Although the anti-cancer activity of PD-1 and PD-L1 inhibitors is exciting, this type of immunotherapy is not effective for all patients, and meta-analyses indicate that a higher risk of rash, thyroid dysfunction, pruritus, pneumonia, and colitis in patients treated with PD-1/PD-L1 inhibitors (18–20). Here, PDCD1 is linked to susceptibility to pneumonia measurement.