Immunotherapy: The Exciting Prospect of Harnessing the Body’s Immune System to Treat Cancer

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Is immunotherapy the answer to skin cancer? Image by National Cancer Institute

Improved outcomes in cancer patients can be achieved by improving their immune responses to the tumor. People are living longer with cancer, and a diagnosis of cancer in 2013 is not necessarily a death sentence. Here’s how immunotherapy is helping patients survive cancer.

What is Immunotherapy?

Immunotherapy, which is also described as biological therapy, harnesses the body’s immune system to shrink tumors, control the growth factors that stimulate tumor growth, and aid in the repair of damage caused by other cancer treatments. Early immunotherapy research used T cells to target skin cancer cells, particularly melanoma. The early attempts to improve human immune responses concentrated on the interleukins and interferon. These agents were toxic with poor overall survival rates and this area of research was disappointing.

Immunotherapy has improved as a treatment option due to extensive comparisons to the dynamics of the immune system in chronic infectious diseases, such as tuberculosis (TB) and HIV.

Cancer-Fighting T Cells Can Be Directed Against Tumors

T cells are an additional therapy that can be used with chemotherapy and radiotherapy. Certain T cell populations are specific for tumor cells and used to treat patients with small tumors because of consistently successful outcomes. Fortunately, the immune system has a memory, and an induced response may not only be effective, but can also last for a long period of time.

Trials of immune-stimulatory antibodies targeting cell death proteins have shown promising results in difficult-to-treat cancers, such as melanoma and kidney cancer, as well as certain types of lung cancer. Bristol-Myers Squibb has conducted clinical trials with some of these agents – they also market Yervoy, the brand name for ipilimumab, a treatment for metastatic melanoma.

Immunotherapy Cancer Treatments

There are currently a number of well-established immunotherapy treatments available, including bone marrow and stem cell transplantation for blood disorders. Therapeutic vaccines are more promising, however, because most human cancers have many causal factors. Researchers develop vaccines from a variety of sources, which may reduce their efficacy, and are currently conducting a number of vaccine trials for lung cancer.

Chemotherapy May Induce Immunological Effects

The evident successes of chemotherapy and radiotherapy treatments may be due to immunological factors, not just cell toxicity. Chemotherapy does suppress the immune system, but the immune response to tumor antigens may not decrease, but actually alert the immune system to the cancer.

Immunotherapy and Cancer: Problems

There is little correlation between drug exposure and the efficacy and toxicity of immunotherapy. Unexpected side effects, such as kidney failure, may occur and be difficult to treat in a clinical situation, and the high cost of these drug treatments means that patients must be pre-selected and can only be treated if they have pre-existing antibodies. Although  immunotherapy shows promise, science is still looking for the ever-elusive cancer-cure.

References

Lesterhuis, W.J., et al. Cancer Immunotherapy Revisited. (2011). Nature Reviews Drug Discovery. Accessed February 3, 2013.

MD Becker Partners. Cancer Immunotherapy Catalysts. Accessed February 3, 2013.

Skin Cancer Foundation. New Melanoma Treatment Approved. (2011). Accessed February 3, 2013.

Beishon, M. We told you so: How the persistence of immunotherapy researchers is finally paying off. (2012). Cancerworld. Accessed February 3, 2013.

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