Neuren Pharmaceuticals' European Setback Overshadows US Sales Strength
Strong US sales of its Rett syndrome drug couldn't offset a dimming European approval outlook and a slower FDA timeline for its follow-on treatment.
28 Feb 2026 · 2 min read
In short
Neuren Pharmaceuticals gained 53% after Endeavor Asset Management rotated out of CSL, driven by strong US sales of Rett syndrome drug trofinetide through partner Acadia Pharmaceuticals.
European regulators indicated trofinetide is unlikely to be approved for Rett syndrome, limiting potential sales outside the US, while the FDA flagged a longer development timeline for follow-on drug NNZ-2591.
Neuren Pharmaceuticals announced an on-market buyback of up to 5% of issued capital even as the stock remained weak amid European regulatory uncertainty and broader sentiment concerns.
Neuren Pharmaceuticals had gained 53 percent since a switch out of CSL as its Rett syndrome drug trofinetide delivered strong US sales through partner Acadia Pharmaceuticals, before European regulators signalled trofinetide was unlikely to gain approval outside the US and the FDA flagged a longer development timeline for follow-on drug NNZ-2591, prompting a sharp share price decline that management responded to with a buyback.
A strong switch out of CSL pays off
Endeavor Asset Management said it continued to hold Neuren Pharmaceuticals following its February rotation out of CSL, with the position having gained 53 percent since the switch.
Neuren Pharmaceuticals (NEU), which we continue to hold following our February rotation out of CSL, has gained 53% since the switch.
— Endeavor Asset Management, Monthly Report, October 2025
European regulatory setback and a slower FDA pathway
Endeavor Asset Management said Neuren declined after regulatory updates weighed on sentiment, with European regulators indicating trofinetide is unlikely to be approved for Rett syndrome, limiting potential sales outside the US, while feedback from the US FDA suggested a longer development timeline for follow-on drug NNZ-2591. Offsetting this somewhat, partner Acadia Pharmaceuticals provided strong guidance for US sales of trofinetide, marketed as DAYBUE, highlighting continued domestic strength. NorthStar Impact Funds said Neuren was weak amid uncertainty around the European regulatory pathway and broader sentiment concerns, even as the company announced an on-market buyback of up to 5 percent of issued capital.
European regulators indicated trofinetide is unlikely to be approved for Rett syndrome, limiting potential sales outside the US, while feedback from the US FDA suggested a longer development timeline for NNZ-2591.
— Endeavor Asset Management, Monthly Report, February 2026
What fund managers say they are watching next is resolution of the European regulatory pathway for trofinetide, progress on the FDA's longer development timeline for NNZ-2591, continued strength in US trofinetide sales through Acadia Pharmaceuticals, and execution of the up-to-5-percent on-market buyback as a signal of management confidence.
Questions
Why did Neuren Pharmaceuticals' share price decline sharply?
Neuren Pharmaceuticals declined after European regulators indicated its trofinetide drug is unlikely to be approved for Rett syndrome, limiting sales outside the US, while the FDA flagged a longer development timeline for follow-on drug NNZ-2591.
How is Neuren Pharmaceuticals' trofinetide performing in the US?
Partner Acadia Pharmaceuticals provided strong guidance for US sales of trofinetide, marketed as DAYBUE, highlighting continued domestic strength even as European approval prospects dimmed.
What did Neuren Pharmaceuticals do in response to the share price weakness?
Neuren Pharmaceuticals announced an on-market buyback of up to 5% of issued capital, even as the stock remained weak amid European regulatory uncertainty and broader sentiment concerns.
7 managers, 14 comments, with each manager's latest recorded position.
See NEU