Sanofi breast cancer drug fails in pivotal trial

March 14, 2022

Sanofi’s oral selective estrogen receptor degrader (SERD), amcenestrant, failed to meet its primary endpoint in a phase 2 trial after data showed that the drug was no better than physicians’ choices at improving progression-free survival, the company announced this week. 

The AMEERA-3 trial included 367 patients, and the cohorts received either amcenestrant or a physician’s choice of drugs, including Astrazeneca’s oral SERD Faslodex. The trial results did not demonstrate meaningful clinical differences between the groups, limiting the possibility of amcenestrant's approval for its use as second-line or later treatment for ER+/Her2- breast cancer. 

Amcenestrant is an optimized oral SERD that 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.

Head of research and development at Sanofi, John Reed said, “This Phase 2 trial evaluated amcenestrant as a monotherapy in a patient population with advanced disease where limited treatment options remain. While we are disappointed with the AMEERA-3 results, we continue to investigate amcenestrant in patients with earlier stages of breast cancer with different tumor profiles and where a different standard of care treatments are used.”

Sanofi says they will continue to evaluate data from the trial and work with researchers on the publication to understand the full scope of the results. The company is also moving forward with two other trials of amcenestrant — one in combination with Pfizer’s Ibrance as the first line of treatment and another to explore its potential in early-stage breast cancer patients in the adjuvant setting (AMEERA-6).