First Fiscal Quarter 2009 And Recent Business Highlights:

Calando Pharmaceuticals (Calando) completed its Phase I trial for IT-101, its first anti-cancer drug candidate;

Calando announced the potential application of its RONDEL systemic delivery technology for sepsis, representing an extension of its siRNA delivery technology beyond its initial application to oncology;

Mark Tilley, vice president of Advanced Materials at Arrowhead, was appointed chief executive officer (CEO) of Unidym, Inc. (Unidym);

Subsequent to the close of the quarter, Unidym announced the consolidation of its operations to California’s Silicon Valley as part of a series of steps to improve efficiencies and reduce costs within the subsidiary.

“We continued to pursue opportunities to commercialize our subsidiaries’ nanotechnology-based solutions in the first fiscal quarter, while simultaneously taking steps to improve our balance sheet,” said Christopher Anzalone, Arrowhead’s president and CEO. “Our subsidiaries’ solutions gained further traction, most notably via key milestones reached and a strengthening of existing partnerships with industry leaders such as Samsung Electronics and Tokyo Electron. Furthermore, Calando’s IT-101 anti-cancer therapeutic completed its Phase I trials and moved forward with Phase II trials for ovarian cancer, while Calando’s first RNAi therapeutic, CALAA-01, continues to move quickly through Phase I trials.”

“At the same time, we are clearly operating in an unprecedented economic environment that requires us to take decisive action to ensure that Arrowhead and its subsidiaries remain competitive through the downturn. Central to this effort is a reorganization that focuses each subsidiary’s business model on nearer-term revenue streams and is supplemented by aggressive cost-cutting measures. We believe these measures will result in a leaner, more nimble organization.”

Anzalone concluded, “The impact of the cash saving actions taken by Arrowhead and our subsidiaries is expected to become more fully realized as part of our consolidated results in the coming quarters. We expect that our subsidiaries’ lower cost structures, coupled with real near-term value creation via partnerships and commercial opportunities, will provide Arrowhead and its subsidiary companies with access to the capital required to realize their potential. As owners of key nanotechnology assets in the areas of advanced materials, biotechnology and clean energy technologies, we believe that Arrowhead has the potential to capitalize on a vast market opportunity.”

Selected First Quarter Fiscal 2009 Financial Results:

The company’s operational use of cash during the first quarter of fiscal 2009 was $7.4 million, compared to $5.8 million in the year-ago period. The company’s consolidated cash flows include about $2.5 million raised or committed through a note offering by Calando and $2.0 million of mezzanine financing at Unidym, together with the $0.7 million cash sale of Unidym’s equity interest in Ensysce BioSciences, Inc. Cash and cash equivalents totaled $7.6 million as of December 31, 2008, compared with $10.1 million for the fiscal year ended September 30, 2008.