Biktarvy

Biktarvy is a fixed-dose combination tablet. It combines 50mg of bictegravir, 200mg of emtricitabine and 25mg of tenofovir alafenamide. Biktarvy is manufactured by Gilead Sciences.

Bictegravir is an HIV integrase inhibitor. Emtricitabine is a nucleoside reverse transcriptase inhibitor. Tenofovir alafenamide is a nucleotide reverse transcriptase inhibitor. Emtricitabine and tenofovir alafenamide are also marketed as the fixed-dose combination product Descovy and included in the fixed-dose products Odefsey, Genvoya and Symtuza.

Biktarvy was approved in the European Union for the treatment of HIV in adults in June 2018. Biktarvy was approved in the United States in February 2018.

Biktarvy was approved based on clinical trials in previously untreated people and people with suppressed viral load who switched from another regimen.

In previously untreated people, a pooled analysis of studies 1489 and 1490 showed that 91% of people who received Biktarvy had a viral load below 50 copies/ml after 48 weeks, compared to 93% receiving either Triumeq (dolutegravir, abacavir and lamivudine) or dolutegravir, emtricitabine and tenofovir alafenamide. Biktarvy showed no significant difference in viral suppression compared to dolutegravir-containing treatment when analysed by baseline CD4 cell count, viral load, age, sex or race. (Gallant) (Sax 2017) 144-week follow-up of the two studies showed that viral suppression was equivalent in those receiving Biktarvy or a dolutegravir-based regimen (82% vs 85%). After 144 weeks, 5% of people assigned to Biktarvy in study 1490 had experienced virological failure compared to 3% in the dolutegravir group. No cases of integrase inhibitor or NRTI resistance emerged in those with virological failure in either study. (Orkin)

Two studies evaluated switching to bictegravir in virally suppressed people. In study 1844, there was no significant difference in the proportions virally suppressed 48 weeks after switching from dolutegravir, abacavir and lamivudine to Biktarvy or maintaining the existing regimen. (Daar) In study 1878 there was no significant difference in the proportions virally suppressed 48 weeks after switching from an atazanavir or darunavir-containing regimen or continuing the regimen. (Molina)

Switching to Biktarvy maintained viral suppression in adults aged 65 and over, an analysis of the registration studies showed. Biktarvy was well tolerated in this population and only one out of 140 participants discontinued treatment. (Ramgopal)

Biktarvy is not recommended for people with severely impaired kidney function (< 30ml/min).

Biktarvy is recommended as a preferred option for first-line HIV treatment in US treatment guidelines.

Biktarvy is recommended as the preferred option for first-line treatment by the British HIV Association during the COVID-19 pandemic due to its high barrier to drug resistance, lower risk of drug-drug interactions and no need for kidney function monitoring.

Taking it

Biktarvy is dosed as one purple-brown tablet once a day, with or without food. Biktarvy should be taken at least two hours before, or six hours after, antacids containing magnesium or aluminium. Biktarvy can be taken at the same time as supplements containing calcium or iron if food is taken as well. Biktarvy should be taken at least two hours after supplements containing calcium or iron if taken on an empty stomach.

Side effects

Common side effects of Biktarvy include nausea, diarrhoea, depression, abnormal dreams, headache, dizziness and tiredness.

Weight gain has been observed in people with HIV after starting antiretroviral treatment.

An analysis of eight clinical trials of new drugs introduced after 2003 found that weight gain was significantly greater in people taking an integrase inhibitor and that dolutegravir or bictegravir were associated with a higher risk of substantial weight gain (>10% of body mass) than other drugs of this type. (Sax 2019)

Drug interactions

You should not take Biktarvy if you are currently taking medicines from the following groups:

• products that contain St John’s wort (a herbal remedy used for depression and anxiety)
• rifabutin, rifampicin and rifapentine (used to treat some bacterial infections such as tuberculosis)
• carbamazepine, oxcarbazepine, phenobarbital and phenytoin (used to treat epilepsy and prevent seizures)
• ciclosporin (an immunosuppressant)
• dofetilide (used to treat heart rhythm disorders)
• sucralfate (a treatment for stomach ulcers and severe gastric reflux).

Resistance

The development of resistance to bictegravir is rare. No cases of treatment failure on a bictegravir-containing regimen resulted in resistance to any study drug in studies 1489 or 1490 despite 1.3% prevalence of integrase inhibitor resistance at baseline. (Acosta)

Pregnancy

There are very limited data on the use of bictegravir or tenofovir alafenamide in pregnant women and Biktarvy should not be used during pregnancy unless the benefits are considered to outweigh the risk.

Children

Biktarvy has been studied as a switch option in adolescents with suppressed viral load in a single-arm study. At week 48, 74 out of 75 participants maintained an undetectable viral load and drug-related adverse events were rare. (Gaur)

In the European Union and the United States, Biktarvy is approved for use in children weighing at least 25kg, with reduced strength tablets available for children weighing between 14 and 25kg. It is not yet approved for use by children in the United Kingdom.

References