Purpose of review: We review recent advances leading to a new understanding of immunology of breast cancer with its potential clinical applications.
Recent findings: With the exception of antibody-based HER2 targeting, immunotherapy in breast cancer has largely been an unsatisfying experience. To improve the efficacy of breast cancer immunotherapeutics, a better understanding of the relation between innate and adaptive immune responses, of the immune escape mechanisms, the discovery of mechanisms underlying immunological tolerance, and the acknowledgment of the importance of both cell-mediated and humoral adaptive immunity for the control of tumor growth are needed.
Summary: Cancer takes advantage of the ability to hide from the immune system by exploiting a series of immune escape mechanisms. Among these mechanisms are the hijackings of immune cell-intrinsic checkpoints that are induced on T-cell activation. Blockade of these checkpoints - cytotoxic T-lymphocyte-associated antigen 4 or the programmed death 1 receptor - recently provided the first evidence of activity of an immune-modulation approach in the treatment of solid tumors. The future frontier in the immunotherapeutics of breast cancer requires identification of predictive factors. The immune system remembers what it targets, so once the system is correctly activated, it may mediate a long-lasting tumor response.