The second man to undergo stem-cell treatment for HIV has been cured for 30 months, according to doctors.

Adam Castillejo is still free of the virus and has no trace of it in his blood, urine, semen, or tissues more than 30 months after stopping anti-retroviral therapy, according to a report in the journal Lancet HIV.

The donors of those stem cells have an uncommon gene that gives protection against HIV. While this isn’t a widely acceptable cure, it is a step forward. However, the doctors involved note that while stem-cell transplants appear to stop the virus from being able to replicate inside the body by replacing the patient’s own immune cells with donor ones that resist HIV infection, the treatment is high-risk.

“It is important to note that this curative treatment is high-risk and only used as a last resort for patients with HIV who also have life-threatening haematological malignancies,” Professor Ravindra Gupta said. Adding, “Therefore, this is not a treatment that would be offered widely to patients with HIV who are on successful anti-retroviral treatment.”

It is worth noting that stem cell therapy was primarily used to treat the patient’s cancer, not his HIV.

Currently, HIV drugs remain very effective allowing those infected to live healthy normal lives, so most won’t undergo this risky treatment even if it has positive results.

Still, doctors are hopeful that this is a step forward in reaching a universal cure for HIV potentially using gene therapy.

The most commonly used receptor by HIV-1 is CCR5 and scientists believe that those humans who are born with mutated copies of this receptor may be the answer.

A very small number of people who are resistant to HIV have two mutated copies of the CCR5 receptor. This mutation apparently stops the penetration of cells in the body that HIV normally infects.

Researchers say it may be possible to use gene therapy to target the CCR5 receptor in people with HIV.

The lead researcher, Professor Ravindra Kumar Gupta from the University of Cambridge, told BBC News:

This represents HIV cure with almost certainty.

We have now had two and a half years with anti-retroviral-free remission.

Our findings show that the success of stem-cell transplantation as a cure for HIV, first reported nine years ago in the Berlin Patient, can be replicated.

In 2011, another patient, Timothy Brown, became the first person reported as cured of HIV three and half years after having a similar treatment to Castillejo. Despite being cured of the virus, both men still have remnants of it inside their bodies so it is impossible to know whether or not the HIV will someday return.

As professor Sharon Lewin, from the University of Melbourne, Australia, stated:

Given the large number of cells sampled here and the absence of any intact virus, is the London Patient truly cured?

The additional data provided in this follow-up case report is certainly encouraging but unfortunately, in the end, only time will tell.