Ionis receives FDA approval for Zanvastro, the first treatment for Alexander disease, as Pfizer partners on new ADC program

The U.S. Food and Drug Administration approved Zanvastro, marking the first approved medicine for the rare and often fatal neurological disorder Alexander disease. Developed by Ionis Pharmaceuticals, the drug works by lowering the production of a protein that forms toxic clumps in the brain.

The approval was based on a study that showed patients receiving Zanvastro were significantly more stable in a walking test. Ionis said the drug will be available in the United States in the coming weeks and the company earned a priority review voucher.

Separately, Pfizer and Medicus Pharma announced a co‑development agreement to advance an antibody‑drug conjugate (ADC) program, expanding Pfizer’s oncology pipeline.

These developments underscore continued innovation in rare‑disease therapeutics and ADC technology, offering potential benefits for patients and the broader pharma market.