“It is clear that the degree to which HIV was cleared by the transplant is unprecedented,” Steven Deeks, an AIDS researcher at the University of California at San Francisco who was not involved in the study, said Wednesday in an e-mail.
Last summer, Timothy Henrich and Daniel Kuritzkes, physician-researchers in the Division of Infectious Diseases at Brigham and Women’s Hospital, announced that the virus was easily detected in both men before their transplants and became undetectable by eight months post-transplant. At the time, both remained on antiretroviral therapy. One transplant took place three years ago, and the other took place five years ago.
A spokesman for Brigham and Women’s said the patients asked not to be identified other than to say they were men who had lymphoma.
Since coming off antiretroviral therapy in the spring, the men have been monitored frequently and continue to have no detectable HIV DNA or RNA in their blood.
Deeks said the most obvious explanation is that the new transplanted immune system killed the patient’s original immune system, leading to loss of the infected cell population.
“We were sort of holding our breath,” said Christine Durand, an assistant professor of infectious diseases at the Johns Hopkins School of Medicine, referring to how long the Boston patients would show no sign of infection. A bone marrow transplant typically takes a few hours, but it takes months and possibly years for the donor cells to kill and replace the host cells.
In the Boston patients, it is still possible that “there’s one infected cell left in the brain,” said Durand, who specializes in transplant infectious diseases.
Durand and a team of researchers have begun a similar study of HIV-infected patients who need bone marrow transplants to treat their blood cancers. The Hopkins researchers are keeping the patients on the antiretroviral medication.
“This will change the way bone marrow transplant doctors think about HIV medication during bone marrow transplants,” Durand said.
“This means HIV cure could be an immediate goal when [patients] undergo bone marrow transplant.”