New weapon against Kaposi's sarcoma.Researchers studying Kaposi's sarcoma Kaposi's sarcoma (käp`əshē', kəpō`sē), a usually fatal cancer that was considered rare until its appearance in AIDS patients. (KS) may have found a promising new weapon against this cancer, which strikes many people with the AIDS virus AIDS virus n. See HIV. (HIV HIV (Human Immunodeficiency Virus), either of two closely related retroviruses that invade T-helper lymphocytes and are responsible for AIDS. There are two types of HIV: HIV-1 and HIV-2. HIV-1 is responsible for the vast majority of AIDS in the United States. ). Robert C. Gallo of the National Cancer Institute in Bethesda, Md., reports that a compound called SP-PG (sulfated polysaccharide-peptidoglycan), isolated from the outer wall of Arthrobacter bacteria, reverses the growth of KS tumors more effectively and safely than present chemotherapy treatments. His findings appear in the March 13 SCIENCE. Once restricted mainly to elderly Jewish or Mediterranean men and to people, such as transplant recipients, using drugs that suppress the immune system immune system Cells, cell products, organs, and structures of the body involved in the detection and destruction of foreign invaders, such as bacteria, viruses, and cancer cells. Immunity is based on the system's ability to launch a defense against such invaders. , Kaposi's sarcoma has become epidemic among people infected with HIV. The disease causes swollen, purple-colored tumors to appear on the skin, created by the cancer's feeding techniques. To grow, KS tumor cells tap into the surrounding blood by sprouting a thick network of blood vessels Blood vessels Tubular channels for blood transport, of which there are three principal types: arteries, capillaries, and veins. Only the larger arteries and veins in the body bear distinct names. . The disease also causes nearby vessels to leak, bathing the tumor in blood. In laboratory experiments conducted at the National Cancer Institute and at Daiichi Pharmaceutical Co., Ltd., in Tokyo, researchers tested SP-PG on cultured KS cells and on KS-like tumors in mice. They found that SP-PG blocked tumor growth more effectively than any of three current drug treatments - interferon-A, suramin suramin a trypanocidal agent that is also toxic, causing degeneration of the liver, kidney and adrenal glands. It is also an inhibitor of reverse transcriptase, some types of growth factors, and causes suppression of the adrenal cortex, leading to investigations of its usefulness and pentosan polysulfate. In addition, SP-PG proved less toxic to the mice than the other drugs. Gallo points out, however, that the SP-PG mice were observed for only six days following the experiment. SP-PG starves the KS tumor by destroying its vascular supply lines and by mending leaky blood vessels. Gallo speculates that SP-PG may prove useful against other cancers that feed like KS. SP-PG has not yet been tested in humans. |
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