HIV ‘cure’: a step in the right direction
Elinour Jones discusses the revelation that a second person has been cured of HIV
In recent weeks, the world of HIV research has been a place of stark contrast, with painful lows and tremendous highs. World-renowned researcher Gita Ramjee sadly passing due to COVID-19, having committed a career to promoting access to prevention and treatment for HIV, occurred in the same month as the second-ever patient to be cured of HIV was announced as Adam Castillejo.
“The second-ever patient to be cured of HIV was announced as Adam Castillejo”
Known as the ‘London Patient’, Castillejo had been diagnosed with lymphoma, a type of blood cancer, as well as HIV. Whilst receiving a stem cell transplant to treat the cancer, he was cured of human immunodeficiency virus simultaneously, according to the Lancet. Having taken anti-retroviral drugs previously, doctors have said that the stem cell replacement acted as the treatment for his HIV due to a mutation that acts as protection for a very small number of individuals. This uncommon gene produces altered CCR5 receptors, usually used by HIV-1 to get into human cells, providing a barrier to penetration of these cells; the transplant aims to replace at least 99 percent of the affect immune cells.
In 2011, the ‘Berlin Patient’ underwent the same procedure, reporting anti-retroviral free remission. However, stem cell replacements are not without their challenges, most notably due to the aggressive stress placed on the body. Stem cell treatments to treat blood cancers often come from a close relative such as a sibling, meaning they are closely matched and result in fewer side effects. By requiring stem cell replacements with the mutated CCR5 gene it may not be possible to guarantee these from close family, as these appear rarely in the population. One of the reasons closely matched transplants are necessary is the body’s own response, as ‘foreign’ cells can be attacked, resulting in graft versus host disease (GvHD), which can be life-threatening.
“However, stem cell replacements are not without their challenges”
Also, in preparation for replacement chemotherapy is required to destroy damaged cells, risking anaemia, excessive bleeding and increased infection, as well as the common side effects of chemotherapy.
We do not yet know the long-term impact of these stem cell transplants on reoccurrence of HIV in the future, especially as 100 percent replacement of cells is not guaranteed. As such, the word ‘cure’ is often said in hushed tones in this field, synonymous with remission. Still, there is hope in the search for an effective ‘cure’ for HIV, with Castillejo’s case providing encouraging insight for a genetic therapy in the coming decades.
