GC-only and GC+DMARD (cs- or bDMARDs) groups. The primary endpoint was the steroid-sparing effect of DMARDs, with secondary endpoints evaluating time to cancer progression. RESULTS: Among 31 patients (68% male, mean age 69.5 years), the most common cancers were non-small cell lung cancer (35%) and melanoma (19%). Arthritis presentations included arthralgias, mono/oligoarthritis, polyarthritis, and polymyalgia rheumatica-like syndrome. Eighteen patients were treated with cs- or b-DMARDs, of whom 61% within 2 months and 72% within 4 months from the onset of ICI-induced arthritis. DMARD-treated patients had significantly lower cumulative steroid use (p=0.047) with no adverse impact on time to cancer progression (p=0.27). IL-6 inhibitors showed particular promise in managing chronic arthritis without compromising oncologic outcomes. CONCLUSIONS: DMARDs offer a safe and effective steroid-sparing strategy for ICI-induced arthritis, preserving cancer treatment efficacy. Early DMARD initiation could benefit patients needing long-term management of R-irAEs. Prospective studies are needed to refine treatment protocols, balancing immune modulation with oncological outcomes.
