Merck Challenges Gilead's HIV Dominance with Positive Drug Trial
Investigational two-drug regimen proves non-inferior to Gilead's blockbuster Biktarvy in pivotal Phase 3 study, setting the stage for a new competitor in the lucrative HIV market.
Merck is positioning itself to challenge Gilead Sciences’ long-standing dominance in the HIV treatment market after announcing its investigational two-drug combination therapy met the primary goals in a pivotal Phase 3 trial. The results show the therapy is as effective as Gilead’s market-leading blockbuster, Biktarvy.
The pharmaceutical giant, with a market capitalization of over $240 billion, revealed Wednesday that its single-tablet regimen of doravirine and islatravir (DOR/ISL) demonstrated non-inferiority to Biktarvy for treating adults with HIV-1 infection who had not previously received treatment. This successful outcome is a critical step for Merck as it seeks to diversify its revenue streams ahead of the 2028 patent expiration of its top-selling cancer drug, Keytruda.
For years, Gilead’s Biktarvy has been the undisputed leader in HIV treatment. The three-drug tablet generated nearly $12 billion in sales in 2023 and commands over 50% of the U.S. market share. Merck’s ability to produce a competitive two-drug alternative could disrupt this dynamic, offering patients a potentially more streamlined treatment with a comparable safety profile.
“These encouraging results demonstrate that the investigational DOR/ISL regimen has the potential to be an important new once-daily option for the treatment of HIV-1,” said Dr. Eliav Barr, president of Merck Research Laboratories, in a company statement. The study found that after 48 weeks, 89.6% of patients taking Merck’s therapy achieved viral suppression, compared to 93.3% for the Biktarvy group, meeting the statistical definition of non-inferiority.
The development is central to Merck's broader strategy of de-risking its portfolio. With Keytruda responsible for a substantial portion of its revenue, the company has been actively pursuing new growth areas through internal development and strategic acquisitions. A successful entry into the multi-billion-dollar HIV market would provide a significant new revenue pillar.
Market reaction to the news was measured, with Merck’s (MRK) shares trading down about 1.7% at $94.75 in morning trading, suggesting that investors may have largely anticipated the positive outcome. Similarly, shares of Gilead (GILD) saw a slight dip of 0.4% to $126.69. The muted response indicates the market is now looking ahead to the next hurdles: regulatory approval and the subsequent commercial battle.
Merck confirmed that the U.S. Food and Drug Administration (FDA) has accepted its New Drug Application (NDA) for the combination therapy and has set a target action date of April 28, 2026. If approved, Merck will face the formidable task of unseating a well-entrenched incumbent.
While Gilead's Biktarvy is a three-drug cocktail, the push toward regimens with fewer components is a key area of research in HIV treatment, aiming to reduce the long-term toxicities and drug-to-drug interactions for patients on lifelong therapy. Merck’s positive results for a two-drug option align with this trend and could become a key marketing point. The road ahead involves a complex interplay of regulatory milestones, physician adoption, and insurance coverage negotiations, but Merck's successful trial marks the first significant step toward reshaping the competitive landscape of HIV therapy.