Case report: PRES associated with fruquintinib in a patient with metastatic colon cancer.

Posterior reversible encephalopathy syndrome (PRES) is a rare, reversible neurological disease that is frequently associated with the use of targeted therapy agents. In this case study, we examine the development of posterior reversible encephalopathy syndrome (PRES) in a 44-year-old woman with metastatic colon cancer following 1 month of treatment with the vascular endothelial growth factor receptor (VEGFR) inhibitor, fruquintinib. The occurrence of PRES after 1 month of VEGFR inhibitor administration is a common phenomenon. However, it is noteworthy that this is the first reported case of PRES associated with fruquintinib. The patient's neurological function improved upon discontinuing the drug for a week, but worsening was observed following a lower-dose fruquintinib treatment. This patient's experience highlights the potential for neurological deterioration in those treated with fruquintinib, prompting physicians to consider the possibility of PRES. Notably, this may be the first reported case linking fruquintinib to the syndrome, underscoring the importance of recognizing the association between PRES and fruquintinib.