Arrowhead to Form New Nanomedicine Subsidiary and Acquire Nanotherapeutics Company, C Sixty, Inc.

PASADENA, Calif. -- Arrowhead Research Corporation (NASDAQ:ARWR) announced today that it has formed a new wholly-owned subsidiary and has agreed to acquire the assets, as well as the name, of C Sixty, Inc. (C-60), a company pioneering the development of new drugs based on buckministerfullerenes (also known as fullerenes or buckyballs).

The new subsidiary joins Arrowhead as its third focused on nanomedicine. Arrowhead operates two other majority owned subsidiaries commercializing nanotherapeutics. Calando Pharmaceuticals is a leading RNAi company specializing in the design and delivery of siRNA therapeutics. Insert Therapeutics is commercializing drug-delivery-enhanced small-molecule therapeutics and nucleic acids. Insert's first anti-cancer drug candidate is in Phase I clinical trials.

"The future of medicine lies in targeted delivery of therapeutics through nanotechnology," said R. Bruce Stewart, Arrowhead's Chairman. "Our experience and expertise in this area makes C-60 a great strategic complement to our other majority owned subsidiaries."

Fullerenes are a highly structured, water soluble, nanoscale form of carbon, similar to carbon nanotubes, discovered by Richard Smalley, who received the Nobel Prize for his work in this area. Roughly one nanometer in diameter, the molecules are composed of 60 carbon atoms and have the symmetry of soccer balls. The spherical shape, hollow interior, and 60 carbon atoms of the molecule allow drug designers the opportunity to attach therapeutic and targeting chemical groups in many configurations.

C Sixty, Inc. has secured and developed a strong patent position covering the strategic biomedical uses of fullerenes. Initially, C-60 will focus on the antioxidant activity of fullerenes. Arrowhead believes that drugs based on fullerene antioxidant molecules may have significant impact on several unsolved diseases, including Parkinson's disease, Alzheimer's, stroke, atherosclerosis, complications from diabetes and protection of bone marrow cells from cancer chemotherapy and radiotherapy. Solutions for any of these diseases could represent billion dollar annual market opportunities.

About Arrowhead Research Corporation

Arrowhead Research Corporation (www.arrowheadresearch.com) is a publicly-traded nanotechnology company commercializing new technologies in the areas of life sciences, electronics, and energy. Arrowhead is building value for shareholders through the progress of majority owned subsidiaries founded on nanotechnologies originally developed at universities. The company works closely with universities to source early stage deals and to generate rights to intellectual property covering promising new nanotechnologies. Currently, Arrowhead has four subsidiaries commercializing nanotech products and applications, including anti-cancer drugs, RNAi therapeutics, carbon-based electronics and compound semiconductor materials.

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995:

This news release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These statements are based upon our current expectations and speak only as of the date hereof. Our actual results may differ materially and adversely from those expressed in any forward-looking statements as a result of various factors and uncertainties, including the recent economic slowdown affecting technology companies, the future success of our scientific studies, our ability to successfully develop products, rapid technological change in our markets, changes in demand for our future products, legislative, regulatory and competitive developments and general economic conditions. Our Annual Report on Form 10-K and 10-K/A, recent and forthcoming Quarterly Reports on Form 10-Q and 10-Q/A, recent Current Reports on Forms 8-K and 8-K/A, our Registration Statements on Form S-3, and other SEC filings discuss some of the important risk factors that may affect our business, results of operations and financial condition. We undertake no obligation to revise or update publicly any forward-looking statements for any reason.