A small study out of UCSF is reporting that two people with HIV have suppressed the virus to undetectable levels after a single infusion of engineered immune cells, one of them for nearly two years without antiretroviral drugs.

The approach is essentially CAR-T therapy adapted from cancer.

Caring Cross, a nonprofit, engineered participants' T cells to carry two surface molecules: one that targets and kills HIV-infected cells, and another that protects the engineered cells themselves from infection. That dual mechanism seems to be what made the difference compared to earlier attempts going back to the 1990s.

Notably, the three participants who responded had all started antiretroviral therapy early after infection. The three who had lived with HIV longer before treatment did not respond. That pattern of early intervention correlating with smaller viral reservoirs and less immune damage will likely shape how future trials are designed.

This is still a very small study, and the ex vivo approach (extracting cells, modifying, reinfusing) is too expensive and invasive to scale to the 40+ million people living with HIV globally...

The more interesting long-term path is probably in vivo engineering, i.e. modifying immune cells directly inside the body, which cancer researchers are already showing success with. That could eventually bring costs below $10,000 per treatment (as per NYT article).

It is a proof of concept, not a cure, but it looks like a very promising one. The results are said to be shared today at the American Society of Gene & Cell Therapy, according to a NYT article and Reuters.