Essential Thrombocythemia (ET) and Polycythemia Vera (PV) have been difficult diseases to treat. RG7388 is a selective inhibitor of the p53-MDM2 binding that frees p53 from negative control and activates the p53 pathway in cancer cells, leading to cell cycle arrest and apoptosis in vitro and in vivo. It has been used to treat solid tumors and Acute Myelogenous Leukemia (AML) in clinical trials. Pegasys is a drug that is the standard of care for patients who have Chronic Hepatitis B (CHB).