FDA: Protecting America's Health : Part 3

by Food and Drug Administration (FDA)

(Page 3 of 3)

Proteomics and Cancer Detection

Much like a grocery store cashier swipes a cereal box over a simple bar code reader to get a price, FDA scientists send blood and tissue through a sophisticated bar coder to read protein patterns. These patterns are helping researchers to detect early-stage cancers and changes in cancer cells that could aid doctors in choosing an appropriate treatment for their patients.

Using proteomics, the study of proteins in living cells, scientists at the FDA and the National Cancer Institute (NCI) have developed a finger-stick blood test that may help detect ovarian cancer before it has spread outside the ovary. Early detection dramatically increases the chances of survival, but currently available screening methods detect only 10 percent to 15 percent of ovarian cancers at this earliest stage.

The new test requires only one drop of blood to detect specific patterns of proteins that signify cancerous cells. Using a sensitive analytical method called mass spectrometry, the scientists sort the proteins by weight and electrical charge, resulting in what looks like a bar code, or a fingerprint, of each protein.

But whereas a store product bar code may have 30 lines, protein bar codes have hundreds of thousands of lines, says Emanuel Petricoin, Ph.D., co-director of the FDA-NCI Clinical Proteomics Program. Using computers to read the line patterns, scientists can discriminate a cancerous cell from a normal cell.

"We have several test models that have given us 100 percent accuracy in detecting ovarian cancer in small studies of several hundred women," says Petricoin. Thousands more women are being recruited for clinical trials at NCI this spring. "If we get good preliminary data, we'll look at other types of cancers, such as breast and prostate," adds Petricoin. Blood tests for these cancers could revolutionize screening tests, eliminating the need for many unnecessary biopsies.

In addition to detecting protein patterns in blood, FDA and NCI scientists have developed a new type of protein array technology for analyzing the cellular "wiring diagram" from only a few hundred cells. Using a laser microscope they developed to pluck cells from tissue and magnify them, the investigators can analyze the proteins by their protein arrays. "We found patterns that were changing as disease occurs," says Petricoin. These protein patterns also change when different drugs are used, which may one day help doctors determine which drugs and doses of those drugs might work best in treating individual cancer patients.

"For the first time, we can now gain insights into the functional state of the cellular circuitry in patients' tissue before, during, and after therapy," says Petricoin. This work is now leading to NCI-based clinical trials where proteomic tools are being used and evaluated in the clinic. "While DNA is the information archive, it is the proteins that do the work and are the targets for therapy," Petricoin adds. "The critical information we get here cannot be predicted by gene arrays, so this technology was sorely needed."

Petricoin will be leading the breakout session, "Serum Proteomic Pattern Diagnostics Using Artificial Intelligence Based Bioinformatics" at the Science Forum.

Blood Substitutes

Blood can be a life-saving fluid for trauma victims, heart surgery patients, organ transplant recipients, and many others. An average of 34,000 units of red blood cells are needed each day in the United States, according to the American Association of Blood Banks, and the demand for blood continues to increase.

Researchers have been searching for an effective blood substitute for more than half a century, and they appear to be getting closer to finding one. FDA scientists are currently reviewing several chemically and genetically modified hemoglobin solutions at different stages of development. Hemoglobin is the protein in red blood cells that carries oxygen throughout the body and gives blood its bright red color.

"These unique products present a research and regulatory challenge because there is no precedent and there has been very little research done in the field," says Abdu Alayash, Ph.D., a research chemist in the FDA's Center for Biologics Evaluation and Research. Human hemoglobin is encapsulated within red-cell membranes, unlike hemoglobin-based blood substitutes, which are derived from human or bovine outdated blood and are then chemically modified. "Since the hemoglobin is not encapsulated in protective gear, we must ensure that it's not toxic to tissues," says Alayash. Only a few animal species, such as the earthworm, have hemoglobin in free form, he adds.

For the last 12 years, FDA researchers have been studying hemoglobin toxicity. "We have defined several pathways of toxicity and we have suggested ways and means of controlling it," says Alayash. Through continued research and collaboration with other scientists, FDA researchers are contributing to the design of safe and effective blood substitutes.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.