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New Cancer-Fighter? You Might Have Walked on It
Jan. 27, 2000 (Reuters)

For years, doctors have known that a slimy bacterium found in the dirt produces compounds that have strong effects against cancer.

But while the compounds, known as epothilones, are found literally underfoot, they cannot be produced in the lab in any great amounts.

Today, a small California biotechnology company said it had figured out how to produce large amounts of the substance by genetically engineering another bacterium.

Li Tang and colleagues at Kosan Biosciences in Hayward, California, said their bacteria literally pump out epothilones. "It should not take long now to develop our strain into one that produces the amounts of epothilone needed for clinical trials," Daniel Santi, one of the founders and chairman of Kosan, said in a statement.

Successor to Taxol? Epothilones have long been considered the natural successor to Taxol, Bristol-Myers Squibb's powerhouse cancer drug. Based on compounds found in yew trees, Taxol works especially well against ovarian cancer. "Although Taxol is the largest-revenue anti-cancer agent in history, it has two major shortcomings," Kosan said in a statement. "First, many cancers are resistant to the drug." Also, Taxol does not dissolve in water, so to infuse it into a patient, other chemicals must be added. These can have side-effects. "For these reasons, epothilone is widely perceived as a potential successor to Taxol," the statement read.

Hard to Grow But it is hard to grow. The bacteria that naturally produce it live in slimy colonies on the ground, and when grown in laboratory dishes cannot be coaxed to produce more than a little bit of precious epothilone.

Writing in the journal Science, Tang and colleagues described how they found the genes for epothilone A and B and spliced them into another bacterium, Streptomyces coelicolor. "S. coelicolor is more amenable to metabolic engineering and strain improvement and grows about 10-fold as rapidly as the natural producer, thereby offering the opportunity to develop a practical production system," Kosan said.

More Work Ahead The company, which got a grant from the National Cancer Institute to do the work, said it will now try to manipulate epothilones even more, to see if they can find a way to make it even more effective against cancer.

Annual sales of Taxol, known generically as paclitaxel, and Taxotere, a related drug made by Aventis, were $1.6 billion in 1998, with total sales expected to grow to more than $2 billion in 2000, Kosan said.

Copyright 2000 Reuters. All rights reserved.

Copyright© 1999 All rights reserved.