Kick-starting cancer immunity by eliminating non-cancer cells within tumors.

Tumors are complex mixtures of normal (stromal) cells and cancer cells. Researchers using mouse models have shown that stromal cells can block immune function.  The stromal cells were found to produce a protein, fibrobast activation protein-alpha (FAP), that inhibits the immune system.  When the stromal cells making FAP were eliminated, the tumors could be killed by the immune system.