[Nivolumab‒Induced Severe Thrombocytopenia in a Patient with Advanced Gastric Cancer].

Here, we report a case of severe thrombocytopenia induced by nivolumab. A 70‒year‒old woman with advanced gastric cancer was treated with nivolumab. After the first dose, she noticed an erythematous rash. During the second cycle, fever and purpura on the lower extremities were also noted. Laboratory examinations revealed severe thrombocytopenia of grade 4, mild hemolytic anemia, leukopenia, and coagulopathy. Immune‒related adverse events(irAE)were suspected, and we started 40 mg(0.7 mg/kg)prednisolone(PSL)per day. Her symptoms and laboratory data immediately improved. However, when we reduced the dose of PSL, she developed rash and thrombocytopenia again. We increased the dose of PSL to 40 mg, which was effective for improving these abnormalities. We then gradually reduced the PSL, paying attention to avoid a relapse of irAEs. We could not restart chemotherapy thereafter, and she died from progression of gastric cancer. As shown in this case, PSL is effective for immune‒related thrombocytopenia; however, determining how to reduce the dose of PSL and when to restart chemotherapy requires careful consideration.