Exosomal MicroRNA Predicts Response to Preoperative Chemoradiotherapy in Locally Advanced Rectal Cancer

Area of Science:

• Oncology
• Molecular Diagnostics
• Biomarker Discovery

Background:

• Locally advanced rectal cancer (LARC) treatment involves preoperative chemoradiotherapy (PCRT) followed by surgery.
• Identifying patients who will respond to PCRT is crucial for treatment optimization.
• Previous research identified blood-based transcriptomic biomarkers for predicting PCRT response.

Purpose of the Study:

• To develop a liquid biopsy assay utilizing exosomal microRNAs (miRNAs) for predicting response to preoperative chemoradiotherapy in rectal cancer patients.
• To establish a risk-assessment model integrating miRNA biomarkers and CEA levels for enhanced predictive accuracy.

Main Methods:

• Retrospective analysis of serum specimens from 81 patients across two independent international multicenter cohorts (training and validation sets).
• Development of a 5-miRNA panel and integration with Carcinoembryonic Antigen (CEA) levels into a risk-assessment model.
• Evaluation of diagnostic performance using Area Under the Curve (AUC), sensitivity, and specificity for predicting pathological complete response.

Main Results:

• A 5-miRNA panel demonstrated significant predictive performance for PCRT response (AUC = 0.86 in training, AUC = 0.87 in validation).
• The integrated risk model incorporating the miRNA panel and CEA level showed superior accuracy (AUC = 0.90) compared to the miRNA panel alone.
• The risk model outperformed current pathological features in identifying pathological complete response (AUC = 0.92, specificity = 1.00).

Conclusions:

• The developed miRNA signature panel shows potential for clinical translation as a non-invasive liquid biopsy assay for predicting PCRT response in rectal cancer.
• This assay could aid in personalizing treatment strategies and improving outcomes for patients with locally advanced rectal cancer.
• Further validation in prospective studies is warranted to confirm its clinical utility.