Although endostatin might prevent blood vessels in the body other than those around a tumor from forming, Corey said normal adult tissue can remain healthy without angiogenesis. Only tumors would be adversely affected, he said.

"The [new blood vessel] requirement for existing tissue is minimal," Corey said. "The requirement for rapidly-growing tissue is substantial."

The first endostatin testing on humans will be conducted by Dana-Farber/Partners CancerCare--a coalition of Massachusetts General Hospital, Brigham and Women's Hospital and the Dana-Farber Cancer Institute. Two other institutes, one in Houston and another in Wisconsin, will begin testing the drug later in the year.

Todd Ringler, a spokesperson for Dana-Farber/Partners CancerCare, said that the first phase of testing will look only for toxic side effects. Endostatin's effectiveness will be noted, but it will only be studied directly if the drug proves non-toxic.

Ringler said "hundreds" of applicants volunteered for testing. Only three were selected for the initial round of tests, although up to 27 more will be selected later. No control patients will be used, he added.

Ringler said the first phase of the study will take 9 to 12 months. Final, complete approval for human use will take years, he said.

Despite high public expectations, Ringler said that researchers are remaining cautious.