• 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.