RSVAlnylam Pharmaceuticals has announced the top-line results from a Phase 2b trial with ALN-RSV01, an inhaled RNAi therapeutic designed for the treatment of respiratory syncytial virus (RSV) infection in lung transplant patients.

The Phase 2b trial was an international, multi-centre, randomised, double-blind, placebo-controlled study of ALN-RSV01 conducted in 87 RSV-infected lung transplant patients who were randomised in a one-to-one, drug-to-placebo ratio.

The trial’s primary endpoint was the incidence of new or progressive bronchiolitis obliterans syndrome (BOS) at 180 days after RSV infection.

"The data provided important evidence that ALN-RSV01 reduces the incidence of new or progressive BOS."

The study missed the primary endpoint of reduced BOS in an intent-to-treat (ITT) analysis of confirmed RSV infected patients, but achieved considerable reductions in prospectively defined analyses of ITT patients with their last observation carried forward (LOCF) with a p-value of 0.028 and of ITT patients treated per protocol (PP) with a p-value of 0.025.

In all analyses, ALN-RSV01 demonstrated a clinically meaningful treatment effect, with a reduction of over 50% in the incidence of day 180 BOS compared with placebo.

Based on local study site diagnosis of RSV infection, a total of 45 patients were randomised to receive ALN-RSV01 and 42 patients were randomised to receive placebo, defining the overall ITT study cohort.

Akshay Vaishnaw, Alnylam senior vice president and chief medical officer, said the data provided important evidence that ALN-RSV01 reduces the incidence of new or progressive BOS in RSV-infected lung transplant patients, replicating the findings from the Phase 2a study of the drug.

"We plan to discuss the results of this study with US and European regulatory authorities later this year and, thereafter, determine appropriate next steps, if any, on our ALN-RSV programme," Vaishnaw added.

Image: Transmission electron micrograph of RSV. Photo courtesy of: CDC.