CRD-1835439

CRD-1835439 is a preclinical, orally bioavailable small-molecule anticancer candidate developed by Chordia Therapeutics and later referred to publicly as CTX-439. It is described in public sources as a highly selective, first-in-class cyclin-dependent kinase 12 inhibitor, with later disclosures characterizing the program as a CDK12/13 inhibitor. By inhibiting CDK12-driven RNA polymerase II transcription elongation, the compound suppresses expression of DNA damage response genes including **BRCA1** and **BRCA2**, increases DNA damage, promotes apoptosis, and has shown dose-dependent antitumor activity in preclinical xenograft models. The mechanism also provides a rationale for combination use with PARP inhibitors and DNA-damaging therapies in solid tumors and other cancers.