Longitudinal Relationship between Idylla Plasma ctBRAF V600 Mutation Detection and Tumor Burden in Patients with Metastatic Melanoma

• Published in: Molecular diagnosis & therapy Vol. 25; no. 3; pp. 361 - 371
• Main Authors: Linder, Mark William, Egger, Michael E., Van Meter, Tracy, Rai, Shesh N., Valdes, Roland, Hall, Melissa Barousse, Wu, Xiaoyong, Alghamdi, Norah, Chesney, Jason A.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.05.2021; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Biomedicine; Cancer Research; Circulating Tumor DNA - genetics; Computed tomography; Cross-Sectional Studies; Deoxyribonucleic acid; DNA; Feasibility Studies; Gene frequency; Human Genetics; Humans; Kinases; Laboratory Medicine; Longitudinal Studies; Male; Mathematical analysis; Medical imaging; Melanoma; Melanoma - blood; Melanoma - diagnostic imaging; Melanoma - genetics; Melanoma - pathology; Metastases; Molecular Medicine; Monitoring; Mutation; Neoplasm Metastasis; Original Research Article; Pharmacotherapy; Pilot Projects; Polymerase chain reaction; Proto-Oncogene Proteins B-raf - blood; Proto-Oncogene Proteins B-raf - genetics; Radiography; Raf protein; Sensitivity and Specificity; Skin cancer; Solid tumors; Standard of Care; Telemedicine; Tomography, X-Ray Computed; Tumor Burden; Tumors
• ISSN: 1177-1062; 1179-2000
• DOI: 10.1007/s40291-021-00528-4

Background Circulating tumor DNA (ctDNA) may complement radiography for interim assessment of patients with cancer. Objective Our objective was to explore the relationship between changes in plasma ctDNA versus radiographic imaging among patients with metastatic melanoma. Methods Using the Idylla system, we measured B-Raf proto-oncogene ( BRAF ) V600 ctDNA in plasma from 15 patients with BRAF V600E/K-positive primary tumors undergoing standard-of-care monitoring, including cross-sectional computed tomography (CT) imaging. BRAF V600 mutant allele frequency (%MAF) was calculated from the Idylla Cq values and directly measured using droplet digital polymerase chain reaction (ddPCR). Results The Idylla ctDNA assay demonstrated 91% sensitivity, 96% specificity, 91% positive predictive value, and 96% negative predictive value for the presence of > 93 mm metastatic disease. Qualitative ctDNA results corresponded to changes in RECIST (Response Evaluation Criteria in Solid Tumors) 1.1 status determined by CT imaging in 11 of 15 subjects (73%). Calculated %MAF results correlated with ddPCR ( R 2 = 0.94) and provided evidence of progressive disease 55 and 97 days in advance of CT imaging for two subjects with persistently positive qualitative results. Conclusions Overall, interim ctDNA results provided evidence of partial response or progressive disease an average of 82 days before radiography. This pilot study supports the feasibility of using the Idylla plasma BRAF V600 ctDNA assay as a complement to CT scanning for routine monitoring of therapeutic response. Somatic mutation quantification based on Cq values shows promise for identifying disease progression and warrants further validation.