After undergoing medical treatment using the pioneering gene-editing technique CRISPR, a 27-year-old man is in remission from leukemia but remains infected with HIV, health news outlet STAT reported Wednesday.

The team behind the treatment, led by Deng Hongkui of Peking University, had been inspired by the 2007 case of Timothy Ray Brown, the first adult to be cured of AIDS after receiving a bone marrow transplant also meant to treat his leukemia. Brown’s bone marrow donor had a rare genetic mutation, CCR5, that blocks HIV from recognizing and hijacking the body’s immune cells.

Deng had hoped to replicate the success of Brown’s case by using CRISPR — a sort of copy-and-paste function for genes — to induce the CCR5 mutation in the bone marrow of a health donor. However, 19 months after the procedure, the percentage of bone marrow cells with the mutation remained too low to eliminate the patient’s HIV, though his leukemia went into remission as a result of the treatment. (Image: From STAT)