Chimeric antigen receptors: a costimulatory boost promotes immunological memory to B-cell malignancies

Cellular immunotherapies offer perhaps the best proof of concept of the ability of immune cells to eradicate malignancy. However, the majority of these data derive from either the use of expanded tumor-infiltrating lymphocytes to treat metastatic melanoma or the use of donor lymphocytes in relapsed hematological malignancies following allogeneic hematopoietic stem cell transplantation. Genetic engineering of T cells to redirect specificity against tumor-associated antigens potentially overcomes one of the major hurdles to more widespread application. Despite early evidence of possible activity, limited in vivo expansion and persistence of adoptively transferred cells has been associated with disappointing clinical efficacy. A report from Porter and colleagues now demonstrates more fully the potential of such genetic modification in a patient with chronic lymphocytic leukemia, illustrating that when delivered in the right setting with appropriate costimulatory signaling, these cells can expand and persist, and in doing so effect quite remarkable anti-tumor activity.