Ablynx RSV drug set to enter PhII after clearing early-phase infant trial

respiratory syncytial virus
(By https://secure.flickr.com/photos/pulmonary_pathology/ Yale Rosen (Yale Rosen collection) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons)

Ablynx (EBR:ABLX) has posted positive safety data from a Phase I/IIa trial of its inhaled treatment for respiratory syncytial virus (RSV) infections. Having seen no treatment-related serious adverse events in the 53 infants who enrolled in the study, Ablynx is now preparing to advance the candidate into a larger Phase II trial before the end of the year.

Ghent, Belgium-based Ablynx split the Phase I/IIa study into three stages, starting with an open-label lead-in period that gave ALX-0171 to five infants who had been hospitalized and diagnosed with RSV infection. Once this stage was complete, Ablynx moved into a double-blind placebo-controlled study, which initially set the minimum age for participation at three months. Ablynx lowered the minimum age for participation in the study to one month following a review by the data safety board, leading to the enrollment of 18 infants toward the lower end of the age range.

In total, Ablynx enrolled 53 infants aged one to 24 months, more than two-thirds of whom received ALX-0171. No treatment-related serious adverse events were detected. The finding is one of several factors that have given Ablynx the confidence to ramp up its plans to advance ALX-0171 into a larger study, which is currently expected to enroll up to 200 infants and set the company back as much as €15 million ($17 million). These figures could change as Ablynx sifts through the Phase I/IIa data and finalizes its design for the next stage of development.

The decisions depend, in part, on Ablynx’s assessments of the secondary outcomes it included in the study to gauge the potential efficacy of ALX-0171. Viral load fell faster in the treatment arm than the placebo group, although the measure wasn’t powered for statistical significance. Similar trends were seen in the time to undetectable virus and performance on the Global Severity Score, a composite measure created by Ablynx to assess parameters including respiratory difficulty, medical intervention and feeding intolerance.

While the size of the trial makes it hard to draw concrete conclusions about the efficacy of ALX-0171 from the data, Ablynx has seen enough to be optimistic it could translate into clinically meaningful effects. “When folks have looked at RSV infected infants, … they've found that as little as a one-log difference in virus titer can lead to a significant difference in both disease severity … [and] length of hospitalization,” Ablynx CSO Antonin de Fougerolles said on a conference call with investors to discuss the data.

- read the release (PDF)