The Safe-SeqS tumor-informed personalized ctDNA assay was used to detect ctDNA in the experimental group. Patients with a ctDNA-positive result at 4 or 7 weeks after surgery received oxaliplatin-based or fluoropyrimidine chemotherapy; those who were ctDNA-negative were observed during follow-up.
Fewer patients overall in the ctDNA-guided group, compared with the standard management group, received adjuvant chemotherapy (15.3% vs. 27.9%; odds ratio, 2.14).
Two-year recurrence-free survival (RFS) in the ctDNA-guided treatment group was noninferior to that in the standard management group (93.5% vs. 92.4%). Three-year RFS was 86.4% in ctDNA-positive patients who received chemotherapy, 92.5% in ctDNA-negative patients without chemotherapy, and 96.7% in a clinical low-risk subgroup.
ASCO expert Cathy Eng, MD, applauded the findings, stating in a press release that “thanks to the results of this study, we may now be able to use it to better identify which patient with stage 2 colon cancer would benefit from post surgery treatment with chemotherapy and which ones can be spared the additional treatment, without compromising relapse-free survival.”
Dr. Eng is the David H. Johnson Chair in Surgical and Medical Oncology, co-leader of the Gastrointestinal Cancer Research Program, co-director of GI oncology, and professor of medicine in hematology and oncology at Vanderbilt University, Nashville, Tenn.
Next steps
The authors note that a randomized trial is being considered in which ctDNA-positive and -negative patients would be randomized to treatment versus no treatment. This could provide more definitive evidence of treatment impact, or lack of impact, in each of the patient subsets, according to the press release.
The DYNAMIC trial was funded by the Australian National Health and Medical Research Council, U.S. National Institutes of Health, the Marcus Foundation, the Virginia and D.K. Ludwig Fund for Cancer Research, Lustgarten Foundation, the Conrad R. Hilton Foundation, the Sol Goldman Charitable Trust, John Templeton Foundation, and Eastern Health Research Foundation. Dr. Tie has reported receiving honoraria from Inivata and Servier and serving as a consultant or advisor for AstraZeneca/MedImmune, Bristol-Myers Squibb, Haystack Oncology, Inivata, MSD Oncology, and Pierre Fabre.
A version of this article first appeared on Medscape.com.