This press release states that InterImmune, Inc has been issued two composition of matter patents that together cover the manufacture, use and sale of Actimmune in the United States. These patents expire in 2022 and extend a portfolio of intellectual property rights relating to Actimmune, which includes another composition of matter patent that expires in 2014.

The press release further quotes Dan Welch, President and CEO of InterMune:

"The issuance of these patents marks an important step in extending the proprietary position of Actimmune(R) as we continue to make significant investments in the clinical development of Actimmune(R) in our pivotal Phase III INSPIRE trial in idiopathic pulmonary fibrosis (IPF) and our pivotal Phase III GRACES trial in ovarian cancer."

I personally do not know much about the patent legalese. Actimmune� is a bioengineered interferon gamma, already FDA approved and indicated for treatment of serious infections associated with chronic granulomatous disease (CGD) and delaying progression of severe, malignant osteopetrosis. Why would they need to expand the composition of matter patent?

Any insights from patent experts out there?