HIV treatment could move to weekly or monthly injections rather than pills every day, but what exactly is in the pipeline?
By and large, current HIV treatment regimes are extremely effective – indeed, they are undoubtedly one of the crowning achievements of medical science of the past thirty years. However they are not perfect, requiring strict compliance and in some cases not achieving full viral suppression. Two experimental treatments are working to resolve this through the development of drugs which are injected either every week or every month, rather than taken every day in pill form.
The first treatment is under development jointly by GlaxoSmithKline and Johnson and Johnson, and involves administration of two drugs. One of these is already on the market as Edurant (a reverse transcriptase inhibitor) and the second, GSK744, is an injectable form of the integrase inhibitor Dolutegravir – it is currently awaiting FDA approval. Reverse transcriptase inhibitors and integrate inhibitors are types of drug commonly used to prevent stop HIV replicating once it has entered a cell.
In animal studies, injection of both drugs has been found to prevent HIV proliferation and even infection for months at a time. Further, a recent report indicates that injections in non-HIV+ humans are generally well tolerated and that the drugs persisted in the bodies of the participants for a month after injection. This means that rather than taking a pill a day – which some people can find difficult – a possibly more simple approach could be used. Unfortunately, there is still no data on how effective this drug is in humans with HIV how effective it would be in patients with HIV. More trials, involving HIV patients, will be needed before the effectiveness of the drugs is certain.
The second approach is being attempted by smaller pharmaceutical firm CytoDyn, which hopes to develop a twice-weekly injection using its PRO-140 treatment. This involves a new class of HIV therapy; rather than preventing the virus from replicating inside the cell, PRO-140 aims to block the entry of the virus into the cell. HIV normally enters T-cells through a ‘door’ called CCR5. PRO-140 blocks this door, and – importantly – does not seem to interfere with normal immune function.
An ongoing study has revealed that treatment with PRO-140 alone can achieve viral suppression over extended periods. This is important as other treatment approaches, including both the currently prescribed HAART and the injection system being developed by GlaxoSmithKline, involve a number of different compounds. PRO-140 is much further down the ‘development pipeline’ than GSK’s offering – Cytodyn hope to apply for FDA licensing in November 2016.
As HIV treatment advances, a new aim is the development of treatments which can be more tailored to HIV+ individuals. A variety of approaches ensures that effective HIV suppression will be available for all. Pills are not universally tolerated by all individuals, and the heavy drug load complicates treatment in older individuals, or those with liver problems. Should these drugs be developed beyond clinical trials and make it to market, there is the possibility that HIV treatment won’t simply become a question of ‘which is best’, but ‘which is best, for this person, right now’.