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Alnylam Releases New Data from Failed Phase IIb Study of RSV Drug


Alnylam Pharmaceuticals this week released the complete results from a phase IIb study of its respiratory syncytial virus drug ALN-RSV01, roughly three months after the company confirmed that the trial failed to meet its primary endpoint.

The company said that it still plans to meet with US and European regulators about the data, and that it aims to make a final decision by year end on whether development of the drug will continue.

In the phase IIb study, 87 lung-transplant patients were randomized in a one-to-one drug-to-placebo ratio, with 45 patients receiving ALN-RSV01 and 42 receiving placebo, defining the overall intent-to-treat study cohort. In May, Alnylam said that the trial did not meet its primary endpoint of reduced incidence of new or progressive bronchiolitis obliterans syndrome, or BOS, a non-reversible obstructive lung disease, at 180 days (GSN 5/31/2012).

However, ALN-RSV01 treatment was associated with “a statistically significant reduction in the incidence of day 180” BOS in certain subsets of enrolled patients.

Newly released study findings, which were presented this month at the European Respiratory Society's annual congress in Vienna, show that ALN-RSV01 treatment triggered a statistically significant reduction in day 90 BOS as compared with placebo as measured in the overall intent-to-treat study cohort with an overall effect size of 52, according to Alnylam.

“Further, ALN-RSV01 showed an enhanced treatment effect size of 88 percent toward day 180 BOS in patients treated within five days from symptom onset,” the company said. “In aggregate, the newly presented results support the conclusion that treatment of RSV-infected lung transplant patients with ALN-RSV01 is generally safe and well tolerated and associated with a decreased incidence of new or progressive BOS.”