Individualized treatment of patients with advanced NSCLC: potential application for Circulating Tumour Cells (CTCs) molecular and phenotypical profiling

NSCLC is a major cause of cancer-related death in both men and women globally. Despite recent advances in early tumour detection, surgical treatment, radio-chemotherapy, and targeted therapy, the NSCLC-related high mortality rate remains a daunting challenge. The therapeutic choice is driven by the molecular/genetic assessment of the primary tumour as determined at diagnosis. This practice needs to be integrated with other methods for real time tumour mutational screening. Indeed, a body of evidence is emerging that the feasibility of new tools for monitoring the malignancy throughout the continuum of care may offer major benefits to the patients. Since predictive biomarkers are lacking so far, CTC assays have gained interest to assist clinicians in patient management. Recent experiences demonstrated that CTC detection could help improve the diagnosis and predict a prognosis in patients with non–small cell lung cancer (NSCLC). However, EpCAM positive CTCs are less frequently detected in NSCLC patients compared to other epithelial tumours. In NSCLC, CTCs show a different cytokeratin (CK) pattern and a lower expression of full-length Epithelial Cell Adhesion Molecule (EpCAM) compared to other carcinomas. Indeed, 80% of patients were CTC-positive by the EpCAM-independent ISET compared to only 23% by standard CellSearch assay. The primary aim of the Project is to determine the percentage of CTC-positive patients, and the total CTC numbers in advanced NSCLC at baseline, before starting treatment. We questioned whether we could detect a higher number of CTCs by implementing the standard CellSearch assay. Secondary aim is to evaluate if CTCs count modifications are an early predictor of response to treatment. The exploratory aim is set and applying the molecular and phenotypic profiling of CTCs, in order to verify if these data could be relevant to manage patient therapy. We then investigated in some selected NSCLC patients, the potential of the combined use of CTCs and cfDNA assays as a dynamic indicator of treatment efficacy. We evaluated 189 patients, enrolled from December 2012 to June 2016 in trial no. NCT02407327 (http://www.clinicaltrials.gov). To address these aims we determined the percentage of CTC-positive patients and total CTC number in our cohort using standard assay (SA) and an expanded assay (EA) that was set to tailoring the cytokeratin panel for NSCLC. We demonstrated that the presence of tumour cells was associated with a poor prognosis leading to the definition of a cut-off value (=1 cell) in metastatic NSCLC with standard assay (SA) and with expanded assay (EA), we showed a better predictive value concern STP. The CTCs level variation during the treatment predict a good response to therapy, and the phenotype and molecular characterization of CTCs is feasible using different methods with several degrees of in depth investigation. All data collected provides useful information about disease evolution. We compared, where possible, the EGFR mutational status of the NSCLC primary tumour and that of the CTC and cfDNA collected at baseline and after the first line of treatment, and found consistent results in all the analysed samples. Our data suggests a potential complementary use of Circulating Tumour Cells and cfDNA in solid Tumours concerning molecular information. To indicate that in the circulating compartment we could find a window to survey the disease evolution, the relationship between subpopulation of cancer cells, the therapy response and the host relationship. This evidence documents and confirms the great impact that the detections and the characterization of CTCs, with malignant proprieties, could have in tailored medicine if this biomarker will be inserted in the decisional tree used in the clinical management of patients.