Second, the lead candidate MA4-hFc-CD16AM19 exhibited potent cytotoxicity against GPC3+ HCC cells (IC50 = 15–35 ng/mL) and synergized with sorafenib, reducing its IC50 by 2.5–5.2-fold through dual targeting of immune and kinase pathways. Here, GPC3 is linked to hepatocellular carcinoma.