"Immunotherapy, a way to cure cancer by increasing the patient's resistance to carcinogens, is a subject worthy of serious academic research and has relatively less side effects compared to chemotherapy or radiation therapy. Immunotherapy, combined with surgery, chemotherapy and radiation therapy, can help maximize therapeutic effects."
Professor LEE Choon-Taek, director of the Seoul National University Bundang Hospital Immunotherapy Research Center, stressed the importance of immunotherapy in cancer treatment during an interview. Once immunotherapy becomes fully established as an efficient clinical method, it will have huge advantages compared to previous cancer treatment.
Cancer refers to a cluster of genetically mutated cells that have replicated uncontrollably. Cancer cells evade the resistance of the normal immune system and can proliferate infinitely. Many carcinogens -- genetic, environmental, chemical, or any otherwise -- change the genes of normal cells. The accumulation of such small genetic changes makes normal cells turn into cancer cells. Normally the body’s immune surveillance detects these genetic changes in their early stages. However, genetically altered cells can secrete chemicals that confuse the body’s immune system so that they can escape detection. Once these abnormal cells evade the body’s immune surveillance and become clusters of cancer cells, they can spread throughout the body in spite of the immune system.
Immunotherapy started from the idea that the immune surveillance which has been broken down by cancer cells can be revived. Since cancer is allowed to develop due to the failure of the body's immune surveillance, the fundamental treatment would be to activate the body’s immune system. Once revived, the immune surveillance can slow down the proliferation of cancer cells and stop their replication. Clinical research on immunotherapy was galvanized after Dr. Rosenburg proved that LAK (lymphokine activated killer) cell therapy could kill cancer cells completely in 1982. After LAK cell therapy was introduced and immunotherapy became a promising area of research, researchers classified human white blood cells and lymphocytes into different types. Nowadays, dendritic cells, CTL (cytotoxic T lymphocyte) and NK (natural killer) cells are the most popular subjects of immunotherapy research. Cases in which immunotherapy was successful in treating kidney cancer and colorectal cancer have been reported in America and it still remains a promising method for treating the most immune resistant types of cancers, such as melanoma. There have been several clinical trials in Korea in the effort to cure patients using NK cells.
Current immunotherapy can be classified into two main types -- immunomodulatory gene therapy and immunocyte therapy. Immunomodulatory gene therapy, also called 'tumor vaccine', tries to cure cancer by extracting the cancer cells from the body, mutating their genes and then inserting the mutated cancer cell back into the body. Immunocyte therapy, on the other hand, tries to extract the immune cells from the body and activate their immune functions so that when the immune cells are reinserted into the body, they will fight the cancer cells effectively. Most recent immunotherapy research involves extracting and reinserting dendritic cells, CTL and NK cells, after maximizing their anticancer characteristics outside the body. “Currently, CTL and NK cells are most commonly used for research”, Professor Lee explains."Adult stem cells are also a rising subject of research and several important results have recently been reported in using them for anticancer immunotherapy."
Immunotherapy has not been fully developed yet to produce independent results. However, at the current stage, it can contribute to the curing of some forms of cancer completely in combination with other anticancer methods. After the number of cancer cells is lowered by chemotherapy or radiation therapy, activated immune cells can be inserted in order to kill the remaining cancer cells. In order for immunotherapy to be more effective, the most important task is to make cancer patients’ immune cells recover and function normally. Professor Lee says,"These days developing target anti-cancer medicine is the fastest growing field in cancer treatment. However, since cancer cells can develop resilience to such drugs over time, it is extremely difficult to find a fundamental cure with pharmaceutical methods." He predicts,"Although immunotherapy in practice is not showing clear effects, contrary to its theoretical basis, it will ultimately become the mainstream of cancer treatment research."
Professor Lee graduated from SNU's College of Medicine in 1982, and after working at the Korea Cancer Center Hospital, has been a professor of internal medicine at SNU since 1998. He has been the director of the Seoul National University Bundang Hospital Lung Center since 2003 and became the director of the Immunotherapy Research Center in March 2011. Professor Lee’s main clinical interest is early detection of lung cancer and developing gene therapy for lung cancer.
Professor Lee first became interested in immunotherapy while doing his post-doctoral research at Southwestern University Medical Center in Texas in 1994. Around that time, some genetic causes for cancer such as the p53 gene and the K-ras gene were discovered, which marked the start of immunotherapeutic research. When mutants for the p53 or K-ras gene were found in the tissues of lung cancer patients and pancreatic cancer patients, Professor Lee extracted white blood cells from the patients. The white blood cells were treated with 20 kinds of tumor specific antigens specially designed for the cell, so that the cells could recognize such antigens and become immune to them. Now, Professor Lee has expanded his field to using adenoviruses for cancer treatment, especially for lung cancer. He is also conducting research on tumor vaccines, a potential treatment which uses gene therapy on cancer cells extracted from a patient’s body and then reinserts the modified cells after their carcinogenicity is removed.
Seoul National University Bundang Hospital cooperates with NKBio, a corporation that produces immunotherapeutic drugs, to operate laboratories for fundamental and clinical research on immunotherapy. Professor Lee has published more than 60 SCI papers on immunotherapy, and is one of the most recognized Korean scientists in this field. Currently he is engaged in a joint research project with NKBio on developing a new immunotherapy method that combines NK cell treatment and gene therapy.
Written by JANG Eunju, SNU English Editor, ejjang1025@snu.ac.kr ?
Reviewed by Eli Park Sorensen, SNU Professor of Liberal Studies, eps7257@snu.ac.kr
Proofread by Brett Johnson, SNU English Editor, morningcalm2@gmail.com