Efficacies of programmed cell death 1 ligand 1 blockade in non-small cell lung cancer patients with acquired resistance to prior programmed cell death 1 inhibitor and development of diabetic ketoacidosis caused by two different etiologies: A retrospective case series

The programmed cell death 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) axis is vital for immune resistance during tumor development, while PD-L1 inhibitors can also inhibit the PD-L1/B7-1 (CD80) interaction, indicating one of the molecular differences between PD-1 and PD-L1 inhibitors. However, the clinical benefits of PD-L1 inhibitors in patients previously treated with PD-1 inhibitors remain unknown. In this study, we retrospectively analyzed the clinical data of eight patients with non-small cell lung cancer who received the PD-L1 inhibitor atezolizumab and previously treated with the PD-1 inhibitor nivolumab. The median progression-free survival was 2.1 months (1.8–18.7 months), and 4 of 8 patients achieved at least stable disease. In two of these patients, atezolizumab treatment resulted in longer progression-free survival (PFS) compared with that of nivolumab. Conversely, one patient exhibited grade 4 diabetic ketoacidosis (DKA) within 2 weeks after the initial administration of atezolizumab. Another patient had developed type 1 diabetes mellitus (T1DM) during the prior nivolumab treatment and then developed DKA due to an infection after the initiation of atezolizumab. Both of them had highrisk human leukocyte antigen-DR/DQ types relevant to T1DM. These results demonstrate the potential efficacy of PD-L1 inhibitors to some tumors that have acquired resistance to PD-1 inhibitors and suggest that appropriate managements are required for not only a newly onset of T1DM but also blood glucose control after the development of T1DM during a reiteration of the PD-1/PD-L1 blockade.