#United States #San Diego #Cancer Research #Biotheryx #BTX-9341

Biotheryx Announces First Patient Dosed in Dose Expansion Phase of BTX-9341-101

Biotheryx, Inc., a pioneering biopharmaceutical firm, is making strides in cancer treatment with its recent progress in the clinical trial of BTX-9341-101, specifically targeting HR+/HER2- breast cancer. On March 18, 2026, the company proudly announced that it has successfully dosed its first patient in the dose expansion phase of this crucial trial. This phase is significant as it seeks to explore the efficacy of BTX-9341, a selective CDK4/6 degrader, in combination with fulvestrant, for patients who have already undergone CDK4/6 inhibitor therapy and are in advanced or metastatic stages of breast cancer.

The randomized nature of this trial aims to collect substantial data regarding the safety and effectiveness of the drug combination. Biotheryx plans to enroll around 80 patients at multiple locations across the United States. This expansion phase follows a preliminary dose escalation phase where the company evaluated the safety, tolerability, and pharmacokinetic properties of BTX-9341. The main goal here is to achieve an improved Overall Response Rate (ORR), with additional focus points on the Clinical Benefit Rate (CBR) and Progression Free Survival (PFS). This structured approach highlights Biotheryx's commitment to understanding and enhancing patient outcomes.

Dr. Leah Fung, the Chief Executive Officer of Biotheryx, expressed optimism about this new stage in their clinical journey. She stated, "We are exceedingly pleased to have reached this milestone with our first patient dosed. The initial results from the dose escalation stage have provided us with a solid foundation, showcasing the safety and promising activity of BTX-9341. Our proprietary CDK4/6 degradation mechanism could be a formidable solution for the resistance currently faced with existing CDK4/6 inhibitors. We eagerly anticipate further advancements in assessing BTX-9341 alongside fulvestrant, aiming to significantly improve treatment outcomes for patients battling HR+/HER2- breast cancer who have previously undergone CDK4/6 inhibitor therapy."

Understanding BTX-9341

BTX-9341 represents a groundbreaking approach as a first-in-class oral degrader targeting CDK4/6. These are crucial components in a variety of cancer types, particularly in HR+/HER2- breast cancer. Prior studies in breast cancer models have shown that BTX-9341 demonstrates enhanced efficacy over traditional CDK4/6 inhibitors. This is attributed to its ability to achieve potent and selective degradation of CDK4 and CDK6 while also robustly inhibiting CDK2 and Cyclin E, leading to effective cell cycle arrest and improved efficacy in various in vivo settings.

Unlike conventional methods, BTX-9341's unique mechanism can potentially overcome significant resistance pathways associated with prior CDK4/6 inhibitors, particularly in patients with metastatic HR+/HER2- breast cancer.

About Biotheryx, Inc.

Biotheryx, Inc. is at the forefront of clinical research and development, focusing on a portfolio of pioneering protein degraders, which include molecular glues and bifunctional degraders. With a founding team that has previously ushered in the first FDA-approved modulators of Cereblon - an E3 ligase heavily involved in the protein degradation process - they are poised to tackle various oncology and inflammatory conditions.

The company utilizes its PRODEGY platform to craft innovative therapies that specifically target proteins otherwise deemed undruggable, a game-changer in cancer treatment paradigms. Alongside BTX-9341's development, Biotheryx is progressing with several undisclosed bifunctional degraders and molecular glues, further solidifying its commitment to transforming cancer care for millions worldwide.

For additional insights into Biotheryx's groundbreaking work, visit www.biotheryx.com or connect with them on LinkedIn.