(Bloomberg) -- 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 the road for amcenestrant, but it raises the risk of failure for other trials underway, according to Bloomberg Intelligence. The company said it would press ahead with the other tests.
Rival drugmakers including Roche Holding AG and Radius Health Inc. are piling into this class of treatments, seeking to develop an oral successor to AstraZeneca Plc's injected Faslodex. Analysts at Jefferies estimate the market for these medicines, known as oral-SERDs, is worth at least $7 billion to $8 billion.
What Bloomberg Intelligence Says:
Competition is hot, with Radius Health already reporting success in its Emerald trial of elacestrant. More detail is needed to assess why Sanofi's drug failed and Radius' worked. Next up this year is Roche, with data for giredestrant.
--John Murphy and Sam Fazeli, BI Pharma analysts.
In the Sanofi trial, the patients had advanced disease and few treatment options remaining, and the medicine wasn't combined with another as is often the case in cancer.
“We continue to investigate amcenestrant in patients with earlier stages of breast cancer with different tumor profiles and where different standard of care treatments are used,” said John Reed, the company's head of research.
The drug binds to the estrogen receptors in breast-cancer cells to inhibit their normal function and trigger degradation so they can no longer be used by tumor cells to grow. Other trials include one called Ameera-5, an advanced study in which amcenestrant is combined with Pfizer Inc.'s Ibrance as a first-line treatment of breast cancer that has spread.
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