Detection of CTCs in Patients Undergoing Surgery for Stage IV Colorectal Cancer

More sensitive techniques to detect occult disease are needed for metastatic CRC (mCRC) patients, and perioperative analysis of circulating tumor cells (CTCs) may provide an outstanding opportunity to develop such innovative methods.

Determine kinetics of CTC shedding into the circulation: Perioperative CTC detection has the potential to explain how and when CTCs are shed into the blood. Findings could explain the nature of CTCs with important impact on understanding metastatic spread and relevant clinical applications.

Since this protocol includes blood draws at multiple time points at different distances from the metastases, results could further clarify if the rarity or absence of CTCs in the peripheral blood of some mCRC patients can be explained by dilution. Comparison of patients with CRC liver to lung metastases might help explain different patterns of organ spread. Results of this study could establish CTCs as a prognostic biomarker identifying candidates who will benefit from metastasectomy or for those who are candidates for additional or palliative systemic treatments because of a high risk for later recurrence.

• Develop effective system for isolation, enumeration, enrichment and further characterization of live CTCs: One of the current issues of CTC analysis is the enrichment of those rare cells from blood. We plan to analyze perioperatively drawn blood using the flexible micro spring array (FMSA) device. The FMSA mitigates the stresses experienced by CTCs during their isolation from blood and enables viable capture. The geometric design and filtration pressures have been optimized to maximize capture efficiency, enrichment against leukocytes, and tumor cell viability. Peripheral blood as well as blood from the direct tumor environment (taken from the OR suctioning system) will be analyzed to compare the sensitivity of the FMSA and CellSearch device. Since the FMSA allows for isolation of live CTCs, they will be processed for further single cell characterization.
• Find characteristics of different CTC populations: We hypothesize that CTCs will be enriched for cancer stem cell markers as well as markers for poor prognosis and aggressive tumor growth. Our novel approach to screen and quantify a panel of biomarkers simultaneously with analysis of the CTC markers utilized by the CellSearch system to analyze of CTCs is unique. We view our assays as potential "liquid biopsies" that can screen for markers of prognosis, sensitivity to chemotherapy, response to therapy, as well as for proteins involved in proliferation, apoptosis, and immune response.

Furthermore, we plan to perform single cell analysis of gene mutations and gene expression. Next generation genomic sequencing of single CTCs may allow us to determine a genetic signature for colorectal CTCs and to identify novel biomarkers for CTC detection, disease monitoring, and therapeutic efficacy. Furthermore, the extent of heterogeneity among initially isolated CTCs, which can be compared to the primary tumor and CTCs growing in vitro, will be studied. Single CTC analysis has the potential to identify novel gene and signal transduction pathways that are activated in CTCs and to compare this genomic profile to that of the primary tumor and patient metastasis. Single cell genomic analysis in CTCs is highly innovative and will provide important information for disease monitoring as well as shed light on the underlying biology of CTCs.

Inclusion criteria

• Subjects older than 18 years will be included.
• Subjects with colorectal primary carcinomas metastatic to the liver and/or lungs who will undergo a synchronous resection of both primary tumor and liver metastases will also be enrolled.
• Subjects of all genders and ethnicities will be included.
• Subjects with the diagnosis of stage IV primary CRC will be included if metastases are limited to liver and/or lungs at the time of primary surgery.
• The histopathology of the CRC primary tumor must be documented to be adenocarcinoma.
• Subjects with the diagnosis of syn- and metachronous liver and/or lung metastases from colorectal carcinoma will be included, as long as metastases at both sites are resectable by minimal invasive or conventional approach (usually sequentially and not simultaneously).
• Liver and lung metastases must be defined according to radiological criteria. In case of doubt on radiologic findings, percutaneous biopsy will have to be obtained.
• Subjects must be capable of giving informed consent or have an acceptable surrogate capable of giving legally authorized consent on the subject's behalf.

Exclusion criteria

• Subjects with the concurrent diagnosis of an active second malignancy besides basal cell carcinoma of the skin will be excluded, if there is evidence of disease burden or the patient is currently treated with chemotherapy.
• Subjects with a Hemoglobin of <8g/dl in the morning of the procedure will be excluded.
• In subjects who had needed intraoperative transfusions >4 units of RPBCs, no further blood will be drawn for CTC analysis.
• Pregnant women will be excluded.