Scientists are exploring whether a cancer-style cell therapy could offer a new path toward controlling or curing HIV by borrowing from the body’s own immune system. At a meeting of the American Society of Gene and Cell Therapy in Boston, researchers described early results from a small study that adapted CAR-T cell therapy—designed for some cancers—to target HIV-infected cells. The work, led by Dr. Steven Deeks of the University of California, San Francisco, sought to see whether revving up a patient’s immune cells could suppress the virus without requiring the usual HIV drugs.
Deeks’ team reported that on Tuesday, researchers said a single dose of CAR-T cells strongly suppressed HIV in two people—one for nearly a year and the other for nearly two years—after they stopped their usual medications when they received the treatment. Deeks cautioned that larger and longer studies are needed to show whether CAR-T can provide long-lasting benefit for HIV. “We find the fact that two people have had such a really sustained response provocative,” he said. “There is a real need for a one-and-done, safe and scalable cure … and this is one of the strategies that we’re pursuing.”
The study, which investigators said is early-stage, tested different dosing strategies. Researchers designed the experiment so participants stopped taking their HIV medicine the day they received their CAR-T cells, and Deeks said there were no serious side effects reported in the study. Under one strategy, the first three recipients showed no response and resumed their usual medicines.
In the dosing strategy that produced the strongest signals, six other people received a small amount of chemotherapy meant to make space for the new T cells. Deeks said the two strongest responders in that group saw their HIV drop to undetectable levels, with only occasional increases when, researchers said, the CAR-T cells presumably began working again. He said a third patient had a temporary response and then resumed regular HIV treatment.
Deeks said the patients who responded most strongly had started their original HIV treatment soon after infection. He said that makes sense because people treated early tend to have less HIV hiding in the body and a healthier immune system. Researchers have long pursued an HIV cure by looking at clues that include rare gene mutations that make some people naturally resistant to the virus, as well as cases involving patients who were considered cured or in long-term remission after receiving stem cell transplants for certain cancers.
The therapy described at the meeting involves taking immune cells called T cells from a patient’s blood and genetically engineering them into CAR-T “living drugs” before infusing them back into the patient. CAR-T therapies are already used to treat certain types of cancer, and scientists have been studying variants for other diseases. For HIV, Deeks’ team said the nonprofit drug developer Caring Cross created CAR-T cells with dual features—programmed to better find and kill HIV-infected cells and engineered with protection against infection by the same virus.
Because the CAR-T cells are expected to function as immune “soldiers,” the added protection is intended to let them persist and reproduce enough to keep HIV in check, Caring Cross executive director Boro Dropulić said. In describing the broader need, the researchers noted that nearly 40 million people live with HIV worldwide and that today’s medicines have turned AIDS from a fast killer into a manageable chronic disease—often with the virus kept at undetectable levels if people can afford treatment and can adhere to it.
The main challenge, scientists said, is that HIV can hide in reservoirs within the body and can rebound quickly if people stop therapy. Dr. Hans-Peter Kiem, a gene therapy expert at Seattle’s Fred Hutchinson Cancer Center who was not part of the new study, said the results are intriguing but cautioned that more research is required to confirm whether CAR-T can truly help. Separately, Andrea Gramatica, vice president for research at amfAR, The Foundation for AIDS Research, said in support of the general approach that it is exciting because it “boost[es] what our body, our immune system, can already do,” adding that amfAR is funding work to create easier-to-use versions of the strategy.