Clinical application of personalized ddPCR assays in liquid profiling of blood and saliva allows early recurrence detection of head and neck tumors

Introduction Liquid profiling could provide improved tumor monitoring in patients (pts.) with head and neck cancer (HNSCC) and improved early recurrence detection. As part of a proof-of-concept study, we designed personalized, tumor-specific ddPCR mutation assays and analyzed their suitability for early recurrence detection by measuring ctDNA in blood and saliva.

Material and Methods In 8 HNSCC pts. blood and saliva samples were prospectively collected. In 7 pts. we collected pre-operative plasma samples, in 7 pts. additional saliva samples in the postoperative course. Mutations in the primary tumor tissue were analyzed with panel sequencing (45 genes, 224 amplicons). Based on NGS-results, tumor-specific ddPCR-mutation assays were designed and ctDNA was analyzed in plasma and saliva.

Results On average, 6 blood and 2 saliva samples per patient were examined. Using tumor-specific ddPCR assays, ctDNA was detected in preoperative plasma samples in 71 %  of the pts. (5/7). During the follow-up period, we detected ctDNA in 50 %  (4/8) in plasma and 100 %  (7/7) in saliva samples. 5 of the pts. developed a recurrence, 3 pts. are currently clinically tumor-free. An increase in ctDNA levels was associated with a clinical recurrence in 80 %  (plasma) and/or 100 %  (saliva) of the examined pts. . Using minimally invasive liquid profiling a ctDNA increase was measured in a median of 6 months (1 to 20 mo.) in plasma and 7 months (1 to15 mo.) in saliva before clinical recurrence diagnosis.

Conclusion CtDNA detection with tumor-specific ddPCR-mutation assays is a promising minimally invasive tool for tumor monitoring. Saliva appears to be well-suited for the early recurrence detection of even small tumors of the oral cavity and oropharynx.

Poster-PDF A-1626.pdf

Publication History

Article published online:
13 May 2021