December 1, 2016 | by Samantha Bonar
Dec. 1 marks World AIDS Day – a day when communities across the globe reflect on the great progress that has been made in the fight against HIV/AIDS, and continued efforts to end this global epidemic.
Currently, more than 34 million people are living with HIV/AIDS worldwide. Nearly 1.1 million of these individuals are in the U.S., and an estimated 18,000 Americans still die of HIV/AIDS each year.
The good news is that the incidence of HIV infection continues to drop. Researchers – including experts at City of Hope – are making great strides in preventing and treating the disease. HIV/AIDS no longer is a death sentence. With the proper therapy, it can be managed as a chronic condition for many patients.
“In 10 years, cellular therapy will become a functional cure for HIV,” said Zaia, the Aaron D. Miller and Edith Miller Chair in Gene Therapy. “Meaning you don’t have to take any medications, but you still have the virus. Your immune system is able to control it.”
Stem cell and gene therapy for HIV appear to offer great promise. Gene editing is one approach currently being tested in clinical trials at City of Hope. This involves “editing” the immune system’s T cells to control HIV infection.
The approach uses an enzyme called a zinc-finger nuclease as a pair of molecular “scissors” that can edit the HIV patient’s stem cell genes so that they no longer produce a key protein the virus requires to infect cells. It aims to spur the immune system to produce T cells resistant to HIV by infusing the patient with these altered stem cells.
“It’s the first use of editing of the stem cell. It’s a big trial,” Zaia said. “We’re literally cutting the gene itself. It destroys that gene permanently. If we could get this to work, it would be a single treatment that would be curative. You wouldn’t have to take medications.”
However, the trick is getting the cells to replicate. And the technique only works on one version of the HIV virus.
“There are patients who have other forms of the virus that can use other genes to get into a T cell,” Zaia said. “But the concept is pretty amazing. We’ve performed this on some patients and we are learning from them.”
Since the technique requires a complete stem cell transplant, patients are vetted through a meticulous, multiweek Food and Drug Administration-mandated screening process and informed of the considerable risks.
“Explaining the risks takes hours,” Zaia said. “It's revolutionary to even consider stem cell transplants for patients who don't otherwise desperately need them, say for leukemia treatment.”
Another approach being studied at City of Hope inserts new genes into T cells to deactivate the genes that HIV needs for infection. The new genes are taken from an inactive virus called a lentivirus. This technique is a little more complicated.
“Here you have to put in a new gene and it has to remain active. The problem is, cells tend to be able to turn genes on and off,” Zaia explained.
Following chemotherapy, Zaia’s team is infusing these genetically modified cells into HIV-positive patients who are being treated for lymphoma.
“We’re taking lymphoma patients who are cured and we say, ‘Now that you’re cured of lymphoma, why don’t we try to cure your HIV?’” Zaia said. By infusing them with the genetically modified cells, “We are asking the question, ‘Will they show up in the peripheral blood, and can you do this safely?’” The technique has only been tried in two patients so far and the results are not yet available.
“I think the field of HIV research is changing so fast, and we have other things coming along that we think are going to be even better than the current trials,” Zaia said. “It’s an exciting time to be a part of this effort.”
Click here to learn more about City of Hope's groundbreaking HIV/AIDS research. If you are looking for a second opinion or consultation about your treatment, request an appointment online or contact us at 800-826-HOPE. Please visit Making Your First Appointment for more information.