The Menarini Group and Stemline Therapeutics announced that the U.S. Food and Drug Administration (FDA) has accepted the Company's New Drug Application (NDA) for elacestrant, an investigational selective estrogen receptor degrader (SERD), for patients with ER+/HER2- advanced or metastatic breast cancer. The FDA has granted the application Priority Review and assigned a PDUFA date of February 17, 2023. The FDA grants Priority Review designation to medicines that it considers having the potential to provide significant improvements over current SOC in the safety and effectiveness of the treatment, diagnosis, or prevention of serious conditions.

The FDA granted Fast Track designation for elacestrant in 2018. The NDA submission was supported by results of the Phase 3 data from the EMERALD study. EMERALD met both of its pre-specified primary endpoints of progression-free survival (PFS) in the overall population and in patients with the ESR1 mutation (mESR1) compared to SOC endocrine monotherapy; the trial's comparator arms were investigators' choice of either fulvestrant or an aromatase inhibitor.

The PFS rate at 12 months with elacestrant was 22.32% vs. 9.42% with SOC in the overall population, and 26.76% vs. 8.19% in the ESR1 mutation population.

The clinical trial data showed that elacestrant reduced the risk of disease progression or death by 30% in all patients and by 45% in patients with ESR1 mutation. The data also showed a manageable safety profile. Elacestrant is an investigational compound and is not approved by any regulatory authorities.

The Marketing Authorization Application (MAA) has also been submitted to European Medicines Agency (EMA) in July 2022.