Positive results from RXi NeuVax Phase 2 trial on breast cancer presented at ASCO 2011

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.
• 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.
• 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."