( HAYWARD Calif. June 04 2007 /PRNews...)Kosan Presents Preliminary Phase 2 Data Showing Antitumor Activity,of Hsp90 Inhibitor Tanespimycin in Metastatic Melanoma at ASCO,Health

HAYWARD, Calif., June 04, 2007 /PRNewswire-FirstCall/ -- Kosan Biosciences Incorporated presented preliminary data from a Phase 2 monotherapy trial showing that tanespimycin demonstrated antitumor activity and tolerability in patients with metastatic melanoma, including one patient with a BRAF mutation (V600E) who had failed prior chemotherapy (within 6 weeks of initiation) and while on tanespimycin demonstrated progression-free survival for more than six months and 20% lesion reduction by RECIST as well as reduction in the size and number of extensive subcutaneous nodules. Data from the ongoing trial were presented on Sunday, June 3, 2007, by Richard Kefford, M.D., Ph.D., Westmead Hospital, University of Sydney, Australia, in a poster titled, "Phase 2 Trial of Tanespimycin (KOS-953), a Heat Shock Protein-90 (Hsp90) Inhibitor in Patients with Metastatic Melanoma," at the 2007 Annual Meeting of the American Society of Clinical Oncology (ASCO).

"Hsp90 inhibition is of significant interest for exploration as an antitumor approach in melanoma, as members of the BRAF signaling pathway are client proteins and are implicated in the majority of melanomas," said Dr. Kefford. "These very early data with tanespimycin demonstrate tolerability in this advanced metastatic melanoma patient population. The conditions have been fulfilled for expanded patient accrual in this Phase 2 trial to further explore efficacy."

"Metastatic melanoma is the fourth cancer indication in which a Kosan Hsp90 inhibitor has demonstrated antitumor activity and a high degree of tolerability, providing additional proof-of-concept that Hsp90 inhibition has applicability in a broad range of tumor types and that our lead Hsp90 inhibitor, tanespimycin, has significant therapeutic potential," said Robert G. Johnson, Jr., M.D., Ph.D., Kosan's President and Chief Executive Officer. "Tanespimycin will be the first Hsp90 inhibitor to enter regi
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