Clonal Evolution of B Cells in High-risk CLL After Idelalisib-rituximab

Inclusion Criteria: * Age over 18 * Ability to provide informed consent * Ability to provide peripheral blood samples * Diagnosis of CLL * Indication(s) for CLL therapy * At least one criterion for high-risk disease * Disease refractory (e.g., no response) to at least one round of chemotherapy * Disease that has relapsed (i.e., returned) after at least one round of chemotherapy * Proven presence of the 17p deletion within CLL cells * Planned receipt of idelalisib-rituximab as per FDA guidelines and patient's oncologists Exclusion Criteria: * Patients who do not meet the diagnostic criteria for CLL or at least one indication for treatment. * Patients who are receiving idelalisib with an off-label indication * Patients who do not or cannot provide informed consent to donate peripheral blood tumor samples to our stem cell core facility * Patients who do not provide informed consent to collect clinical, prognostic, and outcomes data during the time period that they are treated with idelalisib-rituximab