WASHINGTON, 03 june 2009– A gene that is highly active in up to 20 percent of breast cancer cases might be blocked by a generically available blood pressure drug, U.S. researchers reported on Tuesday.
The gene, called AGTR1, caused normal breast cells to behave like cancer cells but the blood pressure drug losartan stopped them, the team at the University of Michigan found.
They transplanted human tumors that expressed AGTR1 -- meaning the gene was active -- into mice. Eight weeks after they gave the mice losartan the tumors shrank by 30 percent, they reported in the Proceedings of the National Academy of Sciences.
"What's also exciting is this gene is blocked by a drug that's already available on the market," Dr. Arul Chinnaiyan, who led the study, said in a statement.
Chinnaiyan and colleagues looked at nearly 3,200 microarrays -- gene chips -- taken from cancer patients and available in a database called Oncomine, which was set up to allow just such comparisons.
The gene they found the most often was ERBB2 -- already known to be behind 25 percent to 30 percent of breast tumors. This gene mutation is targeted by Genentech's drug Herceptin, known generically as trastuzumab.
Number two in the scan was AGTR1, also known as angiotensin II receptor type I. They found it was busy in 10 percent to 20 percent of the breast tumors -- none of them ERBB2-positive tumors.
"AGTR1 is very analogous to HER2 or ERBB2. HER2 is a bona fide treatment target for patients with that type of breast cancer," said Chinnaiyan, whose work is funded by the Howard Hughes Medical Institute.
"Losartan may be a viable therapy for women with AGTR1 over-expressing breast tumors. This study lays the groundwork for a clinical trial to test losartan to treat breast cancers positive for AGTR1," Chinnaiyan says.
Losartan, made generically by India's Aurobindo Pharma Ltd, is the generic equivalent of Merck & Co Inc's Cozaar.