Objective: PD-1 inhibitors have demonstrated improved health outcomes in cancer patients. PD-1 inhibitors are well-tolerated and associated with immune-related adverse events. The objectives of this study are to analyze use patterns of PD-1 inhibitors in patients with cancer and to investigate the incidence of thyroid-related adverse reactions in patients treated with PD-1 inhibitors. Methods: The study included patients who had been administered PD-1 inhibitors (either nivolumab or pembrolizumab) at the Samsung Medical Center between October 1, 2016 and June 30, 2017. Data was collected from electronic medical records and tested using Mann-Whitney tests and Chi-Square tests for statistical significance. Associations between PD-1 inhibitors and incidence of adverse events were tested using Cox regression for age, gender, BMI, ECOG PS and medication. Results: Two hundred fifteen patients were identified as eligible for analyses. Thyroid-related adverse events occurred in 20% of patients (n=43). Thyroid function tests (TFTs) was performed in 109 patients (50.7%). Positive results of PD-L1 testing were found in 53.2% of the 94 patients who had the test. Approved doses of nivolumab (3 m/kg) and pembrolizumab (200 mg) were administered in 70.4% and 53% of patients, respectively. The analysis of risk factor of thyroid-related adverse reaction did not show statistically significant differences (Cox regression). Conclusion Thyroid-related adverse events are common in patients treated with PD-1 inhibitors and hypothyroidism is the most frequent adverse reaction. Routine TFTs monitoring is strongly recommended to evaluate thyroid function in real-world clinical practice.

Objective: PD-1 inhibitors have demonstrated improved health outcomes in cancer patients. PD-1 inhibitors are well-tolerated and associated with immune-related adverse events. The objectives of this study are to analyze use patterns of PD-1 inhibitors in patients with cancer and to investigate the incidence of thyroid-related adverse reactions in patients treated with PD-1 inhibitors. Methods: The study included patients who had been administered PD-1 inhibitors (either nivolumab or pembrolizumab) at the Samsung Medical Center between October 1, 2016 and June 30, 2017. Data was collected from electronic medical records and tested using Mann-Whitney tests and Chi-Square tests for statistical significance. Associations between PD-1 inhibitors and incidence of adverse events were tested using Cox regression for age, gender, BMI, ECOG PS and medication. Results: Two hundred fifteen patients were identified as eligible for analyses. Thyroid-related adverse events occurred in 20% of patients (n=43). Thyroid function tests (TFTs) was performed in 109 patients (50.7%). Positive results of PD-L1 testing were found in 53.2% of the 94 patients who had the test. Approved doses of nivolumab (3 m/kg) and pembrolizumab (200 mg) were administered in 70.4% and 53% of patients, respectively. The analysis of risk factor of thyroid-related adverse reaction did not show statistically significant differences (Cox regression). Conclusion Thyroid-related adverse events are common in patients treated with PD-1 inhibitors and hypothyroidism is the most frequent adverse reaction. Routine TFTs monitoring is strongly recommended to evaluate thyroid function in real-world clinical practice.