Molecular pathways in renal cell carcinoma: recent advances in genetics and molecular biology

Advanced renal cell carcinoma (RCC) remains a largely incurable disease with a grave prognosis despite the availability of a multiplicity of systemic therapies targeted against vascular endothelial growth factor, its receptors, and the mammalian target of rapamycin. Although immune 'checkpoint inhibitors' appear to have activity in clear cell RCC based on recent early phase trials, the true magnitude of the benefit conferred by these agents remains to be fully understood. Given the limitations of existing treatment paradigms, ongoing research into new targetable pathways is critical. This review will highlight some of the more promising avenues of investigation into the molecular biology of RCC.

The hypoxia-inducible factor and mammalian target of rapamycin pathways remain critical targets in clear cell RCC. In addition, genes involved in chromatin remodeling such as polybromo 1 (PBRM1), SET domain containing 2 (SETD2), and BRCA-1-associated protein-1 (BAP1) have been shown to influence tumor biology and predict survival. MET alterations and the Krebs cycle enzyme fumarate hydratase are associated with familial type 1 and type 2 papillary RCC (PRCC), respectively. Alterations in nuclear factor (erythroid-derived 2)-like 2, Kelch-like erythroid-derived cap-n-collar homology-associated protein 1, and cullin 3, components of an oxidative stress response pathway, have been recently recognized in some sporadic papillary tumors as well as in fumarate hydratase-deficient tumor and may serve as additional therapeutic targets. In addition, whole-genome sequencing and integrated genomic analysis strategies are beginning to uncover unique molecular signatures associated with distinct subtypes of RCC, laying the foundation for a molecular classification of RCC and more precise, mechanism-based therapeutic intervention.

The complex molecular changes underlying individual RCC variants are yet to be fully elucidated and remain the subject of ongoing investigation. The findings summarized here further exemplify the diversity of RCC and the need to tailor our therapeutic approaches to the unique genetic alterations specific to individual subtypes of RCC.