Nanotechnology Now - Press Release: Calando Pharmaceuticals Announces Preclinical Efficacy and Safety Data of Targeted, Systemic Delivery of siRNA at AACR Annual Meeting

Home > Press > Calando Pharmaceuticals Announces Preclinical Efficacy and Safety Data of Targeted, Systemic Delivery of siRNA at AACR Annual Meeting

Abstract:
Data Indicate Significant Anti-Tumor Effects of Targeted, Systemic siRNA Therapeutic at Doses Significantly Lower Than the Limits of Safe Administrations in Rodent and Non-Human Primates

Calando Pharmaceuticals Announces Preclinical Efficacy and Safety Data of Targeted, Systemic Delivery of siRNA at AACR Annual Meeting

Pasadena, CA | Posted on April 16th, 2007

Calando Pharmaceuticals, aleading siRNA therapeutics company and a majority-owned subsidiary of
Arrowhead Research Corporation (Nasdaq: ARWR) 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,
demonstrates potent anti-proliferative activity across multiple types of
cancer types in vitro and in vivo.

"These studies were performed to demonstrate both the safety and
efficacy of this siRNA-containing formulation in animals," said Jeremy
Heidel, Chief Scientific Officer at Calando Pharmaceuticals. "This
formulation was well-tolerated in mice and monkeys at concentrations that
elicited a significant anti-tumor effect in a murine cancer model. These
results suggest that this formulation has promise for human use."

Calando's cyclodextrin-containing polymers form the foundation for its
two-part siRNA delivery system. The first component is a linear,
cyclodextrin-containing polycation that, when mixed with small interfering
RNA (siRNA), binds to the anionic "backbone" of the siRNA. The polymer and
siRNA self-assemble into nanoparticles of approximately 50-80 nm diameter
that fully protect the siRNA from nuclease degradation in serum. The siRNA
delivery system has been designed to allow for intravenous injection. Upon
delivery to the target cell, the targeting ligand binds to membrane
receptors on the cell surface and the RNA-containing nanoparticle is taken
into the cell by endocytosis. There, chemistry built into the polymer
functions to unpackage the siRNA from the delivery vehicle. In addition to
targeting tumors, the targeting of liver cells has also been accomplished
in vivo.

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About Calando Pharmaceuticals
Calando Pharmaceuticals Inc. ( http://www.calandopharma.com ), a majority-owned
subsidiary of Arrowhead Research (Nasdaq: ARWR), is using its proprietary
technologies in targeted polymeric delivery systems and siRNA design to
design and create new, targeted siRNA therapeutics. Small interfering RNAs
(siRNA) induce RNA interference, or RNAi, a naturally occurring mechanism
within cells to selectively silence and regulate specific genes. The
ability to silence genes through RNAi could provide a new way to treat a
wide range of human diseases. The company is pursuing this goal through its
internal research and development and also through collaborations and
partnerships with pharmaceutical and biotechnology companies.

About Arrowhead Research Corporation
Arrowhead Research Corporation (http://www.arrowheadresearch.com) is a
publicly-traded nanotechnology company commercializing new technologies in
the areas of life sciences, electronics, and energy. 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 latest Annual Report on Form 10-K, recent and
forthcoming Quarterly Reports on Form 10-Q, recent Current Reports on Forms
8-K, 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.

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Contacts:
Calando Pharmaceuticals, Inc.
2585 Nina Street
Pasadena, CA 91107
PHONE: 626.305.9322, Ext. 222
FAX: 626.305.9094

INVESTOR RELATIONS

Patty Hess
Vice President, Administration
Calando Pharmaceuticals, Inc.
626.305.9322, Ext. 222