Alector said a GSK-partnered antibody failed a pivotal Phase III study and the company will cut roughly half its staff as it ends development of that asset. The Bay Area biotech also announced leadership changes and a reassessment of its development priorities following the disappointing clinical readout. The failed program was part of a broader collaboration with GSK and its termination triggers an immediate portfolio reset and substantial cost reductions. Investors reacted sharply to the data, and the company is repositioning remaining resources toward prioritized programs while seeking new strategic options for its pipeline.