PDCD1 and renal cell carcinoma: Over the last decade, improved understanding of the angiogenic and immunogenic biology of renal cell carcinoma (RCC) has led to development of tyrosine kinase inhibitors (TKI) that target the vascular endothelial growth factor receptor (VEGFR) and immune checkpoint inhibitors that target the programmed cell death 1 (PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) receptors [1, 2].