ESMO 2019 — Circulating tumour DNA may direct intensity of treatment in colorectal cancer


  • Michael Simm
  • Oncology Conference reports
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Takeaway

  • For the first time, the independent prognostic value of circulating tumour DNA (ctDNA) is confirmed in patients coming from a prospective phase 3 trial.

Why this matters

  • There is consensus that the duration of adjuvant chemotherapy in stage III colon cancer should be based on risk. ctDNA has recently been suggested as a major prognostic factor.
  • However, there are no large series of data coming from prospective trials with well annotated patients in this indication.

Study design

  • Analysis of ctDNA by detection of 2 methylated markers (WIF1 and NPY) from blood samples of 805 patients enrolled in the IDEA-FRANCE trial for both its prognostic value and its predictive value for treatment duration (3 months vs 6 months).
  • Funding: Association de Recherche contre le Cancer.

Key results

  • Disease-free survival after 2 years was 82.39% in ctDNA-negative patients vs 64.12% in ctDNA-positve patients (HR=1.85; P
  • Differences were highly significant for 3 and 6 months of treatment and for high-risk stage patients (T4, N2 or both), with a trend but no significance in low-risk patients (T1-3/N1).
  • 3 months of treatment seems associated with a particularly poor outcome in ctDNA-positive patients.

Limitations

  • The sampling on EDTA tubes was done at room temperature.
  • Post-hoc analysis.

Expert commentary

“In the future, it may be possible to use liquid biopsy to direct therapy and identify which patients can avoid chemotherapy after their surgery and which should have it,” said Professor Alberto Bardelli, University of Turin (Italy), who was not involved in the study.