Material Event (Form 8-K)

On October 29, 2025, the United States Food and Drug Administration (the "FDA") verbally informed the Company that the FDA has placed a clinical hold on the Investigational New Drug applications for the MAGNITUDE and MAGNITUDE-2Phase 3 clinical trials for nexiguran ziclumeran ("nex-z").FDA indicated that it would provide a formal Clinical Hold Letter within 30 calendar days.

The clinical hold follows the previously disclosed report of Grade 4 liver transaminases and increased total bilirubin in a patient who was dosed with nex-zin the MAGNITUDE trial. As previously announced on October 27, 2025, the Company had temporarily paused dosing and screening in the MAGNITUDE and MAGNITUDE-2Phase 3 clinical trials for nex-zbased on the MAGNITUDE trial's protocol-defined pausing criteria.

The Company intends to work with the FDA to address the clinical hold as expeditiously as possible.

Forward-Looking Statements