CD226 and neoplasm: Recent evidence in melanoma patients suggests a high TIGIT:CD226 ratio on Tregs is an indicator of poor response to ICB.33 Indeed, we observed a significant reduction in the bioavailable TIGIT-to-CD226 ratio on tumor infiltrating Tregs in all groups receiving αTIGIT, as monotherapy or in combination (p < .0001; online supplemental figure 2C).