Biotheryx Announces First Patient Dosed in the Dose Expansion Phase of BTX-9341-101 for the Treatment of HR+/HER2- Breast Cancer

Excerpt from the Press Release:

SAN DIEGO, March 18, 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 the first patient has been dosed in the dose expansion phase of its clinical trial evaluating 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.

The dose expansion portion of the trial is a randomized study designed to evaluate the efficacy and safety of BTX-9341 in combination with fulvestrant. The trial is being conducted at multiple sites in the United States and is expected to enroll approximately 80 patients across two treatment arms based on the recommended dose identified in the earlier dose escalation phase. This dose expansion study builds on the recently completed dose escalation phase that evaluated the safety, tolerability, pharmacokinetics and pharmacodynamic activity of BTX-9341. The primary endpoint of this study is the Overall Response Rate (ORR), with key secondary endpoints including the measurement of investigator-assessed Clinical Benefit Rate (CBR) and Progression Free Survival (PFS).

“We are pleased to have dosed the first patient in the dose expansion portion of our clinical trial evaluating BTX-9341 in combination with fulvestrant.” said Dr. Leah Fung, Chief Executive Officer of Biotheryx.

Click the button below to read the entire Press Release:

Continue Reading The Press Release