On May 30, 2025 MEDSIR reported the positive results of the TUXEDO-3 trial at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting 2025 (Press release, MedSIR, MAY 30, 2025, View Source [SID1234653526]). This phase II study funded by Daiichi Sankyo and Merck, known as MSD outside of the United States and Canada, evaluates the efficacy and safety of patritumab deruxtecan (HER3-DXd) in patients with active brain metastases and leptomeningeal disease, serious complications associated with advanced stages of the cancer.
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The study was carried out to evaluate HER3-DXd in patients with metastatic breast cancer (mBC) and advanced non-small cell lung cancer (aNSCLC) with active brain metastases, and patients with leptomeningeal disease from solid tumors. This is an antibody-drug conjugate to target HER3, a protein receptor found on the surface of cancer cells in brain metastases. HER3-DXd is an investigational agent consisting of a fully human anti-HER3 IgG1 monoclonal antibody attached to a number of topoisomerase I inhibitor payloads (an exatecan derivative, DXd) via tetrapeptide-based cleavable linkers. The DXd ADC Technology payload causes tumor DNA damage, killing cancer cells within and surrounding the tumor microenvironment
The study showed promising results, which were presented today in an oral session. Results from the leptomeningeal cohort have been simultaneously published in the renowned journal Nature Medicine due to its potential benefit in patients with a high unmet medical need. In patients with breast cancer and brain metastases, intracranial responses were observed across all breast cancer subtypes, including luminal, HER2-positive, and triple-negative. Furthermore, some patients with breast cancer who had previously received antibody-drug conjugates also responded to HER3-DXd, highlighting the potential of HER3-DXd to overcome resistance and expand treatment options in refractory disease. Intracranial activity was also observed in patients with aNSCLC and brain metastases, intracranial responses were observed in patients whose tumors contained no activating driver mutations as well as patients whose tumors contained an EGFR or KRAS mutation. Overall, the data suggest that HER3-DXd may offer a novel treatment option for patients with secondary CNS involvement.
KEY HIGHLIGHTS OF THE TUXEDO-3 STUDY
The TUXEDO-3 study aimed to assess whether HER3-DXd could be an effective treatment option for patients with mBC and aNSCLC with active brain metastases, and leptomeningeal disease from solid tumors.
The study met its primary objectives, with 23.8% and 30% patients achieving intracranial responses in active brain metastases from patients with mBC and aNSCLC, respectively, and 65% patients with leptomeningeal disease alive after 3 months. Side effects were consistent with previous studies using HER3-DXd. Tests evaluating quality of life and neurocognitive functions showed that patients remained stable or improved during the treatment follow-up.
The primary objectives consisted of assessing the intracranial objective response rate in patients with active brain metastases from mBC and aNSCLC, and determining the number of patients with leptomeningeal disease alive after 3 months of starting the treatment.
A NEW HOPE FOR DIFFICULT-TO-TREAT METASTASES
"This study represents a significant advancement in our understanding of how to treat brain metastases and leptomeningeal disease, and we are hopeful that our findings will pave the way for new, effective therapies for these patients," stated Dr. Matthias Preusser, MD, Medical Oncologist and Head of the Clinical Division of Oncology, Medical University of Vienna and Principal Investigator of TUXEDO-3. Dr. Rupert Bartsch, MD, PhD, Consultant Hematology and Medical Oncology, Medical University of Vienna, added: "Brain metastases and leptomeningeal disease represent severe complications in cancer, leading to increased morbidity and mortality, and HER3-DXd could be a promising therapeutic alternative for these patients."
ABOUT UMMET CANCER NEEDS
Unmet cancer needs refer to gaps in resources, support, and treatment options that exist for cancer patients. Addressing unmet cancer needs is crucial to improving quality of life and outcomes for cancer patients. Through the collaborative work of healthcare providers, policymakers, and patient advocacy groups unmet cancer needs can be identified to help provide patients with comprehensive and quality care.
SHOWCASING PROMISING COLLABORATIVE TRIALS AT ASCO (Free ASCO Whitepaper)
In addition to the oral presentation of TUXEDO-3, MEDSIR will present both ADELA and WIN-B studies in poster format. The ADELA clinical trial is an ongoing international phase III study in collaboration with The Menarini Group, a leading international pharmaceutical and diagnostics company, and Stemline Therapeutics, Inc., a wholly-owned subsidiary of the Menarini Group focused on bringing transformational oncology treatments to cancer patients. The study is being conducted across multiple countries which combines elacestrant with everolimus to treat advanced ER+/HER2- breast cancer with ESR1 mutations, aiming to delay disease progression.
Regarding WIN-B, is a phase Ib/II, multi-center investigator-initiated trial, evaluating the safety and preliminary efficacy of combining Debiopharm’s selective WEE1 inhibitor, Debio 0123 and Gilead’s antibodydrug conjugate Trodelvy (sacituzumab govitecan-hziy) in advanced HR+/HER2- and triple-negative breast cancers.
MEDSIR active presence at the ASCO (Free ASCO Whitepaper) Annual Meeting 2025 reinforces its leadership in excellence-driven oncology research and highlights its focus on addressing unmet needs in cancer treatment, with the aim of not leaving any patient left behind.