Systemic Sclerosis Induced by Immune Checkpoint Inhibitors from the Canadian Research Group of Rheumatology in Immuno-Oncology (CanRIO): A Case Series

Objectives Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy, improving outcomes in multiple advanced malignancies. Their use is often limited by immune-related adverse events (irAEs), including rare rheumatic irAEs, such as ICI-induced systemic sclerosis (ICI-SSc). Compared to idiopathic SSc, ICI-SSc typically presents with fewer extra-cutaneous manifestations and negative serologies, but data remains limited.[1] This case series describes the clinical presentation, management, and outcomes of patients with ICI-SSc to guide clinicians in balancing autoimmune toxicities with cancer control. Methods A retrospective chart review was conducted on 7 adults diagnosed with systemic sclerosis following ICI exposure between March 2021 and August 2025. All patients were referred to a Canadian academic rheumatology clinic specializing in Immuno-Oncology during ICI therapy. Clinical data was abstracted from medical records, including patient demographics, malignancy type and stage, ICI type and duration, clinical features, serologies, treatment, and outcomes. Results Of the 7 patients identified, 5 (71.4%) were female and 2 (28.6%) were male, with a mean age (SD) of 63 (10.9) years. Malignancies included: metastatic melanoma (n=4), metastatic squamous cell carcinoma (n=1), breast cancer Stage IIA/IIB (n=1), and metastatic endometrial adenocarcinoma (n=1). ICIs used included: pembrolizumab (n=2), nivolumab (n=1), cemiplimab (n=1), and ipilimumab/nivolumab combination followed by nivolumab monotherapy (n=2), which were discontinued due to SSc symptoms within 1-13 months of initiation. Serologies showed ANA positivity in 4 patients (57.1%), with SSc-specific antibodies (anti-Scl-70) detected in 1 patient. Other antibodies detected included anti-RP-11, anti-RP-155, anti-Ro-52, anti-chromatin, and anti-OJ. 2 patients had negative serologies, 1 with elevated inflammatory markers. All patients had scleordactyl (diffuse 57.1%, limited 42.9%) and extra-cutaneous features, most commonly Raynaud’s phenomenon (71.4%). Other manifestations included inflammatory arthritis (42.9%), nailfold capillary changes (42.9%), esophageal dysmotility (28.6%), telangiectasia (14.3%), and sicca symptoms (14.3%). No patients developed interstitial lung disease, pulmonary arterial hypertension, or scleroderma renal crisis. Management included ICI cessation for all patients, prednisone (85.7%), disease-modifying antirheumatic drugs (mycophenolate mofetil 57.1%, methotrexate 28.6%, hydroxychloroquine 28.6%), infliximab and intravenous immunoglobulins, and vasodilatory therapies. All malignancies were stable at 6 months post-ICI therapy. Conclusion ICI-SSc is a significant irAE primarily characterized by cutaneous manifestations but, in contrast to previous reports, this case series demonstrates that extra-cutaneous manifestations and seropositivity can occur. Along with ICI-cessation, immunosuppressive therapy was effective in symptom control without compromising cancer stability. This work may assist those involved in caring of patients with ICI-SSc to initiate immunosuppressive therapy and minimize the risk of end-organ complications. References [1.] Cho LK. Rheum Dis Clin North Am 2024;50:301-12.