CXCL12 and B-cell chronic lymphocytic leukemia: Preclinical studies established that PI3Kδ blockade withidelalisib inhibited CLL cell migration in response to tissue homing chemokines(CXCL12 and CXCL13) and impaired leukemia cell adhesion and migration beneathstromal cells that secrete chemokines (Hoellenriegel et al. 2011).