Biotheryx to Present Results from its Phase 1A Dose Escalation Study of BTX-9341 for the Treatment of HR+/HER2- Breast Cancer at the 2026 European Society for Medical Oncology Breast Cancer Annual Congress
SAN DIEGO, May 4, 2026 /PRNewswire/ — Biotheryx, Inc., a biopharmaceutical company focused on the discovery and development of first-in-class protein degraders for cancer and inflammatory diseases, today announced that data from its Phase 1A Dose Escalation Study of BTX-9341, a potent and selective CDK4/6 degrader, in combination with fulvestrant for the treatment of HR+/HER2- breast cancer in patients who have previously received CDK4/6 inhibitor therapy in the advanced and/or metastatic setting, will be presented as an oral presentation at the 2026 European Society for Medical Oncology (ESMO) Breast Cancer Annual Congress, taking place May 6 – 8 in Berlin, Germany.
2026 ESMO Breast Cancer Presentation Details:
Title: Dose optimization of BTX-9341, a first-in-class CDK4/6 bifunctional degrader, in CDK4/6 inhibitor-pretreated HR+/HER2− advanced/metastatic breast cancer
Presenter: Dr. Matthew Goetz, MD, Mayo Clinic, Rochester, USA
Presentation #: 421RO
Session: Rapid Oral Session 2, Berlin Hall
Session Date and Time: Friday, May 8, 2026 | 8:30-10:00 AM
About BTX-9341
BTX-9341 is a first-in-class, oral degrader of CDK4/6, important targets for a range of cancers and clinically validated in HR+/HER2- breast cancer. In preclinical breast cancer models, BTX-9341 demonstrated superiority to CDK4/6 inhibitors through potent and highly selective catalytic degradation of CDK4 and CDK6, robust inhibition of CDK2 and Cyclin E transcription, cell cycle arrest, and ultimately superior in vivo efficacy in breast cancer xenografts. Beyond this increased efficacy potential, BTX-9341 is differentiated from CDK4/6 inhibitor approaches through the ability to overcome key resistance mechanisms that limit the impact of inhibitors in second line HR+/HER2- metastatic breast cancer.
About Biotheryx, Inc.
Biotheryx is a clinical-stage, biopharmaceutical company discovering and developing a portfolio of first-in-class protein degraders, including molecular glues and bifunctional degraders. Members of our founding and scientific teams previously developed the first U.S. Food and Drug Administration (FDA) approved modulators of Cereblon, the most widely validated E3 ligase involved in protein degradation. We have applied our expertise in Cereblon modulation to build our proprietary PRODEGY platform and pipeline of protein degraders for oncology and inflammatory diseases. Our approach deploys molecular glues to target undruggable proteins and bifunctional degraders to target validated proteins that conventional strategies, like protein inhibition, have insufficiently addressed. The Biotheryx pipeline includes BTX-9341, a first-in-class, oral, CDK4/6 bifunctional degrader that inhibits the transcription of CDK2 and Cyclin E, in first-in-human dose escalation and optimization clinical study in HR+/HER2- breast cancer patients who have progressed on CDK4/6 inhibitor therapy. Our pre-clinical pipeline advances undisclosed bifunctional degraders and molecular glues, including degraders as payloads for antibody drug conjugation. For more information, please visit www.biotheryx.com and engage with us on LinkedIn.
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SOURCE Biotheryx, Inc.
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