Vigil's ALSP Drug Fails Phase 2 Trial, Sanofi Acquisition Proceeds

Vigil Neuroscience's experimental drug for a rare brain disease has failed to meet its primary endpoints in a phase 2 study, casting doubt on its future development. Despite this setback, Sanofi's planned acquisition of Vigil remains on track, highlighting the pharmaceutical giant's strategic focus on other assets within the biotech company's pipeline.

Phase 2 Study Results and Implications

Iluzanebart, Vigil's TREM2 agonist aimed at treating adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), failed to demonstrate significant benefits in an open-label proof-of-concept trial. The study evaluated the drug's impact on brain volume loss, clinical measures of disease progression, and biomarkers of neurodegeneration.

While iluzanebart showed a favorable safety and tolerability profile across both doses tested, it failed to drive beneficial effects on biomarker or clinical efficacy endpoints. This outcome has prompted Vigil to halt a long-term extension trial of the compound, signaling a significant setback in the development of potential treatments for ALSP.

Sanofi Acquisition and Strategic Focus

Last month, Sanofi announced a $470 million deal to acquire Vigil Neuroscience. Notably, the agreement excluded the rights to iluzanebart, which Vigil agreed to return to Amgen. This arrangement allows Sanofi to focus its efforts on VG-3927, a small-molecule TREM2 agonist in Vigil's pipeline.

The phase 2 failure of iluzanebart is not expected to impact the Sanofi-Vigil deal, which is scheduled to close in the third quarter. William Blair analysts, who had previously expressed skepticism about iluzanebart's prospects, noted that they were "unsurprised by the result" and reiterated that the trial outcome would have no bearing on the acquisition.

Industry Implications and Future Outlook

The failure of iluzanebart in the ALSP trial underscores the challenges in developing treatments for rare neurological disorders. It also highlights the strategic decisions made by large pharmaceutical companies like Sanofi in their pursuit of promising biotech assets.

As Amgen regains control of iluzanebart before the Sanofi-Vigil deal closes, the future of this compound remains uncertain. Meanwhile, the industry will be watching closely to see how Sanofi leverages Vigil's remaining pipeline assets, particularly VG-3927, in its ongoing efforts to advance treatments for neurodegenerative diseases.