Researchers are one step closer to a possible “functional cure” for HIV. At a conference in Boston, scientists from the University of California, San Francisco unveiled promising results from a new immune therapy.

In three participants, the virus was successfully suppressed for an extended period following a single treatment using genetically modified immune cells, without the need for standard medication. In two patients, HIV even remained undetectable for several months to nearly two years. The therapy works by modifying immune cells so they can both destroy HIV-infected cells and protect themselves from becoming infected.

Although the research is still in its early stages, scientists see this as an important step towards a long-term, potentially one-time treatment for HIV. More than 40 million people worldwide are currently living with the virus.