  June 10, 2013 by Krista Conger   And there's the rub: The
immune system's ability to protect against foreign invaders like
bacteria or viruses hinges on its ability to differentiate them
from our body's own tissues, to which it must not react (a
phenomena called ). So it's a catch-22 when researchers attempt
to prime B and T cells, macrophages and all of our many other to
wipe out cancer cells. Often, what seems to be a promising
response is dulled over time as immune cells called T , or
Tregs, recognize the cancerous tissue as "self" and call off the
attack.  Now, Ronald Levy, MD, professor of oncology at the
School of Medicine and pioneer in the field of , and
postdoctoral scholar Aurelien Marabelle, MD, have shown it's
possible to perpetuate an anti-cancer immune response in by
blocking the activity of Tregs with specific antibodies injected
directly into the tumor site. The work, which has resulted in
the recent initiation of a phase-1 and -2 clinical trial in
humans, was published May 24 in the Journal