Additional Study Information: This research is being done because Richter's transformation, which is a life-threatening complication of chronic lymphocytic lymphoma (CLL), and is associated with poor overall survival rate. The study drug administration is a combination of the investigational drug, Polatuzumab vedotin, in combination with Rituximab, Etoposide, Prednisone, Cyclophosphamide, and Hydroxydaunorubicin, also referred to as PolaR-EPCH. An investigational drug means it has not been approved by the FDA or any other international regulatory agencies. The purpose of this study is to find out what effects the study drug, Polatuzumab vedotin, in combination with a standard chemoimmunotherapy regimen has on subjects with Richter's Transformation. Additionally, we would like to see how safe the study drug administration is for subjects with Richter's Transformation.