Off-label use of immune checkpoint inhibitors for the treatment of solid tumors: analysis of a nationwide patient sample

Purpose Immune checkpoint inhibitors (ICIs) have become an indispensable part of clinical practice; however, off-label use of these agents is unknown. We aimed to define the patterns of off-label use of ICIs in a nationwide sample of patients. Methods The online database (Reçetem) was retrospectively searched for off-label use cases related to ICIs approved during a 6-month period. Adult patients with metastatic solid tumors were included. Ethics approval was obtained. Reasons for off-label use were recorded in eight categories and cases were assessed for adherence to current guidelines. Statistical analysis was performed with GNU PSPP version 1.5.3. Results Five hundred seventy-seven reasons for use were recorded for 538 cases related to 527 patients (67.5% male). Non-small-cell lung cancer (NSCLC) (35.9%) was the most common cancer type. Nivolumab (49%), pembrolizumab (25.5%), and atezolizumab (25%) were commonly used. The top reason for off-label use was lack of approval for the cancer type (37.1%), followed by use beyond the approved treatment line (21%). Nivolumab was more frequently used than atezolizumab and/or pembrolizumab in patients with malignant melanoma, kidney cancer, head and neck cancer, and hepatocellular carcinoma (Chi-square goodness-of-fit test, p