Their analysis shows that the sales of therapeutic protein products are concentrated in a relatively small number of branded products, which may be the most attractive targets for follow-on development. Many of these products are complex proteins that are reported to have patent coverage for several more years.

However, if reported patent expiration estimates hold, in the not-too-distant future, a significant number of important protein products with large current sales will lose patent protection. For the years 2013–2015, they estimate that products representing US$20 billion (Euros 14.3 billion) in annual sales – approximately half of all sales in 2006 – can be expected to lose patent protection.

The majority of the products were licensed under the Public Health Service Act, which lacks an abbreviated pathway for approval of follow-on products, creating uncertainty for potential developers of follow-on products.