Gene-Expression Signature Assay Identifies High-Risk Stage II Colon Cancer

Key Points

  • High-risk stage II colon cancer on ColDx was independently predictive of a reduced recurrence-free interval.
  • The probability of remaining recurrence-free at 5 years was 82% in the high-risk group.

In an analysis reported in the Journal of Clinical Oncology, Niedzwiecki et al found that the ColDx gene-expression signature assay identified high-risk stage II colon cancer among patients in the phase III Alliance C9581 trial. This assay has been shown to be independently prognostic for recurrence-free interval and overall survival in colon cancer.

Study Details

The aim of the study was to further validate ColDx using formalin-fixed, paraffin-embedded specimens from patients in the C9581 trial, which found no survival benefit for edrecolomab vs observation in patients with stage II disease. (Edrecolomab is a mouse-derived monoclonal antibody directed against the 17-1A antigen located on the cell surface of the various carcinomas.) The analysis included a randomly selected subgroup of 360 patients with available tissue and 58 relapse events as well as an additional 33 patients with relapse events. Risk status was determined for each patient using ColDx.

Risk Classification

Overall, 216 of 393 patients (55%) were classified as high risk. On multivariate analysis adjusting for mismatch-repair (MMR) deficiency and additional prognostic factors, patients at high risk on ColDx had significantly worse recurrence-free interval vs low-risk patients (hazard ratio [HR] = 2.13, P < .01). Age (HR = 1.02, P = .07, as continuous variable) and MMR status (HR = 0.55, P = .05, for deficient vs intact) had marginal significance. The probability of remaining recurrence-free at 5 years was 82% in the high-risk group vs 91% in the low-risk group.

The investigators concluded: “ColDx is associated with [recurrence-free interval] in the C9581 subsample in the presence of other prognostic factors, including MMR deficiency. ColDx could be incorporated with the traditional clinical markers of risk to refine patient prognosis.”

The study was supported by grants from the National Cancer Institute.

Donna Niedzwiecki, PhD, of the Alliance Statistics and Data Center, Duke University Medical Center, is the corresponding author of the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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