• Each year in Europe more than 550,000 patients are diagnosed with breast cancer, of whom 70% have estrogen receptor (ER)-positive disease¹; more than 147,000 breast cancer patients in Europe die annually from the disease²
• ORSERDU is the first treatment specifically for patients with ER+, HER2- advanced or metastatic breast cancer tumors that harbor ESR1 mutations, representing the first innovation in endocrine therapy in nearly 20 years
• ESR1 mutations are present in up to 40% of ER+, HER2- advanced or metastatic breast cancers, and are a known driver of resistance to standard endocrine therapy, making these tumors more difficult to treat

The European Commission’s approval follows the positive opinion of the Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA), which was issued in July 2023. With this approval, ORSERDU is the first and only therapy specifically indicated for the treatment of ER+, HER2- tumors that harbor ESR1 mutations. ESR1mutations are acquired mutations that develop as a result of exposure to endocrine therapy, and they are found in up to 40% of patients with ER+, HER2- mBC. ESR1 mutations are a known driver of resistance to standard endocrine therapy, and until now, the tumors that harbor these mutations have been more difficult to treat.

“We have long known that patients living with metastatic breast cancer need effective and tolerable options which treat their disease while enabling them to focus on the things that matter to them,” said Elcin Barker Ergun, CEO of the Menarini Group. “We are proud of delivering a new breast cancer treatment that offers efficacy in a once-daily pill and represents the first innovation in endocrine therapy in nearly two decades; we are also incredibly grateful for the support of the oncology researchers and all the patients who participated in the clinical studies that made today’s achievement possible.”

“With a significant number of ER+ HER2- patients ultimately developing ESR1 mutations at some point in their metastatic journey, it is important to test for ESR1 each time an mBC patient experiences disease progression, to understand what is fueling their breast cancer. Today’s approval gives us the first-ever treatment option that directly acts against the very mutations that make this form of breast cancer more difficult to treat, and provides hope to our patients and their families,” said Giuseppe Curigliano, MD, PhD, Professor of Medical Oncology at the University of Milano and the Head of the Division of Early Drug Development at the European Institute of Oncology, IRCCS, Italy.

The approval of ORSERDU is supported by data from the Phase 3 EMERALD trial, which demonstrated statistically significant progression-free survival (PFS) with elacestrant versus standard-of-care (SOC), defined as investigator’s choice of an approved endocrine monotherapy. The primary endpoints of the study were PFS in the overall patient population and in patients with ESR1mutations. In the group of patients whose tumors had ESR1 mutations, elacestrant achieved a median PFS of 3.8 months vs 1.9 months on the SOC, and reduced the risk of progression or death by 45% (PFS HR=0.55, 95% CI: 0.39, 0.77) vs SOC.

A post hoc subgroup analysis of the EMERALD PFS results, which was presented at the San Antonio Breast Cancer Symposium (SABCS) 2022, demonstrated that the duration of prior CDK4/6i treatment was positively associated with longer PFS on elacestrant but not with SOC. For patients with ESR1 mutations who were treated with CDK4/6i for ≥12 months prior to randomization on EMERALD, elacestrant achieved a median PFS of 8.6 months versus 1.9 months on SOC, with a 59% reduction in the risk of progression or death (HR=0.41 95% CI: 0.26-0.63).³

Safety data were consistent with previously reported results. The most common (≥ 10%) adverse reactions with ORSERDU were nausea, triglycerides increased, cholesterol increased, vomiting, fatigue, dyspepsia, diarrhoea, calcium decreased, back pain, creatinine increased, arthralgia, sodium decreased, constipation, headache, hot flush, abdominal pain, anaemia, potassium decreased, and alanine aminotransferase increased. Important Safety Information for ORSERDU is provided below.

Stemline and its affiliates will commercialize the product within Europe.