RXi Pharmaceuticals Presented New Pre-Clinical Animal Data at its Annual Investor Day

New Data Include Use of Novel sd-rxRNA with Improved Pharmacology with Both
Local and Systemic Administration
WORCESTER, Mass.--(Business Wire)--
RXi Pharmaceuticals Corporation (Nasdaq: RXII), a biopharmaceutical company
pursuing the development and commercialization of proprietary therapeutics based
on RNA interference (RNAi), today announced the presentation of new preclinical
data from its advanced RNAi therapeutic platform at its Annual Investor Event
held in New York City on Monday, October 5, 2009.

The presented data include results with novel self-delivering (sd-rxRNA) RNAi
compounds, which do not require an additional delivery vehicle to enter cells.
The data show significantly improved pharmacological properties of these
molecules, with applicability in a broad range of therapeutic applications.

"We are excited about the progress we are making in our sd-rxRNA research
efforts," said Tod Woolf, Ph.D. President and CEO of RXi Pharmaceuticals. "A key
highlight from our presentation was that recently obtained data with our
proprietary sd-rxRNA markedly improves the delivery of systemically and locally
administered RNAi compounds. RXi and our collaborators in RNAi consider advances
in the delivery to be the most important factor for the successful
commercialization of RNAi therapeutics. "

RXi`s therapeutic platform leverages its Next Generation rxRNA compounds and
advanced delivery technologies to enable its internal programs and external
collaborations. This provides RXi with multiple opportunities for the potential
development of a sustainable pipeline of RNAi based products for unmet medical
needs.

Key findings and highlights from the event include the following:

* Dr. Craig Mello, Nobel Laureate and RXi`s co-founder and Chairman of its
Scientific Advisory Board, provided novel insights into the RNAi mechanism which
have aided in the design of RXi`s novel rxRNA compounds.
* Data presented on the length of compounds showed that reducing the size of
RNAi compounds could be important for cellular uptake.
* sd-rxRNA compounds were shown to have improved pharmacological and drug-like
properties compared to unmodified classic siRNA (short interfering RNA).
Research findings on sd-rxRNAs show:

* Increased serum stability
* Improved retention in the circulation
* Minimal immune response activation
* Efficient cellular uptake and internalization to many diverse cell types
* Systemic delivery to the liver with effective gene silencing
* Local delivery via intradermal injection with effective gene silencing

* An update to the status of indications currently being pursued by RXi was
provided:

* Compromised skin - RXi is performing animal studies based on positive data
showing spontaneous uptake and enhanced tissue penetration with sd-rxRNA
compounds.
* Inflammatory diseases - RXi is working with researchers from the University of
Massachusetts to deliver rxRNA compounds using an advanced delivery vehicle that
targets macrophage cells.
* Liver diseases - RXi is exploring sd-rxRNA delivery to the liver upon
subcutanteous administration to animal models without the use of an additional
delivery vehicle. Delivery to the liver may have many applications such as
controlling hypercholesterolemia as well as several other metabolic indications.

* Ocular diseases - RXi has shown spontaneous cellular uptake of its sd-rxRNA
compounds by retinal cells and is working with an academic collaborator to
further address retinal diseases.
* Amyotrophic lateral sclerosis (ALS or Lou Gehrig`s disease) - RXi has
established an academic collaboration with one of the leading ALS researchers to
explore delivery of sd-rxRNA compounds to the spinal cord.
* Oncology - RXi has an active pharmaceutical collaboration to explore the
potential of using the rxRNA therapeutic platform in this area.

* RXi summarized its intellectual property position including its alternative
path to RNAi based on the length of rxRNA duplexes and distinct end-structures
and multiple layers of patent protection for both rxRNA compounds and delivery
vehicles.

About RNA Interference (RNAi)

Regarded as a revolutionary discovery in biology, RNA interference (RNAi) is a
naturally occurring mechanism whereby short, double-stranded RNA molecules
interfere with the expression of genes in living cells. This mechanism has the
potential to be harnessed to "silence" or specifically block the production of
disease-causing proteins before they are made. This technology can potentially
be used to treat human diseases by "turning-off" genes that lead to disease in
the first place. RXi Pharmaceuticals is using RNAi technology to develop
RNA-derived molecules targeting disease-causing genes.

About RXi Pharmaceuticals Corporation

RXi Pharmaceuticals is a discovery-stage biopharmaceutical company pursuing the
development and potential commercialization of proprietary therapeutics based on
RNA interference (RNAi) for the treatment of human diseases. RXi has a
comprehensive therapeutic platform that includes both RNAi compounds and
delivery methods. RXi uses its own version of RNAi compounds -- rxRNA -- that
provide an advanced alternative to conventional small interfering RNAs (siRNAs)
and define the next generation of RNAi technology. rxRNA compounds are designed
specifically for therapeutic use and contain many of the properties needed to
move RNAi based drugs into the clinic. RXi Pharmaceuticals believes it is well
positioned to compete successfully in the RNAi-based therapeutics market with
its accomplished scientific advisors, including Dr. Craig Mello, recipient of
the 2006 Nobel Prize for his co-discovery of RNAi; a management team that is
experienced in developing RNAi products; and a strong early intellectual
property position in RNAi chemistry and delivery. www.rxipharma.com

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the
Private Securities Litigation Reform Act of 1995. Such statements include, but
are not limited to, statements about future expectations, plan and future
development of RXi Pharmaceutical Corporation`s products and technologies. These
forward-looking statements about future expectations, plans and prospects of the
development of RXi Pharmaceutical Corporation`s products and technologies
involve significant risks, uncertainties and assumptions, including the risk
that the development of our RNAi-based therapeutics may be delayed or may not
proceed as planned and we may not be able to complete development of any
RNAi-based product, the risk that the FDA approval process may be delayed for
any drugs that we develop, risks related to development and commercialization of
products by our competitors, risks related to our ability to control the timing
and terms of collaborations with third parties and the possibility that other
companies or organizations may assert patent rights that prevent us from
developing our products. Actual results may differ materially from those RXi
Pharmaceuticals Corporation contemplated by these forward-looking statements.
RXi Pharmaceuticals Corporation does not undertake to update any of these
forward-looking statements to reflect a change in its views or events or
circumstances that occur after the date of this release.

RXi Pharmaceuticals
Donna Falcetti, 508-929-3615
ir@rxipharma.com
or
Investors
S. A. Noonan Communications
Susan Noonan, 212-966-3650
susan@sanoonan.com
or
Media
Rx Communications Group
Eric Goldman, 917-322-2563
egoldman@rxir.com

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