Clinical Utility of Liquid Biopsy to Detect BRAF and NRAS Mutations in Stage III/IV Melanoma Patients by Using Real-Time PCR

Abstract

Background: Liquid biopsy is a potentially useful tool for melanoma patients, also for detecting BRAS/NRAS mutations, even if the tissue analysis remains the current standard. Methods: In this work, we tested ctDNA on plasma samples from 56 BRAF-V600/NRAS mutant stage III/IV melanoma patients using a real-time quantitative PCR (qPCR)-based platform. The study population was divided into two cohorts: the first including 26 patients who had undergone radical resection (resected cohort) and the second including 30 patients who had unresected measurable disease (advanced cohort). Moreover, for 10 patients in the advanced cohort, ctDNA assessment was repeated at specified timepoints after baseline testing. Data were analyzed and correlated to the clinicopathologic characteristics and outcomes. Results: In the baseline cohort, a higher tissue–plasma concordance was seen in patients with high burden of disease (sum of diameters ≥30 mm, ≥2 metastatic sites, elevated LDH levels); furthermore, monitoring of these patients through ctDNA analysis was informative for therapeutic responses. On the other hand, the low sensitivity of this technique did not allow for clinically valuable prediction of relapses in radically resected stage III/IV patients. Conclusions: Overall, our data suggest that qPCR-based ctDNA analysis could be informative in a subset of locally advanced and metastatic melanoma patients with specific clinical–radiological characteristics, supporting further investigations in this setting.

Use of ctDNA in identifying an actionable BRAF mutation in stage 4 metastatic melanoma

“…Prior to implementation in routine NHS diagnostic practice for melanoma, further refinement of methods is required to ensure valid, reliable and standardised testing technologies across laboratories are adopted and formal assessment of cost-effectiveness considered. In a recent study, results were obtained within 120 min of venepuncture; the time from collection to centrifugation of the samples was less than 1 hour 12. Rapid turnaround of results would be resource intensive, and review of local pathways would be necessary to consider if this could be consistently achieved.…”

Tumor-Type Agnostic, Targeted Therapies: BRAF Inhibitors Join the Group

“…If FFPE of the primary or metastatic cancer is unavailable, a blood sample or liquid biopsy using circulating tumor DNA (ctDNA) may be an alternative (Guardant 360, Table 3). Although ctDNA presents an essential innovation in cancer diagnostics and management (e.g., diagnosis and molecular profiling of advanced non-small cell lung cancer or the monitoring of BRAF status in melanoma patients during the targeted treatment with BRAF/ MEK inhibitors) (34703985), it has certain limitations, including lower sensitivity (47-84%) compared with the PCR-based assays performed on FFPE (112)(113)(114)(115)(116). BRAF analysis is usually performed using various DNA-based molecular assays.…”

A group of three miRNAs can act as candidate circulating biomarkers in liquid biopsies from melanoma patients

“…In this regard, liquid biopsy has been proven to be a suitable method for monitoring and treatment response evaluation but also for early diagnosis. Several studies in metastatic melanoma patients highlighted the clinical utility of liquid biopsy in detecting and monitoring BRAF/NRAS mutations (3)(4)(5). Nonetheless, wild-type patients currently cannot benefit from this monitoring approach.…”