PDCD1 and melanoma: As shown in Fig. 8B, in a human PBMC-reconstituted mouse model bearing human melanoma A375, compared to the vehicle group, ZGGS15 plus anti-PD-1 significantly inhibited tumor growth (mean volume 126.13 ± 55.88 mm3, TGI = 95.80%, p = 0.001), surpassing the efficacy of anti-LAG-3/anti-TIGIT plus anti-PD-1 groups with volumes of 199.22 ± 58.99 mm3 (TGI = 79.38%, p = 0.006) and 313.89 ± 71.18 (TGI = 54.02, p = 0.173).