Stem cell transplantation
In 2007, a 40-year-old HIV-positive man was given a stem cell transplant as part of his treatment for acute myelogenous leukemia (AML). A second transplant was made a year later after a relapse. The donor was chosen not only for genetic compatibility but also for being homozygous for a CCR5-Δ32 mutation that confers resistance to HIV infection. After 20 months without antiretroviral drug treatment, it was reported that HIV levels in the recipient's blood, bone marrow, and bowel were below the limit of detection. Virus remained undetectable over three years after the first transplant. Although the researchers and some commentators have characterized this result as a cure, others suggest that the virus may remain hidden in tissues such as the brain (a viral reservoir). Stem cell treatment remains investigational because of its anecdotal nature, the disease and mortality risk associated with stem cell transplants, and the difficulty of finding suitable donors.
Immunomodulatory agents
Complementing efforts to control viral replication, immunotherapies that may assist in the recovery of the immune system have been explored in past and ongoing trials, including IL-2 and IL-7.