Exciting “new” breast-cancer drug progresses to human trials
One purpose of this blog is to highlight the ever-increasing number of scientific findings that illustrate the benefits of animal testing for human health. Not all of us have time to digest the intricacies of peer-reviewed scientific journals and are forced to rely on the popular press to tell us about the latest medical research. Often, the reliance on animal testing is assumed and not reported.
This week, human trials have begun using a previously known anticancer drug, carboplatin, which could transform anticancer treatment for women who develop breast cancer as a result of a common genetic mutation (Reference 1 & 2). Carboplatin has been around for a long time and is often used in the treatment of lung and ovarian cancers, but has not been tested in the subset of breast cancer caused by mutations in the genes BRCA1 and 2 (present in about 5% of breast cancer patients). Carriers of a mutation in BRCA1 are thought to have a 50 to 85 percent lifetime risk of breast cancer and a 20 to 40 percent lifetime risk of ovarian cancer. Women with a mutation in BRCA2 appear to have a similar risk of breast cancer and a 10 to 20 percent risk of ovarian cancer (3).
Cancers are well known to arise from DNA mutations, so mimicking this in animals makes for a viable and accurate model. The key issue I would like to highlight here is that researchers had been able to create the genetic mutation in a breed of mice (4), and thus test carboplatin in this animal model of human disease. The rodent model demonstrated that cells with a mutation in the BRCA gene are more sensitive to carboplatin compared with normal cells.
Following confirmation in other laboratory experiments and pre-clinical trials, human clinical trials of carboplatin in patients with breast cancer and the BRCA1/2 mutation are now underway. Previous animal studies and years of use for the treatment of other cancers in humans have the allowed rapid progression to human clinical trials.
Animal testing is not a guarantee of a successful outcome in humans – but our understanding of breast cancer and the discovery that carboplatin could be effective for a subgroup of patients with the disease was possible through investigations involving animals.
(1) An excellent website describing the current trial and its scientific rationale (far more detailed than in this blog) can be found at http://www.geneticbreastcancertrial.usilu.net/Home.html
(2) Lung cancer drug may fight breast tumour in women, The Times, May 1, 2006. http://www.timesonline.co.uk/article/0,,2-2159380.html
(3) Haber, D. Prophylactic oophorectomy to reduce the risk of ovarian and breast cancer in carriers of BRCA mutations. N Engl J Med May 23; 346 (21) 1660-2 (2002)
(4) Fedier, A., et al. The effect of loss of brca1 on the sensitivity to anticancer agents in p53-deficient cells. Int J Oncol 22, 1169-73 (2003).
posted by Kristina Cook at 11:59 PM