Palbociclib Impurity 42 is an impurity of Palbociclib, a medication for the treatment of HR-positive and HER2-negative breast cancer. It is a selective inhibitor of the cyclin-dependent kinases CDK4 and CDK6.

Palbociclib Impurity 63 is an impurity of Palbociclib, a medication for the treatment of HR-positive and HER2-negative breast cancer. It is a selective inhibitor of the cyclin-dependent kinases CDK4 and CDK6.

Palbociclib Impurity 53 is an impurity of Palbociclib, a medication for the treatment of HR-positive and HER2-negative breast cancer. It is a selective inhibitor of the cyclin-dependent kinases CDK4 and CDK6.