Wyeth has announced its decision to discontinue the HORIZON Phase III clinical trial program of the investigational drug temsirolimus oral tablets in combination with letrozole (Femara), a currently approved breast cancer therapy, for first-line use in postmenopausal women with hormone-receptor positive metastatic breast cancer. This decision was based upon the recommendation of an independent data monitoring committee (IDMC) after review of data from a planned interim analysis.

The HORIZON study compared the combination of temsirolimus oral tablets and letrozole versus letrozole alone. The IDMC advised that continuation of the trial was unlikely to achieve the targeted level of efficacy for the combination therapy compared to letrozole alone. The IDMC concluded, therefore, that the risk/benefit ratio for treatment of metastatic breast cancer did not favor continuation and recommended that the trial be discontinued.