CD8A and digestive system neoplasm: In patients with gastrointestinal (GI) tumors, increased serum levels of SLAMF8 bear high diagnostic significance [37], while its value for predicting response to immunotherapies has also been shown since immunohistochemistry analysis revealed enhanced CD8+ T cell infiltration in GI tumors with increased expression levels of SLAMF8 taken from patients under anti-PD1 treatment [38].