ctDNA-guided treatment stratification for nasopharyngeal carcinoma patients: A retrospective cohort.

Abstract

e18071 Background: Liquid biopsy based on circulating tumor DNA (ctDNA) has recently been used to treat various cancers. Studies on the use of ctDNA in nasopharyngeal carcinoma (NPC) are not available. Methods: Our retrospective analysis encompassed 45 patients diagnosed with nasopharyngeal carcinoma, all of whom underwent ctDNA analysis and received comprehensive systemic treatment. Logistic regression analysis was employed to evaluate the impact of relevant factors on the objective response rate (ORR). Results: The multivariate Logistic analysis showed that the increase of ctDNA (OR=1.051, 95%CI 1.001-1.104, p=0.046) increased the risk of non-ORR after systemic treatment. We also demonstrated that patients with persistently ctDNA-positive had poor outcomes and that patient outcomes were associated with ctDNA clearance. ctDNA can also assist plasma Epstein-Barr virus (EBV) DNA in screening for NPC. Accordingly,we explore the longitudinal relationship between ctDNA levels and patient characteristics. The results showed that ctDNA levels were significantly greater in patients with tumor stage N3 than in patients with stage N0-N2.ctDNA levels were significantly greater in patients with positive-EBV DNA than in patients with negative. And the GTVnd (lymph node load) is associated with ctDNA levels. The comparison of ctDNA and tDNA revealed good concordance of gene mutation levels, especially for genes with a high frequency of mutations in NPC. Conclusions: In conclusion, ctDNA is an effective biomarker for comprehensive systemic treatment for NPC, which is associated with late clinical stage, late N stage and high lymph node tumor load. ctDNA can guide the treatment of escalation and de-escalation in NPC. This approach will lead us to a minimally invasive and personalized era.