But while the case has novel medical implications, experts say it will be of little immediate use in treating AIDS. Top American researchers called the treatment unthinkable for the millions infected in Africa and impractical even for insured patients in top research hospitals.
“It’s very nice, and it’s not even surprising,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases. “But it’s just off the table of practicality.”
The patient, a 42-year-old American resident in Germany, also has leukemia, which justified the high risk of a stem-cell transplant. Such transplants require wiping out a patient’s immune system, including bone marrow, with radiation and drugs; 10 to 30 percent of those getting them die.
“Frankly, I’d rather take the medicine,” said Dr. Robert C. Gallo, director of the Institute of Human Virology at the University of Maryland School of Medicine, referring to antiretroviral drugs.
Moreover, the chances of finding a donor who is a good tissue match for the patient and also has the rare genetic mutation that confers resistance to H.I.V., the virus that causes AIDS, are extremely small. Nonetheless, the man has been free of the virus for 20 months even though he is not using antiretroviral drugs, and the success in his case is evidence that a long-dreamed-of therapy for AIDS – injecting stem cells that have been genetically re-engineered with the mutation – might work.
Attempts to use bone-marrow transplants in AIDS treatment have been made since the 1980s. In one case, a patient with both AIDS and lymphoma died of the cancer two months later, but was found to harbor no H.I.V.; it was not known if something in the transplant had protected him.
And in a famous 1995 case, Jeff Getty, a prominent San Francisco advocate for AIDS patients, received bone marrow from a baboon, which is resistant to the human virus. He survived 11 years, but died of AIDS and cancer; the transplant had not protected him but antiretroviral triple therapy had been invented in time to help.
Dr. Hütter said one of the 80 potential donors who matched his patient closely enough for leukemia treatment also happened to have the mutation.
That mutation, discovered in a few gay men in the 1990s and known as Delta 32, must be inherited from both parents. With it, the white blood cells produced in the marrow lack the surface receptors that allow H.I.V. to invade the immune system.
Even if it is prevented from replicating by drugs, the H.I.V. can lie dormant in lymph and nerve cells for years. But without the necessary receptors, any virus coming out of dormancy has no way to infect them.
Doctors say the case gives hope for therapies that artificially induce the Delta 32 mutation.
For example, Dr. Irvin S. Y. Chen, director of the AIDS Institute at U.C.L.A. , is working on using RNA “hairpin scissors” to cut out the bits of genetic material in blood stem cells that code for the receptors. The concept is working in monkeys, he said. Eventually, he hopes, it will be possible to inject them into humans after wiping out only part of the immune system with drugs. “I think that would carry no risk of death,” he said.
By DONALD G. McNEIL Jr.
Published: November 13, 2008
Source: The New York Times