November 5, 2004

Blocking HIV’s path key to AIDS treatment: Gallo

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Robert Gallo, M.D.

Blocking HIV’s path key to AIDS treatment: Gallo

The next big advance in AIDS treatment likely will come from methods that block the human immunodeficiency virus (HIV) from infecting its target cell, according to HIV co-discoverer Robert C. Gallo, M.D.

“I believe the future belongs to HIV entry inhibitors,” Gallo said Saturday during a mini-symposium at the Vanderbilt-Ingram Cancer Center co-sponsored by the Meharry-Vanderbilt Alliance.

Gallo's lecture was given in memory of the late Philip Browning, M.D., an internationally known expert on virus-related cancers at Vanderbilt who had trained with Gallo at the National Cancer Institute.

HIV infects and kills a type of white blood cell that is important in orchestrating the body's immune response. The virus can cripple the body's defenses against other infections.

Gallo, who directs the Institute of Human Virology at the University of Maryland in Baltimore, discussed ways to prevent the virus from entering its target cell. One promising approach involves blocking a co-receptor on the surface of vulnerable white blood cells to which the virus binds.

Another potential target studied by Gallo and his colleagues is a viral protein, called Tat, which with interferon alpha can suppress uninfected T cells. A Tat vaccine, designed to trigger production of antibodies that can block the protein and improve the immune response, is being tested in AIDS patients. “To me, this is the heart of the future,” Gallo said.

Much of the daylong meeting, which was aimed at young scientists, dealt with emerging technologies for cancer diagnosis. One of these approaches, called proteomics, is finding associations between patterns of proteins detected in tissues and in the blood with early disease and with response to therapy.

Vanderbilt researchers, for example, have found distinctive protein patterns or “molecular signatures” that indicate lung cancer has spread to patients' lymph nodes, even before lymph node involvement can be detected by X-ray.

“This is obviously a very important clinical characteristic which would alter therapy and potentially change curability,” said David Carbone, M.D., Ph.D., Ingram Professor of Cancer Research and professor of Medicine and Cancer Biology.

Proteomics also may help doctors determine whether their patients will respond to a given medication — even after a single dose, added Richard Caprioli, Ph.D., director of the Mass Spectrometry Research Center and Stanley Cohen Professor of Biochemistry.

In collaboration with Genentech, the Vanderbilt researchers have identified a protein profile in an animal model of breast cancer that predicts response to the cancer drug Tarceva, hours after the drug is given. In comparison, it can take several days to confirm tumor shrinkage through surgical or radiological means, Caprioli said.

Although the work is preliminary, “the walls are breaking down,” Carbone said. “Molecular biology is helping us understand cancer biology. In the future, truly clinically useful molecular signatures of lung cancer will become available.”

Other speakers included Otis W. Brawley, M.D., associate director for cancer control at Emory University's Winship Cancer Institute, who spoke on population genetics and the biology of prostate cancer.

The event was co-chaired by Ann Richmond, Ph.D., professor of Cancer Biology and Medicine at Vanderbilt, and Steven Wolff, M.D., professor of Medicine and director of the Sickle Cell Center at Meharry Medical College.