Diseases for which there are no treatments are not the only under-served markets. Diseases for which there are well-known and widely sold products also may be under-served, though it may be harder for investors to see their potential.

One way to demonstrate value is to sign up a corporate partner, who presumably has done the due diligence that investors can't perform. Biogen Inc., which has been looking for new products for its pipeline, has provided that kind of validation for CV Therapeutics' CVT-124, a selective adenosine A1-receptor antagonist for the treatment of edema associated with chronic heart failure (CHF).