BioTheryX Announces First Patient Dosed with BTX-A51 in Phase 1 Clinical Trial in Patients with Advanced Solid Tumors

SAN DIEGO, June 9, 2021 /PRNewswire/ —

BioTheryX, Inc., a clinical-stage company focused on degrading proteins to create life-saving medicines, today announced the dosing of the first patient in a dose escalation clinical trial of BTX-A51 in advanced solid tumor malignancies that are dependent upon MYC, one of the most commonly known oncogenic drivers. BTX-A51, the company’s lead multi-kinase inhibitor is also currently in a phase 1 dose escalation clinical trial for advanced hematological malignancies.

“This is a significant milestone for BioTheryX, as we look to deliver a much-needed therapeutic option to patients with advanced solid tumor malignancies that are dependent upon MYC,” said Robert Williamson, President and CEO of BioTheryX.  “We are excited for the potential of BTX-A51 to provide a meaningful therapeutic option for patients and are working aggressively to advance our pipeline of molecular glues, Proteolysis Targeting Chimeras and monovalent degraders towards the clinic.”

BTX-A51 is an oral small molecule, multi-kinase inhibitor designed to block a specific leukemic stem cell target (CK1α) as well as super enhancer targets (CDK7/CDK9) preventing transcription of key oncogenic genes. This therapeutic mechanism entails activation of p53, an important tumor suppressor, and its sustained stabilization by super-enhancer shutdown of MDM2, a protein degrader of p53, in combination with transcriptional shutdown of leukemia oncogenes, such as MYC and MCL-1.  Blocking CKIα, CDK7, and CDK9 augments and synergistically stabilizes p53 and downregulates MYC and MCL-1 promoting the rapid killing of leukemia cells as well as leukemic stem cells. Pre-clinical results have been published in a peer-reviewed Cell article, demonstrating BTX-A51’s favorable efficacy in animals.

“In the fight against solid tumor cancers, which have extremely poor survival rates and limited treatment options, clinical trials with new therapies are desperately needed,” added Zung Thai, M.D., Ph.D., Chief Medical Officer of BioTheryX.  “We are excited to be initiating the dose escalation portion of this study and progressing to the selection of the Phase 2 dose.”

BioTheryX’s Phase 1 clinical trial of BTX-A51 is currently ongoing and recruiting patients.   The clinical trial is designed to assess the safety and tolerability of BTX-A51 and to determine the recommended Phase 2 dose.  Following determination of the recommended Phase 2 dose, we plan to further evaluate the safety and efficacy of BTX-A51 in expansion cohorts in both hematological and solid tumor malignancies.

About BioTheryX, Inc.

BioTheryX is a clinical-stage biopharmaceutical company focused on restoring protein homeostasis, including protein degradation and modulation, and multi-kinase inhibition to develop treatments intended to extend and improve the quality-of-life of patients with cancer and other diseases. Our principal technology platform centers on targeted protein degradation, PHM® ‘molecular glues’, that enable the design of small molecules to regulate protein equilibrium. This technology is designed to utilize the body’s own protein disposal system to selectively degrade and remove disease-causing proteins. It has potential applicability for a broad range of diseases, including targets that have to date been considered ‘undruggable’, and BioTheryX is initially focused on treating oncology indications with high unmet need.  For more information, please visit and engage with us on LinkedIn.


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