The body launches an immune response to kill
cancer cells upon detection, both before and
after tumor formation. Cancer cells evade this
response by deactivating effector immune cells
such as cytotoxic T cells and macrophages.
Evasion mechanisms include blocking immune cell
activation signaling, downregulating
surface antigens to prevent detection, and
secreting cytokines and chemokines to prevent
immune cell recruitment and infiltration into
the TME^4.Immune Evasion
Lets Cancer Cells
Hide in Plain Sight
While furthering tumor growth, blood vessels also
carry therapeutic agents to their intended targets.
Researchers are now exploring the possibility of
stimulating angiogenesis in order to maximize
anti-cancer agent delivery. As stabilizers of vascular
integrity and maturation, pericytes appear essential
to this approach^3.Turning Angiogenesis
Against TumorsLike any tissue, a tumor needs nutrients and oxygen
from the blood to survive. Cancer cells stimulate
new vessel formation through a variety of signaling
pathways. This tumor-directed angiogenesis is
haphazard and unchecked, making it difficult to
control. Key pathways involved include those of
hypoxia-inducible transcription factors (HIFs),
pro-inflammatory molecules (prostaglandins
and cyclooxygenases), and growth factors.
Neovascularization is essential for tumor expansion
and metastasis1,2.Angiogenesis
Paves the Road to
Tumor Growth
Researchers have used molecular antagonists
(including custom antibodies) to downregulate pro-
angiogenic signaling, either by blocking receptors or
targeting ligands to prevent binding^1. Over a dozen
such inhibitors have US FDA approval, and they are
currently employed concurrently with other anti-
cancer therapeutic approaches^1.
Putting the Brakes on
Angiogenesis
Proteins such as angiostatin can target the physical
processes of neovascularization. These compounds
block vessels from assembling by preventing
endothelial cell migration, preserving extracellular
matrix integrity, or inducing endothelial cell
apoptosis^2.Roadblocks to Vessel
Formation