Rare Diseases Symptoms Automatic Extraction

Prospective Blinded Study of BRAFV600E Mutation Detection in Cell-Free DNA of Patients with Systemic Histiocytic Disorders.

[erdheim-chester disease]

Patients with Langerhans Cell Histiocytosis (LCH) and Erdheim-Chester Disease (ECD) have a high frequency of BRAFV600E mutations and respond to RAF inhibitors. However, detection of mutations in tissue biopsies is particularly challenging in histiocytoses due to low tumor content and stromal contamination. We applied a droplet-digitial PCR assay for quantitative detection of the BRAFV600E mutation in plasma and urine cell-free (cf)DNA and performed a prospective, blinded study in 30 ECD/LCH patients. There was 100% concordance between tissue and urinary cfDNA genotype in treatment naïve samples. cfDNA analysis facilitated identification of previously undescribed KRASG12S mutant ECD and dynamically tracked disease burden in patients treated with a variety of therapies. These results indicate that cfDNA BRAFV600E mutational analysis in plasma and urine provides a convenient and reliable method of detecting mutational status and can serve as a non-invasive biomarker to monitor response to therapy in LCH and ECD.