CTLA4 and melanoma: Further analysis showed that among these melanoma patients, not those with primary melanoma (stages 0-II, n = 122, p = 0.14) (Figure 2E), but those with metastatic melanoma (stages III-IV, n = 48) had a significant association between low blood CTLA4 expression and worse OS based on the optimal cut point (log –5.93) (p = 0.017) (Figure 2F).