ViiV's regimen of Tivicay, lamivudine shows non-inferiority to three-drug HIV treatment

ViiV Healthcare reported Thursday that two Phase III studies investigating a two-drug regimen of the integrase strand transfer inhibitor Tivicay (dolutegravir) and lamivudine met their primary endpoints, demonstrating non-inferiority to a three-drug regimen of Tivicay and Gilead Sciences' Truvada (tenofovir disoproxil fumarate/emtricitabine) in treatment naïve HIV-1 infected adults.

John Pottage, chief scientific and medical officer at ViiV, said the results "affirm our two-drug regimen strategy, and reinforce our belief that many patients can control their disease with two drugs instead of three or more." ViiV indicated that it plans to file regulatory submissions for the two-drug regimen later this year.

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. ViiV noted that no patients who experienced virologic failure in either treatment arm developed treatment-emergent resistance. The drugmaker indicated that full results from the studies will be presented at an upcoming medical meeting.

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. However, last month, both the FDA and European Medicines Agency began investigating reports of serious cases of neural tube birth defects involving the brain, spine, and spinal cord in babies born to women treated with dolutegravir as part of an ongoing observational study.

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 ($467 million). ViiV's minority shareholders include Pfizer and Shionogi. Analysts predict that annual sales of Tivicay will reach 5.2 billion pounds ($7 billion) by 2022, with revenue from the combination treatment with lamivudine hitting 1.1 billion pounds ($1.5 billion) by 2025.

Commenting on the study results, Jefferies analyst Ian Hilliker said the findings should help GlaxoSmithKline defend its dolutegravir franchise against competition from Gilead Sciences' triple therapy Biktarvy (emtricitabine/tenofovir alafenamide/bictegravir), which was approved in the US in February. Hilliker also noted that the combination of Tivicay and lamivudine will likely have an edge over Juluca. "Key opinion leaders we have spoken to see the dolutegravir/ lamivudine combination as a more attractive initial therapy or switch strategy as lamivudine has a very good toxicity profile and generic versions are available, which should reduce cost," the analyst remarked.

For related analysis, see ViewPoints: Why EU approval could be pivotal to success for ViiV, Johnson & Johnson’s Juluca.

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