Additional Study Information: The purpose of this research study is to determine the preliminary safety and effectiveness (how well something works) of alvocidib when used after the standard drug decitabine in patients with MDS. The study will also gain information about the PK (the process by which a drug is absorbed, distributed, metabolized and eventually eliminated by the body), pharmacodynamic (PD) biomarkers (which study how the drug effects the body) and other biomarkers that may help understand more about how your disease responds to the drug.