A second individual has experienced sustained remission from HIV even after their ARV treatment ended, scientists from the University of Central London and Imperial College have found. The report, published in Nature, comes ten years after the first ever case of someone being “cured” of HIV in Berlin.

While 37 million people globally are living with HIV, only 59% of them are receiving ARV treatment, with drug-resistant HIV an increasing concern. While chemotherapy, which kills cells as they are dividing, can be effective against HIV, replacing immune cells with those which don’t have the CCR5 receptor is vital to defeating HIV entirely.

In both recorded cases, the patients were treated with stem cell transplants from donors carrying a genetic mutation which prevents HIV receptor CCR5 from expressing. CCR5 is the most commonly-used HIV receptor. Those individuals with two mutated copies of the CCR5 allele are immune to HIV which uses this receptor.

The individual has now been in remission for 18 months after his treatment ended. The study says that currently it is “too early to say” that the individual is completely cured, with his condition set to remain monitored.

The treatment comes with some side effects, including mild graft-versus-host disease, where the donor immune cells attack the recipient’s immune cells.

This new treatment differs from the first Berlin patient’s treatment, where two stem cell transplants were received from a donor with two CCR5-32 alleles in order to treat leukaemia, and full-body irradiation was undertaken.

The researchers noted that the treatment was not appropriate as a standard treatment for HIV due to its toxicity, but could lead to new strategies which could end HIV entirely.