( Tanespimycin Shown to Have No Effect on...)Kosan Presents Data on Cardiac Safety Profile of Hsp90 Inhibitor,Tanespimycin (KOS-953) at AACR,Health

HAYWARD, Calif., April 16, 2007 /PRNewswire/ -- Kosan Biosciences Incorporated today presented safety data from preclinical and clinical studies of its lead Hsp90 inhibitor, tanespimycin (KOS-953). Serial electrocardiogram (ECG) monitoring of patients was conducted in four Phase 1 trials of tanespimycin. Cardiac monitoring analyses were conducted in more than 85 patients. Tanespimycin was found to have no effect on QTc interval (a measure of the heart's electrical cycle) in these patients based on data analyses from manually read ECGs in a central laboratory or by site cardiologists.

"The analyses performed by cardiac specialists confirm that tanespimycin had no effect on QTc interval," said Robert G. Johnson, Jr., M.D., Ph.D., Kosan's President and Chief Executive Officer. "Moreover, it is clear from these analyses that two previously reported incidents of possible QTc interval effects in studies of tanespimycin conducted by the National Cancer Institute's (NCI) Cancer Therapy Evaluation Program (CTEP) were based on artifactual QTc prolongation data from automated computer reads and were unrelated to drug product. Our Hsp90 inhibitors have been administered to more than 600 patients in trials conducted by Kosan and by the NCI and the safety profile of the compound class has been well characterized. With the anticipated initiation of our TIME registration program for tanespimycin in patients with multiple myeloma, and with plans underway to advance second- generation alvespimycin into later-stage trials in patients with HER2-positive metastatic breast cancer, we look forward to further characterizing the efficacy and safety profiles of these exciting and potentially important new cancer therapies."

The data from the cardiac monitoring analyses were presented at the 2007 Annual Meeting of the American Association for Cancer Research (AACR) in a p
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