Repligen Reports Phase 2b Results for RG2417 for Bipolar Depression

WALTHAM, MA - March 07, 2011 - Repligen Corporation (NASDAQ: RGEN) announced today results of a Phase 2b clinical trial of RG2417, an oral formulation of uridine, in patients with bipolar depression. The study did not demonstrate a statistically significant improvement in the symptoms of depression in all patients receiving RG2417 when compared to placebo over the eight-week treatment period. RG2417 was well tolerated and there were no serious adverse events related to drug treatment. A preliminary analysis indicates that the subset of patients (n=50) enrolled through academic medical centers showed a clinically meaningful improvement on the Montgomery-Asberg Depression Rating Scale (MADRS) score from weeks 2 through 8 when compared to placebo. No difference was observed between RG2417 and placebo for patients (n=125) enrolled at the commercial clinical trial sites. A similar pattern of response was observed with several of the secondary endpoints.

"While we are disappointed with the top-line results of the study, we plan to conduct further evaluation of the data including the observation of differences between the patients treated in academic and commercial sites to determine if there is a path forward with RG2417," stated Walter C. Herlihy, President and Chief Executive Officer of Repligen Corporation. "In the short term, our efforts remain focused on completing the Phase 3 trial for RG1068, our pancreatic imaging agent, for which we expect to announce results later this month, as well as advancing our lead compounds for Friedreich's ataxia and for spinal muscular atrophy into the clinic while maintaining a low cash burn and a strong balance sheet. For FY2011, ending March 31, 2011, we anticipate $27-$28M in revenues, and $60M in cash and investments and no debt."

This was a double-blind, placebo-controlled trial in which 175 patients were enrolled at 12 academic and 17 commercial study sites, and randomized on a 1:1 basis to receive either RG2417 or a placebo twice a day for eight weeks. Patients in the RG2417 and placebo groups were clinically and statistically well matched in their symptoms at baseline. Evaluations for symptoms of depression were conducted at baseline and then weekly using the MADRS, a standardized, rater-administered scale, which has been used for numerous drug trials in bipolar disorder. In addition, patients conducted a weekly self-assessment of their symptoms, referred to as a patient-based MADRS. Additional secondary objectives included the Clinical Global Impression scale, subset analysis of patients based on prior episodes of depression, responder rates and remission rates.

About Repligen Corporation
Repligen Corporation is a biopharmaceutical company focused on building an integrated company by developing and marketing innovative drugs that deliver the benefits of protein therapies in the fields of neurology and gastroenterology. We have a core competency in the development and manufacturing of biologics products, which is the basis for our bioprocessing business and we have out-licensed certain biologics intellectual property, which provide ongoing sources of revenue. Repligen's corporate headquarters are located at 41 Seyon Street, Building #1, Suite 100, Waltham, MA 02453. Additional information may be requested at