A leukemia patient in the United States has become the first woman and only the third person to be cured of HIV after obtaining a stem cell transplant from a donor who was highly resistant to the virus that causes AIDS, according to researchers on Tuesday.

The situation of a middle-aged mixed-race woman, introduced at the Conference on Retroviruses and Opportunistic Infections in Denver, was the first ever to use umbilical cord blood, a newer approach that could make the treatment more accessible to more people.

Since obtaining cord blood to treat her acute myeloid leukemia – a cancer that begins in blood-forming cells in the bone marrow  the woman has been in recovery and virus-free for 14 months, without the need for powerful HIV treatments recognized as antiretroviral treatment. The previous two cases involved males – one white and one Latino – who had obtained adult stem cells, which are more commonly used in bone marrow transplantation.

“This is now the third report of a cure in this setting, and the first in a woman living with HIV,” Sharon Lewin, President-Elect of the International AIDS Society, said in a statement.

“Taken together, these three cases of a cure post stem cell transplant all help in teasing out the various components of the transplant that were absolutely key to a cure,” Lewin stated.

According to the study, the transplantation of HIV-resistant cells is an important factor in the study’s success. Earlier, scientists believed that reconstruction disease, a common stem cell transplant side effect where the donor immune system attacks the recipient’s immune system, played a role in a potential cure.

Patients in the trial are first given chemotherapy to kill cancerous immune cells. Doctors then transplant stem cells from people who have a specific genetic mutation that makes them to lack receptors that the virus uses to contaminate cells.