A new discovery in the treatment of AIDS

A German man with HIV, nicknamed “the next Berlin patient”, has become free of the virus after receiving non-resistant stem cells against HIV.

According to Zomit, a 60-year-old man in Germany is the seventh known HIV-infected person who has become free of the virus after receiving a stem cell transplant. However, this man, who has been free of the virus for nearly 6 years, is only the second person to receive stem cells that are not resistant to the virus.

The first person to become HIV-free after undergoing a bone marrow transplant to treat leukemia was Timothy Ray Brown, known as the Berlin Patient. Brown and a handful of others received stem cells from special donors who carried mutations in a particular gene. This mutation encodes a receptor called CCR5 that prevents most strains of the HIV virus from entering immune cells. According to many scientists, targeting CCR5 is the best way to treat HIV.

But the latest survivor of HIV, who was introduced at the 25th International AIDS Conference, challenged previous beliefs. Dubbed the “next Berlin patient,” the person received stem cells from a donor who carried only one copy of the mutated CCR5 gene; This means that his cells express the CCR5 receptor, but at a lower level than usual.

Simply put, the patient was cured of HIV even though the donor cells were not completely immune to the virus; An amazing event that shows new possibilities for HIV treatment. Sharon Levin, an infectious disease physician who directs the Peter Doherty Institute of Infection and Immunity in Melbourne, Australia, says the seventh cured case of AIDS sends a clear message that finding a cure for HIV is not limited to CCR5.

The findings of the subsequent Berlin patient increase the number of potential stem cell transplant donors. These transplants are a high-risk procedure usually used for people with leukemia and are unlikely to be used for most people with HIV. About one percent of people of European descent have mutations in both versions of the CCR5 gene; But about 10% of people with such ancestry have a mutated version.

New findings show that even donors with only one copy of the mutation can help cure HIV. HIV researcher Sarah Weibel believes this opens up the potential for new treatments. Currently, about 40 million people worldwide are living with HIV.

Six years without HIV

The next Berlin patient was infected with HIV in 2009. In 2015, he was diagnosed with a type of blood and bone marrow cancer known as acute myeloid leukemia. Her doctors were unable to find a matching stem cell donor with mutations in both versions of the CCR5 gene. But they found a female donor with a mutated copy that matched the patient. The next Berlin patient received a stem cell transplant in 2015.

Christian Gabler, a physician and immunologist at the Medical University of Berlin, where the subsequent Berlin patient was treated, described the cancer treatment as highly successful. Within a month, the patient's bone marrow stem cells were replaced with the donor's. The patient stopped taking antiretroviral drugs that suppress HIV in 2018. Now, after almost six years, researchers can't find any signs of HIV in the patient.

Reduction of hidden virus

In the past, when stem cells from donors with normal CCR5 genes were used, HIV usually relapsed within weeks or months after stopping antiretroviral therapy. However, there was one exception. In 2023, Dr. Asir Saez Sirion, an HIV researcher at the Institut Pasteur in Paris, shared information about a person called the Geneva patient who had stopped taking antiretroviral therapy for 18 months. Now, after about 32 months, this person is still free of the virus.

Now researchers are trying to find out why these two connections were successful; while other links have failed. Researchers suggest several reasons for the effectiveness of the treatment:

Antiretroviral therapy: This significantly reduces the amount of HIV in the body.

Chemotherapy: Before the stem cell transplant, chemotherapy destroys many of the patient's immune cells where HIV hides.

Donor cells: Transplanted donor cells may recognize the patient's remaining cells as foreign and destroy them along with any HIV inside them.

Replacement of stem cells: rapid and complete replacement of the patient's bone marrow stem cells with donor cells helps to eliminate the virus.

According to Levine, if you can reduce the amount of latent HIV enough, you can cure people. Gabler also says the fact that both the subsequent Berlin patient and his stem cell donor had a mutated copy of the CCR5 gene may have created a barrier to the virus' entry into cells.

The case of the subsequent Berlin patient has important implications for new treatments that are undergoing early clinical trials. In these treatments, the CCR5 receptor is removed from the individual's own cells using the CRISPR technique and other gene editing methods. According to Levin, even if these treatments do not reach individual cells, they can still be effective.