GSK’s ViiV is poised to take a bite out of Gilead’s HIV empire, after its dual HIV regimen — Dovato — secured FDA approval on Monday, after the British drugmaker submitted its marketing application with a priority review voucher (PRV) last October, enabling a speedy response from the US regulator.
Dovato is an improvement over GSK’s existing two-drug regimen Juluca, which does not include a nucleoside analog reverse transcriptase inhibitor or a ‘nuke.’ This family of drugs are used to thwart an enzyme called reverse transcriptase, which is used by the HIV virus to make copies of itself inside a healthy cell.
Akin to Juluca, GSK’s new two-drug regimen Dovato also includes its integrase inhibitor, dolutegrevir (DTC). Integrase inhibitors, such as dolutegrevir and Gilead’s bictegrevir, work against HIV’s integrase protein, blocking its ability to integrate its genetic code into human cells.
However, unlike Gilead, GSK has a chronic issue with its HIV combination regimens: suboptimal nukes, Evercore ISI’s Umer Raffat highlighted in a note. For example, GSK’s Triumeq — which includes DTC and two nukes — features abacavir, a nuke that has been linked to hypersensitivity and CV issues, he said, underscoring that due to patent issues GSK was not able to use a nuke better than abacavir in the past.
This has had an impact on GSK’s HIV sales. Prescription volumes indicate that demand for its DTC monotherapy, Tivicay, and DTC combo Triumeq are similar, according to Raffat. In effect, it looks like half the patients taking DTC undergo the hassle of taking another pill in addition to Tivicay: Gilead’s clean two-nuke combo Truvada, he said.
Due to these issues, Gilead’s single tablet with two good nukes in it — Biktarvy — has done extremely well, Raffat noted.
With the Dovato approval, GSK now has a product that does not require separate Truvada administration, does not include an abacavir component which has safety concerns, and can compete directly against Biktarvy. (Although the data from patients in Botswana suggested a link between DTC and birth defects, prompting the WHO to recommend that women in the early stages of their pregnancy not use the drug). In addition, GSK’s Dovato features an off-patent nuke called lamivudine, which allows for a comparatively cheaper list price versus Biktarvy.
According to Raffat, Biktarvy carries annual price tag of $37,000, while Dovato is 26% cheaper at $27,500.
GSK’s approach to grabbing market share from Gilead $GILD — which currently dominates the HIV market that is estimated to hit $22.5 billion by 2025 — is to convince regulators, doctors and patients to adopt its two-drug regimens, versus Gilead’s triple-drug cocktails, that could potentially result in fewer toxic side-effects, reduce dosing frequency, and be more cost-effective — although critics suggest this may not be the most effective strategy because the virus will only have to fight against two drugs which could culminate in drug resistance.
Results of two phase III GEMINI trials testing Dovata presented last year showed that GSK’s therapy worked as well as standard three-drug therapy in treatment-naive patients with both low and high levels of the virus, and significantly, no patient in the 1,400 patients enrolled across the trials, developed drug resistance. This was a crucial worry as there was a reported case of drug resistance in a previous study.
The regimen is currently under review in Europe, Canada, Australia, Switzerland, and South Africa.
According to WHO estimates, 36.9 million people were living with HIV globally in 2017. The best way to thwart the spread of HIV is to use condoms. But for those already afflicted with the virus, antiretroviral therapy must be taken every single day to suppress the virus or unbridled replication can overwhelm the immune system and eventually cause AIDS. Daily pills also rack up expensive bills in the United States, with monthly expenditure on treatment hitting thousands per month — depending on the regimen, insurance provider and rebates/discounts.
“With Dovato, the first complete, single-tablet, two-drug regimen for treatment-naïve adults, ViiV Healthcare is delivering what patients are requesting—a chance to treat their HIV-1 infection with as few drugs as possible,” ViiV chief Deborah Waterhouse said in a statement.
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