In the past decade major advances in tumor immunology, a better understanding of antigen recognition by T-cells likewise discovering the regulatory inhibitory signals resulted in the development of new immunotherapies with promising durable responses in various solid tumor types and in hematologic malignancies. This review focuses on immunomodulatory antibodies, namely immune checkpoint inhibitor therapy. The prototype of this new class of immune stimulating agents was cytotoxic T-lymphocyte antigen-4 (CTLA-4) antagonists. After demonstrating enhanced survival, ipilimumab was approved first in the United States in 2011, further on in the European Union for second-line (2011) and for first-line therapy (2013) of metastatic melanoma. Additional T-cell intrinsic pathways were identified and targeted for clinical development. Antibodies blocking the PD-1 pathway also showed promising clinical activity and objective tumor response in several types of tumors, including metastatic melanoma, non-smallcell lung cancer. On the other hand antitumor activity is frequently accompanied by significant reversible immunerelated adverse events. To explore potential new immune checkpoint targets bring forth several challanges. Future clinical development will involve identifying potential biomarkers anticipating responsiveness to pathway blockade and additional tumor types likely to respond to the therapy. Furthermore, combination strategies, immune checkpoint inhibitors combined with cancer vaccines, targeted inhibitors and traditional chemotherapies are being evaluated in pre-clinical studies.
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