ViiV Healthcare presented detailed results on Tuesday at the International AIDS conference from the late-stage GEMINI 1 and 2 studies, showing that a two-drug regimen of the integrase strand transfer inhibitor Tivicay (dolutegravir) and lamivudine has similar efficacy to a three-drug regimen of Tivicay and Gilead Sciences' Truvada (tenofovir disoproxil fumarate/emtricitabine) in treatment naïve HIV-1 infected adults. ViiV announced last month that the trials met their primary endpoints by demonstrating non-inferiority.
Principal investigator Pedro Cahn remarked "for the last 15-20 years, the standard of care for HIV has revolved around three-drug regimens. Now that we have more potent drugs, the focus is shifting to tolerability and convenience." Cahn added "the GEMINI studies show that we can get the efficacy of three drugs in a two-drug regimen with the tolerability and drug interaction profile of [Tivicay and lamivudine]."
The GEMINI 1 and GEMINI 2 studies randomised around 1400 treatment naïve HIV-1 infected adults with baseline viral loads less than 500 000 copies per mL to receive Tivicay in combination with either the nucleoside analogue lamivudine or the nucleoside reverse transcriptase inhibitor Truvada as a first-line treatment regimen.
A pooled analysis of the two studies showed that at week 48, 91 percent of patients taking Tivicay and lamivudine had HIV-1 RNA below 50 copies/mL compared with 93 percent of patients taking the combination of Tivicay and Truvada. ViiV added that viral suppression was "broadly consistent" across individuals with higher viral loads of over 100 000 copies per mL and those with a lower viral load of below 100 000 copies per mL HIV-1 plasma RNA.
According to ViiV, rates of virologic failure were no more than 1 percent across all arms of the studies, while no patient who experienced virologic failure in either treatment arm developed treatment-emergent resistance. The drugmaker added that the percentage of patients that withdrew due to adverse events was 2 percent in each study arm, while 18 percent of patients who received Tivicay and lamivudine experienced drug-related adverse events, compared with 24 percent of those on the Tivicay and Truvada regimen.
ViiV noted that it plans to seek regulatory approval for a fixed-dose combination of Tivicay and lamivudine later this year. For related analysis, see ViewPoints: ViiV inches forward with effort to disprove a negative for HIV doublet.
Last year, the FDA approved Tivicay in a fixed-dose combination with Johnson & Johnson's non-nucleoside reverse transcriptase inhibitor Edurant (rilpivirine) under the name Juluca, with regulators in Europe also recently clearing the product. In April, GlaxoSmithKline, which has a majority stake in ViiV, reported that first-quarter sales of Tivicay lifted 15 percent year over-year to 348 million pounds ($456 million). ViiV's minority shareholders include Pfizer and Shionogi.
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