Gilead Shares Fall After Key Cancer Drug Trial Misses Primary Goal
Trodelvy failed to meet its progression-free survival endpoint in a Phase 3 breast cancer study, overshadowing a potential positive trend in overall survival.
Shares of Gilead Sciences (GILD) fell in early trading after the biopharmaceutical giant announced its key oncology drug, Trodelvy, failed to meet its primary goal in a late-stage clinical trial for a specific type of breast cancer. The news represents a significant setback for a drug considered central to the company's expansion beyond its core virology business.
In a statement released Friday morning, Gilead disclosed that the Phase 3 ASCENT-07 study did not achieve its primary endpoint of statistically significant improvement in progression-free survival (PFS) for patients with HR+/HER2- metastatic breast cancer who had received at least one prior line of endocrine therapy. The stock reacted immediately, dropping 3.6% to $118.92 in morning trading.
Progression-free survival measures the length of time patients live with a disease without it worsening. Failing to meet this primary endpoint complicates the path for expanding Trodelvy's use in this patient population, which is a large and competitive market segment. Trodelvy, an antibody-drug conjugate, is already approved for other forms of breast cancer and bladder cancer and is a cornerstone of Gilead's growing cancer drug portfolio.
Despite the primary endpoint miss, Gilead executives pointed to a potential silver lining. The company noted that the study revealed "an early trend toward an overall survival (OS) benefit" in the Trodelvy arm compared to the physician's choice of chemotherapy. Overall survival, a key secondary endpoint, is considered the gold standard in oncology trials as it measures whether a treatment helps patients live longer.
"While the primary endpoint of progression-free survival was not met in ASCENT-07, we are encouraged by the early trend in the key secondary endpoint of overall survival," said Merdad Parsey, MD, PhD, Chief Medical Officer at Gilead Sciences. The company confirmed the study will continue to its final analysis of overall survival.
This nuanced result leaves investors and clinicians in a wait-and-see position. A definitive overall survival benefit could still provide a path for regulatory approval, but the failure to improve progression-free survival makes the drug's clinical profile less compelling against existing and emerging competitors. According to a report from Benzinga, the safety profile of Trodelvy in the trial was consistent with previous studies, with no new safety concerns identified.
The trial miss underscores the challenges Gilead faces in its strategic pivot to become a major player in oncology, a move designed to diversify its revenue streams which have long been dominated by its HIV and hepatitis C franchises. The company has invested heavily in this area, most notably through its $21 billion acquisition of Immunomedics in 2020, which brought Trodelvy into its pipeline.
Analysts have set an average price target of $129.51 for Gilead, a figure that will likely be revisited in light of the ASCENT-07 results. The outcome puts more pressure on other assets in Gilead's oncology pipeline to deliver clear wins.
Coincidentally, Gilead also released positive long-term data for another drug, Livdelzi, for the rare liver disease primary biliary cholangitis on the same day. However, the market's focus remained squarely on the setback for Trodelvy, a product with significantly higher commercial expectations. The mixed news highlights the volatile nature of biopharmaceutical development, where a single trial outcome can significantly alter a company's growth trajectory and investor sentiment.