WASHINGTON — In a finding that could offer vital clues to scientists working to cure AIDS, Boston researchers reported Thursday that the virus was quashed beyond detection in two HIV-infected patients who underwent bone marrow transplants while taking powerful drug cocktails.
Scientists from Brigham and Women’s Hospital and Harvard, who presented their research at the 2012 International AIDS Conference, were careful to say the patients had not been cured of the disease.
Still, some HIV specialists not involved in the research said it yielded important insights into how a cure for AIDS might eventually be developed.
“These researchers have done some elegant work, and found results that I think are going to be very provocative,” said Dr. Steven Deeks, an HIV researcher at the University of California, San Francisco.
The Boston patients, who came to the hospital seeking treatment for cancer, share similarities with a man known as the “Berlin patient.” German doctors reported in 2009 that an American, Timothy Brown, was given a bone marrow transplant for leukemia and appeared to have been cured of HIV.
Although multiple laboratories continue to analyze Brown’s samples, most scientists believe that Brown remains the only person to have been cured of HIV.
Dr. David Margolis, an HIV researcher at the University of North Carolina at Chapel Hill, said the Boston cases could drive new interest in research for a cure, much like Brown’s case did. “You want to see it happen more than once and at least begin to understand how it happened,” Margolis said.
The Boston patients both 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.
Unlike Brown and many other HIV-positive cancer patients, the two men received only mild chemotherapy and remained healthy enough to continue their HIV medications during cancer treatments.
Dr. Daniel Kuritzkes and Dr. Timothy Henrich of the Brigham, who studied the patients, said they believe antiviral drugs provided HIV protection that allowed the donated bone marrow cells to rid the body of cancer while not becoming infected with the AIDS virus.
The patients’ blood showed no trace of HIV — not even in the smallest genetic building blocks — within eight to nine months of their transplants. “They went from this easily measured amount in their blood to no measurable amount in their cells,” Kuritzkes said. “We frankly didn’t expect that.”
Not all scientists at the conference were impressed. “The real news would be if they could stop the drugs and not have the virus come back,” said Dr. Jay Levy, an HIV researcher at UC San Francisco. Brown has remained free of HIV without the use of medications.
Levy also noted that antiretroviral therapies are so successful at controlling HIV in many people that the virus all but disappears.
Many researchers also pointed out that the virus could still be present in the patients, in the lymph nodes or bowels, where it is known to hide.
Kuritzkes and Henrich said more extensive tests will be crucial in determining whether the virus has truly been eradicated. At the same time, they are discussing with the patients, their oncologists, and hospital regulatory committees about whether to stop HIV drug treatments.
“There’s a chance that the virus could come back, so we have to make sure that this is done safely and ethically,” Henrich said.
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 fail. So, the treatment could not be broadly applied to HIV patients, especially those who are managing the infection well with medication.
For scientists, even if there are not immediate applications of the research for patients, it points to intriguing avenues.
Brown’s doctors selected a bone marrow donor who carried two copies of a gene mutation, called CCR5-delta32. The rare double mutation is thought to provide resistance to HIV, and has been of intense interest to researchers pursuing an HIV cure. Previously, researchers had not observed similar results with ordinary donor cells, such as those given to the Boston patients.
In these men, circulating donor cells lack the protective gene mutation evident in the bone marrow given to Brown. The Boston results suggest that infusing ordinary cells under the cover of antiretroviral therapy could be one component of a future HIV cure.
“We’re not there in terms of a broadly applicable approach, but every step really gets people excited,” Deeks said. “It’s not easy, but it’s not as hard as we thought.”