What happened, in summary

An 86-year-old woman was diagnosed with Stage IV poorly differentiated gastric adenocarcinoma with diffuse peritoneal disease. She began palliative FOLFOX chemotherapy with nivolumab in January 2025. After the third cycle, she developed fever, confusion, swelling, abdominal pain, inflammation, and kidney injury. Infection testing did not find a source, and the episode was considered Grade 2 cytokine release syndrome. After a dose-reduced fourth cycle, she developed a very similar reaction again, this time before receiving growth-factor support. The repeated pattern made nivolumab-related cytokine release syndrome the leading explanation. Nivolumab was removed from future treatment, while reduced-dose FOLFOX continued. She received cycles 5 and 6 without another episode, and CT imaging in early May showed a partial response. Over the following weeks, however, recurrent oral and esophageal candidiasis, poor appetite, weight loss, and declining performance status made continued treatment increasingly difficult. Chemotherapy was reduced further. In late June, she chose to stop chemotherapy because of persistent side effects and the effect on her quality of life. She was still living with metastatic gastric cancer at the latest documented follow-up.