"The immune system has this blind spot by design – an immune system that has an ability to attack itself leads to autoimmune diseases, so as protection, it screens out its own tissue.
"For decades, scientists assumed that cancer was beyond the reach of the body's natural defenses. But after decades of skepticism that the immune system could be trained to root out and eliminate these malignant cells, a new generation of drugs is proving otherwise.
"The treatment consists of infusing antibodies that enhance the immune system to recognize cancer cells and attack it. What's more, since the immune system has a built-in memory, it continues to go after cancer cells, so the response can be longer lasting and more complete.
"The trick is that this treatment doesn't work for everybody, and researchers don't yet understand why. But when it does work, the results have been particularly impressive."