Second patient free of HIV after stem-cell therapy

Second patient free of HIV after stem-cell therapy

Scientists found no rebound of HIV in two patients who stopped taking their HIV medication after they received stem cell transplants for a hematological [blood] disease. Both patients underwent stem cell transplantation as part of their cancer treatment.

The transplanted donor cells had a gene defect [CCR5delta32mutant] which results in the absence of one of the critical entry gatekeepers that HIV generally needs to infect cells.

Thus far, only one person in the world - Timothy Ray Brown, known in 2008 as the 'Berlin patient' - has been cured of HIV. Although Brown had traces of HIV, the virus never rebounded and he is now celebrating 12 years' cured of HIV.

Transplanted cells from a CCR5delta32 donor most likely protected Brown's immune system. He also received aggressive chemotherapy, total body irradiation, and two stem cell transplants. For over a decade, the HIV field has puzzled over which of these factors were essential for his cure.

Groundbreaking research on the 'London patient' and the 'Düsseldorf patient' was presented at the Conference on Retroviruses and Opportunistic Infections, in Washington, 4-7 March 2019, and published in Nature.

Professor Ravi Gupta of University College London and the University of Cambridge presented a potential cure of HIV after stem cell transplantation in his 'London patient', while Dr. Björn Jensen from Düsseldorf University found his 'Düsseldorf patient' similarly potentially cured.

The London patient has not experienced HIV rebound during the 18 months since he stopped taking his antiviral medication. This is the longest adult HIV remission after stem cell transplantation since the Berlin patient.

The Düsseldorf patient stopped his HIV medication for a shorter period of just three-and-a-half months, but has also remains HIV free. Using the most sensitive techniques available to date, only traces of HIV DNA were detected.

The London and Düsseldorf patients show that after a single transplant and with even mild cancer chemotherapy and without radiation, remission may be achieved.

Both the London patient and the Düsseldorf patient were registered with the IciStem programme. IciStem is the International Collaboration to guide and investigate the potential for HIV cure by Stem Cell Transplantation.

"Although delta32 donors are primarily found in Caucasian people, the London patient long-term remission case gives important insights into the potential mechanisms of cure and should fuel development of strategies that can be more broadly applied," says Wensing.

IciStem has the largest programme to investigate HIV cure following stem cell transplantation. More than 22 000 donors with the rare CCR5delta32 gene defect have been identified and there are currently 39 patients registered with IciStem who have received transplants.

"To be clear, this is not an option yet for people with HIV, even in very rich countries, but it is a major step forward. This is incredibly exciting, as it furthers our understanding of the complex immunology of HIV and should get us closer to a cure," says Professor Francois Venter.