CTLA4 and hepatitis A virus infection: The reported incidence of hepatitis depends on its severity and the number and type of ICIs used, ranging from 19-37% for grade 1 hepatitis in those treated with the combination of anti-PD1 and anti-CTLA-4 agents, to 0.67-3.0% for severe hepatitis in patients receiving monotherapy with anti-PD1 or anti-PD-L1 agents.36