Gilead Sciences Inc (NASDAQ:GILD, ETR:GIS) dropped up to 4% on Tuesday following an announcement that the US Food and Drug Administration (FDA) has placed clinical holds on studies involving two of the company’s investigational HIV drugs.
The FDA’s clinical hold affects trials of GS-1720, an integrase strand transfer inhibitor, and GS-4182, a capsid inhibitor.
The hold was prompted because the combination of the two drugs appeared to cause a drop in CD4+ T-cell counts and absolute lymphocyte counts in some patients.
In a statement, Gilead said it remains committed to investigating the potential of both compounds and working closely with regulators to address the issues behind the hold. "The safety of individuals taking Gilead medicines is our foremost priority," the company added.
Jefferies analysts described the clinical hold as a headline risk but maintained a positive long-term outlook on Gilead. They noted the hold pertains to a Phase II trial of a weekly oral combination pill for HIV treatment—not pre-exposure prophylaxis (PrEP)—which uses two novel agents: GS-1720 and a lenacapavir prodrug GS-4182.
“While this development may introduce some investor uncertainty ahead of the pivotal June 19 PDUFA date for lenacapavir-based PrEP, we do not anticipate a major impact on the approval timeline or the broader outlook for Gilead,” Jefferies analysts wrote.
Jefferies further clarified that the clinical hold is limited to this specific oral formulation and trial population and does not affect other Gilead programs involving lenacapavir or integrase inhibitors, including the injectable versions of the drugs.
The analysts also pointed to Gilead’s strong pipeline, highlighting ongoing development of long-acting injectable treatments that could reshape the market, notably the potential to replace the $15 billion Biktarvy franchise with a twice-yearly injectable regimen.
Shares of Gilead were down around 1.7% around midmorning Tuesday.