Press Releases

SRI International to Advance Clinical Development of TAS-108, a Late-Stage Breast Cancer Drug

Breast cancerMENLO PARK, Calif. —August 19, 2010—SRI International, an independent nonprofit research and development organization, announced today that it has assumed responsibility for further clinical development of the TAS-108 breast cancer program, in cooperation with Taiho Pharmaceuticals Co., Ltd., a leading Japanese pharmaceutical company. Further clinical development will focus on the lead compound's registration for the treatment of tamoxifen and aromatase inhibitor-resistant breast cancers.

Commercial partners interested in advancing this late stage drug through Phase III clinical development, regulatory approvals including Orphan Drug indications, and global commercialization outside of Japan are welcome to contact SRI.

SRI and Taiho have had a long-term collaboration on the discovery, development, and evaluation of novel endocrine approaches for the treatment of tamoxifen-resistant breast cancers, an area of significant unmet medical need. Together, they made significant progress in successfully advancing the lead compound, TAS-108, a novel breast cancer drug, through Phase II clinical development at multiple sites around the world.

TAS-108 is an oral steroidal anti-estrogen drug that was designed to have both efficacy and safety advantages over tamoxifen (TAM) and aromatase inhibitors (AIs) in the treatment of advanced or metastatic breast cancers. To date, TAS-108, administered as an oral, once-a-day tablet, has completed a series of five Phase I studies (n=67) and two Phase III studies (n=242). The key benefits demonstrated in these studies include:

  • Significant clinical anti-tumor efficacy in patients who have failed treatment with tamoxifen and/or AI therapy.
  • No reduction in bone mineral density, a side effect seen with AIs.
  • No endometrial thickening, a side effect seen with TAM.
  • An excellent overall safety profile, demonstrated in hundreds of patients.