Tanespimycin Shows High Level Of Activity In Trastuzumab Resistant/Refractory Her2-positive Breast Cancer

Kosan Biosciences Incorporated announced that its lead Hsp90 inhibitor, tanespimycin, demonstrated a high level of antitumor activity in a Phase 2 trial when administered in combination with trastuzumab (Herceptin(R)) to patients with HER2-positive metastatic breast cancer whose disease had either progressed after, or did not respond to, treatment with trastuzumab immediately prior to entering the trial. Of 27 evaluable patients, 17 patients showed clinical benefit including 7 patients with partial response (PR), 5 patients with tumor regression (minor response or MR) and 5 patients with extended stable disease (SD, greater than 4 cycles), yielding an overall clinical benefit incidence of 63%. Common toxicities were mainly mild to moderate...