Ans. C. Negative immune regulationNobel Prize in Physiology or Medicine jointly, has been awarded to James P. Allison/Tasuku Honjo for their discovery of cancer therapy by inhibition of negative immune regulation.James P. Allison studied a known protein that functions as a brake on the immune system. He realized the potential of releasing the brake and thereby unleashing our immune cells to attack tumors.Cytotoxic T-Lymphocyte-associated Antigen 4 (CTLA-4) and Programmed Death 1 (PD-1) immune checkpoints are negative regulators of T-cell immune function. Inhibition of these targets, resulting in increased activation of the immune system, has led to new immunotherapies for melanoma, non-small cell lung cancer, and other cancers.For several types of cancer, including lung cancer, renal cancer, lymphoma and melanoma checkpoint therapy against PD-1 has proven more effective and positive results found.But recent clinical studies indicate that for melanoma the combination therapy of both CTLA-4 and PD-1 is more effective.Thus, Allison and Honjo combine different strategies to release the brakes on the immune system with the aim of eliminating tumor cells even more efficiently.Their paper formed the basis of current cancer immunotherapy.But the original concept of cancer immunotherapy was discovered by William Bradley Coley (1872).