We used qPCR to analyze the ALDH3A2, PDCD1, PDCD1LG2, and CTLA-4 mRNA expression levels in 52 tumor tissues, which indicated a negative spatial correlation between ALDH3A2 and PDCD1 (Fig. 8a, R2 = 0.3576), PDCD1LG2 (Fig. 8b, R2 = 0.3878), and CTLA-4 (Fig. 8c, R2 = 0.2556). Here, PDCD1 is linked to neoplasm.