Genomic Classifiers (Coloprint/Msi-Print) Predict Outcome And Chemotherapy Benefit In Stage Ii And Iii Colon Cancer Patients.

378 Background: Although the benefit of chemotherapy in stage II and III colon cancer patients is significant, many patients might not need adjuvant chemotherapy because they have a good prognosis even without additional treatment. ColoPrint is a gene expression classifier that distinguish patients with low or high risk of disease relapse. It was developed using whole genome expression data and has been validated in public datasets, independent European patient cohorts and technical studies (Salazar 2011 JCO, Maak 2012 Ann Surg). Methods: In this study, the commercial ColoPrint test was validated in stage II (n=96) and III patients (n=95) treated at the MD Anderson Cancer Center from 2003 to 2009. Frozen tissue specimen, clinical parameters, MSI-status and follow-up data (median follow-up 64 months) were available. The 64-gene MSI-signature developed to identify patients with deficient mismatch repair system (Tian 2012 J Path) was evaluated for its accuracy to identify MSI patients and also for prognosis. Results: In this cohort, ColoPrint classified 56% of stage II and III patients as being at low risk. The 3-year Relapse-Free-Survival (RFS) was 90.6% for Low Risk and 78.4% for High Risk patients with a HR of 2.33 (p=0.025). In uni-and multivariate analysis ColoPrint and stage were the only significant factors to predict outcome. The MSI-signature classified 47 patients (24.6%) as MSI-H and most MSI-H patients were ColoPrint low risk (81%). Patients who were ColoPrint low risk and MSI-H by signature had the best outcome with a 3-year RFS of 95% while patients with ColoPrint high risk had a worse outcome independently of the MSI-status. Low risk ColoPrint patients had a good outcome independent of stage or chemotherapy treatment (90.1% 3-year RFS for treated patients, 91.4% for untreated patients) while ColoPrint high risk patients treated with adjuvant chemotherapy had 3-year RFS of 84%, compared to 70.1% 3-year RFS in untreated patients (p=0.026). Conclusions: The combination of ColoPrint and MSI-Print improves the prognostic accuracy in stage II and stage III patients and may help the identification of patients at higher risk who are more likely to benefit from additional treatment