Why Sanofi (SNY) Shares Are Falling Today - Sanofi (NASDAQ:SNY)

Sanofi SA SNY said it would stop further work on breast cancer drug amcenestrant, putting pressure on Sanofi to bolster its drug development pipeline as it grows increasingly dependent on its best-seller, eczema and asthma treatment Dupixent.
A trial dubbed AMEERA-5, which was testing amcenestrant on women with newly-diagnosed advanced breast cancer was stopped early because an independent monitoring panel found no signs of it working. "All other studies of amcenestrant, including in early-stage breast cancer (AMEERA-6), will be discontinued," Sanofi said.
No new safety signals were observed. Trial participants will be transitioned to letrozole in combination with palbociclib or another appropriate standard of care therapy, as determined by their physician.
In March, Sanofi announced disappointing results of a breast cancer study involving previously treated women.
Sanofi said the drug, which was used with Pfizer's Inc's PFE Ibrance (palbociclib) in the study, "did not meet the prespecified boundary for continuation" when compared to a group of patients in the trial on standard hormone therapy.
Amcenestrant belongs to a drug class known as selective estrogen receptor degraders (SERD) to fight tumors that grow in response to estrogen.
Price Action: SNY shares are down 6.40% at $41.94 during the premarket session on the last check Wednesday.

Sanofi Ends Development Of Breast Cancer Drug Amcenestrant After Trial Failure