CHICAGO --- Captopril, a drug taken by over 5 million people to treat high blood pressure and congestive heart failure, has recently been shown to act simultaneously as an anti-cancer agent able to slow the growth of tumors by depriving them of their essential blood supply.
These findings by Volpert et al. at Robert H. Lurie Cancer Center of Northwestern University were published in the Aug. 1 issue of the Journal of Clinical Investigation. They raise the possibility that patients taking captopril for its hypotensive action may reap an unexpected dividend in the form of decreased incidence or severity of a variety of diseases, including cancer, that depend on growth of new blood vessels, or angiogenesis.
In an animal model, captopril slowed the growth of nest of precancerous cells in the liver as well as that of larger tumors under the skin. Although captopril had no direct effect on the tumor cells themselves, it nonetheless halted their growth in the animal model.
The drug appeared to act by slowing the growth of new blood vessels that are essential to the delivery of the ever-increasing amounts of nutrients and oxygen that growing tumors require. Without new blood vessels, small tumors remain the size of a pinhead and large tumors expand less rapidly.
The mechanism by which captopril inhibited new vessel growth appeared to be distinctly different from the mechanism by which it is thought to lower blood pressure and may depend on its ability to block the cells that form the new vessels from moving toward the tumor and to inhibit enzymes that clear a path along which sprouting blood vessels can grow.
It remains to be documented that the antitumor activity of captopril seen so clearly in the animal model also occurs in humans. If the effects are similar, captopril may be helpful in ameliorating the effects of other angiogenesis-dependent diseases, such as diabetic retinopathy and arthritis.