Comparison of liquid biopsy in saliva versus blood in head and neck squamous cell carcinoma patients

Introduction:

The examination of body fluids for tumor components (liquid biopsy) could lead to faster and more accurate patient stratification with improved medical aftercare in patients with head and neck squamous cell carcinoma (HNSCC). The aim of this study is to analyze the frequency of circulating cell free HPV-DNA and tumor-DNA (ctDNA) in HNSCC and determine which material is more suitable.

Methods:

In 84 patients with HNSCC, blood was prospectively collected before therapy and in the course of the disease. In part of the patients (n = 9) mutations in the primary tumor were analyzed with panel sequencing (45 genes, 224 amplicons) and ctDNA was examined with digital droplet PCR (ddPCR) in plasma and in four patients in saliva. In patients with tumors in the oropharynx and oral cavity (n = 46), cell-free DNA (cfDNA) was tested for HPV (E7 oncogene specific for HPV16) in plasma.

Results:

On average 23 mutations per patient (10 to 52 mut./pat.) were detected in the primary tumor with panel sequencing. In 33% of patients tumor-DNA was found in plasma with tumor-specific designed ddPCR assays. In p16 positive patients (n = 13) cell-free HPV type 16-DNA was identified in plasma in 8% (1 of 13) and thus the HPV type identified. Specific mutations were observed in 75% of saliva probes (n = 4) and HPV16 DNA in 25% of cases (1 out of 4) to date.

Conclusions:

Cell free tumor DNA can be detected with digital droplet PCR especially in patients with advanced stages (III/IV) in plasma. Saliva probes seem to be better suited for the detection of ctDNA than plasma.

Publikationsverlauf

Publikationsdatum:
23. April 2019 (online)