Since their discovery approximately 25 years ago, adenosine receptors
have now emerged as important novel molecular targets in disease and
drug discovery. These proteins play important roles in the entire
spectrum of disease from inflammation to immune suppression. Because of
their expression on a number of different cell types and in a number of
different organ systems they play important roles in specific diseases,
including asthma, rheumatoid arthritis, Parkinson's disease, multiple
sclerosis, Alzheimer's disease, heart disease, stroke, cancer, sepsis,
and obesity. As a result of intense investigations into understanding
the molecular structures and pharmacology of these proteins, new
molecules have been synthesized that have high specificity for these
proteins and are now entering clinical trials. These molecules will
define the next new classes of drugs for a number of diseases with unmet
medical needs.