The Menarini Group ("Menarini") and Radius Health, Inc. ("Radius") announced that Menarini, with support from Radius, has submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for elacestrant in patients with ER+/HER2- advanced or metastatic breast cancer. As part of the submission, the Companies have requested Priority Review with the FDA. If Priority Review is granted, the Companies anticipate that the FDA would conduct an 8-month review, incorporating a 6-month priority designation review.

The NDA submission is based on positive phase 3 data from the EMERALD study that was previously announced on October 20, 2021. EMERALD met both of its primary endpoints, which were progression-free survival (PFS) in the overall population and PFS in the estrogen receptor 1 (ESR1) mutation subgroup as compared to standard of care (SoC) with the options of fulvestrant or an aromatase inhibitor. Elacestrant is the first and currently only investigational oral SERD to show positive topline results in a pivotal trial for the treatment of ER+/HER2- advanced or metastatic breast cancer in postmenopausal women, and men.

Notably, these results showed elacestrant is also active in patients whose tumors harbor an ESR1 mutation, one of the key resistance mechanisms that develops in later treatment lines of metastatic breast cancer. Following the completion of EMERALD, data from the study was presented at the San Antonio Breast Cancer Symposium (SABCS) on December 8, 2021, published in the Journal of Clinical Oncology (JCO) on May 18, 2022, and further subset analyses were presented at the 2022 American Society of Clinical Oncology (ASCO) annual Meeting on June 6, 2022. With the submission of the NDA, based on the original agreement of the Companies, Menarini takes over activities and will be responsible for registration and commercialization.

Menarini plans to use its fully owned subsidiary in the U.S., Stemline Therapeutics, to commercialize elacestrant if approved by the FDA. Elacestrant is an investigational selective estrogen receptor degrader (SERD), out-licensed to Menarini Group, which is being evaluated for potential use as a once daily oral treatment in patients with ER+/HER2- advanced breast cancer. In 2018, elacestrant received fast track designation from the FDA.

Preclinical studies completed prior to EMERALD indicate that the compound has the potential for use as a single agent or in combination with other therapies for the treatment of breast cancer. The EMERALD Phase 3 trial is a randomized, open label, active-controlled study evaluating elacestrant as second- or third-line monotherapy in ER+/HER2- advanced/metastatic breast cancer patients. The study enrolled 477 patients who have received prior treatment with one or two lines of endocrine therapy, including a CDK 4/6 inhibitor.

Patients in the study were randomized to receive either elacestrant or the investigator's choice of an approved hormonal agent. The primary endpoint of the study was progression-free survival (PFS) in the overall patient population and in patients with estrogen receptor 1 gene (ESR1) mutations. Secondary endpoints included evaluation of overall survival (OS), objective response rate (ORR), and duration of response (DOR).