Clinical Utility of Plasma KRAS, NRAS and BRAF Mutational Analysis with Real Time PCR in Metastatic Colorectal Cancer Patients—The Importance of Tissue/Plasma Discordant Cases

Abstract

Background: Tumor tissue (T) mutational analysis represents the standard for metastatic colorectal cancer (mCRC); however, circulating tumor DNA (ctDNA) detected by liquid biopsy in plasma (PL) can better represent tumor heterogeneity. Methods: mCRC patients undergoing standard first-line chemotherapy with known T-KRAS/NRAS/BRAF status were enrolled in the present prospective study. PL mutations were assessed within 2 weeks before chemotherapy start with real time PCR and correlated with T status and Progression free survival (PFS). Clinical and biochemical variables including also total number of tumor lesions (TNL) and the sum of maximum diameter (SMD) of all lesions were assessed as potential predictors of T/PL discordance. RESULTS: Among 45 enrolled patients, all BRAF mutations were concordant between T and PL and there were 20% of patients RAS discordant: 9% wild type in T and mutated in PL and 11% mutated in T and wild type in PL. T mutations were significantly associated to median PFS (mPFS of 4.5, 8.3 and 22.9 months for T-BRAF mutated, T-RAS mutated, and T-wild type patients, respectively, p for trend 0.00014). PL mutations further refined prognosis: RAS wild type in T and mutated in PL had significantly shorter PFS than concordant RAS wild type in T and PL: mPFS 9.6 vs. 23.3 months, respectively, p = 0.02. Patients RAS mutated in T and wild type in PL had longer PFS than concordant RAS mutated in T and PL: 24.4 vs. 7.8 months, respectively, p = 0.008. At a multivariate cox regression analysis for PFS, PL mutations were independent prognostic factor superior to T analysis (HR 0.13, p = 0.0008). At multivariate logistic regression analysis TNL and SMD were significant predictors of discordant cases. Conclusions: PL mutational analysis allows a better prognostication than T analysis alone and could help in mCRC treatment management.

Rapid Multiplex Strip Test for the Detection of Circulating Tumor DNA Mutations for Liquid Biopsy Applications

“…Moreover, the test involves many washing and incubation steps with a total analysis time of about 2 h [ 48 ]. Compared to the previously reported biosensors for ctDNA detection in real samples ( Table S3 ) [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ], the advantages of the proposed multi-plex test are related mostly to the cost, run time, and simplicity, as well as the universality and advanced multiplexing potential.…”

Management of Colorectal Cancer with Synchronous Liver Metastases: The Final Results of the Cosmic Inception Cohort Study

“…Current knowledge of the mutational burden of colorectal cancer influences choice of chemotherapy but is yet to impact meaningfully on surgical decision making. [47][48][49] Better understanding of this cancer biology may influence a direction towards more systemic treatment, even in patients with apparently 'easy-to-resect' liver metastases and primary tumours. The recently reported RAPIDO study in patients with rectal cancer confirms that systemic chemotherapy delivered prior to surgery confers benefit.…”

Liquid biopsy: Novel perspectives on the importance and spectrum of PIK3CA, PTEN and RET mutations in solid tumors

“…Several studies have evaluated the concordance between KRAS , BRAF and NRAS point mutations detected by ctDNA and tumor-tissue analysis ( 24 , 25 ). More mutations were detected by ctDNA analysis than by tumor biopsy, reflecting the ability of liquid biopsy to reflect tumor heterogeneity.…”