In order to achieve that serendipitous "cure", Brown had to undergo aggressive treatment for his acute myeloid leukemia that involved two hematopoietic stem cell transplantations - in which a patient's bone marrow is damaged - and full body irradiation.
Around 22,000 people are known have the CCR5 mutation, and they are mostly northern European.
Current therapies are said to be effective; meaning they help people infected with the virus live longer and healthier lives, but they are still not a cure, drugs will always be needed.
"The stem cell transplant primarily involves reprogramming the immune system to be HIV-resistant".
Stem cell transplants or bone marrow transplants are painful, costly and time consuming-and there are several ways in which such transplants go wrong. After receiving treatment, both patients were eventually taken off their anti-retroviral medications and subsequent examination showed that that even with very sensitive blood tests, the team could not detect HIV in their blood. When HIV-infected individuals are compliant with the prescribed use of the AIDS cocktail, their viral load is undetectable and they become untransmittable, meaning they can not sexually transmit the HIV virus to others. Scientists are describing the condition as a long-term remission, but the news has given hope for a cure. "At the moment HIV isn't cured". Add to this that only about one percent of Caucasians are CCR5 negative-this being a mutation that only appears in European bloodlines-and it quickly becomes apparent that we can not feasibly use stem cell transplants to make every person with HIV enter remission. Though their procedures were different from those the London Patient and the Berlin Patient, this demonstrates that caution is critical when we talk about this as a "cure".
While a second patient experiencing HIV viral remission with a slightly less toxic cancer treatment is certainly encouraging progress, an 18-month remission does not equal a cure.