orteronel orteronel orteronel (tak-700) is a nonsteroidal cyp17a1 inhibitor that was being developed for the treatment of cancer by takeda pharmaceutical company in conjunction with millennium pharmaceuticals. it completed two phase iii clinical trials for metastatic, hormone-refractory prostate cancer but failed to extend overall survival rates, and development was voluntarily terminated as a result. orteronel names iupac name 6-(7-hydroxy-6,7-dihydro-5h-pyrroloimidazol-7-yl)-n-methylnaphthalene-2-carboxamide other names tak-700 identifiers cas number 566939-85-3 y 3d model (jsmol) interactive image chembl chembl1921976 chemspider 8058704 kegg d10146 y pubchem cid 9883029 unii ue5k2fns92 inchi inchi=1s/c18h17n3o2/c1-19-17(22)14-3-2-13-9-15(5-4-12(13)8-14)18(23)6-7-21-11-20-10-16(18)21/h2-5,8-11,23h,6-7h2,1h3,(h,19,22) smiles o=c(nc)c2ccc1cc(ccc1c2)c4(o)c3cncn3cc4 properties chemical formula c18h17n3o2 molar mass 307.353 g·mol−1 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references orteronel is an androgen biosynthesis inhibitor. it selectively inhibits the enzyme cyp17a1 which is expressed in testicular, adrenal, and prostatic tumor tissues. cyp17 catalyzes two sequential reactions: (a) the conversion of pregnenolone and progesterone to their 17α-hydroxy derivatives by its 17α-hydroxylase activity, and (b) the subsequent formation of dehydroepiandrosterone (dhea) and androstenedione, respectively, by its 17,20-lyase activity. dhea and androstenedione are androgens and precursors of testosterone. inhibition of cyp17 activity thus decreases circulating levels of testosterone.