( Data Indicate Significant Anti-Tumor Ef...)Calando Pharmaceuticals Announces Preclinical Efficacy and Safety,Data of Targeted, Systemic Delivery of siRNA at AACR Annual Meeting,Health

PASADENA, Calif., April 16, 2007 /PRNewswire/ -- Calando Pharmaceuticals, a leading siRNA therapeutics company and a majority-owned subsidiary of Arrowhead Research Corporation presented positive results of preclinical efficacy testing in mice using multiple, systemic dosing with Calando's lead siRNA therapeutic candidate CALAA-01, a nanoparticle containing non-chemically modified siRNA and a transferrin protein targeting agent at the American Association for Cancer Research (AACR) annual meeting on April 17, 2007 in Los Angeles, California.

The presentation is entitled "Development and in vivo tolerability and efficacy testing of a therapeutic formulation containing siRNA against the M2 subunit of ribonucleotide reductase in mice and monkeys." Calando's presentation details the results of a pilot safety study of Calando's lead siRNA-containing nanoparticle formulation CALAA-01 in rodents and monkeys. Additionally, data from a multi-dose efficacy study in mice using systemically-administered siRNA nanoparticles showed significant anti-tumor activity at dose levels that are significantly below the upper limits of safe, systemic, multi-dose administrations in both rodents and monkeys.

"Based on this data, we are very optimistic as we move closer to an IND filing later this year." said John Petrovich, Calando's CEO. "This data combined with other recently announced data shows efficacy as well as an overall lack of toxicity using CALAA-01."

The formulation investigated contains Calando's proprietary delivery technology and utilizes RNA interference in cancer cells with an siRNA duplex targeting the M2 subunit of ribonucleotide reductase, a well-established cancer target. This duplex, developed at Calando, demon
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