Posterior Reversible Encephalopathy Syndrome (PRES) Following Fruquintinib in a Normotensive Patient With Metastatic Colorectal Cancer: A Case Report.

We report a rare case of posterior reversible encephalopathy syndrome (PRES) following fruquintinib treatment in a 71-year-old female with metastatic colorectal adenocarcinoma harbouring a KRAS G12D mutation. The patient had previously undergone multiple lines of chemotherapy and surgical resections with stable disease before receiving fruquintinib under compassionate access. After two cycles, she developed headaches and acute encephalopathy. MRI confirmed PRES without associated hypertension. Fruquintinib was discontinued, and the patient made a full neurological recovery. This case highlights a rare but significant toxicity of anti-vascular endothelial growth factor (VEGF) therapy in the colorectal cancer setting and underscores the importance of early radiological evaluation in suspected PRES.