Neither the general activity of both drugs nor the difference in activity between regorafenib and sorafenib observed in this study were found to be associated with any clinical characteristics published by Gu et al. [20] such as tumor stage, hepatitis B virus infection status, or genetic parameters (e.g. expression levels of alpha-fetoprotein or TP53 mutation status); this lack of association may be attributed to the small sample size. The gene discussed is AFP; the disease is hepatitis B virus infection.