Of the 108 patients treated with ICI, 56% of patients with low ACTA2 expression responded to ICI versus 25% of patients with high ACTA2 expression (p=0.004)...the patient who responded to ICI had lower tumor stromal ACTA2 expression than the 4 non-responders. Digital spatial profiling of tumor samples from 4 ICI responders and 5 ICI non-responders revealed that responders may have lower ACTA2 expression...ACTA2 expression is associated with survival and ICI response in gastric cancer patients.