Macrophages are immune cells responsible for fighting bacteria. However, they are not normally programmed to attack cancer cells. They can even help metastasizing (wandering) tumor cells grow.
In this video Cold Spring Harbor Laboratory Professor Mikala Egeblad and her lab grew cells from mice with breast cancer in petri dishes. They found that a combination of drugs added to a dish could reprogram macrophages to attack tumor cells. Once activated, the macrophages killed the cancer cells and consumed the cell debris.
A similar treatment in living mice prevented cancer metastases and prolonged the survival of tumor-bearing mice. Egeblad and her colleagues hope this method can be applied to fight human cancers in the future.
To find out the whole story, read the peer-reviewed paper.