The FDA has approved emtricitabine (FTC) 200 mg and tenofovir alafenamide (TAF) 25 mg (Descovy, Gilead) as a new pre-exposure prophylaxis (PrEP) treatment for certain populations at risk of contracting HIV-1 through sex.
FTC and TAF are both HIV nucleoside analog reverse transcriptase inhibitors that were first approved as a therapy in 2015 to be administered either in combination with other antiretroviral agents in adults and pediatric patients weighing at least 35 kg, or in combination with other antiretroviral agents other than protease inhibitors that require a CYP3A inhibitor in pediatric patients weighing at least 25 kg to 35 kg.
The recent approval was based upon results from a randomized, double-blind, multinational trial in which 5,487 HIV-negative men and transgender women who have sex with men and were at risk for HIV-infection were examined for a period of 48 to 96 weeks. The primary endpoint of the study, which compared FTC/TAF to Truvada (another PrEP treatment produced by Gilead), showed that FTC/TAF was similar to Truvada in reducing the risk of HIV-1 acquisition in the targeted at-risk populations.
Currently, FTC/TAF is not approved for the use as a PrEP treatment in patients at-risk for contracting HIV-1 through vaginal sex due to a lack of evaluation in those populations, according to the FDA’s approval release.
FTC/TAF is contraindicated in patients with an unknown or positive HIV-1 status—all patients must be tested for HIV-1 immediately prior to starting therapy.
A boxed warning for FTC/TAF warns of severe Hepatitis B exacerbations when treatment is discontinued. Hepatic function should be monitored in patients considering discontinuation, and anti-Hepatitis B therapy might be warranted in some situations. Other warnings issued with the use of FTC/TAF include immune reconstitution syndrome during treatment, new onset or worsening renal impairment, and lactic acidosis/severe hepatomegaly with steatosis.
Adverse reactions reported with the use of FTC/TAF include nausea in HIV-1 infected patients and diarrhea in uninfected patients.