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Alnylam, Cubist Say 90-Day Data Shows RSV Drug to Be Safe, Suggests Efficacy


Alnylam Pharmaceuticals and Cubist Pharmaceuticals this week said that 90-day data from a recently completed phase II study of their siRNA-based respiratory syncytial virus drug ALN-RSV01 indicate the drug met the trial's primary endpoint of safety and tolerability.

The company also said that clinical data indicate a certain level of efficacy for the drug, but cautioned that these data were "exploratory."

In the trial, 24 lung-transplant patients with confirmed RSV infections were randomized to receive inhaled ALN-RSV01 or placebo once daily for three consecutive days. Last month, Alnylam and Cubist announced that preliminary data showed the drug to have met the trial's primary endpoint.

Today, the companies said that these findings were supported by clinical evaluations conducted at 90 days.

Further, Alnylam and Cubist collected new 90-day clinical data related to secondary endpoints including recovery of lung function as defined by forced expiratory volume in the first second, or FEV1, and clinical determination of new or progressive bronchiolitis obliterans syndrome, a non-reversible obstructive lung disease.

"In the study, FEV1 measurements were obtained at screening and at day 90 in order to determine the percentage of patients with FEV1 at least 20 percent below baseline at those time points," the companies said. "Thirty-eight percent of placebo patients had an FEV1 at least 20 percent below baseline at day 90 compared to only 14 percent of ALN-RSV01-treated patients."

Meanwhile, bronchiolitis obliterans syndrome scoring was "based on the decline in FEV1 during the study as well as the physicians' determination of whether there was a cause other than [bronchiolitis obliterans syndrome] responsible for a change in FEV1," they added.

"In the study, ALN-RSV01 treatment was associated with a statistically significant decrease in the total incidence of new or progressive [bronchiolitis obliterans syndrome] at 90 days compared to placebo," with 50 percent of placebo patients showing new or progressive bronchiolitis obliterans syndrome versus 7.1 percent of ALN-RSV01-treated patients.

"While the study was not powered for efficacy and is too small to make firm conclusions, we are encouraged by the 90-day clinical endpoint data," Akshay Vaishnaw, senior vice president of clinical research at Alnylam, said in a statement.

Alnylam and Cubist, which licensed the worldwide rights to ALN-RSV01 outside of Asia from the RNAi drug shop in January (see RNAi News, 1/15/2009), said they plan to evaluate these and other data, including ones related to second-generation RSV agents, "to determine the optimal development strategy and specific plans for all RSV indications."