HORMONE ELIMINATES KAPOSI'S SARCOMA TUMORS
by Christopher TedeschiA recent surprise finding by a research team from USC/Norris Comprehensive Cancer Center was that a hormone produced by pregnant women can lead to the complete regression of a common tumor associated with AIDS.
Furthermore, the scientists showed that increasing doses of the hormone meant a better chance that the Kaposi's sarcoma-or KS-tumors would disappear altogether. But they're not sure why.
Parkash Gill, M.D., professor of medicine and pathology at USC School of Medicine, and his colleagues found that a commercial preparation of a hormone called human chorionic gonadotropin can halt the growth of KS tumors. In some patients, administering the hormone caused the red, blotchy skin lesions to disappear altogether.
Gill worked on the KS project with researchers from the University of Maryland's Institute of Human Virology.
The group studied 36 patients with AIDS-related Kaposi's sarcoma. Of those patients, 24 received different amounts of chorionic gonadotropin three times a week for two weeks. The remainder were split into a double-blind trial, half receiving the hormone and the other half receiving a placebo.
Of the six study patients who received the highest dose of chorionic gonadotropin, five demonstrated complete regression of their tumors.
And in the placebo-controlled study, 10 of 12 lesions in the six patients who received the treatment regressed, while none of the lesions in patients taking placebo showed any change.
Furthermore, by examining lesions on a microscopic level, the researchers confirmed that cells in the KS tumors died by a process called apoptosis, or programmed cell death. Tumor cells that were not treated with the hormone showed no microscopic change.
Gill says that chorionic gonadotropin could be used in patients almost immediately. "I would expect the hormone to be used for the treatment of localized KS disease," he predicts.
Yet the researchers remain unsure as to why the hormone preparation causes tumor cells to die.
"We don't have the answer right now," says Gill. "We believe that a fragment of the original hormone could be attacking the tumors, or that an entirely different molecule could be getting co-purified along with the gonadotropin."
That might explain why a synthetic version of the gonadotropin hormone failed to shrink KS tumors, while a commercial preparation derived from the urine of pregnant women did.
And even among hormone compounds provided by different pharmaceutical companies, the response of KS tumors differed. Such variation could suggest that a portion of the hormone molecule-or a completely different substance-possesses the beneficial tumor-killing effect.
About a year ago, the Maryland researchers, including AIDS virus co-discoverer Robert Gallo, found that KS cells failed to grow in pregnant mice, even when the mice had no immune systems.
That early research led to the finding that chorionic gonadotropin could kill tumor cells in mice that already had KS.
Kaposi's sarcoma is the most common tumor found in patients with HIV. Current treatments for advanced KS lesions often involve toxic chemotherapy.
Human chorionic gonadotropin is currently used to treat infertility. During pregnancy, the fetal portion of the placenta normally produces the hormone, which in turn causes placenta cells to produce progesterone. Progesterone helps to maintain the uterine wall as a fetus develops.
