RXi Pharmaceuticals Announces Pharmacokinetic Results of its Single Dose Phase 1 Study with RXI-109 in Healthy Volunteers

  RXi Pharmaceuticals Announces Pharmacokinetic Results of its Single Dose
  Phase 1 Study with RXI-109 in Healthy Volunteers

   Results show limited systemic exposure, supporting the excellent safety
            profile of this intradermally injected drug in humans

Business Wire

WESTBOROUGH, Mass. -- November 15, 2012

RXi Pharmaceuticals Corporation (OTC: RXII), a biotechnology company focused
on discovering, developing and commercializing innovative therapies addressing
major unmet medical needs using RNA-targeted technologies, today announced the
pharmacokinetic results of their single dose Phase 1 study with RXI-109 in
healthy subjects. This drug candidate is a highly selective CTGF targeting
sd-rxRNA® compound that is administered through intradermal injections to 
prevent or reduce dermal scarring following surgery or trauma, as well as for
the management of hypertrophic scars and keloids.

In this study, 15 volunteers divided over 5 cohorts received single
intradermal injections in a dose escalating manner, and blood was drawn at
various time points to evaluate the distribution of the drug beyond the
injected tissue, into the systemic circulation.Previous primate toxicology
work with RXI-109 had shown that the peak blood levels obtained after
intradermal injections with 10 mg/kg were approximately 3.5% of the peak
levels obtained after intravenous injections with the same dose. With the
different doses in the primate study, the dermal and systemic side effects in
the animals were minimal. The maximum dose administered intradermally in the
human subjects was on average only 0.3 mg/kg at the highest dose, i.e., more
than 30 times lower than the dose given to the primates. The calculated
relative systemic exposure in the 15 volunteers was between1 and 7% (mean
5%), which is very similar to the systemic exposure in primates. As reported
earlier, the drug was very well tolerated in all volunteers tested.

"These data confirm our first clinical observations, that subjects had no
significant side effects or complaints after intradermal injection with
RXI-109," said Dr. Geert Cauwenbergh, President and CEO of RXi
Pharmaceuticals. He added that, "Considering theabsence oftoxicity in our
primate toxicology studies at much higher doses, given both intradermally and
intravenously, and considering the very similar low degree of systemic
exposure we have found in our volunteers, we are confident in moving forward
into a multiple dose Phase 1 study in the very near future. The subjects from
our first study with RXI-109 are currently in the process of undergoing their
abdominoplasty, which will provide samples that will allow us to also make a
clinical and histological evaluation of single dose RXI-109 treatment versus
placebo in these subjects."

About Scarring

With cosmetic surgical procedures becoming increasingly more common to improve
appearance, or to correct skin imperfections as a result of trauma or disease,
scarring has become a much more significant side effect of such interventions.
In humans, scarring of the skin after surgery, trauma, or burns can cause
debilitating aesthetic, functional and psychological effects. Particularly
problematic are raised or hypertrophic scars and keloids, scars which extend
beyond the original skin injury. Medical treatment for scarring remains
limited. Often with severe scarring, acceptable treatment plans include scar
revision surgery which may alter the scar initially, but may also result in
further exacerbation of the surgically-intervened area. Such exacerbation of a
scar can often be a debilitating and painful experience for the patient and,
to date, there are no FDA-approved therapeutics for the treatment of
post-operative scars. RXI-109 has been shown in cell culture and animal models
to reduce CTGF, a growth factor that is essential in the wound healing
cascade. Elevated levels of CTGF-dependent signaling can prolong the tissue
repair process and lead to pathological scarring.

About RXI-109

RXi Pharmaceuticals first clinical program centers around RXI-109, a
self-delivering RNAi compound (sd-rxRNA) developed by RXi for the reduction of
dermal scarring in planned surgeries. RXI-109 is designed to reduce the
expression of CTGF (connective tissue growth factor), a critical regulator of
several biological pathways involved in fibrosis, including scar formation in
the skin. The first clinical trial of RXI-109, initiated in June 2012, will
evaluate the safety and tolerability of several dose levels of RXI-109 in
humans and may provide preliminary evidence of surgical scar reduction. As
there are currently no FDA-approved drugs to prevent scar formation, a
therapeutic of this type could have great benefit for trauma and surgical
patients (especially relating to raised or hypertrophic scarring), as a
treatment during the surgical revision of existing unsatisfactory scars, and
in the treatment, removal and inhibition of keloids (scars which extend beyond
the original skin injury).

RXi’s sd-rxRNA compounds are designed for therapeutic use and have drug-like
properties, such as high potency, target specificity, serum stability, reduced
immune response activation, and efficient cellular uptake. They are hybrid
oligonucleotide molecules that combine the beneficial properties of both
conventional RNAi and antisense technologies. The sd-rxRNAs have a
single-stranded phosphorothioate region, a short duplex region, and contain a
variety of nuclease-stabilizing and lipophilic chemical modifications. The
combination of these features has been shownin vitroand in animal tissues,
to allow sd-rxRNAs to achieve efficient spontaneous cellular uptake and
potent, long-lasting intracellular activity.

About RXi Pharmaceuticals Corporation

RXi Pharmaceuticals Corporation (OTC: RXII) is a biotechnology company focused
on discovering, developing and commercializing innovative therapies based on
its proprietary, next-generation RNAi platform. Therapeutics that use RNA
interference, or “RNAi,” have great promise because of their ability to
“silence,” or down-regulate, the expression of a specific gene that may be
over-expressed in a disease condition. Building on the pioneering work of
scientific founder and Nobel Laureate Dr. Craig Mello, a member of the RXi
Scientific Advisory Board, RXi’s first RNAi product candidate, RXI-109, which
targets CTGF (connective tissue growth factor), entered into a human clinical
trial in June 2012 to evaluate its safety, tolerability and potential efficacy
for scar prevention. For more information, please visit 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 Pharmaceuticals Corporation’s products and
technologies.These forward-looking statements about future expectations,
plans and prospects of the development of RXi’s products and technologies
involve significant risks, uncertainties and assumptions, including the risk
that RXi may not be able to successfully develop its candidates, 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 development process for our product
candidates may be delayed, 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
contemplated by these forward-looking statements.RXi 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.

Contact:

RXi Pharmaceuticals Corporation
Tamara McGrillen, 508-929-3646
tmcgrillen@rxipharma.com