Immune thrombocytopenia triggered by dostarlimab in a patient with endometrial carcinoma: first reported case.

Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape for various malignancies, but they are associated with a range of immunerelated adverse events, including rare hematological complications. Immune thrombocytopenia (ITP) has been reported with other antiPD1 agents such as nivolumab and pembrolizumab, but to date, no cases have been described with dostarlimab. We report the first case of ITP in a patient receiving dostarlimab for relapsed endometrial carcinoma. A 55yearold woman developed severe thrombocytopenia (3 × 109/L) accompanied by rectal bleeding, resulting in a lifethreatening condition. Secondary causes were excluded, and bone marrow findings supported a diagnosis of ITP. Initial treatment with highdose corticosteroids and intravenous immunoglobulin achieved only a partial response, while sustained platelet recovery was obtained with the addition of romiplostim. The patient remained on dostarlimab following hematological recovery without further episodes of ITP. This case highlights a potentially lifethreatening adverse effect of a widely used immunotherapy and underscores the importance of early recognition and timely escalation of treatment in ICIinduced ITP.