( Novel Systems May Provide Cancer Patien...)Arrowhead Subsidiaries Insert & Calando Present Data on,Cyclosert Drug Delivery System at AACR Meeting,Health

PASADENA, Calif., April 16, 2007 /PRNewswire-FirstCall/ -- Arrowhead Research Corporation announced today that two of its majority-owned subsidiaries, Insert Therapeutics Inc. and Calando Pharmaceuticals Inc., are presenting data at the 2007 American Association for Cancer Research (AACR) Annual Meeting. The presentations summarize the latest research findings on two anticancer therapies currently under development. Both therapies employ a novel delivery system called Cyclosert(TM), developed at the and exclusively licensed to Insert Therapeutics and, through Insert, to Calando.

"We are pleased that our companies have outstanding data to present at this prestigious conference," said R. Bruce Stewart, Chairman and Chief Executive Officer of Arrowhead. "We see great promise going forward for the treatment of cancer using our delivery system."

Cyclosert is the first nanoparticle drug transport platform to be designed de novo and synthesized specifically to overcome limitations in existing technologies used for the systemic transport of therapeutics to targeted sites within the body. Based on small cyclic repeating molecules of glucose called cyclodextrins, Cyclosert promotes the ability of cytotoxic drugs to inhibit the growth of human cancer cells while reducing toxicity and remaining non-immunogenic at therapeutic doses. In particular, the system is designed to reduce the toxicity of the drugs until they actually reach the targeted tumor cells where the active drug is released in a controlled fashion.

Insert's Chief Scientific Officer, Thomas Schluep, Sc.D., will present data from in vitro and animal studies using the Cyclosert system to deliver tubulysin A, a potent, but highly toxic, antitumor agent. In vitro studies have shown the tubulysin-Cyclosert conjugate to be effective against multiple human c
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