Subsequently, ourselves and others have shown that PDE5 inhibitors have anti-cancer properties in combination with multi-kinase inhibitors and can enhance the lethality of standard of care chemotherapeutic agents such as doxorubicin or cisplatin; two clinical trials using sildenafil in combination with other drugs are presently open at VCU Massey Cancer Center (NCT02466802; NCT01817751) [4-8]. This evidence concerns the gene PDE5A and cancer.