Investing.com -- AstraZeneca shares fell Thursday after an outside panel of experts to the U.S. Food and Drug Administration voted against supporting the risk-benefit profile of the company’s experimental breast cancer treatment camizestrant.

The stock slipped 1.6% in London by 07:37 GMT.

The FDA’s Oncologic Drugs Advisory Committee voted 6 to 3 against the oral drug, which AstraZeneca is developing as a first-line treatment for a form of breast cancer driven by a specific genetic mutation. The panel concluded the drug did not show a "meaningful benefit" for patients with the condition whose disease had not progressed on existing therapy.

While advisory panel votes are not binding, the FDA typically follows their recommendations. A final agency decision is expected later.

The decision creates "regulatory overhang and a dent to investor sentiment," Morgan Stanley analysts led by Sarita Kapila said.

"We see a decreased likelihood of approval in the SERENA-6 setting following the 6–3 negative ODAC vote, though approval remains possible," they noted.

AstraZeneca said it was "disappointed" by the outcome but expressed confidence in its trial results and the drug’s potential benefit for patients.

In clinical trials, camizestrant delayed disease progression by more than six months. Used in combination with other cancer medicines, it helped patients live a median of 16 months without progression, compared with 9.2 months for those on the current standard of care.