( CNN ) -- Researchers in Germany are reporting that they may have cured a man of HIV infection . If true , that would represent a scientific advance , but not necessarily a treatment advance , said researchers familiar with the work . In the study , published last week online in the journal Blood , researchers at Charite-University Medicine Berlin treated an HIV-infected man who also had acute myeloid leukemia -- a cancer of the immune system -- by wiping out his own immune system with high-dose chemotherapy and radiation and giving him a stem-cell transplant . Stem cells are immature cells that can mature into blood cells . At the time of the transplant , which occurred in February 2007 , he stopped taking anti-HIV medications . Why HIV advance is n't a universal cure . Thirteen months later , after a relapse of the leukemia , he underwent a second round of treatment followed by another stem-cell transplant from the same donor . The donor 's stem cells contained a rare , inherited gene mutation that made them naturally resistant to infection with HIV , according to the authors , led by Kristina Allers , who hypothesized that HIV would nevertheless rebound over time . But that has not happened . After three-and-a-half years off of anti-HIV drugs , the patient shows no sign of either leukemia or HIV replication and his immune system has been restored to normal health , the researchers reported , concluding , `` our results strongly suggest that cure of HIV has been achieved in this patient . '' But AIDS researchers predicted the report will have little impact on practice . `` This probably is a cure , but it comes at a bit of a price , '' said Dr. Michael Saag , professor of medicine and director of the University of Alabama at Birmingham AIDS Center . `` For him to receive the donor cells , his body had to have all of his immune system wiped out '' and then receive a bone marrow transplant , Saag noted . `` The Catch-22 here is that the best candidates for a cure , ideally , are people who are healthy '' and do n't have leukemia . The treatment associated with wiping out the immune system `` is very hazardous , '' he said in a telephone interview . `` Even if somebody does n't die from a transplant , there are complications that make it very unpleasant for people to live with , '' he said , citing graft-versus-host disease , where the infused donor cells attack the body . In a number of cases , the transplant proves fatal . The study is a proof of the concept `` that our understanding of HIV biology is correct , and that if you eliminate -- not just in theory but in practice -- all of the cells in the body that are producing HIV and replace them with uninfected cells , you have a cure , '' Saag said . But remaining infected with HIV is not always associated with the same grim outcome that was the norm prior to the mid-1990s , when more effective anti-HIV drugs were developed , he said . `` We can keep people alive for a normal life span , '' he said . `` That means a 25-year-old diagnosed today with HIV has a reasonably good chance of living to 80 , 85 , 90 . '' Further limiting the treatment 's potential appeal is the fact that it could cost hundreds of thousands of dollars for each patient who gets it , he said . `` It 's not going to be applicable unless they develop leukemia or lymphoma and need a bone-marrow transplant , '' Saag said . Dr. Anthony Fauci , director of the National Institute of Allergy and Infectious Diseases , called it impractical . `` It 's hard enough to get a good compatible match for a transplant like this , '' he said in a statement . `` But you also have to find ( a ) compatible donor that has this genetic defect , and this defect is only found in 1 % of the Caucasian population and 0 % of the black population . This is very rare . '' But HIV itself is not . According to the World Health Organization , 33.4 million people worldwide have the virus that causes AIDS .
A Berlin man has been off anti-AIDS medication for 3-1/2 years . He was diagnosed with HIV in 2009 and had to take daily pills until he stopped taking them last year. ` This is probably a cure , but it comes at a bit of a price , '' says one AIDS doctor .