While past approaches to treating psoriasis have largely taken a hit-or-miss approach to developing drugs, a new understanding of immunology has led to the next generation of compounds and biologics targeting the autoimmune process underlying the condition. As the majority of such compounds are just beginning to enter late stage testing, clinical data will be required to validate these efforts. However, last week's Phase II data from Biogen Inc. is a first sign that immune-based therapies may reach the market.

Psoriasis is characterized by thickened patches of inflamed, red and often scaly skin that has a fluctuating course in terms of severity - the condition can flare at any time.