@article {YONEYA873, author = {TAKAAKI YONEYA and KENJI TANIGUCHI and RYO NAKAMURA and TOSHIAKI TSUNENARI and IWAO OHIZUMI and YOSHITAKE KANBE and KAZUMI MORIKAWA and SHIN-ICHI KAIHO and HISAFUMI YAMADA-OKABE}, title = {Thiochroman Derivative CH4986399, A New Nonsteroidal Estrogen Receptor Down-regulator, Is Effective in Breast Cancer Models}, volume = {30}, number = {3}, pages = {873--878}, year = {2010}, publisher = {International Institute of Anticancer Research}, abstract = {Background: Tamoxifen, a selective estrogen receptor modulator, and fulvestrant, a selective estrogen receptor down-regulator (SERD), are now available for estrogen receptor-positive breast cancer patients. However, these patients acquire drug-resistance during the treatments. We identified a new orally active nonsteroidal SERD, CH4986399, which is structurally unrelated to fulvestrant and tamoxifen. Materials and Methods: We examined the oral antitumor activity and down-regulation of ER by CH4986399 in human breast cancer Br-10 and ZR-75-1 xenografts. Results: In the Br-10 xenografts, CH4986399 (100 mg/kg p.o.) as well as fulvestrant (3 mg/body s.c.) strongly reduced tumor weight. In the ZR-75-1 xenografts, CH4986399 (100 mg/kg p.o.) strongly reduced tumor weight and ER content without agonistic activity. In contrast, tamoxifen (100 mg/kg p.o.) showed only moderate antitumor activity and no ER down-regulation. Conclusion: With a chemical structure different from both fulvestrant and tamoxifen, CH4986399, may help overcome drug resistance from the endocrine treatment sequence for breast cancer patients. Copyright{\textcopyright} 2010 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved}, issn = {0250-7005}, URL = {https://ar.iiarjournals.org/content/30/3/873}, eprint = {https://ar.iiarjournals.org/content/30/3/873.full.pdf}, journal = {Anticancer Research} }