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.

Glossary

resistance

A drug-resistant HIV strain is one which is less susceptible to the effects of one or more anti-HIV drugs because of an accumulation of HIV mutations in its genotype. Resistance can be the result of a poor adherence to treatment or of transmission of an already resistant virus.

virological suppression

Halting of the function or replication of a virus. In HIV, optimal viral suppression is measured as the reduction of viral load (HIV RNA) to undetectable levels and is the goal of antiretroviral therapy.

regimen

A combination of medications and the way it is taken.

viral load

Measurement of the amount of virus in a blood sample, reported as number of HIV RNA copies per milliliter of blood plasma. Viral load is an important indicator of HIV progression and of how well treatment is working. 

 

integrase inhibitors (INI, INSTI)

A class of antiretroviral drugs. Integrase strand transfer inhibitors (INSTIs) block integrase, which is an HIV enzyme that the virus uses to insert its genetic material into a cell that it has infected. Blocking integrase prevents HIV from replicating.

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)

Biktarvy is approved in the United States as a treatment option for children weighing 25kg or more.

References

Gallant J et al. Bictegravir, emtricitabine, and tenofovir alafenamide versus dolutegravir, abacavir, and lamivudine for initial treatment of HIV-1 infection (GS-US-380-1489): a double-blind, multicentre, phase 3, randomised controlled non-inferiority trial. The Lancet, 390: 2063-72, 2017.

Sax PE, et al. Coformulated bictegravir, emtricitabine, and tenofovir alafenamide versus dolutegravir with emtricitabine and tenofovir alafenamide, for initial treatment of HIV-1 infection (GS-US-380-1490): a randomised, double-blind, multicentre, phase 3, non-inferiority trial. The Lancet, 390: 2073-82, 2017.

Orkin C, et al. Long-term efficacy and safety of bictegravir/emtricitabine/tenofovir alafenamide in ART-naïve adults. 17th European AIDS Conference, Basel, 2019.

Ramgopal M et al. Pooled analysis of 4 international trials of bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) in adults aged >65 or older demonstrating safety and efficacy: week 48 results. 23rd International AIDS Conference, abstract OAB0403, 2020.

Daar E, DeJesus E, Ruane P, et al. Phase 3 randomized, controlled trial of switching to fixed-dose bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) from boosted protease inhibitor-based regimens in virologically suppressed adults: week 48 results. ID Week 2017, San Diego, abstract LB-4, October 4-8, 2017.

Molina JM et al. Switch to bictegravir/F/TAF from DTG and ABC/3TC. Conference on Retroviruses and Opportunistic Infections, Boston, abstract 22, March 2018.

Sax P et al. Weight gain following initiation of antiretroviral therapy: risk factors in randomized comparative clinical trials. Clinical Infectious Diseases, 71: 1379-89, 2019.

Acosta R et al. Resistance analysis of bictegravir-emtricitabine-tenofovir alafenamide in HIV-1 treatment-naïve patients through 48 weeks. Antimicrobial Agents and Chemotherapy, 63: e02533-18, 2019.

Gaur A et al. Bictegravir/FTC/TAF single-tablet regimen in children and adolescents: 48-week results. Conference on Retroviruses and Opportunistic Infections, Seattle, abstract 46, March 2019.

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