DYNAMIC-Rectal: Circulating Tumour DNA Analysis Informing Adjuvant Chemotherapy in Locally Advanced Rectal Cancer - A Multicentre Randomised Study

Despite guidelines recommending the routine use of adjuvant chemotherapy in locally advanced rectal cancer (LARC), there is little evidence in the modern era to support the routine use of post-operative chemotherapy in patients who received pre-operative chemo-radiotherapy. Although the use of adjuvant FOLFOX appears promising in node-positive disease (ypN+), this comes with a toxicity price and the impact on overall survival yet to be proven. Clearly, better predictors of those patients who actually require adjuvant chemotherapy are needed (e.g. ctDNA-positivity indicating presence of minimal residual disease).

Across multiple colorectal cancer cohorts, our initial studies demonstrated the potential utility of ctDNA as a marker of recurrence risk. The end goal for LARC patients is to integrate ctDNA analysis into routine clinical practice to guide clinical decision making, and most importantly to benefit patients. This initial study is powered to show that a ctDNA-based approach to adjuvant therapy will lead to substantially fewer patients receiving adjuvant therapy, which we believe is the only practical study design with a clinically significant endpoint, within the patient numbers that could be recruited. Importantly, this study will also demonstrate the feasibility of performing such a biomarker-driven study in the rectal cancer population.

The primary endpoint of this study is number of patients receiving adjuvant chemotherapy. Secondary endpoints include: ctDNA results turn-around time; 3-year recurrence free survival; and Overall survival.