Novel Drug Fails to Improve Survival in a Certain Group of Patients With Breast Cancer

Patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer did not have a survival benefit after receiving treatment with amcenestrant when compared with a physician’s choice of a single agent endocrine therapy, according to the novel agent’s manufacturer, Sanofi.

“This phase 2 trial evaluated amcenestrant as a monotherapy in a patient population with advanced disease where limited treatment options remain,” Dr. John Reed, head of research and development at Sanofi, said in a press release announcing the findings of the AMEERA-3 trial. “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 different standard-of-care treatments are used.”

Amcenestrant is an investigational optimized oral selective estrogen receptor degrader (SERD) which, according to Sanofi, binds to the estrogen receptors in breast cancer cells to block their normal function so they can no longer grow.

The aim of the AMEERA-3 trial was to assess amcenestrant’s efficacy in extending progression-free survival (which was defined as the time from the start of treatment to the date of documented tumor progression) versus Faslodex (fulvestrant), anastrozole, letrozole, exemestane or tamoxifen.

Additional goals included measuring amcenestrant’s effect on overall survival (percentage of patients still alive during a defined period after starting treatment), objective response rate (the proportion patients whose disease completely or partially responds to treatment), disease control rate (the sum of partial and complete responses as well as stable disease) and several other outcomes.

An update of the phase 2 trial showed that amcenestrant failed to improve progression-free survival in the patient population. Sanofi announced it will continue to assess data from this study and publish the final results at a later date.

Sanofi, according to the release, will continue to assess the investigational therapy in two other trials that are actively recruiting patients.

In the multicenter, phase 3 AMEERA-5 trial an estimated 1,068 patients with estrogen receptor-positive, HER-2 negative breast cancer will receive either amcenestrant plus Ibrance (palbociclib) or letrozole plus Ibrance to determine if amcenestrant plus Ibrance is superior at improving progression-free survival.

The second trial, AMEERA-6, is a multicenter study including an estimated 3,738 patients with hormone receptor-positive, HER2-negative or positive, stage 2b to 3 breast cancer who have discontinued adjuvant aromatase inhibitor therapy due to treatment-related side effects. In this trial, the study authors plan to evaluate the safety and efficacy of amcenestrant versus tamoxifen in this patient population. The main goal of this trial will be to measure the effects of each treatment on invasive breast cancer-free survival (the time from trial randomization to date of first occurrence of disease recurrence or death).

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