Some of the most exciting possibilities are offered by drugs that work in entirely different ways from the conventional ones. One such approach is immunotherapy, using drugs that cause the body's immune system to attack cancer just as it fights off infections. The concept is based on two theories. First, cancer cells can be perceived by the immune system as "foreign" and, with proper help, rejected. The second is that cancer victims have lost their natural powers of rejection because of their debilitating disease.
The widely publicized drug, interferon, stemmed from immunological research. Discovered in the 1950's,it is a protein produced by body cells to help fight off viral infections. In cancer, researchers think it fastens onto cells and causes the release of enzymes that inhibit growth. And, because it is a natural substance, experts hope the side effects will be limited. So far, this is mostly theory; until recently, large scale testing of interferon hasn't been possible because it could be extracted only in minute quantities and at great cost from donated white blood cells. The emergence of recombinant DNA technology, in which common bacteria can be programmed genetically to manufacture quantities of proteins, has only recently made it possible to obtain enough interferon for cancer research.
On December 5, 1985, the New England Journal of Medicine carried a story on Dr. Steve Rosenberg's treatment of Interleukin II combined with LAK cells. That started a torrent of publicity throughout the winter of 1985-1986. Simply stated, this treatment took the natural killer cells from a patient's blood, treated them with IL-2,and reinjected them and more IL-2 back into the patient. These IL-2 armed white cells, called LAKor lymphokine-activated "killer cells," destroy tumors for months after administration in some cases, until the patient is clear of detectable cancer.
Only patients who had failed all other treatments were accepted for this protocol. The success in reducing tumor burden by 50% or more was striking in several types of advanced cancer. In February, 1986, we received a report that Dr. Rosenberg had been successful in 100% (6 out of 6) of the cases of renal cell cancer and 50% (5 out of 10) of the cases of advanced malignant melanoma. Both of these types of cancers were relatively untreatable using other methods of treatment if surgery failed. Steps are underway to confirm and extend these results in other centers.
The most exciting aspect of this treatment is that IL-2 is not intended to harm the malignant cells. It is solely to stimulate the patient's own immune system which in turn destroys the cancer. Surgery, radiation or chemotherapy, the methods of treatment most physicians are used to discussing in fighting cancer, are each designed to damage malignant cells in their own way. The mere concept of IL-2,as well as the success of the treatments, emphasizes the importance of the patient's immune system. It throws wide open a new and separate field in fighting cancer.
It seems that there are a number of substances that occur naturally in the body to maintain normal growth and development which may be utilized to stimulate the body's natural defenses against cancer. The National Cancer Institute has established a special research program to explore intensively the therapeutic applications of these naturally occurring substances called "Biological Response Modifiers." In addition to IL-2 and interferon, this group includes thymosin, IL-1, IL-3, IL-4, IL-6, IL-12, and tumor necrosis factor (TNF).