A differential response to sunitinib: sustained systemic response paralleled by intra-dural progression in the spine. Should standard response criteria be reviewed?

Orally available tyrosine kinases have revolutionized the treatment of renal cell carcinoma. These agents have impressive response rates compared with interferon and also have a cytostatic effect. We describe a case of a patient treated predominantly with continuous sunitinib who had a good partial response to sunitinib in the lungs, liver, adrenal gland, and lymph nodes but dural progression. We describe prolonged sustained response achieved by continuing sunitinib despite dural progression. This case demonstrates that standard treatment criteria may need reviewing.