Biogen Idec (NASDAQ: BIIB) announced today that its Phase II trial of baminercept (BG9924, LTßR-Ig) in rheumatoid arthritis (RA) patients who have had an inadequate response to conventional therapy with a disease-modifying antirheumatic drug (DMARD) did not meet its primary endpoint. The primary endpoint was defined as the proportion of baminercept-treated patients who achieved an ACR50 response, a standard measure of disease improvement in RA, compared to placebo at 14 weeks. The study also did not meet any of the pre-specified secondary endpoints. Biogen Idec will continue to analyze the study results and will submit the data for presentation at an upcoming medical meeting.

Based on these results as well as preliminary data from a Phase II trial of baminercept in RA patients who have had an inadequate response to a tumor necrosis factor (TNF) inhibitor, the company has decided to discontinue the development of the compound in RA.

About the 104RA202 Study

The 104RA202 study was a Phase II randomized, double-blind, placebo-controlled, multicenter, dose-finding trial involved 380 individuals with active RA who had an inadequate response to conventional DMARD therapy. The trial was designed to assess the efficacy of five different regimens of baminercept when administered over 12 weeks in combination with methotrexate within this patient population.

About the 104RA203 Study

The 104RA203 study was a Phase II randomized, double-blind, placebo-controlled, multicenter trial in patients with active RA who had an inadequate response to TNF inhibitors. About 120 patients were expected to be enrolled in the trial, which was designed to assess the efficacy of 200 mg dose of baminercept administered over 12 weeks in combination with methotrexate.

In both studies, the primary endpoint was the proportion of patients who achieved an ACR50 response, defined as a 50% improvement compared to baseline for swollen and tender joint counts and other clinical measures, at week 14.