In honour of World AIDS Day, we bring you this update about the ‘Berlin Patient’, Timothy Brown, who was cured of HIV thanks to bone marrow transplants in 2007 and 2008.
7 years after his treatment, Timothy Brown remains one of the most studied cases in the HIV epidemic’s history. Today, researchers point to three different factors that could independently or in combination have rid Brown’s body of HIV.
The first is the process of conditioning, in which doctors destroyed Brown’s own immune system with chemotherapy and whole body irradiation to prepare him for his bone marrow transplant. His oncologist, Gero Hütter, of the Free University of Berlin, also took an extra step that he thought might not only cure the leukemia but also help rid Brown’s body of HIV. He found a bone marrow donor who had a rare mutation in a gene that cripples a key receptor on white blood cells the virus uses to establish an infection. The third possibility is his new immune system attacked remnants of his old one that held HIV-infected cells, a process known as graft versus host disease.
In the new study, a team led by immunologist, Guido Silvestri, of Emory University in Atlanta, designed an innovative experiment with monkey to test these possibilities.
Bone marrow transplants work because of stem cells. Modern techniques avoid actually aspirating bone marrow, and instead can sift through blood and pluck out the stem cells needed for a transplant to “engraft.” So the researchers first drew blood from three rhesus macaque monkeys, removed stem cells, and put the cells in storage. They then infected these animals and three control monkeys with a hybrid virus, known as SHIV, that contains parts of the simian and human AIDS viruses. All six animals soon began receiving ARVs (which respond better to SHIVs than SIV itself), and SHIV levels in the blood quickly dropped below the level of detection on standard tests, as expected.
A few months later, the three monkeys that had stored stem cells underwent whole body irradiation to condition their bodies and then had their own stem cells reinfused. After the cells engrafted, a process that took a few more months, the researchers stopped ARVs in the three animals and in the three controls. SHIV quickly came screaming back in the three controls and two of the transplanted animals. (One of the transplanted monkeys did not have the virus rebound but its kidneys failed and the researchers euthanized it.)
The team, which publishes its work online in PLOS Pathogens today, concludes that conditioning by itself likely cannot rid the body of the AIDS virus. Silvestri explains that the monkey study was a proof-of-principle experiment that cleanly isolated the effects of conditioning alone. “There’s no way to do this in humans,” he says.
To read more about Brown’s case and the scientific study examining his recovery, click here.
Earlier this year, Timothy Brown was confirmed to be the first person ever cured of HIV. The news came two years after he underwent a stem cell transplant as treatment for lymphoma, another disease he had been diagnosed with at the time. The stem cell transplant not only cured his lymphoma, but his HIV as well. Now, two other men who underwent similar treatments, seem to be HIV-free.
Upon hearing about Brown’s successful treatment, Dr. Timothy Henrich and a team at Brigham and Women’s Hospital in Boston decided to conduct a search for similar patients. They found two HIV-positive men who had also undergone stem cell transplants for lymphoma. One patient has been HIV-free for 2 years while the other has been without the virus for 3 ½ years.
Doctors at the Brigham and Women’s Hospital believe that the combination of HIV medication, chemotherapy and stem cell transplants worked together to cure the virus. While the chemotherapy killed off the diseased cells, the stem cells replaced them.
This is very positive news for the medical world. Although doctors are hesitant to call this a ‘cure’, it serves as proof that HIV patients can be free of the virus. We hope that it will lead to more in-depth studies using cord blood and bone marrow stem cells to treat HIV and AIDS.