A formerly HIV-positive American living in Germany has continued to test negative for the virus two years after undergoing a stem-cell transplant.
The case first made headlines in November and was featured in the Feb. 12 issue of the New England Journal of Medicine, the first time the case has been officially published.
“The patient is fine,” said Dr. Gero Hutter of Charite Universitatsmedizin Berlin. “Today, two years after his transplantation, he is still without any signs of HIV disease and without antiretroviral medication.”
Although researchers cautioned that the case does not point to a cure for HIV/AIDS, it does pave the way for further investigation.
The 42-year-old patient underwent a stem-cell transplant to counter his acute myeloid leukemia. Doctors selected a stem-cell donor who carried a gene mutation that contains a natural resistance to HIV in the hopes that it would be passed along to the HIV-positive man.
The gene mutation, CCR5 delta 32, cripples the CCR5 receptors, which, along with CD4 receptors, can provide the HIV virus access to T cells, the immune-system cells destroyed by HIV. The mutation is found in 1-3 percent of people of Northern European or Central Asian descent.
Individuals who received a copy of the mutation from one parent usually take longer to develop AIDS from an HIV infection, while people who’ve had the mutation passed down by both parents, like the donor, may not be infected at all after exposure to HIV.
One year after the procedure, the patient did have a relapse of his leukemia, but after another stem-cell transplant has tested negative for both leukemia and HIV.
In an interview with CNN, Hutter called the findings “surprising” and said researchers are still analyzing why the virus has not resurfaced in the patient’s system.
“There really is no conclusive explanation why we didn’t observe any rebound of HIV,” he said.
The patient stopped taking his antiretroviral medications before the stem-cell procedure and has since discontinued them.
In advance of a stem-cell transplant, doctors must intentionally debilitate a patient’s immune system before introducing the new cells. Researchers said the stem-cell transplant procedure is very risky: About one-third of patients don’t survive the operation.
In terms of medications that could target the CCR5 receptors, the pharmaceutical company Pfizer markets one drug, Maraviroc, that seeks to prevent the HIV virus from binding to CCR5. Maraviroc has not yet been proven effective in blocking the binding on all cells, however, and must be taken in conjunction with other antiretroviral medications.
“Basically HIV can find its way around the drug and still use CCR5,” said Dr. John Riley, an HIV researcher at the University of Pennsylvania.
However, Riley did note that this study will lay the groundwork for further research into the use of CCR5 inhibitors.
“It’s a tremendous proof of principle that if you can make the majority of your cells resistant to infection, you can really stop the virus,” Riley said.
Hutter added this case should demonstrate that researchers are still committed to discovering new approaches to treating HIV/AIDS.
“For HIV patients, this report is an important flicker of hope that antiretroviral therapy ... is not the endpoint of medical research,” he said.