A phase 2 study of Vigil Neuroscience’s iluzanebart has missed its biomarker and efficacy endpoints, prompting the Sanofi-bound biotech to stop a long-term extension trial of the TREM2 agonist.
Sanofi struck a deal to buy Vigil for $470 million last month but opted against taking ownership of iluzanebart as part of the takeover. Rather, Vigil agreed to return the rights to iluzanebart to Amgen and allow Sanofi to focus on the small-molecule TREM2 agonist VG-3927. At the time, William Blair analysts expressed doubt that Vigil would have agreed to the terms if iluzanebart data were “clearly promising.”
The skepticism proved well founded. Vigil’s open-label proof-of-concept trial failed to make the case for further development of iluzanebart in the neurological condition adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP).
Iluzanebart showed a favorable safety, tolerability and pharmacokinetic profile across both doses, Vigil said, but failed to drive beneficial effects on biomarker or clinical efficacy endpoints. The study looked at the effect of iluzanebart on brain volume loss, clinical measures of disease progression and biomarkers of neurodegeneration.
William Blair analysts said in a note to investors that they “are unsurprised by the result.” The low dose showed “early promising signals,” the analysts said, but there were “questions on iluzanebart brain bioavailability and [the] reproducibility of these results, as well as interpretability of an open-label study in ALSP.”
Given Vigil had agreed to return iluzanebart to Amgen as part of the Sanofi buyout, the analysts said the phase 2 miss will have no impact on the acquisition. Amgen is set to regain control of the drug candidate before Sanofi closes the Vigil takeover, an event that is scheduled for the third quarter.