Over 30 years into the epidemic, there is renewed hope that a cure for HIV may have been found following the presentation of two HIV cases at the 19th annual International AIDS Conference in Washington, D.C, last week. Two men who were diagnosed with both HIV and cancer appear to be cured of the HIV virus.

The two recent cases appear to be following in the footsteps of the famous “Berlin patient,” who had HIV and was treated for leukemia with a bone marrow transplant. The transplant, which replaced the patient’s own infected cells, came from a donor with a genetic mutation that makes immune cells resist HIV infection. Five years later he is HIV-free.

Researchers at Brigham and Women’s Hospital in Boston hoped to accomplish a similar feat with a simpler treatment. Two patients infected with HIV who endured multiple rounds of treatment for lymphoma both had stem-cell treatments while maintaining HIV therapy — which was key to the treatment’s success.

It appears that the donor cells killed off and replaced the infected cells. Meanwhile, the HIV drugs protected the donor cells. One patient is HIV-free 2 years later, and the other is seemingly uninfected more than 3 years later.

While the patients can’t be told they are cured, they are staying on HIV therapy until they can be carefully taken off under experimental conditions.