PDCD1 and hepatitis A virus infection: In our cohort of patients, the combination therapy group showed the highest hepatitis incidence at 42.8% (3 out of 7 patients), while in the anti-PD1 monotherapy group, 6.7% of nivolumab-treated patients (3/45) and 6.7% of pembrolizumab-treated patients (1/15) developed hepatitis.