Time to test GSK's 2-drug HIV theory
- GlaxoSmithKline has a theory that HIV patients will gravitate to treatment regimens with fewer drugs. The British pharma now gets to test that hypothesis, as one of its subsidiaries just won U.S. approval for a two-drug therapy.
- Dovato comes as a once-daily tablet meant for HIV patients who have never before received antiretroviral therapy and who aren't resistant to either of the drug's two main components: a nucleoside analogue, lamivudine, and an integrase inhibitor, dolutegravir. Regulators approved the combo treatment based on data from a pair of late-stage studies.
- The list price for Dovato clocks in at $2,295 per month, or $27,540 per year, making it the lowest cost single-tablet regimen containing an integrase inhibitor, according to GSK. Other HIV medications that contain integrase inhibitors include GSK's Tivicay, Gilead's Biktarvy and Merck & Co.'s Isentress.
Leading HIV drugmakers are debating what number of drugs are needed to keep the virus in check — as well as carve out market share.
GSK and ViiV bet that, at least for now, the answer is two rather than three or more.
"Given that all drugs have side effects, reducing by a third, we think, is ultimately good for individuals in the longterm," said Kim Smith, ViiV's head of global research and medical strategy, in an interview with BioPharma Dive.
ViiV is majority owned by GSK, with Pfizer and Japanese drugmaker Shionogi holding smaller stakes.
The gamble isn't paying off yet. While GSK and ViiV already got their first two-drug pill, a combo of dolutegravir and rilpivirine branded as Juluca, approved in late 2017, it has thus far brought in moderate sales and is largely viewed as a niche product.
Juluca is just the start, however. GSK is working on a handful of other two-drug HIV treatments, with expectations particularly high for Dovato. David Redfern, the company's chief strategy officer, noted on a recent earnings call that the drug will be a key growth driver once it launches.
Others also foresee Dovato doing well, and even posing competitive problems to Gilead's Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide), a three-drug HIV regimen that has enjoyed an impressive U.S. launch.
Evercore ISI analyst Umer Raffat in an April 8 note to investors called GSK's dolutegravir an "excellent" integrase inhibitor, yet one that has been stymied as a combo by the company's nucleoside analogues, which carry some safety concerns. That dynamic has allowed Biktarvy to do "extremely well" taking market share from GSK, according to Raffat.
But Dovato and its use of lamivudine present a much greater competitive threat. Though its label does list several warnings, including one that cautions against taking Dovato during early pregnancy and another about hepatotoxicity, the drug didn't elicit any cases of resistance after 48 weeks of clinical testing. That's important, given how resistance has been a key question for two-drug regimens.
Additionally, GSK plans to sell Dovato for less than Biktarvy, which has a list price of $37,000. Raffat wrote that "uptake in coming weeks will be critical," and especially so in relation to Biktarvy's new prescription totals.
ViiV's Smith noted that the pregnancy concerns stem from a study in Botswana where there was a safety signal involving neural tube defects. She said different patient cohorts across other countries haven't experienced that safety concern, but it's something to keep an eye on as more results become available.
"We're waiting to see whether or not there's more data that actually makes this signal more definitive, or whether or not there's more data that actually says that this may have been a false signal," Smith said.
Follow Jacob Bell on Twitter