A SECOND case of HIV being cured has been reported in London, UK, 9 years after the first in Berlin, Germany. Following a successful stem cell transplantation, the patient has no active viral infection present 30 months after antiretroviral therapy was stopped.
In comparison to the 2011 patient who underwent total body irradiation, two rounds of stem cell transplantations with donor cells carrying the HIV resistant gene CCR5Δ32/Δ32, and a chemotherapy drug regimen, the most recent patient only had one round of donor stem cell transplantation and a reduced-intensity chemotherapy drug regimen. This less-intense, yet still high-risk, procedure aimed to replace the patient’s immune cells with those of the donor to make the virus unable to replicate in the patient’s body, and eradicate residual HIV virus using chemotherapy.
Ultrasensitive viral load sampling from the patient’s cerebrospinal fluid, intestinal tissue, or lymphoid tissue at 29 months after stopping antiretroviral therapy showed no active viral infection. Remnants of integrated HIV-1 DNA did remain, however, but the study author commented to say that these can be regarded as ‘fossils’ and are unlikely to be capable of reproducing the virus.
Success of the stem-cell transplant was confirmed by a CD4 cell count which identified that 99% of the patient’s immune cells were derived from the donor’s stem cells. The inability to accurately measure replacement of immune cells in the entire body resulted in the authors using a modelling analysis to predict the probability of cure based on two probable scenarios: 1) a 98% cure is predicted if 80% of the patient’s cells are derived from the transplant; and 2) a 99% cure if predicted if 90% are.
Lead author on the study, Prof Ravindra Kumar Gupta, University of Cambridge, Cambridge, UK, said: “We propose that these results represent the second ever case of a patient to be cured of HIV. Our findings show that the success of stem cell transplantation as a cure for HIV, first reported 9 years ago in the Berlin patient, can be replicated.”
Current treatment options allow the majority of people with HIV to control their viral loads and live a long healthy life; however, for those who cannot, there are no approved treatment methods. Such positive results from experimental procedures like this can provide insight into how a scalable cure for HIV can be developed.