Menarini Group and MEDSIR Present the Phase III Study ADELA: A New Therapeutic Strategy for Advanced Breast Cancer

• ADELA, an international phase III study being conducted across multiple countries, combines elacestrant with everolimus to treat advanced ER+/HER2- breast cancer with ESR1 mutations, aiming to delay disease progression.

• The study was presented by the Menarini Group and MEDSIR at the San Antonio Breast Cancer Symposium 2024 (SABCS 2024), one of the world’s most prestigious events in oncology.

• MEDSIR’s participation at SABCS 2024 solidifies its position as a global leader in oncology research and underscores its commitment to innovation and the development of more personalized and effective therapies.

The Menarini Group ("Menarini"), a leading international pharmaceutical and diagnostics company, and Stemline Therapeutics, Inc. ("Stemline"), a wholly-owned subsidiary of the Menarini Group focused on bringing transformational oncology treatments to cancer patients, along with MEDSIR, a leading global independent clinical research company in oncology and part of Oncoclínicas & Co., the largest specialized oncology treatment group in Latin America, presented research on the pioneering clinical trial ADELA. This important research addresses therapeutic resistance in advanced ER+/HER2- breast cancer. Presented at the San Antonio Breast Cancer Symposium 2024 (SABCS), the study represents a key milestone in the quest for more effective and personalized treatment options for patients with disease progression.

The standard first-line treatment for advanced ER+/HER2- breast cancer combines endocrine therapy with CDK4/6 inhibitors. ESR1 mutations develop as a result of prior exposure to endocrine therapy during metastatic treatment, and up to 50% of ER+, HER2- advanced or metastatic breast cancers will develop these mutations. ESR1 mutations cause the tumors to become resistant to endocrine therapy, in turn causing the cancer to progress; therefore, it is important to test for ESR1 whenever mBC progresses. Longer exposure to endocrine therapy during first-line treatment increases the chance of a patient’s tumor developing an ESR1 mutation. With the goal of addressing this unmet medical need, the ADELA phase III clinical trial investigates a new therapeutic option combining elacestrant, a next generation, oral selective estrogen receptor degrader, with everolimus, an mTORC1 inhibitor.

This combination is being evaluated in patients with advanced ER+/HER2- breast cancer that harbors ESR1 mutations, and who have experienced progression after standard first-line treatment. Results from the phase III EMERALD study were the basis for elacestrant’s approval. Meanwhile, everolimus has shown efficacy in inhibiting other resistance mechanisms in this type of cancer. The elacestrant and everolimus combination has demonstrated preliminary efficacy with a manageable safety profile in the phase 1b/2 ELEVATE study (NCT05563220).

“We at Menarini Stemline are delighted to announce the collaboration with MEDSIR to continue advancing the clinical research to explore the combination therapy with elacestrant,” said Nassir Habboubi, MD, Chief Medical Officer of Stemline Therapeutics. “We are committed to driving innovation in cancer treatment by delivering transformational therapies aiming to extend the lives of people living with cancer.”

The primary objective of this international, randomized, double-blind trial is to evaluate whether the combination of elacestrant and everolimus offers greater efficacy in delaying disease progression compared to elacestrant monotherapy. Additionally, it investigates other crucial aspects, such as overall survival, toxicity profile, and the impact on patients’ quality of life.

The ADELA study represents a critical step in understanding how to overcome tumor resistance challenges in patients with ESR1 mutations, with the goal of advancing towards more effective and safer treatments.

“At MEDSIR, we understand innovation not only as achieving clinical results but as the ability to transform patients' lives on a global scale. With ADELA, we take a decisive step toward accomplishing less invasive and more accessible treatments, aiming to offer new hope to those facing the most complex forms of the disease. This advancement reinforces our commitment to increasingly personalized and patient-centered medicine, a fundamental pillar in shaping the future of oncology,” said Dr. Antonio Llombart-Cussac, Senior Scientific Leader at MEDSIR.

The phase III study not only has significant clinical objectives, but also holds the potential to pave the way for regulatory approval of this therapeutic combination, enabling its use in a broader population of patients with advanced breast cancer. Moreover, the international scope of the study, which includes participation from multiple countries, including Spain, Italy, France, Austria, the Czech Republic, Greece, Germany, and the United Kingdom, underscores the study’s global importance and relevance in the scientific community.

The presentation of the ADELA study at an event as prominent as SABCS 2024 reinforces MEDSIR’s leadership in excellence-driven oncology research and highlights its focus on addressing unmet needs in breast cancer treatment. The ADELA study is active and already recruiting patients.

About ORSERDU (elacestrant)

U.S. Indication: ORSERDU (elacestrant), 345 mg tablets, is indicated for the treatment of postmenopausal women or adult men with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression following at least one line of endocrine therapy.

Full prescribing information for the U.S. can be found at www.orserdu.com.

Important Safety Information

Warning and Precautions

Dyslipidemia: Hypercholesterolemia and hypertriglyceridemia occurred in patients taking ORSERDU at an incidence of 30% and 27%, respectively. The incidence of Grade 3 and 4 hypercholesterolemia and hypertriglyceridemia were 0.9% and 2.2%, respectively. Monitor lipid profile prior to starting and periodically while taking ORSERDU.

