Late‐Onset Immunotherapy Toxicity and Delayed Autoantibody Changes: Checkpoint Inhibitor–Induced Raynaud's‐Like Phenomenon

Immune checkpoint inhibitor (ICI)‐induced immune‐related adverse events (irAEs) may affect almost any organ system and occur at any point during therapy. Autoantibody analysis may provide insight into the mechanism, nature, and timing of these events. We report a case of ICI‐induced late‐onset Raynaud's‐like phenomenon in a patient receiving combination immunotherapy. A 53‐year‐old woman with advanced non‐small lung cancer received combination anti‐cytotoxic T‐lymphocyte antigen 4 and anti‐programmed death 1 ICI therapy. She developed early (hypophysitis at 4 months) and late (Raynaud's at >20 months) irAEs. Longitudinal assessment of 124 autoantibodies was correlated with toxicity. Although autoantibody levels were generally stable for the first 18 months of therapy, shortly before the development of Raynaud's, a marked increase in multiple autoantibodies was observed. This case highlights the potential for delayed autoimmune toxicities and provides potential biologic insights into the dynamic nature of these events. KEY POINTS: A patient treated with dual anti‐PD1 and anti‐CTLA4 therapy developed Raynaud's‐like signs and symptoms more than 18 months after starting therapy. In this case, autoantibody changes became apparent shortly before onset of clinical toxicity. This case highlights the potential for late‐onset immune‐related adverse events checkpoint inhibitors, requiring continuous clinical vigilance. The optimal duration of checkpoint inhibitor therapy in patients with profound and prolonged responses remains unclear.