Abstract 4012: Small RNA-sequencing identifies a microRNA signature predictive of response to FOLFOX-based adjuvant therapy in stage II and III colorectal cancer
Authors: Kandimalla Raju , Balaji Uthra , Gu Jinghua , Mendiola Marta , Balaguer Francesc , Bujanda Luis , Maurel Joan , Feliu Jaime , Goel Ajay 
Published: August 2019

Purpose: Current NCCN guidelines for identifying high-risk stage II/III colorectal cancer (CRC) who may benefit from FOLFOX-based adjuvant chemotherapy remain inadequate. While stage III CRC patients often receive six months of oxaliplatin-based therapy following radical surgery, such treatments are frequently toxic and do not benefit all patients. The use of adjuvant chemotherapy in stage II CRC patients is even more controversial. Hence, identification of high-risk CRC patients with the highest likelihood to benefit from such treatments is of paramount clinical importance. Since microRNAs (miRNAs) have emerged as key functional players and important disease biomarkers, using genomewide miRNA expression profiling, we explored their potential as predictive biomarkers of therapeutic response in CRC.

Experimental design: Small RNA-sequencing was performed in a cohort of stage II/III CRC patients who received, at least 6 months of FOLFOX-based therapy (n=71; 30 with recurrence, and 41 without recurrence). Identification of differentially expressed miRNAs was done using DESeq2, and biomarker prioritization using LASSO-Cox's proportional hazards model and AUC (area under the curve) analysis, using recurrence-free survival (RFS) as an outcome. The miRNA-signature was validated by using miRCURY LNA miRNA assays in three, independent patient cohorts of tissue (fresh frozen and FFPE) and serum specimens obtained from stage II/III CRC patients (n=91, 77 and 82, respectively). Univariate and multivariate Cox proportional hazard models were used to evaluate the performance of the miRNA classifier, in conjunction with known clinicopathological risk factors and the microsatellite instability (MSI) status.

Results: The small RNA-expression profiling led to the identification of a 13-gene miRNA classifier that significantly predicted recurrence free survival (HR: 2.72, 95% CI: 1.96-3.76, p&lt;0.0001) with an AUC of 0.90 (95% CI: 0.83-0.97). This classifier was successfully validated in two tissue cohorts, with impressive AUCs of 0.78 (95% CI: 0.64-0.90, fresh frozen cohort) and 0.86 (95% CI: 0.69-1.00, FFPE cohort), respectively. Importantly, our miRNA signature yielded an impressive AUC of 0.73 (95% CI: 0.60-0.88), even in the preoperative serum specimens from CRC patients. Multivariate analyses revealed that our miRNA classifier was the only independent predictor of response to FOLFOX-based treatment in stage II and III CRC patients.

Conclusions: We report a novel miRNA-based classifier, which robustly predicts response to FOLFOX-based adjuvant chemotherapy in stage II/III CRC patients. Validation of this classifier in pre-operative serum provides an attractive opportunity to explore its potential for disease monitoring during the longitudinal follow-up in CRC patients.

Citation Format: Raju Kandimalla, Uthra Balaji, Jinghua Gu, Marta Mendiola, Francesc Balaguer, Luis Bujanda, Joan Maurel, Jaime Feliu, Ajay Goel. Small RNA-sequencing identifies a microRNA signature predictive of response to FOLFOX-based adjuvant therapy in stage II and III colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4012.