Discontinued therapy in 2018

Seventh case worldwide: Berlin resident cured of HIV

(Bild: stock.adobe.com/ktsdesign)

According to the Charité hospital in Berlin, another HIV patient has been cured. Despite discontinuing antiviral therapy, no HIV has been detectable in the man known as the "second Berlin patient" for more than five years, according to the Charité researchers involved.

This makes him the third person in Germany and - depending on how you count it - the sixth or seventh person worldwide to be considered cured. Previously known as the "Berlin patient", Timothy Brown was the first person to be cured of HIV more than 15 years ago.

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

Received stem cell transplant
He was transplanted with stem cells from a healthy donor, including her immune system. "The donor's immune system takes over control, so to speak," explained Olaf Penack, senior physician at the clinic specializing in haematology, oncology and tumor immunology. The special thing about this case is the treatment method, said Christian Gaebler, head of the working group at the Charité's Department of Infectious Diseases and Intensive Care Medicine.

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

Electron microscope image of HI viruses

(Bild: CDC/Dr. Edwin P. Ewing, Jr.)

The first "Berlin patient" to be cured of HIV succeeded in finding a stem cell donor whose tissue characteristics matched those of the recipient and who carried the immunity-inducing mutation. The stem cell donation transferred his immune system, including the mutation.

Treatment is quite risky
So far, four other people worldwide have been treated in this way and are considered cured. The treatment is risky; according to Charité, the risk of mortality due to therapy is around ten percent. However, if it is successful, it combats both the HI virus and the cancer.

The "second Berlin patient" had a slightly different approach. No suitable HIV-immune person was found for the stem cell donation. However, the donor "had the mutated version of the docking site on her cells in addition to the normal version of the CCR5 receptor," said Penack, who also treated the first "Berlin patient". This is the case when a person inherits the delta-32 mutation from only one parent. However, this does not confer immunity against the HI 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 has no effect on existing virus reservoirs that have formed after the infection. "These viral reservoirs are the biggest hurdle in HIV cure research," said Gaebler.

Antiviral therapy discontinued six years ago
The patient discontinued antiviral therapy in 2018 by his own decision. He had long been convinced that he was cured, the researchers reported. Since then, there has been no evidence of the virus replicating again, said Gaebler: "We were all very surprised and delighted." The researchers are currently investigating how this success can be explained. According to Gaebler, the fact that the patient's immune system was very quickly replaced by the donor immune system could play a role.

It is estimated that around 39 million people worldwide are living with HIV infection. Cures are very rare. If one case is included, in which the follow-up period is relatively short, seven people worldwide are currently considered cured of HIV.