A new class of drug, called PARP inhibitors, shrank or stabilized tumors in 12 out of 19 patients with inherited forms of advanced breast, ovarian and prostate cancers caused by mutations of the BRCA1 and BRCA2 genes. Photo Credit: ASTRAZENECAJune 25, 2009, (Sawf News) - A new class of drug, called PARP inhibitors, shrank or stabilized tumors in 12 out of 19 patients with inherited forms of advanced breast, ovarian and prostate cancers caused by mutations of the BRCA1 and BRCA2 genes.
None of the 12 patients had responded to other therapies.
One of first patients to be treated continues to be in remission two years later.
The study, led by the Institute of Cancer Research, was backed by pharmaceutical company AstraZeneca. Its results are published in the June 25 issue of New England Journal of Medicine.
Researcher Dr Johann de Bono believes the drug is now ready for larger trials.
"This drug showed very impressive results in shrinking patients' tumors," he said.
"It's giving patients who have already tried many conventional treatments long periods of remission, free from the symptoms of cancer or major side-effects."
Like other targeted chemotherapy – drugs that target cancer cells but leaves healthy cells relatively unscathed – PARP inhibitors cause few side effects. Some of the patients termed the treatment "much easier than chemotherapy".
PARP inhibitors exploit a weakness in the ability of tumor cells to repair their DNA. While normal cells have different pathways to repair DNA damage, one of these pathways is disabled by the BRCA mutation in tumor cells.
Olaparib blocks one of the repair pathways by shutting down a key enzyme called PARP. While normal cells remain unaffected because of their ability to use an alternate pathway controlled by their BRCA gene, tumor cells die because an alternative pathways is already disabled by the genetic mutation.
There is evidence to suggest olaparib could be effective in treating other cancers linked to defects in the repair of DNA.
Professor Stan Kaye, who also worked on the study, said: "The next step is to test this drug on other more common types of ovarian and breast cancers where we hope it will be just as effective."
Dr Peter Sneddon, of the charity Cancer Research UK, said: "It is very encouraging to see the development of 'personalized treatment', tailored to the requirements of the individual patient, becoming a reality as it offers the opportunity to design new drugs that are truly selective.
"Although development of this drug is in its early stages, it is very exciting to see that it has the potential to work when other treatment options have failed."
News Copyright © Sawf News. May not be reproduced without explicit written permission