For decades cancer specialists have offered patients three main therapies: surgery, chemotherapy and radiation. (Some cancer survivors pointedly refer to this harsh trinity as “slash, poison and burn.”) Over the years continual refinements in these admittedly blunt instruments have made the more severe side effects increasingly manageable. At the same time, effectiveness has improved markedly. And new, very targeted drugs (Herceptin and Gleevec) have become available for a few specific cancers. All told, the average five-year survival rate for invasive cancers as a group has risen from 50 percent to 66 percent in the past 30-plus years. In spite of these gains, many cancer survivors will not have a normal life span.
Researchers have long suspected that they could add a weapon that would dramatically increase cancer survival rates without producing serious side effects if they could just figure out how to prod the body’s own immune system to do a better job of fighting malignancies. But decades of effort met with one failure after another. In the 1980s, for instance, overheated hopes that an immune system molecule called interferon would rouse the body’s defenses to cure all or most cancers were dashed after a few more years of research. Today interferon has a place but is not the cure-all once envisioned. By the first decade of this century a great number of clinical trials were being conducted using lots of different types of vaccine-related approaches, but nothing seemed to be working. It was starting to look as though the long-hoped-for general weapon against a broad range of tumors would never materialize.