WASHINGTON (AFP) ― An American man is still HIV-free more than three years after receiving a stem cell transplant, suggesting the first-ever cure of the virus that causes AIDS, German doctors said Wednesday.
But while the highly risky technique used on the man known as the “Berlin Patient” would not work for most of the 33 million people with HIV worldwide, scientists say the research shows important progress toward a universal cure.
“Our results strongly suggest that cure of HIV has been achieved in this patient,” said the study in the peer-reviewed journal Blood, a publication of the American Society of Hematology.
The process began in 2006 when a U.S. man in his 40s, who had been HIV positive for more than a decade, sought treatment for acute myeloid leukemia, a lethal blood cancer.
After a first round of chemotherapy failed, his German doctor, Gero Hutter, thought he would see if he could perform a bone marrow transplant using a donor with a rare genetic mutation that is naturally resistant to HIV.
About one in 100 Caucasian people, or one percent of the population, have the mutation, known as Delta 32, inherited from both parents which prevents the protein CCR5 from appearing on the cell surface.
Since HIV enters the cell through CCR5 molecules, when they are absent HIV cannot penetrate.
The process was not easy, but after rejecting dozens of potential donors Hutter finally found a match and performed the bone marrow transplant using stem cells from the HIV-resistant donor in February 2007.
Hutter’s first study, published in the New England Journal of Medicine in 2009, showed no sign that HIV had re-emerged even though the patient had ceased anti-retroviral therapy to suppress HIV.
The latest findings show that the patient, 44-year-old Timothy Ray Brown, continues to show no trace of either the AIDS-causing virus or leukemia.
But because Brown’s ordeal left him temporarily unable to walk or talk and statistics showing around 30 percent of patients do not survive bone marrow transplants, AIDS experts sounded a note of caution.
“I think we need a lot more research to try to replicate this without putting a patient’s life in danger,” said Karen Tashima, director of the HIV Clinical Trials Program at The Miriam Hospital in Rhode Island.
“Since we have good anti-retroviral therapy that can control the virus, it would be unethical to give somebody such an extreme treatment.”
Lead study author Kristina Allers acknowledged that the process would not work for most people.
“Nevertheless, as the study tells us that (an) HIV cure is in principle possible, it gives new hope for scientists in HIV cure research,” Allers said.
“So the next challenge is to translate our findings into a strategy that can be applied without being life-threatening.”
Indeed, U.S. researchers are already working on ways to replicate the same process in the cells without going the same risky route.
“I am very excited about it,” said David Baltimore, a co-recipient of the Nobel Prize in Medicine in 1975.
Baltimore is the founder of a biotech company that is working on developing its own stem-cell HIV-AIDS therapy that works functionally the same as the German team’s, and is in the process of organizing clinical trials, he said.
“What we are trying to do is treat a patient’s own cells so there is no immunological problem,” he said.
“The fact that the one patient who was treated then was effectively cured is I think a very strong argument that you want to continue this kind of approach to the HIV problem.”
Jay Levy, an AIDS and cancer researcher at the University of California, San Francisco, described the latest research as evidence of a “functional cure.”
“I mean, one person is not sufficient. It is an encouraging first step but you really need to show it again,” he said.
“I always look on this as a direction for future approaches, recognize what the problems are and then see if we can do better, and I have faith in my scientific colleagues to come up with something better.”
Levy and his team are also looking at ways to manipulate a patient’s own stem cells so that they do not express the receptors that allow HIV infection, much like the CCR5 mutation.
“Three years is not enough ... We will know that in 10 years,” said Levy regarding the study’s assertion that a cure has been found.
“It is too early to say you’ve cured, but my Lord, they have done a nice job.”
혈액줄기세포 이식으로 HIV 감염 치료
혈중 줄기세포 이식으로 인간면역결핍바이러스(HIV) 감염 이 완치된 사례가 의학계에 보고돼, 표준요법을 적용하기 어려운 에이즈 환자 치료 에 청신호가 켜졌다.
미국 버밍엄 소재 앨라배마대학의 마이클 사그 박사팀은 미국 국적의 40대 HIV 보균자가 말초 혈액 줄기세포가 포함된 피를 수혈 받은 후 HIV 감염이 완전히 치료 된 사례를 확인, 학술지 '혈액(Blood)'에 발표했다고 15일 밝혔다.
독일에 사는 이 환자는 2007년 백혈병 치료 목적으로 말초 혈액 줄기세포를 이식받았다. 3년 후 이 환자의 혈액을 분석한 결과 백혈병뿐 아니라 HIV 감염 징후도 나타나지 않았다고 연구팀은 설명했다.
당시 혈액 줄기세포를 제공한 헌혈자는 HIV에 저항성이 있는 유전자를 선천적으 로 갖고 있었던 것으로 확인됐다.
사그 박사는 "이는 매우 특이한 방법으로 HIV 감염이 완치될 가능성을 보여준 흥미로운 사례"라고 말했다.
연구진은 그러나 아직 이 치료법의 위험이 커서 표준치료법이 되기는 어렵다며 과도한 기대를 경계했다.
골수이식, 그리고 최근에는 혈액 줄기세포 이식이 암환자에게 많이 시행되고 있 지만, 건강한 사람에게 이 시술이 어떤 위험을 초래하는지 명확하게 규명되지 않았 기 때문이다.
골수이식은 강력한 면역억제제와 방사선 조사를 거쳐 환자의 면역체계를 파괴하 는 과정을 수반하기 때문에 수술로 인한 사망률이 5%가 넘는다.
연구진은 이 같은 위험을 고려할 때 약물치료가 잘 듣는 환자에게 이 치료법을 적용할 수는 없다면서도 암이나 장기이식을 받은 HIV 감염인이라면 고려대상이 될 수 있을 것으로 내다봤다.
전문가들은 또 이번 사례가 같은 원리를 적용해 에이즈 유전자 치료법을 개발할 수 있는 단서가 될 수 있을 것으로 전망했다. (연합뉴스)