Stribild Safe and Effective in African Americans, 2 Studies Conclude
October 9, 2014
Two studies presented at the 54th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2014) evaluated the safety and efficacy of the single-pill quadruple combination Stribild (elvitegravir/cobicistat/emtricitabine/tenofovir DF) in African Americans, for whom antiretroviral therapy has historically been less effective. Both studies concluded that Stribild was just as safe and effective in African Americans as it was in other population groups.
Stribild vs. Atripla in Treatment-Naive Patients
The first study, led by David Hardy, M.D., was a post-hoc subanalysis of data from a phase 3 clinical trial, the GS-US-236-102 study. That trial compared Stribild with the single-pill triple combination Atripla (efavirenz/emtricitabine/tenofovir DF) in treatment-naive adults. Between 26% and 30% of participants (106 of 348 in the Stribild arm, 91 of 352 in the Atripla arm) self-identified as African American.
The mean age of study participants was 35-39 years, with African-American participants on the younger side (35 and 36 years for the Stribild and Atripla arms, respectively, versus 38 and 39 years for non-African-American participants in the two study arms). Men comprised between 77% (African Americans in the Stribild arm) and 93% (non-African Americans in the Atripla arm) of the study population. African Americans were also more likely to have a history of IV drug use (2% and 6% of the respective study groups in the Stribild and Atripla arms) than non-African Americans (4% and 2%, respectively) and had higher rates of hepatitis C coinfection (7% in the Atripla arm versus 3% for non-African Americans in the same arm).
Among African-American trial participants, the efficacy of Stribild compared to Atripla was higher at each point measured (week 48: 80% for Stribild versus 75% for Atripla; week 96: 84% versus 82%; week 144: 80% versus 75%), and study-related adverse events were significantly lower than those of the general study population. For example, none of the African Americans on Stribild had renal adverse events, while eight of the non-African Americans had such events.
Study authors concluded that "STB [Stribild] compared to ATR [Atripla] is an efficacious, durable, well-tolerated, and safe treatment regimen for HIV-1 infected, treatment-naive Black adults."
Switching to Stribild From PI- or NNRTI-Based Regimen
The second study, led by Joseph Gathe, M.D., a co-author of the first study, analyzed data on African-American participants in the STRATEGY studies, which evaluated switching from a ritonavir-boosted protease inhibitor-based (S-PI study) or non-nucleoside reverse transcriptase inhibitor-based (S-NNRTI study) regimen to Stribild. Participants in both studies (S-PI and S-NNRTI) were randomized to either the Stribild arm or the PI/NNRTI arm, respectively.
The proportion of African Americans in both STRATEGY studies was lower than the proportion in the GS-US-236-102 study (15% [63 of 366] in S-PI and 17% [72 of 362] in S-NNRTI), as was the proportion of men (68% of African Americans in S-PI and 74% of African Americans in S-NNRTI were male). All participants in all study arms had been diagnosed with HIV a median of four to five years ago and had been on antiretroviral therapy for a median of three to four years, with 74% (African Americans on Stribild in S-PI) to 96% (African Americans on NNRTI in S-NNRTI) on their first antiretroviral regimen just prior to this study.
At week 48, between 95% (S-PI) and 92% (S-NNRTI) of African-American study participants on Stribild had maintained an HIV-1 RNA of < 50 copies/mL, the study's definition of virologic success. The corresponding numbers for the PI-based and NNRTI-based regimens were 89% and 74%. Virologic success rates for non-African-American participants were slightly lower, at 93% and 94% for the two Stribild arms, and 87% and 91% for the PI-based and NNRTI-based regimens, respectively.
None of the participants in the overall STRATEGY studies developed treatment-emergent resistance, and African Americans in all study arms experienced fewer adverse events than non-African Americans. African-American participants also had no cases of proximal renal tubulopathy, while there was one such case among non-African-American participants.
Study authors therefore suggested that "E/C/F/TDF [Stribild] may be a viable switch option for virologically suppressed Black patients on a PI +RTV [ritonavir, Norvir] or NNRTI with FTC/TDF [emtricitabine+tenofovir, Truvada] who desire a regimen modification or simplification."
Barbara Jungwirth is a freelance writer and translator based in New York.
Follow Barbara on Twitter: @reliabletran.
Copyright © 2014 Remedy Health Media, LLC. All rights reserved.
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