Sanofi Cancer Drug Setback Hobbles Potential Blockbuster (1)

Sanofi’s experimental medicine amcenestrant failed in a clinical test for breast cancer, dealing a blow to one of the French drugmaker’s potential blockbusters.

The patients who got the drug, rather than endocrine treatment, didn’t live longer without the disease progressing -- a key benefit measure known as progression-free survival -- in the phase 2 trial, Sanofi said Monday. The stock fell as much as 6.2% in Paris trading, the steepest drop in almost two years.

The medicine is one of six products Sanofi has touted as “potentially transformative” and prioritized. The disappointing result doesn’t mean it’s the end of ...