AstraZeneca stock fell Friday after a Food and Drug Administration advisory panel voted against approving its experimental breast cancer drug camizestrant, raising a significant hurdle for one of the company's pipeline medicines.

Thursday's 6-3 vote by the FDA's Oncology Drugs Advisory Committee concluded that the drug had failed to show a "meaningful benefit," according to Bloomberg — specifically for patients with a genetically driven form of metastatic breast cancer who were still responding to their current treatment. Concerns about how the trial was structured and what the results would mean in real-world practice drove the dissenting votes. AstraZeneca's London-listed stock fell 2% in morning trading Friday.

The FDA is not bound by advisory committee recommendations but typically follows them. An official decision on the drug is expected later.

Underlying the committee's deliberations were Phase 3 data from SERENA-6 showing that camizestrant cut the risk of disease progression or death by 56% relative to standard treatment, according to CNBC . Median progression-free survival reached 16 months among camizestrant recipients — nearly double the 9.2 months seen in patients who remained on standard-of-care regimens, Bloomberg reported. The panel did not raise significant concerns about the drug's safety or toxicity.

The panel’s main concern was about timing: they questioned whether switching patients to camizestrant before visible signs of disease progression would lead to a lasting survival benefit. The advisers did not doubt that camizestrant could be helpful, but focused their skepticism on what the trial design actually showed.

In a statement, AstraZeneca pushed back on the vote, saying it stood behind its trial data and maintained that camizestrant offers genuine benefit to patients. "We will continue to work with the FDA as it completes its review," Executive Vice President of Oncology Haematology R&D Susan Galbraith said in a statement.

Camizestrant is an oral drug designed to treat hormone receptor-positive, HER2-negative breast cancer — the most common subtype of the disease — in patients whose tumors carry a mutation in the ESR1 gene, which can drive resistance to standard therapies, AstraZeneca said.

AstraZeneca posted stronger-than-expected first-quarter results earlier this week, with total revenue rising 13% to $15.29 billion and its oncology division leading growth. At the time, CEO Pascal Soriot said the company remained on track to meet its 2030 revenue goals, with camizestrant among the drugs it hoped to bring to market in 2026 pending U.S. regulatory clearance.