BROOKLINE, MA, USA I May 21, 2024 I Edgewood Oncology, a clinical-stage biotechnology company focused on delivering BTX-A51 to patients with hematologic malignancies and genetically-defined solid tumors, today announced that the first two patients with metastatic breast cancer were treated with BTX-A51, a multi-specific kinase inhibitor of casein kinase 1 alpha (CK1α) and cyclin-dependent kinases 7 and 9 (CDK7 and CDK9), that synergistically targets master regulators of cancer. BTX-A51 is being evaluated in a Phase 2a study for the treatment of estrogen receptor positive / human epidermal growth factor receptor 2 negative (ER+/HER2-) metastatic breast cancer with and without GATA binding protein 3 (GATA3) mutations.

GATA3 is a protein that helps maintain healthy breast cells and mutations in this protein, which are found in approximately 15% of breast cancer cases, are associated with shorter progression free (PFS) and overall survival (OS). Moreover, these mutations are almost always accompanied by a wild type (non-mutated) p53 tumor suppressor protein. Recent studies have shown that targeting MDM2, a molecule that degrades the p53 protein, could be particularly effective in treating cancers with these GATA3 mutations. Due to its ability to reduce MDM2 expression, Edgewood Oncology is testing the hypothesis that BTX-A51 may be beneficial in this breast cancer sub-population.

“This represents an important milestone for both Edgewood Oncology and for patients with ER+/HER2- breast cancer, particularly those with a GATA3 mutation, who need better treatment options targeted to their underlying mutation profile,” said Zung L. Thai, M.D., Ph.D., chief medical officer of Edgewood Oncology. “Moreover, while CDK4/6 inhibitors remain a cornerstone of current treatment regimens, resistance to these therapies poses a formidable challenge. By targeting CDK7 and CDK9, key regulators of cell cycle progression, BTX-A51 not only aims to circumvent this resistance but also to transform the treatment landscape.”

The ongoing Phase 2a trial of BTX-A51 is a multicenter, open-label, nonrandomized, multiple dose study evaluating the safety, toxicity, pharmacokinetics and preliminary efficacy of BTX-A51 in patients with ER+/HER2- metastatic breast cancer with and without GATA3 mutations. Multiple sites for the clinical study are open for enrollment. For more information, visit (NCT04872166).

About Edgewood Oncology

Edgewood Oncology is a clinical-stage biotechnology company that was founded to deliver on the promise of BTX-A51 for patients with hematologic malignancies and genetically-defined solid tumors. BTX-A51 is an investigational, first-in-class, small molecule, multi-selective kinase inhibitor of CK1α, CDK7 and CDK9 that synergistically co-targets master regulators of cancer to activate programmed cell death, or apoptosis. BTX-A51 holds promise in acute myeloid leukemia and genetically-defined solid tumors, which are the focus of ongoing clinical programs. For more information, please visit, and follow us on LinkedIn.

SOURCE: Edgewood Oncology