Single-Tablet Regimens RPV/FTC/TDF, EFV/FTC/TDF Non-inferior in ART-Naïve Patients

Debra Hughes, MS

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October 4, 2013

SAN FRANCISCO, CA—Rilpivirine/emtricitabine/tenofovir DF (RPV/FTC/TDF) RDF was non-inferior to efavirenz/emtricitabine/tenofovir DF (EFV/FTC/FTC) with respect to virologic suppression in treatment-naïve patients with HIV-1 infection, results of a Week 48 “snapshot analysis” reported at IDWeek 2013.

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Previously, two studies, ECHO and THRIVE, established RPV/FTC/TDF as non-inferior to EFV+FTC/FTC in ART-naïve patients. Calvin Cohen, MD, MSc, from the Community Research Initiative of New England, Boston, MA, and colleagues conducted the first study that directly compared the two single-tablet regimens in treatment-naïve adults with HIV-1.

STaR (Single Tablet Regimen) is a multicenter, international, randomized, open-label, Phase 3b 96-week study evaluating the safety and efficacy of RPV/FTC/TDF (n=394) to EFV/FTC/FTC (n=392).

Mean age of the patients was 37 years in the RPV/FTC/TDF arm and 35 years in the EFV/FTC/FTC arm; 93% of patients in each arm were male, and 68% and 67% of patients were white, respectively. Patients were randomized 1:1 to RPV/FTC/TDF or EFV/FTC/FTC, stratified by HIV-1 RNA level of ≤100,000c/mL or >100,000c/mL at screening.

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The primary end point was proportion of subjects with HIV-1 RNA <50 copies/mL (virologic suppression) at Week 48 (12% pre-specified non-inferiority margin).

Subjects were randomized to receive at least 1 dose of the study drug. Baseline characteristics were similar in both treatment arms with mean CD4 count of 391 cells/mm³ and HIV-1 RNA of 4.8 log₁₀ copies/mL.

The Week 48 snapshot analysis demonstrated that RPV+FTC/TDF was non-inferior to EFV/FTC/FTC (85.8% vs. 81.6%). Overall, virologic failure was 8.1% in the RPV+FTC/TDF arm vs. 5.6% in the EFV/FTC/FTC arm, said Dr. Cohen, principal investigator of the STaR study.

In patients with a baseline HIV-1 RNA level ≤100,000 and CD4 count >200 at Week 48 the virologic suppression was:

Adherence ≥95%: RPV/FTC/TDF 93% (171/184); EFV/FTC/FTC 89% (154/173)
Adherence <95%: RPV/FTC/TDF 82% (46/56); EFV/FTC/FTC 68% (38/56)

In patients with a baseline HIV-1 RNA level ≤100,000 and CD4 count ≤200 at Week 48 the virologic suppression was:

Adherence ≥95%: RPV/FTC/TDF 80% (8/10); EFV/FTC/FTC 77% (10/13)
Adherence <95%: RPV/FTC/TDF 67% (6/9); EFV/FTC/FTC 67% (2/3)

In patients with a baseline HIV-1 RNA level >100,000 and CD4 count >200 at Week 48 the virologic suppression was:

Adherence ≥95%: RPV/FTC/TDF 87% (69/79); EFV/FTC/FTC 90% (76/84)
Adherence <95%: RPV/FTC/TDF 70% (14/20); EFV/FTC/FTC 72% (16/22)

In patients with a baseline HIV-1 RNA level >100,000 and CD4 count ≤200 at Week 48 the virologic suppression was:

Adherence ≥95%: RPV/FTC/TDF 77% (20/26); EFV/FTC/FTC 81% (22/27)
Adherence <95%: RPV/FTC/TDF 50% (4/8); EFV/FTC/FTC 29% (2/7)

Analysis showed that the subgroup with an adherence rate ≥95% had better virologic outcomes across both treatment arms and all HIV-1 RNA and CD4 categories, with best results in those with baseline HIV-1 RNA ≤100,000c/mL, CD4 >200 cells/mm³ and adherence rate ≥95%.

“Better adherence was associated with better safety outcomes,” he concluded; specifically, less nervous system adverse events.