Dr. Rita Zamarchi, MD

Research topic

Advantage of LB derives from the sample source, since peripheral blood could provide the genetic landscape of all cancerous lesions at any time. To obtain more information from the same sample, we focused on predicting treatment effectiveness by quantifying “druggable” CTCs, whilst ctDNA was collected in parallel to detect actionable mutations.

Background

Technological advance allowed establishing inverse correlations between CTCs and progression-free (PFS) and overall survival (OS) in metastatic cancer of breast, colon-rectum and prostate. Therefore, the Food and Drug Administration approved finally the IVD use of the CellSearch (CS) CTC assay in these three malignancies. Then, CTCs have been reported in several solid tumors, and related to patients’ outcome.
Similar, ctDNA is released in circulation from apoptotic, necrotic or viable tumor cells; since total cell-free circulating DNA has poor diagnostic value, ctDNA has exploited for tracking tumor-associated mutations and/or the early onset of drug resistance.
Finally, in peripheral blood of cancer patients we can found the so-called tdEVs, i.e. micro-particles of variable diameter, with or without nucleus. The tdEVs express Epithelial-Cell-Adhesion-Molecule (EpCAM) and Cytokeratin (CK) and lack the leukocyte marker CD45. Recently, tdEVs were reported as a new marker of poor prognosis in lung and prostate cancer.

Research achievements

We demonstrated that CTCs differ for phenotype, genotype and functional properties.
We found that the lack of apoptosis marker (M30) and of IGF-1R expression on CTCs predicts adverse prognosis in MBC treated with first-line chemotherapy. Conversely, the persistence of RANK-positive CTCs determines denosumab effectiveness in preventing skeletal incidents in MBC patients.
In NSCLC, the presence of EpCAM-high CTCs and elevated levels of tdEVs and ctDNA was associated with a poor OS, whilst the presence of EpCA-low CTCs was not.

In a case of TKIs-treated NSCLC, we showed discordances in the detection timing of L858R mutation between the gold standard analysis of tumor specimens, CTCs and ctDNA. This supports their combined use in clinical practice, to better mirror spatial and temporal heterogeneity of the tumor under the selective pressure of treatment.
Similar, in NSCLC EML4-ALK rearranged CTCs and cell-free mRNA (cfmRNA) were associated to patients’ outcome, and response to ALK-inhibitors treatment.
By analyzing tissue samples from different sites and time points, in a case of metastatic melanoma we discovered a rare KIT V569G mutation, exclusively in circulating melanoma cells (CMCs). This further underlines the importance of CMCs in the early identification of tumor clones putatively responsible for therapy resistance.

We have been collaborating to international consortia:
EPAC-breast, EPAC-lung, focused on CTC value for disease staging
CTCTrap (www.utwente.nl/tnw/ctctrap/);
CANCER_ID (www.cancer-id.eu/).

Conclusions and perspectives

Multi-parametric analysis of LB markers is starting to shed light on tumor heterogeneity and therapeutic resistance mechanisms, mandatory to realize a true “personalized” treatment.