PDCD1 and clear cell renal carcinoma: UGT1A6 is also expressed at significantly higher levels in tumours from patients with advanced renal clear-cell carcinoma who do not respond to the programmed cell death 1 (PD-1)-blocking antibody nivolumab—288-fold higher expression than in responders, on average—along with a more modest, but significantly higher, expression of UGT1A1 and UGT1A3 (by 5- and 7.1-fold, respectively).