Resistance to ABT-199 induced by microenvironmental signals in chronic lymphocytic leukemia can be counteracted by CD20 antibodies or kinase inhibitors

A major clinical problem in chronic lymphocytic leukemia (CLL) is development of chemoresistance, which can be caused by genetic lesions but is also strongly influenced by the leukemic microenvironment. Two compartments can be distinguished in CLL; the blood, where quiescent CLL cells accumulate,