There is a common idea that cancer arises simply because of the weakness of the patient's immune system. Supposedly, our white blood cells patrol the highways and byways of the body, looking for cellular miscreants, just as they hunt for viruses and bacteria. According to this popular view, if a patient were to simply enhance his or her immunity, the tumor would disappear. I have known patients who blamed themselves for letting their immune systems get run down, thereby bringing on their own cancers. This view may have an alternative sound to it, but actually is quite orthodox in its origin. It was first propounded in the 1950s by two established scientists, the Nobel laureate Macfarlane Burnet, and the President of Memorial Sloan-Kettering Cancer Center, Dr. Lewis Thomas.

However, this so-called "immune surveillance theory" does not cover many cancers. In fact, cancer strikes many people who are, in most respects, healthy. This was confirmed by a US National Cancer Institute (NCI) study last year. The subjects, in Linzhou, China, were chosen because they were at high risk of developing cancer, particularly of the upper gastrointestinal tract. The immune competence of 381 such individuals was carefully measured via three different lymphocyte stimulation tests. (Lymphocytes are white blood cells responsible for immunity.) Over the next five years, 53 of these participants developed malignant tumors, mostly of the stomach and esophagus. However, NCI scientists could find no significant association between their subjects' immune competence test scores and the subsequent incidence of cancer, or the total death rate. "This implies that immune competence…is not associated with incident cancer or total mortality in this population," they wrote (Roth 2006). There have been several other studies over the years that have reached similar conclusions.

So, if cancer is not generally a result of a simple failure of immune surveillance, then how can we account for the fact that, in the test tube, immune cells are seen to kill cancer cells? The answer to that riddle has also been known for many years. The immune system can have a constructive role to play in fighting cancer. But the problem is that real live cancers actively block an effective immune response from taking place. Tumors produce what are called "blocking factors." This has been repeatedly shown by (among others) Ingegard and Karl Erik Hellstrom, a husband-and-wife team at the University of Washington, who have coauthored hundreds of articles on cancer and the immune system. Starting in the 1960s, the Hellstroms demonstrated that tumors are capable of stopping an effective immune response from taking place. For instance, in 1969 they showed that blood serum from people who had rapidly growing tumors could block the otherwise destructive effects of immune cells (lymphocytes) on various tumor types (Hellstrom 1969).

If it is true that tumors actively block the immune system, what can be done about that? One new possibility, announced a few weeks ago, comes from the laboratory of Douglas D. Taylor, PhD, of the University of Louisville School of Medicine, Louisville, KY. Dr. Taylor has isolated so-called "exosomes," which are blood-borne particles that suppress the immune response in people with solid tumors, as well as leukemias and lymphomas. These exosomes induce the apoptosis (programmed cell death) of T-cells and block T-cell signaling, proliferation and cytokine production. (Cytokines are hormone-like substances produced by the immune system.) Not surprisingly, a high level of exosomes circulating in the blood correlates with both reduced T-cell production and tumor progression.

Through the use of an experimental device called a Hemopurifier®, Taylor was able to remove 60 percent of the exosomes from the blood of ovarian cancer patients in just 10 minutes. He and his colleagues believe this is likely to reverse the immune suppression that is induced by the tumor and to increase the patient's responsiveness to both immunotherapy and chemotherapy, although this still needs to be proven in clinical trials.

The Hemopurifier® was initially developed as a treatment device for victims of biowarfare. The manufacturer claims that the device is able to filter viruses effectively from the blood. But it also clearly has exciting potential in cancer treatment. There have been other attempts along these lines in the past, using devices that were based on modified dialysis machines. But the Hemopurifier® is very compact, about a foot long and an inch wide. (There is also a consumer size that is the size of a large pen!) It needs emphasizing that these devices are still in the testing phase, both for infection and for cancer. But it is exciting to think that some day, small, portable devices may help rid patients of insidious blocking factors that prevent an effective immune response to their cancer.

--Ralph W. Moss, Ph.D.

References:

Business Wire: Aethlon Medical Announces Cancer Treatment Discovery, July 18 2007. Available at:
http://www.genengnews.com/news/bnitem.aspx?name=20459880

Hellstrom IE, et al. Serum-mediated protection of neoplastic cells from inhibition by lymphocytes immune to their tumor specific antigens. Proc Natl Acad Sci U S A. 1969 February; 62(2): 362–368.

Roth MJ, Qiao YL, Abnet CC, et al. Cellular immune response is not associated with incident cancer or total mortality: a prospective follow-up. Eur J Cancer Prev. 2006 Dec;15(6):548-50.

The Moss Reports is on Facebook (Get Connected)