A small, early trial of a vaccine that mobilizes the immune system to battle advanced kidney cancers appears successful, researchers report.

The vaccine acts like a "wanted poster" unmasking cancer cells that are adept at hiding in the body, only to resurface later. The hope is that the vaccine primes the immune system to seek out and destroy any remaining traces of cancer, improving the chances of being cancer-free in years to come.

Scientists at the Dana-Farber Cancer Institute and elsewhere developed the vaccine, which is designed to prevent advanced cases of kidney cancer from returning. Since the trial patients received the vaccine roughly three years ago,

In a Phase 1 study, nine people with advanced kidney cancer became cancer free after receiving personalized vaccines.