A new heparanase inhibitor/HS mimetic, PG545, suppressed tumor growth and metastasis in various solid tumors and metastasis models [12-14] and also dramatically increased the overall survival in a syngeneic 4T1 breast cancer model which was associated with down regulation of heparanase in primary tumor and lung metastases [15]. The gene discussed is HPSE; the disease is breast cancer.