An HIV positive patient treated with a bone marrow transplant for acute myeloid leukaemia (AML) has remained without any evidence for HIV infection more than 3.5 years after discontinuing antiretroviral drugs, report German researchers. The case report, published in the journal Blood, has been heralded as providing the first evidence of a cure for HIV.

In February 2007 Kristina Allers and colleagues, from the Charité-University Medicine (Berlin, Germany) undertook a stem cell transplant of a male patient who had been HIV positive for more than a decade and had sought treatment for AML with a bone marrow transplant after failure of chemotherapy.

The investigators replaced the patient's HIV infected population of CD4 white blood cells with a rare genetic mutation that was naturally resistant to HIV due to a mutation preventing the CCR5 molecule from appearing on the cell surface. Since HIV requires interaction with CCR5 molecules to enter cells, when they are absent it is unable to penetrate.

Immediately following the transplant, investigators found HIV replication in the patient had stopped, but they expected that the long-lived viral reservoir would lead to HIV rebound and disease progression.

In the first follow-up, published in the NEJM in 2009, investigators found no signs that HIV had re-emerged even though patients had ceased antiretroviral drugs to suppress HIV. In the latest paper doctors undertook extensive testing at the systemic levels as well as in the gut mucosal immune system and could find no trace of either HIV or leukaemia.

Furthermore, during the process of immune reconstitution, the investigators found evidence for the replacement of long-lived host tissue cells with donor-derived cells, indicating that the size of the viral reserve had been reduced over time.

"Our results strongly suggest that cure of HIV has been achieved in this patient," write the authors.

But given that around 30% of patients die when attempting bone marrow transplants AIDs experts have expressed caution about the widespread applicability of this approach. The future challenge is to translate the findings into a strategy that can be applied without being life threatening to patients.

Reference

K Allers, G Hutter, J Hofmann et al. Evidence for the cure of HIV infection by CCR5 {Delta}32/{Delta} 32 stem transplantation Blood Doi: 10.1182/blood-2010-09-309591