“Both the surviving patients had been receiving prolonged antiretroviral therapy and received stem cell transplants with a reduced-intensity conditioning regimen of chemotherapy designed to eradicate the cancer and eliminate the existing bone marrow. In the case of the two patients under investigation, the conditioning regimen did not include radiotherapy and it did not eliminate the residual lymphocyte population. In contrast, the ‘Berlin patient’ received a much more aggressive regimen which eliminated existing bone marrow cells.
The transplants also differed from the ‘Berlin patient’ because they did not come from donors with genetic resistance to HIV infection (a CCR5 delta 32 mutation), so the cells were susceptible to HIV infection.”
“To date, Patient A has been off treatment for seven weeks and Patient B for 15 weeks. Neither patient has yet shown any evidence of viral replication by RNA testing or any evidence of HIV DNA in PBMCs. Week-six testing of larger blood samples from Patient B has similarly failed to detect HIV.
Neither transplant recipient showed any evidence of HIV-specific immune responses.”