Spending on biotech drugs is on the rise, according to a report from pharmacy benefits manager Express Scripts.Spending on biotech drugs increased 21% in 2006. Meanwhile, overall biotech drug costs will reach $99 billion by 2010 accounting for 26% of total drug spending, The biotech spending increase reflects the growing demand for medications once prescribed to treat only rare diseases. Of the six top biotech drug classes, five saw an increase in spending:*Cancer therapies had the largest increase in spending at 39.5%, which was driven by new treatments including three new drugs introduced in 2006 (Onyx’s Nexavar, Celgene’s Revlimid and Pfizer’s Sutent). *Multiple sclerosis spending increased 19% as a result of higher drug prices. *Growth hormone deficiency spending rose 22.8% last year due to a 10.7% increase in the number of units per prescription and a rise in prescriptions for uses other than growth deficiencies in children. *Drugs to treat inflammatory conditions experienced a 22.7% rise with additional treatment indications such as Abbott’s Humira for psoriatic arthritis and an overall increased confidence in prescribing this class of drugs.Hepatitis C was the only therapy class in the top six with a decrease in spending. This class saw an 8.3% drop as a result of lower cost per prescription and lower utilization. The increased use of generic ribavirin was the primary factor contributing to the lower cost per prescription for the class. Hepatitis C is treated with a combination therapy of interferons and ribavirin, a non-biologic, small molecule drug. Generic ribavirin was approved by FDA in 2004.