CTCs are considered indicators of residual disease and thus are associated with an increased risk of metastasis. Moreover, hypoxic microenviroment, a major feature of HNSCC, plays a pivotal role in the emergence of CTCs and cancer stem cells. Although rare and exposed to immune mediated destruction, these cells manage to evade the immune system of the host. Therefore, a better understanding of the immunogenicity of these cells and their cross talk with immune cells may shed light to potential immunotherapy opportunities in HNSCC.
We quantified by RT-qPCR TWIST1, Stem Cell (SC) markers (CD24, CD44, ALDH1) and PD-L1 in immunomagnetically positively selected CTCs from 90 locally advanced (LA) HNSCC, 33 recurrent/metastatic (R/M) HNSCC and 20 healthy individuals. Patients (pts) with LA disease were treated with cisplatin chemoradiotherapy +/- TPF induction chemotherapy (IC). We assessed the expression of TWIST1, SC markers and PD-L1 at baseline, after completion of IC, at end of chemoradiotherapy and at relapse in pts with LA disease and at baseline in pts with R/M HNSCC. To assess univariate differences of study parameters according to gene expression chi-square test was used for the categorical clinicopathological variables, while patients' survival curves according to gene expression were generated by Kaplan-Meier analysis and tested for significance using the Mantel-Cox log-rank test.
Pts with PD-L1 positive CTCs at the end of treatment had shorter Progression Free Survival (PFS) (p
Liquid biopsies could identify pts at high risk for relapse after adjuvant chemoradiation that may derive benefit from adjuvant therapy in LA disease. PD-L1 expression in CTCs at the end of treatment is a potential biomarker for pt selection for treatment with adjuvant PD1 checkpoint inhibitors.
Clinical trial identification
Legal entity responsible for the study
Attikon General University Hospital, National and Kapodistrian University of Athens
National and Kapodistrian University of Athens
All authors have declared no conflicts of interest.