In the war on cancer, vaccines designed to teach immune cells to seek out proteins on cancer cells and swoop in for the kill have delivered less scintillating results than hoped. Now researchers report in the March issue of Nature Biotechnology that inoculating mice with a protein fragment that mimics the shape of abnormal sugars attached to cancer cell proteins seems to do the trick. The new therapy is currently being considered for clinical trials.
The new work--led by Vasso Apostolopoulos of the Austin Research Institute in Heidelberg, Australia--targets sugar molecules on the surface of a protein called mucin (MUC1), which is secreted by epithelial cells of mucous membranes in the kidney, lung, breast, and other tissues. MUC1 on cancer cells is studded with sugar molecules that are shorter and fewer in number than those on normal cells. Previous experiments had shown that these runty sugars themselves don't make good vaccines, since they are poor at stimulating immune cells to attack.
Apostolopoulos and his colleagues circumvented this problem by using a short protein fragment that mimics the structure of the aberrant sugar molecules, and is able to spark a stronger immune response. They tested the mimic in mice that received transplanted human breast cancer cells expressing the altered MUC1 protein. Mice that received injections of the fake sugar vaccine didn't go on to develop cancer, while control animals did.
In an accompanying review, Olivera Finn of the University of Pittsburgh School of Medicine and Sandra Gendler of the Mayo Clinic in Scottsdale, Arizona, call the new strategy an important approach that "may ultimately prove useful in a clinical setting." In fact, efforts are already underway to start clinical trials, says group member Ian McKenzie. "Initially, the testing will be done on patients with cancer," he says. "If that's successful, it will be done on patients in [high risk] groups."