RXi Pharmaceuticals Corporation (NASDAQ: RXII), a biotechnology company focused on discovering, developing and commercializing innovative therapies addressing major unmet medical needs using targeted biotherapeutics, announced updated data from its Phase 2 clinical trial of NeuVax™ at the American Society of Clinical Oncology (ASCO) annual meeting. RXi is developing NeuVax for the adjuvant treatment of low to intermediate HER2 expressing breast cancer.

The NeuVax Phase 2 trials enrolled 182 patients, including node positive and node negative, HER2 1+, 2+ and 3+ patients. All patients received standard of care (SoC) therapy and were confirmed to be disease-free prior to enrollment. Following enrollment, eligible patients were administered the NeuVax vaccine once a month for six months, followed by booster shots one every 6 months thereafter. The efficacy endpoint for the trial was disease free survival (DFS), the same endpoint in the FDA approved SPA (Special Protocol Assessment) for the Phase 3 PRESENT ( Prevention of Recurrence in Early- Stage, Node-Positive Breast Cancer with Low to Intermediate HER2 Expression with NeuVax™ Treatment) study.

“These encouraging clinical results underscore the potential for cancer immunotherapy to develop into potent and well tolerated targeted therapies,” stated Dr. Beth Mittendorf, Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, who was also named the primary investigator for the Phase 3 trial. “The results of this trial suggest that NeuVax addresses an unmet medical need and clearly warrants a randomized, multicenter Phase 3 study to confirm efficacy and safety in a larger population.”

Key highlights from the Phase 2 trial include:
  • Statistically significant increase in disease free survival (DFS) at 36 months in the NeuVax treated group vs the control group for the planned Phase 3 patient population (p=0.035). The vaccine treated group showed no recurrences of cancer (0% recurrence rate), while the control group demonstrated a 22% recurrence rate which is consistent with historical norms. The planned Phase 3 patient population as defined in the FDA approved Special Protocol Assessment (SPA) includes breast cancer patients who are node positive, have low to intermediate HER2 expression (HER2 1+ and 2+ by IHC), are HLA A2+ & A3+ and who are disease free following standard of care therapy.
  • An excellent safety profile, with no serious adverse events (SAE’s) related to drug reported to date. All adverse events (AE’s) reported were minor and resolved within 24 hours.
  • In the ITT (intent to treat) population who received all ranges of doses and schedules, the low to intermediate HER2 expressers continued to show significant activity in improvement of DFS (p=0.045), with the vaccine group demonstrating a reduction of 66% in relative risk for recurrence. This data demonstrates strong support for targeting of low to intermediate HER2 expressers, a group for which there is currently no HER2 directed therapies.
  • The optimally dosed (1 milligram of E75 plus 250 micrograms of GM-CSF) group continues to demonstrate superior efficacy compared to sub-optimal doses (varying doses from 100 - 500 micrograms E75 plus 125 – 500 micrograms GM-CSF), with a recurrence rate of 3% for the optimally dosed group vs 12% for the sub-optimally dosed group and 14% for the control group.

“These promising results strongly build upon and support previously reported efficacy and safety data,” commented Dr. Mark Ahn, CEO and president of RXi. “We are committed to initiating the Phase 3 trial per the approved SPA in the first half of 2012, in order to accelerate this treatment for women who suffer from this terrible disease and who are not eligible for other HER2 directed therapies.”

About NeuVax™ (E75)

NeuVax consists of the E75 peptide derived from HER2 combined with the immune adjuvant granulocyte macrophage colony stimulating factor (GM-CSF). Treatment with NeuVax stimulates cytotoxic (CD8+) T cells in a highly specific manner to target cells expressing any level of HER2. NeuVax is given as an intradermal injection once a month for six months, followed by a booster injection once every six months. Based on a successful Phase II trial, which achieved its primary endpoint of disease free survival (DFS), the Food and Drug Administration (FDA) granted NeuVax a Special Protocol Assessment (SPA) for a Phase 3 clinical trial in adjuvant therapy of women with low-to-intermediate HER2+ status.

According to the National Cancer Institute, over 200,000 women in the U.S. are diagnosed with breast cancer annually. Of these women, about 75% test positive for Human Epidermal growth factor Receptor 2 (IHC 1+, 2+ or 3+). Only 25% of all breast cancer patients, those with HER2 3+ disease are eligible for Herceptin® (trastuzumab; Roche-Genentech) which had revenues of over $5 billion in 2010. NeuVax targets the remaining 50% of HER2 positive patients (HER2 1+ and 2+) who achieve remission with current standard of care, but have no available HER2 targeted adjuvant treatment options to maintain their disease free status.

About RXI-109

RXi Pharmaceuticals has initiated development of clinical candidate RXI-109, a self-delivering RNAi compound (sd-rxRNA) 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. RXi is beginning manufacturing activities with an experienced cGMP oligonucleotide manufacturer to support its IND enabling toxicology program, and is preparing a pre-IND package for submission to the FDA. Pending FDA review, the company intends to use an innovative clinical trial design to study safety and tolerability as well as initial efficacy in its first clinical trial targeted for 2012.

About RXi Pharmaceuticals Corporation

RXi Pharmaceuticals Corporation (NASDAQ: RXII) is a biotechnology company focused on discovering, developing and commercializing innovative therapies addressing major unmet medical needs using targeted biotherapeutics. For more information, 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 the future expectations, plans and prospects of the development of RXi Pharmaceuticals Corporation's products. These forward-looking statements about future expectations, plans and prospects of the development of the Company's products are subject to a number of risks, uncertainties and assumptions, including those identified under "Risk Factors" in the Company's most recently filed Annual Report on Form 10-K, Quarterly Report on Form 10-Q and in other filings the Company periodically makes with the SEC. Actual results may differ materially from those contemplated by these forward-looking statements. The Company 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 presentation.

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