By Anne Harding
NEW YORK, Dec 15 - A new class of drugs derived
from platinum may fight cancers that no longer respond to older platinum-based
drugs, such as cisplatin and carboplatin, researchers reported Thursday.
Platinum drugs are among front-line therapies for ovarian and testicular
cancer, but ovarian cancers quickly develop resistance to them.
The new drug "is the first genuinely new platinum agent to enter
clinical trials in 30 years," Dr. Nicholas Farrell, one of the inventors
of the drug, said in statement. Farrell is a professor of chemistry at Virginia
Commonwealth University in Richmond.
Cisplatin and related drugs contain a single atom of platinum, and work by
binding to DNA to prevent cancer cell division. While they damage DNA, Farrell
explained to Reuters Health, cancer cells learn how to repair this damage,
eventually rendering the drugs useless for many patients.
The new compound contains two or three atoms of platinum. Its mode of attack
is to tie together the two strands of a DNA molecule, so the strands cannot
pull apart to launch cell division. "We cover a larger piece of DNA
because the molecule is larger," Farrell said.
The researcher described the new drugs at the International Chemical
Congress of Pacific Basin Societies in Honolulu, Hawaii. The pharmaceutical
company Roche has licensed one of the drugs, BBR3464. Novuspharma of Monza,
Italy, is conducting clinical trials.
Early studies on 47 cancer patients last year showed that BBR3464 is active
against pancreatic cancer and colon cancer. Other trials--including one in
patients with ovarian cancer who have developed resistance to cisplatin--are
under way in Europe and the United States.
"Early results are encouraging," Farrell said, adding that the
results will be released at the American Society of Clinical Oncology's spring
meeting.
Required dosage for BBR3464, which like cisplatin is given by injection, is
one-twentieth of the dosage for the older drug. While cisplatin and its cousins
cause kidney damage and severe nausea, Farrell said, the main side effects
observed with the new drug have been a drop in the level of a certain type of
infection-fighting white blood cells and diarrhea.
"We anticipate new drugs coming through from this class of compounds in
the next year or two," he concluded.
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