Xilio Therapeutics(XLO) GlobeNewswire·2025-05-31 12:00Core Insights - Xilio Therapeutics announced a preliminary objective response rate (ORR) of 26% in heavily pre-treated patients with metastatic microsatellite stable colorectal cancer (MSS CRC) without liver metastases, demonstrating deep and durable responses lasting up to 37 weeks [1][4][10] - The combination therapy of vilastobart and atezolizumab showed a differentiated safety profile with a low incidence of immune-related adverse events, particularly colitis [2][7][11] - The ongoing Phase 2 trial is evaluating vilastobart in combination with atezolizumab, with plans to expand the study to include a higher dose level [9][13] Patient Data - As of May 12, 2025, 44 patients with metastatic MSS CRC were treated with vilastobart at 100 mg every six weeks and atezolizumab at 1200 mg every three weeks, with a median age of 55 years [3][5] - 80% of patients had previously received three or more lines of anti-cancer therapy, indicating a heavily pre-treated population [3] Anti-Tumor Activity - The preliminary ORR of 26% included seven partial responses, with six confirmed responses, and substantial decreases in tumor biomarkers such as circulating tumor DNA [4][10] - In patients without liver metastases, responses were deep and durable, with reductions in target lesions of up to 71% from baseline [10] Safety Profile - The combination therapy exhibited a low incidence of immune-mediated adverse events, with only 7% of patients experiencing colitis [7][11] - Common treatment-related adverse events included fatigue (30%), infusion-related reactions (23%), and diarrhea (18%) [11] Future Development Plans - Xilio is enrolling a cohort of patients at a higher dose level of 150 mg Q6W for vilastobart in the ongoing Phase 2 trial, with additional data expected in the first half of 2026 [9][12] - The company is seeking partnership opportunities to accelerate the development of the vilastobart program [12]