To date, the only patient that’s been “truly” cured of HIV remains Timothy Ray Brown, aka the Berlin Patient. If you’ll recall, Brown received a bone marrow transplant in Berlin in 2007, a transplant sourced from a donor with a natural genetic resistance to HIV. The transplant was an effort to cure Brown’s leukaemia and it appears to have done so, but it also appears to have eliminated Brown’s HIV infection. In the two years since, Brown has abstained from taking the usual regimine of antiretroviral medication, the rather miraculous stuff that keeps the virus at bay in HIV-infected individuals. The virus remains undetectable in his system but, even now, cure remains a fraught term for Brown, and for us.
This is because Brown hasn’t been alone among the cured. Two patients, known as the “Boston patients,” who underwent a very similar transplant procedure to Brown—albeit without the resistant donor—were also thought cured. After ditching antiretrovirals, HIV remained undetected in the patients’ systems for months. But, eventually, the infection returned in both cases. Likewise, in Mississippi, an infant born HIV positive that had apparently been turned negative thanks to quickly administered very high doses of antiretrovirals, has also seen the infection return. After this succession of failures, being the sole HIV patient on planet Earth with an eradicated infection must be a rather anxious position.
Brown appears to have some new company, however. Doctors presenting at the 20th International AIDS Conference this weekend have announced two recent recipients of bone marrow transplants that appear to have also had their HIV infections eliminated. As reported in Nature, the researchers, led by the Kirby Institute’s David Cooper, combed through the records of St Vincent’s hospital in Sydney, one of the largest bone marrow centers in Australia. “We went back and looked whether we had transplanted [on] any HIV-positive patients, and found these two,” said Cooper in a press briefing. At least one of the two had recieved bone marrow from an HIV-resistant donor.
An important caveat is that neither of the two Australian patients has stopped taking antiretroviral medication. The “elimination” claim is based on viral loads low enough in both patients such that antiretroviral treatment can’t take full credit. It’s possible, if not likely, that if the two were to stop ongoing treatment the virus would bounce back. Even if the patients aren’t cured, however, the finding is potentially a very big deal and, in any case, bone marrow transplantation with its 10 percent fatality rate has never been a real possibility for HIV treatment in the absence of something much more acutely dire, like chemotherapy-resistant leukemia or lymphoma.
“There is something about bone-marrow transplantation in people with HIV that has an anti-HIV reservoir effect, such that the reservoirs go down to very low levels,” Cooper told Nature. “And if we can understand what that is and how that happens, it will really accelerate the field of cure search.”
But again, we’re faced with the tricky relationship between HIV and cures in the very first place. As I wrote last December, “Timothy Brown wasn’t cured of anything; he had his immune system removed and regenerated. That’s a big something else with the convenient side effect of eliminating HIV from the body.” The gap between that something else and a functional cure for the 35.3 million humans living with the disease remains incomprehensible, but hopefully “miracles” like the Berlin Patient will at least make it at least a bit less so.