Validation of CanCatch Surf assay for tissue-agnostic detection of minimal residual disease in colorectal cancer.

Abstract

21 Background: Monitoring molecular residual disease (MRD) status showed prognostic value for recurrence prediction in colorectal cancer (CRC) patients. However, conventional tissue-informed MRD approaches lack the feasibility where tumor biopsy is not available or rapid turnaround time is necessitate for clinical decision making. We previously developed CanCatch Surf, a highly sensitive tissue-agnostic, methylation-based circulating tumor DNA (ctDNA) assay. Here, we report its clinical application in detecting early relapse for patients with surgical resectable CRC. Methods: MUSETALK-CRC01 is a prospective, multicenter study designed to monitor ctDNA status with CanCatch Surf for patients with clinical stage I–III CRC undergoing complete surgical resection. 88 patients were enrolled and blood samples were collected after surgery for longitudinal ctDNA analysis until recurrence. Computed tomography (CT) imaging was performed every 6 months after surgery. Cell-free DNA from blood samples were extracted and subjected to CanCatch Surf testing. A machine learning-based algorithm was trained to classify each blood samples as MRD-positive or MRD-negative as described previously. Sensitivity and specificity were calculated with reference to the clinical recurrence outcomes for each patient. Additionally, the accuracy of ctDNA quantification estimated by CanCatch Surf was validated and compared with a tumor-informed, mutation-based approach. Results: In the MUSETALK-CRC01 cohort (60% male, mean age 56.53±13.22 years), 50 (57%) patients had stage II CRC, and 24 (27%) had stage III CRC with a median follow-up of 16 months. During the period of surveillance, 19 (21%) patients experienced radiologic recurrence. Serial ctDNA analysis during surveillance of the 88 patients with longitudinal collected blood samples identified relapse with 75% (95%CI: 51-91%) sensitivity and 97% (95%CI: 90-99%) specificity. ctDNA positivity during longitudinal surveillance was associated with a reduced recurrence-free survival compared with ctDNA negativity (HR, 22.72; 95% CI, 8.04-64.24; P < 0.005). For 14 relapsed patients with positive ctDNA results, MRD predicted molecular relapse earlier than radiologically confirmed recurrence with a median lead time of 4.7 months (IQR, 6.5 months; Wilcoxon signed rank test P<0.005). ctDNA estimated by tumor methylated fraction (TMeF) derived from CanCatch Surf demonstrated a strong correlation (Pearson correlation coefficient: >0.95) with results predicted by cTAF, a tumor-informed ctDNA quantification metrics. Conclusions: In this study, we demonstrated the high accuracy of tissue-agnostic ctDNA assay. This approach offers a clinical and practical alternative for molecular residual disease detection, especially when tumor tissue is unavailable or insufficient for genomic profiling.