||Conquer Cancer Health News
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
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
"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
Also, Taxol does not dissolve in water, so to infuse it
into a patient, other chemicals must be added. These can
"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.