Detection of MSI in Circulating Tumor DNA of Colorectal Carcinoma Patients

PRIMARY OBJECTIVES:

I. To test the hypothesis that there is high level of concordance between the electrophoretic
mobility profile of microsatellite biomarkers in circulating cell-free deoxyribonucleic acid
(ccfDNA) versus in primary tumor tissues in patients with colorectal carcinomas displaying
microsatellite instability.

II. To test the hypothesis that changes in the electrophoretic mobility profile of
microsatellite biomarkers in liquid biopsies from patients with colorectal carcinoma
correlate with therapeutic responsiveness measured based on Response Evaluation Criteria in
Solid Tumors (RECIST) criteria.

III. To determine whether microsatellite alleles generated as a result of microsatellite
instability detectable in liquid biopsy specimens from patients with colorectal carcinoma
represent the entire cancer cell population or only a subset of cancer cells differentially
affected by genomic instability.

OUTLINE:

Participants undergo collection of blood samples to evaluate microsatellite instability via
serial liquid biopsies at baseline, then every 6 weeks and at progression or 9 months.

Inclusion Criteria:

- Patients newly diagnosed with stage IV colorectal cancer and with defined
microsatellite instability status before initiation of systemic immunotherapy.

- Trackable cancer-driver mutation in the primary tumor documented before initiation of
chemotherapy.

- Zubrod performance status of 0 or 1.

- Patients have measurable disease according to RECIST version (v)1.1.

- Ability to understand and willing to sign a written informed consent.

Exclusion Criteria:

- Severe anemia (hemoglobin [Hb] < 8 g/dL).