Ask Dr. K: Good news in advances in immunotherapy

In some diseases — cancer, for example — the immune system appears ineffective in eliminating the “foreign” cancer cells. Immunotherapy is an attempt to strengthen the immune system in its fight against the cancer.

In some diseases caused by viruses, not enough of the body’s own natural anti-viral molecules (like the interferons) are produced by the body.

In still other diseases — autoimmune diseases, for example — the disease is caused by an immune system attack against the body’s own healthy tissues. In this case, immunotherapy is an attempt to quiet down the overactive immune system.

Immunotherapy for cancer has recently had some dramatic successes in treating kidney cancer, skin cancer (particularly deadly melanoma), certain types of leukemia and lymphoma and certain types of breast cancer.

Your immune system has some natural capacity to recognize and destroy cancer cells. The problem is that it’s usually not strong enough to do this effectively. The immune system recognizes cancer cells because such cells have unique proteins (antigens) on their outer surface. Antibodies — proteins produced by the immune system — recognize these antigens and tag the cancer cells as foreign.

Immunotherapy strengthens the immune response in several different ways. For example, it can:

— Recruit more immune system cells to attack a tumor.

— Make cancer cells more vulnerable to an attack by the immune system.

— Change the way cancer cells grow.

— Coax cancer cells into behaving more like normal cells.

— Neutralize ways that cancer cells are able to hide from the immune system.

A good example of immunotherapy against viral diseases is the use of interferons produced in a laboratory against serious chronic viral infections, such as hepatitis B and hepatitis C.

Immunotherapy against inflammatory autoimmune diseases also is at a more mature stage than for cancer. This is particularly true for rheumatoid arthritis, inflammatory bowel disease and psoriasis. In each of these diseases, certain molecules made by the immune system (called cytokines) orchestrate much of the damage done by the immune system. New drugs (called “cytokine-blockers” or “biologics”) can dramatically “cool off” the destructive immune attack.

One of the most successful forms of immunotherapy involves monoclonal antibodies. These laboratory-created antibodies precisely target particular antigens on the surfaces of particular cells. When they latch onto their target, they can directly or indirectly destroy the cell carrying the target on its surface.

There also are entirely new and different forms of immunotherapy under development, some with enormous potential. After several decades of work, immunotherapy finally seems to be on the verge of providing valuable treatments for human diseases.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.