Additional Study Information: The purpose of this study, which involves research, is to determine if an experimental drug: acalabrutinib is safe and effective in the treatment of this patients with High Risk Chronic Lymphocytic Leukemia (CLL). Acalabrutinib is an investigational drug, which means that it is still being tested in people and has not been approved by government agencies in any countries. Acalabrutinib has been tested previously in more than 800 humans and has been well tolerated. Acalabrutinib is administered as an oral capsule. To be able to participate, you will need to be more than 18 years old and must have CLL that has already been treated. In addition, your CLL must have gotten worse while on your previous treatment (or after stopping your previous treatment) in order for you to be eligible for this study.