( Tanespimycin TIME Registration Program ...)Kosan Presents Data on Lead Hsp90 Inhibitor, Tanespimycin, Showing,Promising Antitumor Activity in Multiple Myeloma at ASCO,Health

HAYWARD, Calif., June 04, 2007 /PRNewswire-FirstCall/ -- Kosan Biosciences Incorporated presented data from a dose-escalating Phase 1b clinical trial of its lead Hsp90 inhibitor, tanespimycin (KOS-953) in combination with bortezomib (Velcade(R)), showing a high degree of antitumor activity and tolerability in patients with multiple myeloma who had previously progressed following treatment with multiple conventional therapies. The data were presented on Saturday, June 2, 2007, by Paul Richardson, M.D., Department of Hematology, Dana Farber Cancer Center, Boston, MA, in a poster titled "A Multicenter Phase 1 Clinical Trial of Tanespimycin (KOS-953) + Bortezomib in Relapsed Refractory Multiple Myeloma" at the 2007 Annual Meeting of the American Society of Clinical Oncology (ASCO).

"Tanespimycin has significant potential as a new treatment for patients with multiple myeloma and is promising in patients with refractory disease whose need for new therapeutic options is especially important," said Dr. Richardson. "The overall profile of tanespimycin in terms of antitumor activity and tolerability, with no additive toxicity to bortezomib, is attractive and we are excited to be moving into later-stage clinical development."

"With the initiation of our TIME clinical program later this year, utilizing our new, superior injectable suspension formulation, tanespimycin will be the first Hsp90 inhibitor to enter registration trials and has the potential to be the first Hsp90 inhibitor to reach the market," said Robert G. Johnson, Jr., M.D., Ph.D., Kosan's President and Chief Executive Officer. "We are highly encouraged by the level of tanespimycin's activity in multiple myeloma and its tolerability and safety profile, and believe that tanespimycin has the potential to represent a breakthrough in the treatment of multiple myeloma. We appreciate th
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