PDCD1 and hepatitis A virus infection: Schoenfeld and colleagues found that six of 41 patients treated with sequential PD-1/PD-L1 inhibitor followed by subsequent osimertinib developed severe irAEs (four cases of grade 3 pneumonitis, one case of grade 3 colitis, and one case of grade 4 hepatitis), whereas no severe irAEs were observed in 29 patients receiving osimertinib followed by PD-1/PD-L1 blockade [85].