Niraparib (MK-4827) displays excellent PARP 1 and 2 inhibition. Inhibition of PARP in the context of defects in other DNA repair mechanisms provide a tumor specific way to kill cancer cells. Niraparib is in development with TESARO, under licence from Merck & Co, for the treatment of cancers (ovarian, fallopian tube and peritoneal cancer, breast cancer, prostate cancer and Ewing's sarcoma). Niraparib was characterized in a number of preclinical models before moving to phase I clinical trials, where it showed excellent human pharmacokinetics suitable for once a day oral dosing, achieved its pharmacodynamic target for PARP inhibition, and had promising activity in cancer patients. It is currently being tested in phase 3 clinical trials as maintenance therapy in ovarian cancer and as a treatment for breast cancer.

4-n-octylphenol is alkylphenol widely used as a surfactant. 4-n-octylphenol exposure was associated with idiopathic male infertility. Fetal exposure to the very weak estrogenicity of 4-n-octylphenol could enhance the induction of mammary carcinomas but not affect the induction of benign proliferative lesions. It is an endocrine-disrupting chemical. 4-n-octylphenol is an agonist and antagonist of estrogen receptor and androgen receptor, respectively. 4-n-octylphenol at high doses caused reduction in mammary tumor development in female human c-Ha-ras proto-oncogene transgenic rats and possibly non-transgenic rats.