Shares of Gilead Sciences (NASDAQ:GILD) fell 4% on Tuesday following the company's announcement that the U.S. Food and Drug Administration (FDA) has placed clinical holds on studies of several of its investigational HIV drugs.
The FDA's decision specifically impacts trials for Gilead's experimental HIV treatments, GS-1720 (an integrase strand transfer inhibitor) and/or GS-4182 (a capsid inhibitor).
The regulatory agency cited a safety signal observed in a subset of participants receiving the combination of GS-1720 and GS-4182, which showed decreases in CD4+T-cell (CD4) and absolute lymphocyte counts.
CD4 cells are crucial for immune system function, and their decline can indicate a weakening of the body's defenses.
In a press release, Gilead stated its commitment to addressing the FDA's concerns.
"We intend to investigate and pursue the potential of both agents and are committed to working with regulatory authorities to resolve the issues underlying the clinical hold," the company said.
"The safety of individuals taking Gilead medicines is our foremost priority and we remain focused on pursuing advances to improve outcomes and expand options for people living with HIV."
The clinical hold introduces uncertainty for Gilead's HIV pipeline, a key area of focus for the biopharmaceutical giant.