Smart Cells. By Dr. Peter W. Kujtan, B.Sc., M.D., Ph.D.

I was positively energized to see that new innovations in cancer treatment are emerging from the laboratory and appearing at the bedside. Melanoma is a very nasty form of skin cancer, and is one of those entities. Recent news that gene therapy has been introduced as a tool to combat this cancer is very encouraging. Scientists at the National Cancer Institute in Washington have employed gene therapy with some success. It involves a very nifty technique called adoptive cell transfer to get the patients own immune system to attack and destroy cancer cells. The idea originated in research showing that some people do produce cells capable of destroying cancer cells, but in small numbers.

Blood is a combination of many different blood cells. The most common are red blood cells, but also floating around are various immune guard cells called lymphocytes. The process begins by collecting a sample of blood from a patient afflicted with melanoma. The lymphocytes are then separated from the rest of the cells and exposed to a manipulated virus to allow infection. Viruses are very small, and amount to a fraction of the size of the cell that they are invading. This is because viruses are little more than a piece of genetic material contained within a protein coat. Viruses infect and borrow the internal machinery of normal cells in order to survive and propagate. The rotavirus that is used to infect the patient's blood cells is special. It contains genetic code that has been artificially modified and inserted. The code that it contains is engineered to produce a receptor protein that will latch onto the surface of the cancer cells. It is called Cytotoxic T lymphocyte-associtated antigen 4 (CTLA-4). The lymphocytes taken from the patients go on to develop the ability to recognize melanoma cells. These cells are then transferred back into the patient, where they circulate and attach to the cancer cells and cause them to disintegrate. The cells go on to multiply, creating an ongoing vigilance for cancer recurrence. The current problems encountered with this technique is that cancer cells are very similar to normal cells and these programmed cells have trouble finding all the cancer cells. They can latch on to normal cells and cause severe reactions. In this case, melanoma vaccine was administered with the engineered cells. It contained non-harmful peptides that prompted other parts of the immune system to also attack the cancer. On the positive side, this whole process was being used in patients with advanced melanoma. It is in the midst of being refined, and potential is under development to employ with other types of cancer and provides compelling evidence to further support genetic engineering and stem cell research.