Durvalumab-induced thyroiditis in a patient with non-small cell lung carcinoma: a case report and review of pathogenic mechanisms

BACKGROUND: Immune checkpoint inhibitors (ICI) targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 and its ligand (PD-1/PD-L1) have become the current standard-of-care for advanced cancers. This novel therapeutic approach comes with its costs in the form of immune-related adverse events (irAE), including endocrinopathy. CASE PRESENTATION: A 63-year-old woman was diagnosed with a non-small cell lung carcinoma of the right superior lobe, cT3N2M0. She developed thyrotoxicosis followed by hypothyroidism induced by consolidation immunotherapy with durvalumab (anti-PD-L1). Analysis of the human leukocyte antigen (HLA) region showed HLA-DR4 (susceptible) and DR13 (protective). The possible mechanisms are subsequently discussed in detail. CONCLUSIONS: The case of a patient with thyroiditis associated with the PD-L1 inhibitor durvalumab is described, highlighting the need for proactive monitoring of thyroid hormone levels. Identifying biomarkers associated with an increased risk of ICI-induced side effects (such as HLA) is of interest for better patient selection, optimal management and improved understanding of the mechanisms involved.