myrtleciclib

Myrtleciclib is an oral small molecule inhibitor targeting cyclin-dependent kinases 4, 6, and 9 (CDK4/6/9), as well as the proto-oncogene protein c-myc. It is being developed by Virostatics under license from Vichem Chemie for the treatment of aggressive cancers and HIV infections. Unlike traditional CDK4/6 or CDK9 inhibitors that act via ATP-competitive mechanisms, myrtleciclib binds to an allosteric site on its targets, which supports greater specificity and a broader therapeutic index with limited cytotoxicity. Myrtleciclib induces cell death and apoptosis selectively in cancer cell lines while sparing non-cancerous cells. Its mechanism allows for synergistic inhibition of both CDK9 and CDK4/6 pathways within a single molecule—an approach designed to overcome resistance seen with other kinase inhibitors. The lead indications include malignant pleural mesothelioma (MPM), metastatic breast cancer, lymphomas (including those resistant to existing CDK4/6 inhibitors), and other aggressive tumors expressing Myc[1][2][3][5].