Antiretrovirals have revolutionised the treatment of HIV and Aids. While there is still no cure for the disease, these medications can extend the lives of HIV-positive people by many years.
They don’t kill the virus, but by controlling the process by which it replicates itself, they significantly reduce its concentration in the bloodstream, minimise damage to the immune system, and delay the onset of full-blown Aids and the illnesses commonly associated with it.
ARVs, which have been around since the 1980s, can be divided into five distinct types or classes, each of which interferes with a different part of the virus’ lifecycle, slowing down its progress.
To be effective and to prevent the development of drug resistance, ARV therapy involves a combination of at least three ARVs, two of which must be from a different class and all of which must be taken on a daily basis. To make treatment easier, the separate drugs are often combined into a single pill.
Read: WHO guidelines recommend early ARVs for all with HIV
Among the problems with ARV treatment, aside from its high cost, are the side effects many patients experience.
These can be short or long-term, mild or severe, and include a loss of appetite, anxiety, mood swings, depression, headaches, dizziness, diarrhoea, nausea, vomiting, fatigue and skin rashes.
Among the more serious side effects are: osteoporosis (brittle bone disease); abnormal blood sugar levels; elevated blood cholesterol levels; changes in the way fat is produced, used, stored and distributed in the body (lipodystrophy); kidney problems; and lactic acidosis. Lactic acidosis is when lactic acid (a metabolic waste product generated when muscle and blood cells convert carbohydrates into energy during intense exercise or while fighting an infection) builds up in the body, potentially resulting in conditions ranging from muscle aches to liver failure.
Genvoya, which combines four different ARVs (elvitegravir, cobicistat, emtricitabine and tenofovir alafenamide) in a single tablet taken once a day, was approved by the US Food and Drug Administration and the European Commission last month.
It’s recommended for the treatment of HIV-1 infection (the genetic variant of the virus responsible for about 95% of the global Aids pandemic) in adults and children aged 12 and above and weighing at least 35 kilograms who have no previous history of ARV treatment or wish to replace their current ARV regiment.
Genvoya is the first HIV treatment that includes a new and improved version of the ARV tenofovir, called tenofovir alafenamide (TAF). Clinical trials suggest that Genvoya has fewer of the side effects typically associated with other ARV drugs. Specifically, it has been shown to be less destructive to the kidneys and bones.
According to the University of North Carolina’s Dr David Wohl, “given its demonstrated efficacy and safety profile, Genvoya represents an important new treatment option for a range of patients who are either new to therapy or who choose to switch treatments”.
Risks and criticisms
Gilead has acknowledged that taking Genvoya does involve a risk of potentially life-threatening conditions, including lactic acidosis and severe hepatomegaly (enlargement of the liver) with steatosis (build-up of fat in the liver), as well as post treatment acute exacerbation of hepatitis B.
Some critics have questioned Gilead’s motivation for replacing its existing Stribild ARV medication with Genvoya, suggesting that the move represents an effort to extend its existing drug patent.
Read: Early-start ARVs ups survival
“By all means, news that an alternate form of tenofovir in Genvoya is less likely to cause kidney damage or bone loss in patients is welcome,” says Michael Weinstein, President of the non-profit Aids Healthcare Foundation.
“However, we believe that Gilead’s updated four-in-one combination was also developed as a means to do an end run and extend the prior patent on Stribild with this updated, but essentially similar combination therapy.”
Coming to SA?
The issue of patents could also play a role in Genvoya’s availability to HIV-positive South Africans. The Treatment Action Campaign’ Lotti Rutter believes that it’s likely that Gilead will patent Genvoya’s combination of four ARVs under South Africa’s existing patent laws and that “this would mean that it would most likely be unaffordable for people to buy here for many years, and most likely not included in the recommended regimens by the Department of Health”.
According to Rutter, “TAC is part of a campaign calling on the South African government to ‘Fix the Patent Laws’. As it stands South Africa pays artificially inflated prices for medicines because it blindly hands out patents, without examining applications to see if they meet criteria defined in the country’s Patents Act.
"This allows pharmaceutical companies to get multiple patents on the same medicine by making small changes, even when such changes have no benefit for patients. This can block more affordable generic competitors from bringing products to market beyond the 20 years required by international trade agreements."
Read: 5 ways to improve adherence to ARVs
She argues that “this kind of behaviour is an attempt to squeeze as much money out of a medicine as possible” and that the outcome is that “millions of people across the country will suffer without access to important medicines for longer”.
Sheldon Purdy, Gilead’s Director: Regional Lead Sub Saharan Africa, says that the company will submit the dossier for the approval of Genvoya in South Africa to the Medicines Control Council in 2016. If approved, it may take another two years or so for it to become available in the country.
Purdy suggests that pricing for the drug will be in line with the Gilead’s strategy to make its drugs accessible and affordable to South Africans. Internationally, Gilead has announced that the new product would be priced on par with its predecessor Stribild.
Read: HIV prevention drugs raise more questions than answers
Earlier this year, the World Health Organisation (WHO) issued a new recommendation that all HIV-positive individuals, regardless of their CD4 count (a measure of the health of a person’s immune system determined by the concentration of CD4 T lymphocytes, or T-helper cells, in the blood), should receive ARV treatment.
Currently, South Africa only provides ARV therapy to people whose CD4 count is less than 500 cells per cubic millimetre as well as HIV-positive pregnant women and children under five.
If government were to implement the new WHO directive, this could result in a doubling of patients on ARVs, taking the total number to 6.4 million people. Health minister Aaron Motsoaledi is expected to make a decision on the matter by the end of the year.
Whether Genvoya could become an affordable and accessible treatment option to satisfy this growing demand for ARVs remains to be seen.
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