Seventh case worldwide: Berliner cured of HIV

This makes him the third person in Germany and, depending on how you count, the sixth or seventh person worldwide to be considered cured. Timothy Brown, formerly known as the “Berlin Patient,” was the first person to be cured of the HIV virus more than fifteen years ago.

According to the Charité, the now presented “second Berlin patient,” a 60-year-old, tested positive for HIV in 2009. In 2015, he was also diagnosed with acute myeloid leukemia (AML), a form of blood cancer. In addition to chemotherapy, he also needed a stem cell transplant.

I have donated stem cells
Stem cells from a healthy donor, including an immune system, were transferred to him. “The donor immune system takes over, so to speak,” explains Olaf Penack, a senior physician at the clinic with a focus on hematology, oncology and tumor immunology. What is special about this case is the treatment method, says Christian Gaebler, working group leader at the Charité Clinic for Infectious Diseases and Intensive Care Medicine.

The HIV virus attacks the body’s immune cells at certain sites, called CCR5 receptors. According to the Charité, about one percent of the population of European descent has a mutation of these CCR5 receptors, called the delta 32 mutation. This prevents the virus from entering; those affected are considered naturally immune to HIV.

For the first “Berlin patient” who was cured of HIV, it was possible to find a stem cell donor whose tissue characteristics matched those of the recipient and who carried the immunity-promoting mutation. Through the stem cell donation, his immune system including the mutation was transferred.

The treatment is quite risky
So far, four other people worldwide have been treated this way and considered cured. The treatment is risky; according to the Charité, the risk of dying from the treatment is about ten percent. But if successful, it will fight both HIV and cancer.

In the case of the ‘second Berlin patient’, a slightly different approach was taken. No suitable HIV-immune person was found for stem cell donation. However, the donor had “in addition to the normal version of the CCR5 receptor, also the mutated version of the docking site on her cells”, says Penack, who has already treated the first “Berlin patient”. This is the case when someone inherits the Delta-32 mutation from only one parent. However, this does not provide immunity against the HIV virus.

After the stem cell donation, the patient also received so-called antiretroviral therapy against the virus. This prevents further production of the pathogen, but does not affect existing virus reservoirs that have formed after the infection. “These viral hiding places are the biggest hurdle in the search for an HIV cure,” says Gaebler.

The antiviral therapy was stopped six years ago
The patient stopped antiviral therapy on his own initiative in 2018. The researchers reported that he had long been convinced that he was cured. Since then, there has been no evidence that the virus has multiplied again, says Gaebler: “We were all very surprised and happy.” The researchers are currently investigating how the success can be explained. One role could be played by the fact that the sick person’s immune system was replaced very quickly by the donor immune system, says Gaebler.

It is estimated that approximately 39 million people worldwide are living with HIV infection. Cures are very rare. If one also includes a case where the follow-up period is relatively short, seven people worldwide are currently considered cured of HIV.