Summary

This phase II/III trial studies how well circulating tumor deoxyribonucleic acid (ctDNA) testing in the blood works to identify patients with stage IIA colon cancer who might benefit from additional treatment with chemotherapy after surgery. ctDNA are small pieces of genetic materials (DNA) that are shed by tumors into the blood. Finding ctDNA in the blood means that there are very likely small amounts of cancer remaining after surgery that may not be detectable using other tests, such as medical imaging. Testing for ctDNA levels may help identify patients with colon cancer who benefit from receiving chemotherapy after surgery. It is not yet known whether giving additional treatment with chemotherapy after surgery to patients who test positive for ctDNA and are at low risk for cancer recurrence would extend their time without disease compared to the usual approach (active surveillance).

Objectives

PRIMARY OBJECTIVES:
I. To compare the rate of ctDNA clearance in "ctDNA detected" patients treated with or without adjuvant chemotherapy following resection of stage IIA colon cancer. (Phase II)
II. To compare recurrence-free survival (RFS) in "ctDNA detected" patients treated with or without adjuvant chemotherapy following resection of stage IIA colon cancer. (Phase III)

SECONDARY OBJECTIVES:
I. To describe the prevalence of detectable ctDNA in patients with stage IIA colon cancer following surgical resection.
II. To estimate time-to-event outcomes (overall survival [OS], recurrence-free survival [RFS], and time to recurrence [TTR]) by ctDNA marker status and treatment for patients with resected stage IIA colon cancer.
III. To estimate the rate of compliance with adjuvant chemotherapy and/or active surveillance for patients with resected stage IIA colon cancer.

EXPLORATORY OBJECTIVES:
I. To describe the association of quantitative ctDNA levels with time to event outcomes (RFS, OS, and TTR).
II. To characterize genomic profiles associated with recurrence using a ctDNA assay in patients with resected stage IIA colon cancer.
III. To model the cost effectiveness of the use of ctDNA versus standard of care in this setting.
IV. To evaluate performance of a ctDNA assay after incorporation of patient tumor and peripheral blood mononuclear cells.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I (BLOOD STORED AND TESTED FOR ctDNA LATER): Patients undergo active surveillance.

ARM II (BLOOD TESTED FOR ctDNA AT BASELINE): Patients are assigned to 1 of 2 groups.

GROUP I (ctDNA DETECTED): At the discretion of the investigator, patients receive either oxaliplatin intravenously (IV) over 2 hours on day 1, leucovorin IV over 2 hours on day 1, and fluorouracil IV bolus over 2-4 minutes on day 1 and then by continuous IV over 46-48 hours repeated every 14 days for up to 12 cycles in the absence of disease progression or unacceptable toxicity or oxaliplatin IV over 2 hours on day 1 and capecitabine orally (PO) twice daily (BID) on days 1-14 repeated every 21 days for up to 8 cycles in the absence of disease progression or unacceptable toxicity.

GROUP II (ctDNA NOT DETECTED): Patients undergo active surveillance.

After completion of study treatment, patients are followed up at 12 months and then every 6 months for 2 years.