Angiogenesis is an essential component of the growth and dissemination of solid
malignancies and is mediated by several proangiogenic factors. The most widely studied proangiogenic factor is
vascular endothelial growth factor (
VEGF). A major class of
molecular targeted therapies (
MTTs) inhibit the
VEGF axis and are referred to as antiangiogenic
MTTs. There are two main types of anti-
VEGF MTTs: drugs targeting circulating
VEGF and drugs interfering with the activity of the
VEGF receptors. The
cancers against which antiangiogenic
MTTs have had the greatest effect are
gliomas,
non-small cell lung cancer,
colorectal cancer,
hepatocellular carcinoma,
renal cell carcinoma, and
gastrointestinal stromal tumor. These
cancers respond to antiangiogenic
MTTs in a different way than they respond to conventional
chemotherapy. Instead of the traditional Response Evaluation Criteria in Solid Tumors (RECIST), each of these
cancers therefore requires its own individualized treatment response criteria (TRC). Examples of individualized TRC include the Response Assessment in Neuro-oncology (RANO) criteria for
gliomas, modified RECIST for
hepatocellular carcinoma, and Morphology, Attenuation, Size, and Structure (MASS) criteria for
renal cell carcinoma. Furthermore, antiangiogenic
MTTs have a unique spectrum of class-specific and
drug-specific toxic effects, some of which can be detected at imaging. Increasing use of antiangiogenic
MTTs in clinical practice necessitates that radiologists be aware of these drugs, their response patterns, and TRC as well as their toxic effect profiles.