GSK, ViiV offer sneak peek of PhIII data on in-house two-drug HIV combo, touting non-inferiority

Pressing on with its ambitious goal to outshine Gilead in the HIV space, GlaxoSmithKline is now armed with positive data on its two-drug regimen from a pair of Phase III studies — if we take their word for it.

John Pottage

ViiV Healthcare — GSK’s dedicated HIV arm — reported overnight that GEMINI-1 and GEMINI-2 met their primary endpoint based on plasma HIV-1 RNA <50 copies per millilitre (c/mL) at week 48, essentially showing non-inferiority of dolutegravir and lamivudine compared to the standard three-drug regimen. In addition to safety information, that’s as much as GSK is willing to divulge at the moment, choosing to save the details for an upcoming medical conference.

“Importantly, the studies show that this two-drug regimen could be an option for treatment naïve patients and can support a broad range of patients living with HIV around the world,” said John Pottage, chief scientific and medical officer of ViiV Healthcare, in a statement.

While dual drug combinations (or “doublets”) promise to reduce toxicity burden — an important longterm concern given that many now receive HIV treatment chronically — GSK still has its work cut out in laying out a convincing case for the paradigm shift. As Credit Suisse analysts note:

HIV clinicians have all grown up with the ethos that hitting the virus with multiple modes of action is the best therapeutic option. They acknowledge this brings tolerability issues. Getting the community to embrace doublet therapy, essentially dropping one possible treatment option, is likely to take time and education. We expect longer term data on treatment emergent resistance will likely be needed to build the doublet category significantly.

Umer Raffat of Evercore has three questions ahead of the full data rollout: first on the exact virologic failure rates between the arms; second on how those rates differ between patients with different levels of viral load at baseline; and third on the “exact nature of resistance mutations.” In their press release, GSK noted that “no patient who experienced virologic failure in either treatment arm developed treatment-emergent resistance.”

If it pans out, the economic upside is clear, compared to both the triplet option and a doublet that GSK has developed with J&J dubbed Juluca (which combines dolutegravir with J&J’s rilpivirine). Both drugs used in the combo are in-house drugs, potentially setting GSK up to snatch market share from Gilead, which currently provides the two nucleoside reverse transcriptase inhibitors needed to pair with dolutegravir in the form of Truvada. That’s what ViiV CEO Deborah Waterhouse would like to see over time, she told the Financial Times.

ViiV plans to get the ball rolling on regulatory submissions later this year. Predicting a launch in the second half of 2019, Credit Suisse is estimating a peak sales opportunity of $500 million.

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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
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Atlas Venture Cambridge, MA

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