Think of cancer as a kind of infection. Like viruses and bacteria, tumor cells can develop ways to avoid detection and destruction by a person's immune system.
Scientists now have found that many human cancers may evade surveillance by exploiting a protein normally found on certain immune cells. In an upcoming Nature Medicine, Lieping Chen of the Mayo Clinic in Rochester, Minn., and his colleagues report that tumor cells bearing this molecule, dubbed B7-H1, spur the death of cancer-fighting immune sentinels called T cells.
This finding may force researchers to rethink so-called cancer vaccines and other cancer-therapy strategies that work by rallying the immune system. "These therapies will be in trouble if the tumor is B7-H1 positive," says Chen. "If you block B7-H1, however, you should improve immunotherapy."