Stribild HIV Post-Exposure Prophylaxis Brings Higher Completion Rate

The co-formulation of elvitegravir (200 mg), cobicistat (150 mg), emtricitabine (FTC, 150 mg), and tenofovir disoproxil fumarate (TDF, 245 mg) prescribed as Stribild® (Gilead), one pill taken once daily for a limited 28-day cycle, is a preferred treatment regimen in the United States and the European Union for post-exposure prophylaxis (PEP) in immunocompetent people without HIV infection. Stribild seems to be a good option due to ease of use, a tolerable adverse effect profile, and high completion rate, according to a study published in BMC Infectious Diseases.¹

Between April 1 and December 31, 2015, a total of 364 potentially exposed participants were prescribed PEP at St. Antoine Hospital in Paris. Of this cohort, 284 (78%) exposed participants received Stribild for a full 28-day cycle; 86% were men, 80% of whom have sex with men, and the median age of all participants was 30 years (range 18 to 69). 

Seventeen percent of patients indicated they were exposed to an HIV-infected partner with no data available on last viral load and current antiretroviral treatment, while 65% reported unprotected anal sex, 26% unprotected vaginal sex, 9% unprotected oral sex, 50% known exposure to ejaculate, and 11% had a known past sexual exposure to HIV with PEP.

More than half of the participants prescribed Stribild for the full 28-day course reported at least one adverse event, with fatigue and central neurological and abdominal side effects being the most frequently reported. Fatigue was reported by 57 of 218 participants, while 3 participants showed minor liver cytolysis (<2.5 the upper limit of normal levels for aspartate transaminase or alanine transaminase). All adverse events were mild to moderate in severity; 3 participants had to switch treatments because of severe diarrhea and abdominal pain or repeated vomiting.

HIV serology results were available for 131 of 234 participants (56%) 2 months after exposure; none had HIV infection. French national guidelines for follow-up exposure include HIV antibody testing at baseline and at 6 weeks after the exposure for those who did not receive PEP and at baseline and at 8 and 16 weeks after the exposure for people who did receive PEP.² The Swedish Reference Group for Antiviral Therapy proposes that completeness of HIV testing follow-up could be increased by reducing the number of HIV testings to one HIV serology test conducted at 6 weeks following completion of PEP.³

A short course (5 days) of Stribild was also conducted. Among 50 participants who received <5 days of PEP, results of HIV serology 6 weeks after exposure were available for 20% and revealed no cases of HIV infection. Adverse events reported were in line with those experienced by participants receiving the 28-day PEP course.

Stribild is considered a good option for HIV PEP in high-resource settings; however, its availability is limited to those in resource-limited settings. In 2014 in France, Stribild cost €980 (approximately $1018). Current pricing from Gilead Sciences — the biopharmaceutical company that developed Stribild and its newer version, Genvoya — was raised in July 2016 to approximately $3469 and $2578 per month, respectively.⁴ Genvoya replaces 300 mg TDF with 10 mg tenofovir alafenamide (TAF), 150 mg elvitegravir, 150 mg cobicistat, and 200 mg emtricitabine.⁵ Genvoya was not considered as a part of this study; however, it’s placement in the current market may warrant further investigation to assess cost and potential toxicities. 

References

1. Valin N, Fonquernie L, Daguenel A, et al.  Evaluation of tolerability with the co-formulation elvitegravir, cobicistat, emtricitabine, and tenofovir disoproxil fumarate for post-HIV exposure prophylaxis. BMC Infect Dis. 2016;16:718. doi: 10.1186/s12879-016-2056-3
2. Ministere des Affaires Sociales et de la Sante. CN.d.S., Agence Nationale de Recherches sur le SIDA et les Hepatites Virales, Prise en Charge Medicale des Personnes Vivant Avec le VIH. Recommandations du Groupe d’Experts. Rapport, 2013.  Available at: http://www.sante.gouv.fr/IMG/pdf/Rapport_Morlat_2013_Mise_en_ligne.pdf.  Accessed November 23, 2016.
3. Gaines H, Albert J, Axelsson M, et al. Six-week follow-up after HIV-1 exposure:  a position statement from the public health agency of Sweden and the Swedish reference group for antiviral therapy. Infect Dis (Lond).  2016;48:93-98. doi: 10.3109/23744235.2015.1089593
4. Silverman E. Gilead’s new price hikes on HIV drugs anger AIDS activists. STAT website. July 5, 2016.  https://www.statnews.com/pharmalot/2016/07/05/gilead-hiv-aids-drug-prices/. Accessed December 27, 2016.
5. Newman E. Genvoya: a new once-daily combo HIV medication.” BETA. November 6, 2015. Available at: http://betablog.org/genvoya-a-new-once-daily-combo-hiv-medication/. Accessed December 27, 2016.