Xilio Therapeutics, Inc. (Nasdaq: XLO), a clinical-stage biotechnology company discovering and developing tumor-activated immuno-oncology therapies for people living with cancer, announced initial data from its ongoing Phase 2 clinical trial evaluating vilastobart (XTX101), a tumor-activated, Fc-enhanced, high affinity binding anti-CTLA-4, in combination with atezolizumab (Tecentriq^®) in patients with metastatic microsatellite stable colorectal cancer (MSS CRC). The data will be presented in a poster session (abstract #206) at the American Society of Clinical Oncology 2025 Gastrointestinal Cancer Symposium (ASCO GI) being held January 23-25, 2025, in San Francisco.

“We are very encouraged by the initial Phase 2 proof-of-concept data for the combination of vilastobart and atezolizumab in heavily pre-treated patients with MSS colorectal cancer, including partial responses accompanied by marked decreases in tumor biomarkers and improvement in clinical symptoms,” said Katarina Luptakova, M.D., chief medical officer of Xilio. “We believe these data highlight the important contribution of vilastobart in this combination, as PD-(L)1 inhibitors alone have demonstrated no meaningful efficacy in patients with MSS CRC to date. The preliminary evidence of anti-tumor activity, together with continued evidence of a well-tolerated safety profile, support the potential for the combination in MSS colorectal cancer, as well as in other tumors that have traditionally been resistant to treatment with immunotherapy. We look forward to sharing additional Phase 2 data, including further follow-up, in patients with metastatic MSS CRC in the middle of this year.”

“These preliminary Phase 2 data for the combination of vilastobart and atezolizumab show clear responses for patients with MSS colorectal cancer, an area of very high and increasing unmet medical need,” said J. Randolph Hecht, M.D., Professor of Clinical Medicine at the David Geffen School of Medicine at UCLA, Director of the UCLA Gastrointestinal Oncology Program and the lead author for the presentation at ASCO GI. “I am excited to see these initial data highlighting the potential for vilastobart, a tumor-activated anti-CTLA-4, in combination with PD-(L)1 inhibitors to have clinically meaningful benefit in a classically immunotherapy-resistant major malignancy.”