Debes et al. [85] assessed serum cytokines in 13 patients who developed HCC following DAA therapy and found that the serum levels of chemokine (C-X-C motif) ligand 9, IL-22, TRAIL, a proliferation-inducing ligand (APRIL), vascular endothelial growth factor (VEGF), IL-3, tumor necrosis factor-like weak inducer of apoptosis (TWEAK), stem cell factor (SCF), and IL-21 were elevated to higher levels in patients who developed HCC after DAA treatment than in those who did not develop tumors [85]. Here, IL21 is linked to hepatocellular carcinoma.