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Scientists make curing HIV a priority

Once seen as impossible, a cure is now viewed as a realistic goal by more and more researchers, who argue the epidemic cannot be contained through treatment and prevention alone.

July 23, 2012|By Erin Loury, Los Angeles Times
  • A man works on a quilt on the National Mall in Washington in memory of an AIDS victim. Researchers say a cure for HIV should be a top priority.
A man works on a quilt on the National Mall in Washington in memory of an AIDS… (Nicholas Kamm, AFP/Getty…)

An influential group of scientists gathered this week at the International AIDS Conference in Washington, D.C., is committing to a goal that just five years ago would have seemed ludicrous: to cure HIV.

After studying the virus for more than 30 years and developing potent drugs that transformed the disease from a death sentence into a manageable chronic condition, a growing number of researchers now say the search for a cure should be a major research priority. While acknowledging substantial challenges, they argue that the effort is necessary because the epidemic cannot be contained through treatment and prevention alone. And recent medical and scientific advances — including the case of the first man definitively cured of HIV — offer proof that it's possible.

Spearheading this audacious challenge is the International AIDS Society, which developed a research agenda in collaboration with more than 40 scientists led by French virologist Francoise Barre-Sinoussi, who won the Nobel Prize in physiology or medicine in 2008 for her role in the discovery of HIV. Two years in the making, the scientific strategy provides a road map for moving research for a cure forward. Among the tasks: investigating where and how the virus can hide out in the body and studying the immune response of the select group of people who are naturally immune to HIV.

Developing drugs that keep HIV in check has so far proved more feasible than trying to eradicate it, said Dr. Steven Deeks, a member of the AIDS Research Institute at UC San Francisco. But now that more than 20 antiretroviral therapies can prolong the lives of people with HIV for decades, he said, it's time to aim higher.

"I think these drugs have gotten as good as they're going to get," said Deeks, who worked with Barre-Sinoussi to develop the research plan. "We need to shift from blocking the virus from replicating to essentially getting rid of the virus."

The antiretroviral drugs are lifesaving, but they have problems. Treatment is toxic and expensive, and only about half of the world's 34 million people living with HIV who need the drugs can get them. Patients must take the drugs daily for the rest of their lives to keep the virus at bay.

"It's just practically difficult to treat people all their life with therapy, even if it's very simple therapy," said Dr. David Margolis, director of the Program in Translational Clinical Research at the University of North Carolina at Chapel Hill.

But for a long time, there has been no alternative. HIV researchers suffered a major setback in the 1990s when they discovered that the strongest drug cocktails could substantially knock down a patient's viral load but couldn't wipe it out completely. If people stopped taking medication, the disease came roaring back.

Pessimism about finding a cure set in, said Paula Cannon, a molecular biologist at USC's Keck School of Medicine. Even five years ago, a scientist who proposed HIV cure research "would be laughed out of the room," she said. "Nobody would give you money."

What changed? "It's come down to one man," Cannon said.

That man is Timothy Brown, known to the medical world as the Berlin Patient.

Brown was an HIV-positive American who was living in Germany when he developed leukemia. After failing to respond to first-line cancer treatments, he opted for a bone marrow transplant in 2007. As his doctors searched for a suitable donor, they looked for one with a rare genetic mutation that disables a receptor known as CCR5, which HIV needs to gain entry into immune cells. Brown had two transplants that not only put his leukemia into remission but replaced his HIV-susceptible immune system with one that could ward off the disease.

Brown no longer takes antiretroviral drugs and no longer tests positive for HIV. Essentially, he is cured.

"There's nothing like success to galvanize the research," Cannon said. "People are daring to hope again that with a lot of hard work and ingenuity, scientists can deliver."

Bone marrow transplants aren't suitable for widespread use: The procedure Brown received ends in death 20% of the time, and finding an appropriate donor would be a long shot in most cases. So scientists are working on alternatives.

There are two general approaches. One, an elimination cure, would rid the body of all HIV-infected cells. The other, a functional cure, would engineer a patient's own immune system to resist HIV, even if the virus remains present in the body.

For an elimination cure to work, researchers must learn to identify the dormant HIV that hides in immune cells and tissues, evading assault from drugs. Much of the International AIDS Society's plan focuses on this problem.

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