WASHINGTON — Two HIV-positive patients in Boston who underwent bone marrow transplants for cancer were later found to have undetectable blood levels of HIV, according to research presented at the 2012 International AIDS Conference Thursday.

Scientists say it is too early to call the patients “cured’’ of the virus, which causes AIDS, because the men are still taking drugs to treat HIV. But the results offer intriguing insights into how an eventual HIV cure might be developed.

“These researchers have done some elegant work,’’ said Dr. Steven Deeks, an HIV researcher at the University of California, San Francisco, “and found results that I think are going to be very provocative.’’


The patients share some similarities with the “Berlin patient’’ — Timothy Brown, an American who was given a bone marrow transplant for leukemia and reported by his German doctors to have been cured of HIV in 2009.

Both of the Boston patients suffered from Hodgkin’s lymphoma, a cancer of the blood. One also had other blood cancers. After chemotherapy and other treatments failed, doctors at the Dana-Farber/Brigham and Women’s Cancer Center performed bone marrow transplants to replace the patients’ cancerous blood cells with healthy donor cells.

Dr. Daniel Kuritzkes and Dr. Timothy Henrich of Brigham and Women’s, who studied the patients, found that the patients’ blood showed no traces of HIV particles and viral DNA within eight to nine months of their transplants.

Unlike most HIV-positive cancer patients, the two men remained healthy enough to continue their HIV medications during cancer treatments. Kuritzkes and Henrich believe the drugs were the key to the patients’ success.

“We’ve shown that you can transplant cells from an uninfected donor that are susceptible to HIV, and protect them from becoming HIV-infected,’’ said Henrich, “so long as the recipient is maintained on antiretroviral therapy.’’

Bone marrow transplantation can cost hundreds of thousands of dollars, and it proves fatal for 15 percent of recipients. Typically, cancer patients receive bone marrow transplants after other options prove ineffective. So, the treatment could not be broadly applied to HIV patients.


“We’re not going to be doing bone marrow transplants on healthy HIV-infected patients who are doing well on antiretroviral therapy,’’ said Kuritzkes.

Brown also received a bone marrow transplant to treat leukemia. However, doctors used a donor who had a rare genetic mutation that provides resistance against HIV. So far, no one has observed similar results using ordinary donor cells such as those given the Boston patients.

Many scientists are waiting to see whether the Boston patients can now remain HIV-free without the help of antiretroviral drugs, like Brown.

“That event was part of what has created a more serious interest in attempts to eradicate HIV,’’ Dr. David Margolis, an HIV researcher at the University of North Carolina at Chapel Hill, said of Brown’s case. “You want to see it happen more than once and at least begin to understand how it happened.’’

Kuritzkes and Henrich said they are in discussons with the patients, their oncologists, and hospital regulatory committees to decide whether to stop HIV treatments for the patients.