HER3-DXd shows significant promise in the TUXEDO-3 Phase II trial for treating brain metastases and leptomeningeal disease in breast and lung cancer patients.
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| TUXEDO-3 study data presented at ASCO 2025 highlight HER3-DXd’s potential to meet urgent needs in treating CNS complications in metastatic cancers. Image: MEDSIR |
CHICAGO, USA — May 31, 2025:
Leading international oncology research company MEDSIR announced today the promising results of the Phase II TUXEDO-3 trial during the American Society of Clinical Oncology (ASCO) Annual Meeting 2025. The study assessed HER3-DXd (patritumab deruxtecan), an investigational antibody-drug conjugate (ADC), in patients with advanced-stage complications such as brain metastases and leptomeningeal disease linked to metastatic breast cancer (mBC) and advanced non-small cell lung cancer (aNSCLC).
Funded by Daiichi Sankyo and Merck (MSD outside the U.S. and Canada), the study evaluated the efficacy of HER3-DXd in targeting HER3—a protein found on the surface of cancer cells associated with CNS metastases. This ADC links a monoclonal antibody to a topoisomerase I inhibitor payload (DXd), engineered to cause DNA damage and eliminate cancer cells within the tumor environment.
The results presented at ASCO and published in Nature Medicine demonstrated HER3-DXd’s capacity to elicit intracranial responses across all breast cancer subtypes—luminal, HER2-positive, and triple-negative. Notably, responses were also observed in patients previously treated with other ADCs, suggesting HER3-DXd could overcome treatment resistance. Patients with aNSCLC, both with and without driver mutations like EGFR and KRAS, also showed significant intracranial activity.
The TUXEDO-3 trial met its primary endpoints, with 23.8% of mBC patients and 30% of aNSCLC patients experiencing intracranial responses. Additionally, 65% of patients with leptomeningeal disease were alive three months post-treatment. Side effects were consistent with earlier trials, while assessments of quality of life and neurocognitive function revealed patient stability or improvement.
“This study represents a significant advancement in our understanding of how to treat brain metastases and leptomeningeal disease,” said Dr. Matthias Preusser, Principal Investigator and Oncology Division Head at the Medical University of Vienna. Dr. Rupert Bartsch, also from the University, emphasized that HER3-DXd presents “a promising therapeutic alternative” for these challenging complications.
MEDSIR also highlighted its broader pipeline at ASCO 2025, including the ADELA and WIN-B studies. ADELA, a Phase III trial in partnership with The Menarini Group and Stemline Therapeutics, investigates the combination of elacestrant and everolimus in treating advanced ER+/HER2- breast cancer with ESR1 mutations. Meanwhile, the WIN-B study explores the combination of Debio 0123, a WEE1 inhibitor, and Gilead’s Trodelvy in hormone-receptor-positive and triple-negative breast cancers.
Founded in 2012 and based in Spain and the U.S., MEDSIR continues to lead innovation in oncology research by offering integrated, expert-driven clinical trial support. With a strategic focus on addressing unmet cancer needs, MEDSIR’s initiatives aim to bring effective, life-extending treatments to patients worldwide.