PD-1 inhibitor-induced systemic sclerosis with early interstitial lung disease and autoimmune thyroiditis in advanced gastric cancer: a case report and literature review.

Immune checkpoint inhibitors (ICIs) have revolutionized anti-tumor therapy, yet their use is increasingly complicated by immune-related adverse events (irAEs). We present a rare case in which sequential administration of two PD-1 inhibitors (ICIs), Camrelizumab and Sintilimab, in combination with conventional chemotherapy led to ICI-related systemic sclerosis (ICI-SSc) with early-stage interstitial lung disease (ILD) and autoimmune thyroiditis (AIT). The clinical presentation also suggested a possible scleroderma overlap syndrome. The underlying pathology is likely linked to widespread immune activation following PD-1 pathway blockade. Early identification of ICI-SSc is crucial. Once the diagnosis is confirmed, the suspected drug should be discontinued immediately, and a personalized treatment plan should be initiated, ideally with consideration of the safety profile of steroid-based regimens. Furthermore, our findings raise important considerations regarding pharmacovigilance in the context of sequential ICIs use.