Rare anti-VEGFR therapy-induced toxicity and long-term response to immunotherapy in a rare non-clear cell renal cell carcinoma patient.

Advanced non-clear cell renal cell carcinoma (nccRCC) has a poor prognosis and clinical data on the therapeutic options currently available, including immunotherapy, are generally limited highlighting an unmet clinical need. Moreover, the onset of rare adverse events raises the need of a better therapeutic management of limited treatment options. We report the clinical case of a 63-year-old man with the diagnosis of metastatic mucinous tubular and spindle cell carcinoma, a rare nccRCC, with sarcomatoid differentiation who developed two episodes of posterior reversible encephalopathy syndrome (PRES) to first-line sunitinib. It appeared after 5 months the start of the targeted therapy and reappeared at the reintroduction of the therapy. PRES is a rare and unusual adverse event to anti-vascular endothelial growth factor receptor (VEGFR) therapies, which is characterized by acute neurological disorders along with typical changes on neurological imaging, especially MRI. Moreover, this rare histotype of RCC experienced a long-term response to immunotherapy which is lasting more than 2 years. This clinical case is interesting for its rarity as a rare neurological adverse event developed twice in a rare type of RCC which also experienced an unusual long-term benefit to immunotherapy.