By Daniel J. DeNoon
WebMD Health News
Reviewed by Louise Chang, MD
The first and only person ever to be cured of HIV/AIDS is a leukemia patient treated in Berlin with HIV-resistant stem cells.
Although the Berlin patient was treated in 2007, researchers are only now officially using the word "cure." That's because extensive tests -- including analyses of tissues from his brain, gut, and other organs -- detect no sign of lingering HIV.
Few people with HIV would want to go through the grueling and life-threatening cancer treatment that was part of this cure. And so far, the cure has not been duplicated in other HIV-positive leukemia patients who underwent similar treatment.
Yet the finding already has transformed AIDS research. What really happened? What does this mean for people who have HIV/AIDS? Here are WebMD's answers to these and other questions about the first HIV cure.
Why is HIV so hard to cure?
HIV infects a kind of white blood cell called a CD4 lymphocyte, a key player in the immune response. What makes HIV so sneaky is that it infects the very cells that are supposed to rub out viral infections.
HIV replicates in CD4 cells when they are activated -- that is, when they are triggered by an infection. But some HIV-infected cells become inactive before the virus replicates. They go into a resting mode -- and the HIV inside them becomes dormant until the cell is activated.
HIV drugs don't affect HIV hiding in resting cells. These cells represent a hidden reservoir of HIV. When treatment stops, the resting cells eventually become active. The HIV inside them replicates and quickly spreads. That's why current HIV treatments don't cure HIV.
How was the Berlin patient cured of HIV?
The Berlin patient was 40 years old when he developed leukemia. He had been infected with HIV for more than 10 years, but he was keeping his infection under control with a standard HIV drug regimen.
Standard treatment for leukemia is to kill off most of a patient's blood cells with chemotherapy -- a process called conditioning -- and then to rescue the patient with infusions of stem cells from a matched donor's blood or bone marrow. The new stem cells then repopulate the immune system and kill off the leukemia cells that survived the conditioning treatment.
The patient's doctor, Gero Hütter, MD, had an idea. Since HIV hides in white blood cells, why not try to cure the patient of leukemia and HIV at the same time? Instead of a normal donor, Huetter looked for a donor who carried the relatively rare mutation called CCR5delta32.
People with this mutation lack functional CCR5, the keyhole that HIV most often uses to enter cells. People who inherit two copies of this gene are highly resistant to HIV infection. So Hütter found a stem-cell donor who carried this mutation and used the cells to repopulate his patient's immune system.
During his recovery from the harsh conditioning treatment, the Berlin patient wasn't able to keep taking his HIV drugs. His HIV viral load shot up. But after receiving the HIV-resistant stem cells, his HIV dropped to undetectable levels -- and remained undetectable, even with extremely sensitive tests.
A year later, the patient's leukemia came back. He underwent a second round of chemotherapy and a second infusion of the HIV-resistant stem cells. It wasn't an easy treatment. The patient suffered intestinal and neurological symptoms, during which time biopsies were taken of various organs.
All of the tissues tested negative for HIV. "That was curious," says John Zaia, MD, chair and professor of virology at City of Hope, Duarte, Calif. Zaia has worked for more than a decade on developing stem-cell treatments for HIV and AIDS and has personally reviewed the Berlin patient's case with Hütter.
"There has been nobody who ever went off their anti-HIV medications without their HIV coming back," Zaia tells WebMD. "But this patient is still off treatment three and a half years later. Dr. Hütter is using the word 'cure' [in his new paper] for the first time. It is remarkable."
The Berlin patient's HIV remains totally undetectable. Moreover, his anti-HIV antibody levels continue to decline, which would not happen if there were still HIV present to stimulate antibody production. That's what led Hütter and colleagues to deem him cured.
Does the Berlin patient's treatment cure other people with HIV?
Not yet. The mutation that confers HIV resistance is relatively rare -- it's found in fewer than 2% of Americans and Western Europeans, in some 4% of Scandinavians, and is not present in Africans. A patient with leukemia can't wait very long for treatment, and it's not easy to find a matched donor who carries the double mutation.
"The Germans have tried and we have tried in the U.S., but we have not found another situation where we had an AIDS patient who could go forward for the transplant," Zaia says.
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