PDCD1LG2 and pneumonitis: A possible mechanism that could explain this finding is the fact that PD‐1 inhibitors can block PD‐1 binding to PD‐L2 leading to increased PD‐L2 binding to the receptor repulsive guidance molecule b, resulting in local T‐cell clonal expansion, which breaks the balance of respiratory tolerance and consequently increases the risk of pneumonitis.