Sequential administration of PD‑1 inhibitor and cetuximab causes pneumonia.

Severe drug-induced lung injury (DLI) has been reported to be associated with sequential administration of osimertinib, a third-generation tyrosine kinase inhibitor, following a programmed cell death ligand 1 (PD-L1) inhibitor. However, the relationship of sequential treatment with an anti-epidermal growth factor receptor (EGFR) antibody and PD-1 inhibitor with the risk of DLI remains to be elucidated. The present study conducted a retrospective review of the medical records of a total of 179 patients with head and neck cancer who had received treatment with cetuximab and/or a PD-1 inhibitor (nivolumab or pembrolizumab) at Chiba University Hospital (Chiba, Japan) between September 2014 and December 2020. The incidence of pneumonia and the clinical background characteristics of the patients were analyzed. The patients were classified into subgroups for analysis of the outcomes in this study: Patients who had received sequential, but not concurrent, cetuximab and PD-1 inhibitor treatment (Group C+P; n=43); patients who had received cetuximab-containing chemotherapy, but not a PD-1 inhibitor (Group C; n=101); and patients who had received PD-1 inhibitor-containing chemotherapy, but not cetuximab (Group P; n=35). The rates of DLI in the three groups were: Group C+P, 18.6%; Group C, 7.9%; and Group P, 11.4%. Prior use of ICI was not associated with any increase in the risk of DLI. DLI is seen frequently in patients receiving sequential PD-1 inhibitor and anti-EGFR antibody therapy.