CTLA4 and neoplasm: CD103+ TRMs have also been described as protective or conveying better prognosis in other tumor types, including oropharyngeal,34 head and neck,32 lung,35 breast36 37 and ovarian cancers.38 However, by contrast, Gabriely et al showed that CD8+CD103+ T cells in murine melanomas had a regulatory phenotype which upregulated IL-10, CTLA4 and CD25, suppressed CD8+ T-cell proliferation and promoted tumor growth.39 This would be in keeping with the findings shown in our study, which suggest a regulatory phenotype for CD8+CD103+ TRMs in human cSCC.