* BSI-201 misses main goals of Phase III study
* Survival benefit seen in second- and third-line patients
* Did not significantly add to toxicity
NEW YORK, Jan 27 An experimental drug for a type of advanced breast cancer being developed by Sanofi-Aventis (SASY.PA) failed to extend life or slow disease progression in a late-stage clinical trial, the French drugmaker said on Thursday.
The news was particularly disappointing as the drug, BSI-201, or iniparib, did extend survival by an average of almost five months over chemotherapy alone in an earlier mid-stage study of women with metastatic triple-negative breast cancer.
However, an analysis of subjects in the 519-patient Phase III study who were undergoing their second or third treatment regimens for the disease did show an improvement in both overall survival and progression-free survival that was consistent with results from the earlier trial, Sanofi said.
"While this trial did not meet its primary goal, we believe that the improvement in overall survival and progression-free survival in patients in the second- and third-line setting are important findings," Debasish Roychowdhury, head of Sanofi-Aventis Oncology, said in a statement.
Also of importance, treatment with BSI-201 did not significantly add to the toxicity of the chemotherapy drugs that were administered along with the Sanofi medicine, the company said.
BSI-201, a new anti-tumor agent, is also being studied against lung cancer and other cancers.
Sanofi said it will conduct an in depth analysis of the new data and plans to discuss the results with U.S. and European health regulators as development of the drug for breast cancer continues.
Triple-negative breast cancer refers to a form of the disease in which the tumors are shown to not be over-expressing estrogen, progesterone or the HER2 protein.
Some 15 to 20 percent of breast cancers lack over-expression of all three proteins, and those patients often have poorer outcomes then those with other types of breast cancer. (Reporting by Bill Berkrot; Editing by Bernard Orr)