By Julie Steenhuysen

CHICAGO (Reuters). – After receiving a stem cells transplant from a donor that was naturally intolerant to HIV, a U.S. woman with leukemia became the first person and only third person to successfully overcome the disease.

At the Conference on Retroviruses and Opportunistic Infections Denver, the case of a mixed-race middle-aged woman is first to involve umbilical blood. This new approach may allow for more patients.

The cord blood was given to the patient for treatment of acute myeloidleukemia. This is a form of cancer that begins in bone-forming cells.

Two cases of males, one from a white background and one from a Latino were reported. They had both received adult stem cell transplants.

Sharon Lewin (President-Elect) of the International AIDS Society stated in a statement that “This is the third report on a cure in the setting and the first for a woman with HIV.”

It is part of a U.S.-funded larger study, led by Dr. Yvonne Bryson of University of California Los Angeles (UCLA), as well Dr. Deborah Persaud of Johns Hopkins University Baltimore. This study will track 25 HIV patients who have stem cells from the umbilical cord to be treated for cancer.

First, patients in this trial receive chemotherapy to destroy cancerous immune cell cells. After removing the infected cells, doctors transplant stem cells taken from patients who have a particular genetic mutation that lacks receptors.

Scientists think these people develop an immune system which is insensitive to HIV.

Lewin claimed that transplants of bone marrow aren’t an effective strategy for most HIV patients. She said that the report does not prove there is a cure, but it “confirms” gene therapy can be used as a possible strategy to cure HIV.

Study suggests that the successful transplantation of HIV resistant cells is an essential element. Previously, scientists believed that a common stem cell transplant side effect called graft-versus-host disease, in which the donor immune system attacks the recipient’s immune system, played a role in a possible cure.

Lewin explained that the three cases of stem cell transplant cures help to unravel which components are crucial to cure.