• 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
• If approved by the European Commission, ORSERDU would be the first and only treatment specifically indicated for patients with ER+, HER2- advanced or metastatic breast cancer tumors that harbor ESR1 mutations
• 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 CHMP opinion will now be reviewed by the European Commission, which has the authority to grant marketing authorization for human medicines throughout the European Union (EU). If approved, Stemline and its affiliates will commercialize the product within Europe. ORSERDU would be the first and only therapy specifically indicated for the treatment of ER+, HER2- tumors that harbor ESR1 mutations. ESR1 mutations 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.

"Patients living with metastatic breast cancer are in need of efficacious and tolerable treatment options. ORSERDU may become the first product, if approved by the European Commission, indicated in ER+, HER2- advanced breast cancer with ESR1 mutations, which are a strong driver of resistance to treatment in up to 40% of patients in second line mBC. ORSERDU, if approved, will also provide a convenient daily oral treatment," said Elcin Barker Ergun, CEO of the Menarini Group. "We are proud of positive CHMP opinion as it reflects our commitment to developing innovative solutions that address the greatest unmet needs in cancer treatment, and brings us one step closer to providing an important new option to the patients and families impacted by ESR1-mutated, ER+, HER2- metastatic breast cancer."

The positive CHMP opinion for 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 ESR1 mutations. 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 were 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

"As an oncologist, it is remarkable that we are on the cusp of having the first treatment option for patients with advanced or metastatic ER+, HER2- breast cancer harboring ESR1 mutations, which occur in up to 40% of patients in the metastatic setting," 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. "Elacestrant has demonstrated efficacy and a manageable safety profile, underscoring the potential benefit this therapy may soon bring to the patients we care for, and to the broader oncology community." 

Safety data were consistent with previously reported results. Serious adverse reactions reported in ≥ 1% of patients included nausea, dyspnoea, and thromboembolism (venous). 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. The most common Grade ≥3 (≥2%) adverse reactions of elacestrant were nausea (2.7%), AST increased (2.7%), ALT increased (2.3%), anaemia (2%), back pain (2%), and bone pain (2%).