At an academic conference on Feb 15, U.S. experts announced the world's first female AIDS "cure," making it the third case of HIV infection to be cured. After therapy and withdrawal of antiviral drugs, HIVs were not identified in the patient's body for more than 14 months, indicating that the virus was in complete remission, according to academics.

 

The key to this patient's recovery was a blood stem cell transplant: The researchers first used chemotherapy drugs to kill the patient's own immune cells and then transplanted new cells that would not be infected by HIV. The blood stem cells she received had a mutation called "CCR5Δ32/Δ32," which protects T cells from infection. This is because the CCR5 gene encodes a protein that HIV virus needs to bind to when it enters a cell, and the mutated version of the protein cannot bind to the virus.

 

The innovation of this treatment is the use of umbilical cord blood stem cells—the two previous cured cases used hematopoietic stem cells from adult bone marrow, while umbilical cord blood stem cells are more readily available and have less stringent mating requirements, so they are expected to be used in more patients. The researchers plan to increase the sample size in the future to confirm the therapy's efficacy and safety.

 

It's worth noting, however, that this treatment has very limited use. Stem cell transplantation is fraught with danger, and if used solely to treat AIDS, it is no better than antiviral drugs. It can only be considered for HIV eradication by chance if the patient requires blood stem cells for other diseases—in this case, the patient was transplanted for acute leukemia treatment.

 

Timothy Ray Brown, a "Berlin patient" with leukemia who underwent a bone marrow transplant when chemotherapy failed, became the first "AIDS cure" in 2007. The CCR5Δ32 mutation was found in the person who donated his bone marrow.

 

The Berlin patient's life was literally hanging by a thread, but as he recovered from the transplant and serious complications, doctors discovered that the bone marrow transplant had not only cured his leukemia, but had also successfully suppressed the HIV in his body. Many others have attempted to duplicate the Berlin patient's result, but transplant cases have consistently failed. It was once considered that the Berlin patient's survival was a fluke, or that the patient had to become exceedingly unwell during the transplant process to live.

 

It was not until 2019 that a second "London patient" emerged.

 

Ravindra Gupta, a virologist at University College London, told the conference that the "London patient" was 36 years old, had Hodgkin's lymphoma and received a bone marrow transplant with the CCR5Δ32 mutation in May 2016. The entire treatment went smoothly and without incident.

 

In September 2017, the London patient ceased taking anti-HIV drugs, and HIV was no longer identified in his blood by the time the article was released in 2019. The HIV antibodies were still present, but levels declined over time, similar to the Berlin patient.

 

At that time, according to media reports, there was also a promising case of the "Düsseldorf patient". However, no further information seems to be available about him.

 

Despite the fact that three people have been cured, it cannot be used to treat all cases of AIDS. For patients who have just been diagnosed with HIV, bone marrow transplantation is not a viable choice. The removal of HIV was only a side effect for all three patients, who received bone marrow transplants first and foremost to cure malignancies. After all, transplantation is a pricey and risky procedure, and there are now a number of drugs that can control HIV in the long run, so it may be more feasible for people who are simply infected with HIV to take antiretroviral drugs.

 

Many teams are now working on ways to precisely modify genes, such as changing only the CCR5 gene in bone marrow cells and not in other cells. It is not yet possible to achieve such precision.