When Timothy Brown, known as the "Berlin patient," was treated for leukemia with a bone marrow transplant in 2007, the donor happened to have a rare genetic mutation that makes immune cells resist HIV infection. The transplant replaced Brown’s own infected cells with healthy, AIDS-resistant cells, and he has remained free of the virus to this day.

Now, two other men who have undergone bone marrow treatments for cancer also appear to be free of the AIDS virus, researchers have reported. And better yet, they received ordinary cells, not the AIDS-resistant ones, surprising scientists who thought that the mutation was a necessary component of Brown’s progress.

The doctors are hesitant to call it a cure, but they note that the men have stopped taking HIV drugs with no return of the virus for nearly four months for one man and almost two months for the other.

“While these results are exciting, they do not yet indicate that the men have been cured,” says Dr. Timothy Henrich of Brigham and Women’s Hospital and Harvard Medical School in Boston.

The cases of the two men, who wish to remain anonymous, were first reported at an international AIDS conference in Washington last July, and have been recently presented at the International AIDS Society in Malaysia.

Henrich along with Dr. Daniel Kuritzkes and their team had actively sought HIV patients with leukemia or lymphoma who had undergone bone marrow stem cell transplants. Transplants work to kill the cancer and replace diseased blood and immune systems with healthy ones from the donor. They found three patients who had continued taking their HIV drugs while undergoing the transplants, which likely protected the donor bone marrow from becoming infected. One died when his lymphoma returned, but the prognosis for the other two looks promising.

“Up to week 14 for both patients, we continue to be unable to detect (HIV) DNA in their cells or virus in their blood,” Henrich says.

The patients will get weekly blood tests for at least a year or more, says Henrich.

The grueling procedure obviously isn’t a treatment for every HIV patient, but it does suggest that the virus can be eradicated, and may change the direction of research.

“Whatever the outcome, we will have learned more about what it will take to cure HIV," added Dr. Rowena Johnston, research director for Foundation for AIDS Research (amFAR).

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