Genetic Profiling by Liquid Biopsy for Initial Characterization and Response Monitoring of Head and Neck Squamous Cell Carcinoma (HNSCC)

Overall survival of patients with head and neck squamous cell carcinoma (HNSCC) remains unsatisfactory due to often advanced clinical stage at diagnosis and high rate of recurrence and second primaries. About 75 % of patients with localized HNSCC are expected to show circulating tumor DNA (ctDNA) pre-treatment. ctDNA reflects tumor genome and disease burden and is termed 'liquid biopsy' (LB) when collected through venous bloodstream. LB has potential to assist in early diagnosis of recurrence and progression, and prediction of response to targeted therapeutic agents. Increased metabolic activity measured in positron emission tomography-computed tomography (PET-CT) is currently the most sensitive technique to detect residual cancer or progression of HNSCC after curative treatment. High metabolically active tumor volume (MTV) is associated with treatment resistance and shows independent prognostic significance. The objective is (i) to investigate whether MTV detected with PET-CT correlates to the pattern and amount of genetic alterations in ctDNA of patients with HNSCC referred to radio- (chemo)therapy (RT/CRT). Another objective is (ii) to determine sensitivity of LB compared to PET/CT in detecting residual tumor 3 months after completion of RT/CRT. Third (iii), genetic landscape in LB and fresh tumor samples will be evaluated to detect resistance genes and targets for immunotherapy and surveillance post-treatment. This prospective study includes 30 patients with stage III/IV HNSCC. Before onset and 3 months from RT/CRT, LB is obtained for next-generation DNA sequencing using a commercial platform. ctDNA and digital droplet PCR will be quantified and compared to MTV in simultaneously acquired PET-CT. The investigators hypothesize that LB could assist or replace PET/CT in response monitoring and detection of recurrence after RT/CRT.