By: Alex Chu, Staff Writer
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On November 5th 2015, the U.S Food and Drug Administration approved Genvoya®, a once daily tablet containing a combination of elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide (TAF) for the treatment of HIV-1 infections in adults and pediatric patients age 12 or older.1
Genvoya® is a combination of antiretroviral drugs that target the HIV virus in different ways. Elvitegravir is an integrase strand transfer inhibitor, which prevents proviral gene incorporation into human DNA.2 Emtricitabine is a cytosine analogue, and tenofovir alafenamide is converted to an analog of adenosine 5′-monophosphate.2 They interfere with HIV DNA polymerase production, therefore inhibiting viral replication. Cobicistat is a CYP3A subfamily enzyme inhibitor, which enhances systemic exposure to elvitegravir.2
A contributing factor towards the approval of Genvoya® was its favorable outcome during the clinical trial phase. Five clinical trials were conducted targeting the safety and efficacy of Genvoya® in various populations. Studies 104, 111, and 109 compared the safety and efficacy of Genvoya® as compared to tenofovir disproxil fumarate (TDF) treatments in both treatment naive and virologically suppressed adults over the course of 48 weeks, while Studies 112 and 106 tested the safety and efficacy of Genvoya® in virologically suppressed adults with renal impairment, and in treatment-naive adolescents over 12 years of age through 24 weeks.3
In Studies 104 and 111, 1,733 treatment naive adults were randomly assigned either Genvoya® or Stribild® 1:1 in a randomized, double blinded, actively controlled trial.3,4 Stribild® is another form of antiviral treatment that contains the same active ingredients as Genvoya®, except that it contains TDF instead of TAF. Of the 1,733 participants, 866 received Genvoya® with 92% having an HIV RNA viral value of >50 copies/mL.3 867 received Stribild® with 90% having a viral value of >50 copies/mL.3 The results of the 48 week trial determined that there was no difference in efficacy of viral treatment between Genvoya® and Stribild® Additionally, there was no statistical difference in frequency of adverse reactions.3 Study 109 determined efficacy of treatment in patients switching from a current HIV treatment regimen containing TDF (Atripla®, Truvada®, or Stribild®) to Genvoya®. The subjects had a suppressed viral value of >50 copies/mL.3 Results have shown that Genvoya® is statistically non-inferior as compared to antiviral treatment containing TDF (96%[n=799] vs 93%[n=397]).3
The renal and bone density effects of Genvoya® vs. Stribild® in treatment-naive subjects were analyzed and found to be statistically significant in favor of Genvoya®. Renal laboratory parameters yielded an estimated glomerular filtration rate (eGFR) of -2.0 mL/min compared to Stribild®’s -7.5 mL/min eGFR ( p<0.001) , a bone mineral density (BMD) decrease of 1.30% vs 2.86% at the spine and 0.66% vs 2.95% at the hip.5 The percentage of subjects who had a 5-7% reduction of BMD in the spine and hip was less in Genvoya® subjects than in Stribild® subjects (7-10% vs 19-22%).5 In virologically suppressed adults, the BMD results were similar but there was less of a difference between Genvoya® and TDF-treated subjects ( 1.86% vs 1.95% for total hip, 0.11% vs 0.14% for lumbar spine).5 Declines of total hip and spine BMD occurred more frequently in TDF-treated subjects than in Genvoya® subjects (4-6% vs 1%).3 The safety profile of Genvoya® with 23 treatment-naive pediatric subjects was similiar to that in adults (mean BMD 1.7% increase at the lumbar spine and 0.8% increase in total body).3 Two Genvoya® subjects had a 4% decrease in BMD at the lumbar spine.3 There is no data of the long term effects Genvoya® may cause in terms of BMD.
A big advantage Genvoya® has over other HIV medications is that Genvoya® is the first FDA approved drug to use TAF. During testing, TAF was found to be at a high intracellular and low blood concentration.5 During Studies 104 and 111, a 10 mg oral dose of TAF from Genvoya® resulted in a 91% reduction of concentration of tenofovir in plasma as compared to a 300 mg oral dose of TDF in Stribild®. Based on clinical trial data, it can be seen that usage of TAF causes less of an effect on BMD and renal eGFR.5
The recent approval of Genvoya® for HIV-1 treatment not only sets a higher standard of safety for HIV treatment regiments, but also gives patients another treatment option. With the use of Genvoya® compared to other TDF-containing drugs, HIV patients can switch their antiviral treatment with less of a risk for development and age-related comorbidities, such as renal impairment and low bone mineral density.
SOURCES:
- FDA approves new treatment for HIV.U.S. Food and Drug Administration. Available at: http://www.fda.gov/newsevents/newsroom/pressannouncements/ucm471300.htm. Accessed 12/23/2015.
- Lexicomp. Genvoya (Lexi-Drugs). Lexicomp Website. Available at: http://online.lexi.com.jero me.stjohns.edu: 81/lco/action/doc/retrieve/docid/pat ch_f/5922034. Accessed 12/23/2015.
- Genvoya (cobicistat, elvitegravir, emtricitabine and tenofovir alafenamide) [package insert]. Foster City, CA; Gilead Sciences, Inc.; Accessed 12/23/2015.
- Press Releases. U.S. Food and Drug Administration approves gilead’s single tablet regimen Genvoya (elvitegravir, cobicistat, emtricitabine and tenofovir alafenamide) for treatment of HIV-1 infection. Available at: https://www.gilead.com/news/press-releases/2015/11/us-food-and-drug-administration-approves-gileads-single-tablet-regimen-Genvoya-elvitegravir-cobicistat-emtricitabine-and-tenofovir-alafenamide-for-treatment-of-hiv1-infection. Accessed 12/23/2015.
- Press Releases. Gilead announces phase 3 results for Genvoya (elvitegravir, cobicistat, emtricitabine and tenofovir alafenamide), an Investigational Once-Daily Single Tablet Regimen for HIV. Available at: http://www.gilead.com/news/press-releases/2015/10/gilead-announces-phase-3-results-for-Genvoya-elvitegravir-cobicistat-emtricitabine-and-tenofovir-alafenamide-an-investigational-oncedaily-single-tablet-regimen-for-hiv. Accessed 12/23/2015.
