In February 1999, the NCI reported that two of its scientists had conducted experiments with mouse endostatin in Folkman's laboratory. These experiments verified the previously published results in mice. Efforts up to that point had not reproduced this result, and the murine endostatin produced in the Folkman laboratory lost activity on attempts to ship the material to NCI.

With the availability of human endostatin produced by EntreMed, Inc., Rockville, Md., using a separate and distinct process that has shown good activity, NCI decided to proceed with two small clinical trials to begin evaluating the safety and preliminary biological activity of endostatin in people. NCI has not attempted to conduct additional experiments with human or murine endostatin in its own laboratories in Maryland, meaning there have been no "failed" laboratory studies with the material to be used in humans. NCI does not routinely require reassessment of the activity of agents ready for clinical evaluation in company-sponsored trials.

The NCI's decision to move endostatin into clinical trials is based solely on science. Other published studies have shown endostatin's antitumor activity and have reported that in mice the human version of endostatin caused a marked inhibition of tumor growth, an indication that the human protein might also be effective in people. Moreover, toxicity studies have shown that endostatin is well tolerated in monkeys, even at extremely high doses, and causes no side effects.

Given the reports of antitumor activity of human endostatin in mice and its documented lack of toxicity, NCI believes that the only way to begin to rigorously evaluate this unique compound in people with cancer is to move it into clinical trials.

For more information about cancer visit NCI's Web site for patients, public, and the mass media at http://www.nci.nih.gov.