Combining radiation therapy, top, with the new drug angiostatin has helped stop tumor growth in mice

WASHINGTON (CNN) - Scientists at the University of Chicago reported Wednesday that the pairing of radiation with the powerful new drug angiostatin helped stop tumor growth in mice.

The findings were reported in the journal Nature.

In the past three or four years, angiostatin and endostatin were found by scientists to not only shrink, but also eliminate tumors in mice. The scientists who discovered them envisioned them in combination with other therapies, including radiation, gene and vaccine therapies.

Radiation aims to stop tumor growth and angiostatin targets growth of blood vessels in tumors.

"Rarely in cancer therapy does a single agent hit a home run so to speak," said Dr. Ralph Weichselbaum, chairman of the Department of Radiation and Oncology at the University of Chicago. "But by combining angiostatin and radiation and targeting the tumor vessels as well as the tumor cells, there's a chance this could work on humans."

Angiostatin, so far, is found to have no side effects. Since radiation can be hard on a patient, this could eventually enable doctors to use less radiation when combined with angiostatin.

Researchers cautioned these positive results have been achieved only on mice. But they said if further trials support initial findings, this therapy may be most promising with brain, head, and neck tumors and prostate cancer.

"There is a potential for new ways and better ways of treating cancer, but it's not here today, as much as I would like to say it is" said Allen Vegotsky of the American Cancer Society.

Reporter Louise Schiavone contributed to this report.