Researchers on Wednesday announced that two men previously infected with HIV, the virus that causes AIDS, show no trace of the virus following stem-cell transplants.

Dr. Timothy Henrich of Harvard Medical School and Brigham and Women's Hospital in Boston presented the findings at the International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Kuala Lumpur, Malaysia, Al Jazeera English reported.

Diagnosed with Hodgkin's lymphoma, a cancer of the blood, the patients underwent a medical procedure to replace their bone marrow.

The men “were given high doses of chemotherapy and radiation. This killed off the existing sick bone marrow, the body's blood factory. Healthy stem cells taken from a donor's bone marrow were then put into their blood in a process like a blood transfusion. The stem cells then found their way to the bones and started to grow and produce healthy blood cells.”

Timothy Ray Brown in 2009 underwent a similar treatment and today is considered the only adult patient believed to be cured of HIV.

In March, scientists announced that a baby born with HIV had been “functionally cured” of the disease.

(Related: Doctor who treated baby cured of HIV says she was surprised by the discovery.)

Researchers said that they would wait up to a year before calling the patients cured.

While the outcomes are encouraging, bone marrow transplants are expensive and only 50 percent of those who have them survive.

“The transplant procedure itself carries with it significant risks. It's really limited to patients who have cancer and require a transplant to treat their cancer,” Daniel Kuritzkes of Brigham and Women's Hosptial told Al Jazeera English. “But I think we can learn from this experience and find ways of applying elements of what we've done in other settings that may apply much more broadly.”