Exhibit 99.1 Xilio Therapeutics Announces Pipeline and Business Updates and Second Quarter 2025 Financial Results Announced updated Phase 2 data at ASCO for vilastobart, a tumor-activated, Fc-enhanced, anti-CTLA-4, demonstrating deep and durable responses and a meaningfully dif erentiated safety and tolerability profile for an anti-CTLA-4 combination therapy On track with plans to nominate first development candidates for wholly owned masked T cell engager programs in second half of 2025 ● In May 2025, Xili ...