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Better understanding of the biology of cancer cells has led to the development of biologic agents that mimic some of the natural signals that the body uses to control cell growth. Clinical trials have shown that this cancer treatment, called biological response modifier (BRM) therapy, biologic therapy, biotherapy, or immunotherapy, is effective for many types of cancer.

Some of these biologic agents, which occur naturally in the body, can now be made in the lab. Examples are interferons, interleukins, and other cytokines. These agents are given to patients to imitate or influence the natural immune response. They do this either by directly altering the cancer cell growth or by acting indirectly to help healthy cells control the cancer.

One of the most exciting applications of biologic therapy has come from identifying certain tumor targets, called antigens, and aiming an antibody at these targets. This method was first used to find tumors and diagnose cancer and more recently has been used to destroy cancer cells. Using technology that was first developed during the 1970s, scientists can mass-produce monoclonal antibodies that are specifically targeted to chemical components of cancer cells. Refinements to these methods, using recombinant DNA technology, have improved the effectiveness and decreased the side effects of these treatments. The first therapeutic monoclonal antibodies, rituximab (Rituxan) and trastuzumab (Herceptin) were approved during the late 1990s to treat lymphoma and breast cancer, respectively. Monoclonal antibodies now are routinely used to treat certain cancers, and many more are being studied.

Scientists are also studying vaccines that boost the body’s immune response to cancer cells. In 2010, the FDA approved sipuleucel-T (Provenge), a cancer vaccine for metastatic hormone-refractory prostate cancer (prostate cancer that has spread and is no longer responding to hormone treatment). Unlike a preventive vaccine, which is given to prevent disease, Provenge boosts the immune system’s ability to attack cancer cells in the body. This treatment has been shown to help certain men with prostate cancer live longer, though it does not cure the disease. It represents an important step forward in cancer treatment.

The future of immunotherapy

Drugs aimed at specific immune checkpoints are being developed to help the immune system better kill cancer cells.