Effectiveness and safety of immune checkpoint inhibitors: A retrospective study in Taiwan

BACKGROUND: Since 2012, several immune checkpoint inhibitors have been approved by the Taiwan FDA for various types of cancer treatment. However, none of them are covered by Taiwan National Health Insurance due to the fact that they are expensive, and there is a lack of clinical evidence as to their effectiveness. OBJECTIVES: This study was aimed toward an exploration of clinical experiences with use of immune checkpoint inhibitors, including indications, prescription types, drug effectiveness, adverse drug event types, and incidence, all of which shall serve as references for future clinical drug use. METHODS: This is a retrospective study focusing on three immune checkpoint inhibitors (ipilimumab, nivolumab, and pembrolizumab), which are available for cancer treatment in Taiwan. We collected data from medical records for the period from January 1st, 2015 to January 12th, 2017 at National Cheng Kung University Hospital (NCKUH), a medical center in southern Taiwan, and recorded these cases until May 31st, 2017. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method, and adverse drug reaction odds ratios were analyzed using a chi-square analysis. RESULTS: The 50 patients under consideration in this study had used any one of the immune checkpoint inhibitors in NCKUH. Non-small cell lung cancer (n = 24, 48%) accounted for the highest percentage, followed by hepatocellular carcinoma (n = 4, 8%). The median OS was not reached, and the PFS for all immunotherapies was 4.9 months. The median OS period and PFS for non-small cell lung cancer (NSCLC) patients were 13 and 4.9 months, respectively, which were similar to those in many clinical trials. For NSCLC patients, the OS and PFS were only 0.63 and 1.37 months for squamous cell type NSCLC, and for patients who were PD-L1 negative, the OS and PFS were only 11.53 and 2.6 months, respectively. The most common adverse events in this study included fatigue (42%), rashes (22%), nausea (20%), and fever (20%), while one patient developed severe deep venous thrombosis and tissue inflammation, which was not confirmed in previous clinical trials. CONCLUSIONS: The histological subtype, the intensity of the PD-L1 expression, and the timing of treatment affected the NSCLC therapeutic results. It is recommended that clinical tests be conducted in order to enhance therapeutic effectiveness. It is expected that more testing, observation-based studies, and research results will validate their efficacy and the tolerance levels of patients.