Abstract
BACKGROUND/AIM: A long-term effect has been confirmed in clinical practice since the introduction of nivolumab for treating various malignant tumors. A similar phenomenon is speculated to occur in head and neck cancer; however, details remain unclear due to the lack of long-term reports. We aimed to investigate the five-year outcomes in long-term responders for over two years, and evaluate the optimal duration of therapy with nivolumab. PATIENTS AND METHODS: In this retrospective observational study, we analyzed 203 cases of recurrent/metastatic head and neck squamous cell carcinoma (R/MHNSCC), including 33 long-term responders. RESULTS: The median overall survival (OS), 5-year OS, median progression-free survival (PFS), and 5-year PFS values in the 203 cases were 13.1 months, 19.2%, 3.1 months, and 13.2%, respectively. Of the 33 long-term responders, 14 (42.4%) continued using nivolumab for more than 2 years. The remaining 19 patients (57.6%) discontinued nivolumab. The most common reason for discontinuation was severe immune-related adverse events (irAEs) (9 cases; 27.3%); in these 9 cases, the median disease-free survival was 33.2 (range=10.7-44.3) months. Nine patients (21.2%) were considered to have progressive disease (PD) after at least 2 years of administration, and 3 patients (9.1%) requested to discontinue treatment because a complete response (CR) was achieved. CONCLUSION: This study demonstrated the durable and long-term benefit of nivolumab in R/MHNSCC. In the future, we aim to accumulate real-world data for the establishment of criteria for completion of nivolumab treatment in long-term responders.