Two men who underwent bone-marrow transplants are reportedly now free of the HIV virus.

ABC News reports that traces of the virus seemed to disappear from both of the men’s DNA after they received new stem cells from donors and maintained a steady diet of antiretroviral drugs. The first patient in his 20s was born with the virus; the other in his 50s acquired HIV at the start of the AIDS epidemic in America. They both had their transplants in 2008 and 2010.

However, the science community is still cautious about claiming this as a cure, namely because finding bone-marrow donor matches is not easy, and it’s still too soon to tell if any of these men will remain HIV- for the rest of their lives.