3819 - Could plasma EBV DNA kinetics predict long-term disease-free survival in metastatic nasopharyngeal carcinoma?

Background

Outcomes are poor for patients with metastatic nasopharyngeal carcinoma (mNPC) and limited number of patients could obtain long-term disease-free survival. The aim of this study was to develop a prediction model which based on EBV-DNA kinetics to identify long-term disease-free survivors for mNPC treated with first-line chemotherapy.

Methods

A total of 177 mNPC patients who received first line chemotherapy between 2012 and 2016 were enrolled in this study. Plasma EBV DNA load was measured by quantitative PCR at completion of 6 weeks of chemotherapy and end of chemotherapy. Log-rank test as well as Cox regression was used to analyze survival data. Receiver operating curves were used to assess the sensitivity and specificity for sustained EBV DNA undetectable (undetectable at 6-week and end of chemotherapy) in predicting long-term disease-free survivors (≥ 30 months).

Results

The median follow-up time was 41.7 months (range, 3.5-74.7 months). Eighty-two percent of patients had detectable EBV DNA at diagnosis of mNPC (median load = 19000). EBV DNA became undetectable in 72 (40.7%) patients at completion of 6 weeks of chemotherapy. From the 6-week landmark, median overall survival time (OS) for patients with undetectable EBV DNA of 54.0 months was superior to patients with detectable EBV-DNA (17.7 months, hazard ratio = 0.266). At the end of chemotherapy, EBV DNA sustained undetectable in 63 (35.6%) patients. Patients with sustained EBV DNA undetectable survived longer than those with detectable (P < 0.001, median OS: 60.1 vs 17.7 months). Interestingly, 20 (11.3%) patients remained disease-free and defined as long-term disease-free survivors. Notably, 17 (85%) of them were in the sustained EBV DNA undetectable cohort. The sensitivity, specificity of sustained EBV DNA undetectable in predicting long-term disease-free survivors were 85.0% and 71.0%.

Conclusions

Sustained EBV DNA undetectable is a significant prognostic factor in patients with mNPC. Achieving sustained EBV DNA undetectable may be a valuable tool to distinguish long-term disease-free survivors. Validation studies are awaited.

Clinical trial identification

Legal entity responsible for the study

Sun Yat-sen University Cancer Center.

Funding

National Natural Science Foundation of China.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.