Milciclib (PHA-848125) is a selective cyclin-dependent kinase (CDK) inhibitor under investigation for the treatment of various cancers, particularly advanced solid tumors such as thymic carcinoma. It targets CDKs involved in cell cycle regulation, inhibiting the proliferation of cancer cells. Clinical trials, including phase II studies, have assessed its efficacy and safety in patients with relapsed or refractory thymic carcinoma and other malignancies like breast cancer and non-small cell lung cancer. Research also explores its use in combination therapies to potentiate anticancer effects and improve outcomes. As a specialty chemical, it serves as a research reagent and potential pharmaceutical intermediate in oncology.