Comparative incidence of immune-related adverse events and hyperprogressive disease in patients with non-small cell lung cancer receiving immune checkpoint inhibitors with and without chemotherapy.

Immune-related adverse events (irAEs) and hyperprogressive disease (HPD) are serious problems arising in the early period of monotherapy (MT) with programmed cell death protein 1 (PD-1) and programmed cell death ligand1 (PD-L1) inhibitors. However, the frequency and clinical features of these problems in patients receiving combination therapy (CT) with cytotoxic chemotherapy in addition to these agents remain unclear. We retrospectively screened patients with pathologically confirmed advanced or recurrent non-small cell lung cancer (NSCLC) who had received PD-1/PD-L1 inhibitors at Kurume University Hospital between February 2016 and March 2020. We recruited 210 patients, of whom 172 (81.9%) had received PD-1/PD-L1 inhibitor MT and 38 (18.1%) had received CT. The incidence of irAE during the 3 months after treatment initiation was significantly higher in the MT group (57 of 172, 33.1%) than in the CT group (6 of 38, 15.8%) (p = 0.049). During the same period, the incidence of pneumonitis was also higher in the MT group (18 of 172, 10.9%) than in the CT group (0 of 38) (p = 0.049). A similar trend was observed in patients who had received these treatments on a first line basis. The HPD rate was significantly lower in the CT group (1 of 34, 2.9%) than in the MT group (25 of 142, 17.6%) (p = 0.031). The incidences of HPD and irAE, especially pneumonitis, during 3 months after treatment initiation were relatively lower in the CT group than in the MT group. The mechanisms underlying these differences warrant further study.