A previously described FEN1 inhibitor, 3-hydroxy-5-methyl-1-phenylthieno [2,3 d]pyrimidine-2,4(1H,3H)-dione) (Figure 4A, also known as PTPD) [29] was evaluated in our pre-clinical ovarian cancer models. The gene discussed is FEN1; the disease is ovarian carcinoma.