British drug giant GlaxoSmithKline wants to claim a larger piece of the HIV drug market. Its strategy: convince patients, doctors and insurance providers that treatments made up of two drugs are better than those made up of three.
But market data suggest the plan hasn't panned out. Prescriptions for Dovato, the latest two-drug HIV pill from GSK and its majority-owned partner ViiV Healthcare, tipped just over 1,100 for the week ending Dec. 27, according to data cited by RBC Capital Markets. Meanwhile, doctors wrote more than 27,000 prescriptions for Biktarvy, a three-drug product developed by GSK's main rival in the HIV treatment market, Gilead.
Sales reflect these different prescribing rates. Dovato, which launched last April, brought in roughly $30 million for GSK by the end of September. Another two-drug GSK pill, Juluca, fetched around $335 million across the first nine months of the year. Yet Biktarvy sales were almost 10 times higher, coming in at $3.2 billion over the same period.
RBC analysts argue that Dovato's impact on Biktarvy prescriptions has been "negligible," and that it's "unlikely to significantly erode" Gilead's share of the HIV drug market. If that forecast holds true, it could mean billions of dollars in unrealized sales for GSK and ViiV.
GSK leadership has maintained it's too early to make such conclusions. "We continued to build momentum with the two-drug regimens but, as anticipated, it will take several quarters for them to become a significant contributor to growth," Iain Mackay, chief financial officer, said in late October while detailing the company's third quarter performance.
There's pressure for GSK to deliver on its strategy sooner than later. Third quarter sales from HIV drugs were flat year over year, while sales from the company's entire pharmaceutical portfolio over the first nine months of 2019 were up 1% under constant exchange rates.
Gilead presents a significant barrier, however. The California biotech commands 75% of the HIV drug market, and analysts see that reign continuing due to strong sales from Biktarvy and several other products, such as Truvada. Piper Jaffray expects U.S. sales from Gilead's five top-selling HIV medications to breach $13 billion this year, representing 92% of the total HIV drug market.
GSK has another problem aside from modest Dovato and Juluca sales. Last month, the Food and Drug Administration decided not to approve a new HIV treatment that combined a ViiV drug called cabotegravir with a Johnson & Johnson drug called rilpivirine. GSK said the rejection wasn't due to safety, but rather issues with the drug's manufacturing.
The combination could help differentiate GSK's portfolio, as it comes in the form of a once-per-month shot rather than a daily pill like most HIV medications. GSK and ViiV said they're working with regulators to remedy the manufacturing problems.
A diverse portfolio may be crucial for GSK and its rivals as competition grows in HIV. Merck & Co., for instance, is developing its own two-drug therapy that executives have been bullish on. Merck's Chief Marketing Officer, Michael Nally, has gone as far as saying the therapy could be a "foundational anchor" for two-drug treatments.
Two-drug options, according to GSK and others, represent a potentially safe option for patients, as there are fewer active ingredients to spur side effects.