Tasuku Honjo’s speech at the Nobel Banquet, 10 December 2018.

Your Majesties, your Royal Highnesses, Excellencies, Dear Laureates, Ladies and Gentlemen.

On behalf of Professor Jim Allison and myself, I wish to express our heartful appreciation to the Nobel Assembly at the Karolinska Institute and the Nobel Foundation.

Cancer has been the No. 1 cause of death during the last half-century. The trend is getting even worse as the average life span increases.

The concept of cancer immunotherapy was theoretically proposed by the Australian Nobel Laureate Sir Frank Macfarlane Burnet over sixty years ago, and since then, a large number of people have tried to apply it, but without success. This was probably because their efforts focused on pushing the accelerators of the immune system. Jim and I independently discovered that the reactivation of the immune system by blocking two major negative regulators, CTLA4 and PD-1, can cure a significant portion of cancer patients. Fortunately, our experiments in mouse models were successfully applied to humans. As a result, Jim and I have experienced many occasions that have made us feel well rewarded, such as meeting cancer patients who say their lives were saved by our therapies.

Cancer immunotherapy is possible because we have a highly sophisticated immune system called “acquired immunity,” which can catch small changes in tumor cells. How could we develop such a sophisticated immune recognition system that employs gene rearrangement? The genetic rearrangement mechanism must have developed accidentally – probably about five hundred million years ago, when vertebrates evolved. Thereafter, it must have persisted through natural selection due to the advantage of surviving infectious diseases.

Considering that the chance of such mutation and selection must be unbelievably low, we human beings are all very fortunate.

Jim and I both know that the development of our discovery is just beginning, as currently only 20 to 30% of patients respond to the immunotherapy. Andy Coghlan and Dan Chen described our discovery as the cancer equivalent of penicillin, which gave rise to a whole generation of antibiotics that changed medicine, and consigned most previously fatal infections to history. We encourage many more scientists to join us in our efforts to keep improving cancer immunotherapy. We sincerely hope this treatment will reach far and wide so that everybody on our planet can benefit from this evolutionary gift for healthy life.

Jim and I acknowledge that we were selected for this highest of all scientific honors. We accept the distinction with our deepest gratitude – gratitude for the great institutions that have supported our work, for our many devoted and skilled coworkers, without whom our achievements would have been impossible, and, finally, for Alfred Nobel for his wisdom to institute the prize and the people of Sweden for a fantastic Nobel Week.

Thank you.