Precision Medicine for Patients with Renal Cell Carcinoma Based on Drug-metabolizing Enzyme Expression Levels

Notable advances have recently been achieved in drug therapies for renal cell carcinoma (RCC). Several tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) have been approved for metastatic RCC (mRCC). The current first-line treatment for mRCC involves combination therapies using TKIs and ICIs. However, there is no consensus on which TKI+ICI therapy is best or how to select the appropriate therapy for individual patients with RCC. The kidney expresses various metabolic enzymes, including CYP and uridine diphosphate glucose (UDP)-glucuronosyltransferase (UGT). Although information on CYP and UGT expression in the kidney is limited compared to our understanding of liver expression, the main CYP and UGT subtypes expressed at high levels in the kidney are estimated to be CYP2B6, CYP3A5, CYP4A11, CYP4F2, UGT1A6, UGT1A9, and UGT2B7. In RCC, the expression profiles and levels of these enzymes are somewhat altered compared with normal kidney. The main known subtypes of CYP and UGT in RCC are CYP1B1, CYP3A5, CYP4A11, UGT1A6, UGT1A9, UGT1A10, and UGT2B7. High CYP expression has been reported in several cancers, possibly conferring resistance to anti-cancer drugs including TKIs, due to extensive drug metabolism. Additionally, CYP and UGT expression levels may possibly affect cancer prognosis by metabolizing endogenous substrates, regardless of their role in anti-cancer drug metabolism. In this review, I discuss CYP and UGT expression level profiles in RCC based on previously published papers, including ours, and examine possible relationships between these enzyme expression profiles and treatment outcomes for patients with RCC.