Repligen plunges as bipolar drug flops in Ph IIb trial

USA-based Repligen (Nasdaq: RGEN) saw its shares plummet 29.1% to $3.48 by mid-afternoon trading yesterday, after the company announced results of a Phase IIb 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 Herlihy, president and chief executive of Repligen.