SAN DIEGO, CA, USA I May 7, 2024 I Biotheryx, Inc., a biopharmaceutical company discovering and developing a portfolio of first-in-class protein degraders with a focus on validated targets in cancer and inflammatory disease, today announced that the U.S. Food and Drug Administration (FDA) has cleared the Company’s Investigational New Drug (IND) application for BTX-9341, a novel cyclin-dependent kinase 4/6 (CDK4/6) bifunctional degrader. The Company plans to initiate the Phase 1 clinical trial in the second half of 2024 and intends to enroll patients with HR+/HER2- breast cancer resistant to CDK4/6 inhibitor therapies.

“Securing FDA clearance for our BTX-9341 IND application marks a significant milestone for Biotheryx, affirming our commitment to advancing innovative, orally bioavailable targeted protein degraders. As we transition from promising preclinical data to clinical trials, we are poised to explore the potential of BTX-9341 in offering tangible clinical benefits to patients battling breast cancer,” said Leah Fung, Ph.D., CEO of Biotheryx.

The Phase 1 clinical trial includes dose escalation for the initial monotherapy administration of BTX-9341 and combination dose expansion combining BTX-9341 with fulvestrant. The initial clinical evaluation will be focused on safety, biological activity and preliminary efficacy.

About BTX-9341

BTX-9341 is a first-in-class, oral degrader of cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6), important targets for a range of cancers and clinically validated in the context of certain breast cancers. In preclinical breast cancer models, BTX-9341 demonstrated superiority to CDK4/6 inhibitors through potent and highly selective degradation of CDK4 and CDK6, robust inhibition of Cyclin E and CDK2 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 potential ability to overcome key resistance mechanisms that limit the impact of inhibitors (~20% of patients have intrinsic resistance and up to 70% have acquired resistance to CDK4/6 inhibitors) and significantly enhanced penetration of the blood-brain-barrier.

About Biotheryx, Inc.

Biotheryx is a biopharmaceutical company discovering and developing a portfolio of first-in-class protein degraders, including bifunctional degraders and molecular glues. Our initial focus is on deploying the differentiated potential of degraders towards validated targets in cancer and inflammatory disease. Members of our founding and scientific teams previously developed the IMiDs, the first U.S. Food and Drug Administration (FDA) approved modulators of Cereblon, the most widely validated E3 ligase involved in protein degradation, and we have applied our expertise in Cereblon binding to build our proprietary PRODEGY platform. Our pipeline of bifunctional degraders includes BTX-9341 for HR+/HER2- breast cancer, the first ever bifunctional degrader of CDK4 and CDK6 to receive IND approval from the FDA, as well as first-in-class degraders of SOS1 for pan-KRAS mutant cancers, and PDE4 for inflammatory diseases. For more information, please visit and engage with us on LinkedIn.

SOURCE: Biotheryx