Exhibit 99.1 Alector Reports Fourth Quarter and Full Year 2023 Financial Results and Provides Business Update Data from INVOKE-2, evaluating the most advanced TREM2 candidate in clinical development for early Alzheimer’s disease (AD), expected in Q4 2024; trial enrollment completed in Q3 2023 First participant in the global PROGRESS-AD Phase 2 clinical trial of AL101 in early AD dosed in Q1 2024 Latozinemab granted FDA’s Breakthrough Therapy Designation for frontotemporal dementia due to a mutation in the p ...