Apr 9, 2002 3 min read

SAN FRANCISCO – A new way of analyzing tumors to see which proteins they produce shows promise in helping doctors tailor treatments for each patient’s cancer. The idea is to see which proteins the cancer uses to fuel its out-of-control growth. That, in turn, would help doctors prescribe medicines that specifically block them.

Many new drugs in development are precisely aimed at the abnormalities that make cancer different form normal tissue.

However, these defects vary from person to person, and any single drug is expected to help only a minority of patients.

Researchers from the Clinical Proteomics Program, operated by the Food and Drug Administration and the National Cancer Institute, described progress with the approach Monday at the American Association for Cancer Research meeting in San Francisco.

They analyzed patients’ cancer cells, drawn from tumors with a needle, to see which proteins they are making.

“We will biopsy patients before, during and after therapy to monitor treatment and to change it if we need to. It’s a new paradigm we are testing,” said Dr. Emanuel Petricoin, the program’s co-director.

So far, they have analyzed 19 patients being treated for breast and ovarian cancer. The patients receive the drug Herceptin, followed a month later by Taxol.

The researchers looked for different protein profiles that can distinguish those who respond to therapy from those who fail. They found that the activated form of a protein called Akt seemed to be crucial to how they eventually did on the therapy.

The activated proteins protect cancer cells so they do not die. Herceptin knocks out this protein. So when the women later get Taxol, the drug is able to kill their cancer cells.

The work suggests that the combination of Herceptin and Taxol is only likely to be effective in women whose tumors depend on Akt for survival. By checking this in advance, doctors would offer the combination to those most likely to benefit.

Petricoin said the FDA hopes to use this approach to help doctors learn how to use the new category of so-called molecularly targeted drugs, which are aimed at the specific abnormalities found in tumor cells. The first of these was Herceptin, approved in 1998.

Petricoin said protein profiles will be used to help figure out which patients are likely to respond to these new drugs, including Gleevec, which was approved last year, and Iressa, a new medicine being developed by AstraZeneca.

“This is science and technology that is moving choices about treating patients with cancer away from population-based decisions,” said Dr. William Evans of St. Jude’s Children’s Research Hospital in Memphis.

“The idea is to determine who should have the first-line therapy and who should move on to other alternatives without spending time on therapies that don’t work.”

Petricoin said the program is still in its “knowledge discovery phase,” seeing if the technology is practical.

“We are entering into a new phase later this year where we will really monitor patient therapy and correlate it with response,” he said. “The next phase in a couple of years will be to actually guide therapy.”

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EDITOR’S NOTE: Medical Editor Daniel Q. Haney is a special correspondent for The Associated Press.

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Conference site: http://www.aacr.org