Embryo-Fetal Toxicity: Based on findings in animals and its mechanism of action, ORSERDU can cause fetal harm when administered to a pregnant woman. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with ORSERDU and for 1 week after the last dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with ORSERDU and for 1 week after the final dose.

Adverse Reactions

Serious adverse reactions occurred in 12% of patients who received ORSERDU. Serious adverse reactions in >1% of patients who received ORSERDU were musculoskeletal pain (1.7%) and nausea (1.3%). Fatal adverse reactions occurred in 1.7% of patients who received ORSERDU, including cardiac arrest, septic shock, diverticulitis, and unknown cause (one patient each).

The most common adverse reactions (≥10%), including laboratory abnormalities, of ORSERDU were musculoskeletal pain (41%), nausea (35%), increased cholesterol (30%), increased AST (29%), increased triglycerides (27%), fatigue (26%), decreased hemoglobin (26%), vomiting (19%), increased ALT (17%), decreased sodium (16%), increased creatinine (16%), decreased appetite(15%), diarrhea(13%), headache (12%), constipation (12%), abdominal pain (11%), hot flush (11%), and dyspepsia (10%).

Drug interactions

Concomitant use with CYP3A4 Inducers and/or inhibitors: Avoid concomitant use of strong or moderate CYP3A4 inhibitors with ORSERDU. Avoid concomitant use of strong or moderate CYP3A4 inducers with ORSERDU.

Use in specific populations

Lactation: Advise lactating women to not breastfeed during treatment with ORSERDU and for 1 week after the last dose.

Hepatic Impairment: Avoid use of ORSERDU in patients with severe hepatic impairment (Child-Pugh C). Reduce the dose of ORSERDU in patients with moderate hepatic impairment (Child-Pugh B).

The safety and effectiveness of ORSERDU in pediatric patients have not been established.

To report SUSPECTED ADVERSE REACTIONS, contact Stemline Therapeutics, Inc. at 1-877-332-7961 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

About The Menarini Group

The Menarini Group is a leading international pharmaceutical and diagnostics company, with a turnover of $4.7 billion and over 17,000 employees. Menarini is focused on therapeutic areas with high unmet needs with products for cardiology, oncology, pneumology, gastroenterology, infectious diseases, diabetology, inflammation, and analgesia. With 18 production sites and 9 Research and Development centers, Menarini’s products are available in 140 countries worldwide. For further information, please visit www.menarini.com.

About Stemline Therapeutics Inc.

Stemline Therapeutics, Inc. (“Stemline”) a wholly-owned subsidiary of the Menarini Group, is a commercial-stage biopharmaceutical company focused on the development and commercialization of novel oncology therapeutics. Stemline commercializes ORSERDU^® (elacestrant) in the U.S. and Europe, an oral endocrine therapy indicated for the treatment of postmenopausal women or adult men with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression following at least one line of endocrine therapy. Stemline also commercializes ELZONRIS^® (tagraxofusp-erzs), a novel targeted treatment directed to CD123 for patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN), an aggressive hematologic cancer, in the United States and Europe, which is the only approved treatment for BPDCN in the U.S. and E.U. to date. Stemline also commercializes NEXPOVIO^® (selinexor) in Europe, an XPO1 inhibitor for multiple myeloma. Stemline also has an extensive clinical pipeline of small molecules and biologics in various stages of development for a host of solid and hematologic cancers.

About MEDSIR

Established in 2012, MEDSIR prides itself on working closely with its strategic partners to drive innovation in oncology research. Operating in Spain and the United States, the company provides end-to-end clinical trial management, from study design to publication, with an extensive global network of experts and integrated technology to streamline the process. The company offers proof-of-concept support and a strategic approach that enables research partners to benefit from the best of both worlds: industry clinical research and investigator-driven trials.

With the aim of promoting independent research worldwide, MEDSIR has formed a strategic alliance with Oncoclínicas, the leading oncology group in Brazil, which offers outstanding research potential in South America. For further information: www.medsir.org

About Oncoclínicas & CO

Oncoclínicas&Co is the largest group dedicated to cancer treatment in Latin America, with a specialized and innovative model focused on the entire oncology care journey, combining operational efficiency, humanized care, and high specialization through a medical team composed of over 2,700 specialist physicians with an emphasis on oncology. With its mission to democratize cancer treatment, it offers a comprehensive system that integrates outpatient clinics with high-complexity cancer centers. The company operates 145 units across 39 Brazilian cities, allowing high-quality access in all regions it serves, aligned with world-class standards.

Focusing on technology, precision medicine, and genomics, Oncoclínicas performed approximately 635,000 treatments in 2023. It is the exclusive partner in Brazil of the Dana Farber Cancer Institute, affiliated with Harvard Medical School, one of the world’s leading cancer research and treatments centers. The company also owns Boston Lighthouse Innovation, a bioinformatics firm based in Cambridge, United States, and holds shares in Medsir, a company dedicated to the development and management of clinical trials for independent cancer research, based in Barcelona, Spain.

Recently, Oncoclínicas expanded its operations to Saudi Arabia through a joint venture with the Al Faisaliah Group, bringing its mission to beat cancer to a new continent and providing advanced oncology care on a global scale by combining oncological hyperspecialization with innovative treatment approaches.

The company is part of the IDIVERSA index, launched by B3, highlighting companies committed to gender and racial diversity. For more information, visit:www.grupooncoclinicas.com.

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