Recent advances in the systemic treatment of metastatic papillary renal cancer

Renal cell carcinoma (RCC) encompasses a heterogeneous group of histological subtypes, of which clear cell RCC (CCRCC) is the most common, comprising more than 70% of all cases. Papillary RCC (PRCC) is the next most common, comprising 10-15% of cases. PRCC is refractory to chemotherapy, immunotherapy and hormonal therapy. Recent improvements in our understanding of the molecular biology of CCRCC have identified multiple pathways associated with the development of this cancer. This has led to drug development targeting these pathways, including the small molecule tyrosine kinase inhibitors sunitinib and sorafenib, the monoclonal antibody bevacizumab and the mTOR inhibitor temsirolimus. These drugs have shown significant clinical benefits in randomized trials of advanced CCRCC and have become the standard of care for most patients. However, since these trials were, on the whole, restricted to patients with clear cell histology, their efficacy in patients with non-clear cell RCC, and particularly PRCC, is unclear. This review will focus on the activity of these targeted agents in the treatment of metastatic PRCC.