The experimental drug AG-33-40 may have the potential to stop the growth of cancer

From Correspondent Dr. Steve Salvatore

NEW YORK (CNN) -- Cancer becomes deadliest when it grows out of control and spreads throughout the body. An experimental drug known only as AG-33-40 holds the potential to stop that growth. And, based on preliminary research, it appears to work in humans.

California-based Agouron Pharmaceuticals, the drug's manufacturer, says AG-33-40 works on two fronts: It blocks angiogenesis, the process in which tumors grow new blood vessels to bring in nutrients, and appears to block the spread of cancer, known as metastasis.

There is no medicine available to block metastasis, which can occur even after a tumor has been removed.

The test drug seems to block the spread of cancer, a process known as metastasis

"In people with highly advanced cancers, we saw about a quarter of them achieve what we call stable disease, meaning that the tumor no longer grew. There was no increase in tumor volume," Agouron President Peter Johnson said.

Still, Johnson doesn't want to raise false hopes about AG 33-40.

"This is a phase one study," he told CNN. "It indicates that these kinds of drugs are on their way, that there's a lot of promise, but a way to go before we have ... answers to the question of whether and how they work."

More research, lasting years, is needed to see if AG 33-40 lives up to its potential to possibly save the lives of cancer patients.