The PITCH study: ‘Prospective Interruption of Therapy towards a Cure for HIV’
Drugs for HIV infection are effective at keeping the virus at bay, but are not a cure. Scientists have discovered that if patients start treatment within a few months of being infected, a significant proportion (up to 14%) enter a state of remission in which HIV stays undetectable and patients remain well if they stop treatment. Some patients have been off treatment for as much as 10 years. This condition - called ‘post treatment control’ (or ‘PTC’) - challenges our understanding of the relationship between HIV and man. We do not understand how much treatment is necessary, when it should be started and if there are laboratory markers that can help predict reaching this state.
In this pilot, the aim was to stop treatment in HIV positive volunteers who started being treated very early to discover how many would reach PTC and what might be causing it. We monitored these volunteers closely for evidence of returning virus and see how their immune system was responding and, crucially, how much of an impact this was having on the HIV ‘reservoir’ (sleeping viruses that remain dormant while people are on treatment). The idea was, because we are starting treatment very early, HIV will not have had as much chance to have a large reservoir and so we have a good chance of reducing it. If HIV returned, volunteers were immediately restarted on treatment, thereby avoiding any harm. We aimed to identify patients who could stop treatment for years, and some who may never need to be treated again. The health-related, psychological and economic implications of this were substantial. Additionally, understanding the mechanism of PTC will help develop new treatments that might allow others patients to stop treatment and enter long term remission, or even cure.