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Apparently, these tumors proliferate because they are able to trick killer T cells into not attacking them. The antibody, nivolumab, inhibits this signaling pathway so that the T-cells are capable of attacking the tumor. From: Gettinger SN, Horn L, Gandhi L, et al. Overall Survival and Long-Term Safety of Nivolumab (Anti–Programmed Death 1 Antibody, BMS-936558, ONO-4538) in Patients With Previously Treated Advanced Non–Small-Cell Lung Cancer. Journal of Clinical Oncology. 2015;33(18):2004-2012. doi:10.1200/JCO.2014.58.3708. Programmed death 1 (PD-1) is an immune checkpoint receptor expressed on activated T cells, which normally serves to dampen the immune response to protect against excessive inflammation and the development of autoimmunity. However, in the setting of malignancy, PD-1 signaling, driven primarily by adaptive expression of programmed death ligand 1 (PD-L1) within the tumor, inactivates primed T cells that recognize tumor-specific antigens, allowing tumor growth and metastasis. PD-1 pathway blockade with monoclonal antibodies offers a novel approach to restoring T cell–mediated antitumor immunity, with the potential for application across a broad population of patients with NSCLC. From the article: In a trial of more than 350 patients, published in the New England Journal of Medicine, 36% treated with the immunotherapy drug nivolumab were alive after one year compared with 17% who received chemotherapy. That seems like a small improvement rather than a "game changer." |
Most advances in cancer treatment (which have together added many years to the lives of cancer patients) are actually much smaller than this: a few weeks added to life expectancy here and a small improvement to the survival rate there. But they steadily add up.