The newly approved HIV drug Idvynso will also help Merck diversify as loss of exclusivity looms over its top-selling product, the mega-blockbuster cancer drug Keytruda.
The HIV has signed off on Merck’s daily pill Idvynso for the treatment of virologically suppressed HIV-1 in adults. The drug will hit U.S. shelves after May 11, according to a Tuesday news release.
The approval “could position Merck as a more meaningful competitor in HIV,” BMO Capital Markets told investors on Tuesday afternoon. The pharma “aims to market Idvynso as the new HIV anchor treatment.”
Indeed, Merck noted that Idvynso is intended “to replace the current antiretroviral regimen in those who are virologically suppressed,” particularly patients with no history of treatment failure or known resistance to doravirine.
Idvynso “is a complete regimen,” the pharma said. “Co-administration with other antiretroviral medications for treatment of HIV-1 infection is not recommended.”
Establishing Idvynso as a cornerstone drug in HIV care, however, “is likely an ambitious goal given Gilead’s longstanding dominance” in the space, BMO said. Gilead strengthen its HIV leadership further in June 2025 with the historic approval of Yeztugo, introducing a twice-yearly prophylactic option to the market. The company expects $800 million in Yeztugo sales this year.
Last year, Gilead brought in $20.8 billion in HIV sales, with the daily pill Biktarvy the top-selling product at $14.3 billion. BMO expects Merck’s new drug to have only “limited impacts to Gilead at most.”
The FDA’s approval is backed by data from two randomized and active-controlled studies looking at patients who had achieved virological suppression on Biktarvy treatment. Switching to Idvynso resulted in a non-inferior maintenance of viral suppression as staying on Biktarvy, Merck said.
“Idvynso expands therapeutic diversity beyond the currently available oral treatment options,” Merck CMO Eliav Barr said in a prepared statement.
Aside from challenging Gilead, Idvynso’s approval also “supports revenue diversification ahead of the Keytruda” loss of exclusivity, BMO said in its Tuesday note. The blockbuster cancer therapy is expected to lose key patent protections in 2028, though erosion could come at a gentler slope for Merck before hitting strongly in 2033, according to an analysis from Bloomberg Intelligence. This could mean up to $22 billion more Keytruda sales from 2030 to 2033.
Keytruda was the top-selling drug in 2025, earning $31.7 billion.
