Biktarvy's success raises doubts about ViiV's 'new era' of HIV treatment
- GlaxoSmithKline subsidiary ViiV Healthcare believes its portfolio of HIV medications will be competitive as treatment for the virus enters an era of two-drug regimens. So far, however, the company's first doublet has performed modestly on the market compared to a key rival's three-drug regimen.
- At a Monday meeting with investors, ViiV claimed dolutegravir — an active ingredient found in GSK's single-agent blockbuster Tivicay and its recently approved doublet Juluca — is the most potent antiretroviral drug to date. ViiV also argued an investigational combination it's working on consisting of dolutegravir and lamivudine is just as effective as the three-drug combo of dolutegravir, emtricitabine and tenofovir disoproxil fumarate in patients with high or low viral loads.
- First approved in November 2017, Juluca sales totaled £71 million ($96 million) during the first nine months of 2018. ViiV management noted that Juluca will be more of a niche product, used only in patients switching from another therapy, according to a Dec. 11 note from investment bank Cowen & Co. Still, Juluca has been largely overshadowed by the early success of Gilead Sciences' triplet Biktarvy.
The Food and Drug Administration approved more than three dozen new HIV medications over the last 20 years. In that now crowded treatment landscape, GSK and Gilead have taken leading positions — accounting for 91% of total prescriptions, according to data cited by Credit Suisse.
Both companies are investigating a variety of treatments, yet each appears to be focusing on one type in particular.
For GSK, it's two-drug combos. The British pharma believes doublets can be just as potent as regimens with more active ingredients, while also reducing pill burdens and the risk of long-term side effects like renal problems and reduced bone mineral density.
Juluca (dolutegravir/rilpivirine) was the first GSK and ViiV doublet to come to market. While sales haven't been astronomical, the companies are bullish on their dolutegravir and lamivudine combo, which they say has promise in treatment-naïve and switch patients. Data from the GEMINI program showed the investigational doublet was non-inferior to a regimen of dolutegravir plus Gilead's Truvada (emtricitabine/tenofovir disoproxil fumarate), with 91% and 93% of patients treated with the respective regimens achieving HIV control.
GSK expects an approval of the new doublet in the second half of 2019. It's also working on a once-a-month injectable combo of cabotegravir and Johnson & Johnson's rilpivirine, with an anticipated U.S. approval in early 2020.
"Both these combinations from GSK demonstrated non-inferiority compared to standard [three-drug regimen] and also indicated the wide variety of patient populations that GSK is targeting at with its developmental HIV drugs," Credit Suisse analyst Vamil Divan wrote in a Dec. 7 note.
Some concerns do remain, however, that doublets could invite treatment-emergent resistance compared to standard triplets, although GSK and ViiV studies have not yet shown that to be a risk.
To that point, much of Gilead's attention has been on triplets like the recently launched Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide). Last year, the drug showed no resistance across two Phase 3 trials of HIV-positive adults who hadn't previously received antiretroviral treatment.
Since its launch earlier this year, Biktarvy has experienced strong pickup. Divan noted that Gilead's share of new-to-brand prescriptions for HIV drugs has increased from 66% to 74%, mostly due to Biktarvy, which held 26% of the market as of Dec. 7. Over the first nine months of 2018, sales of the drug hit $606 million.
GSK and Gilead's hypotheses will likely be tested in the next few years as Biktarvy takes on GSK's advancing doublets.
With each company facing their own set of business challenges, HIV has and should continue to be an important market to lay claim to. ViiV estimates there are 1.34 million U.S. patients living with HIV, yet 39% aren't on antiretroviral therapy and around 50% aren't suppressed.
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