171 Antagonistic interaction between gemcitabine and erlotinib is influenced by EGR1 (early growth response 1) transcription factor expression

Abstract

for 102 (87%) of 117 patients who had both plasma and tissue tested cases (kappa = 0.73, 95% confidence interval 0.61–0.85) with sensitivity 72%, specificity 99%, positive and negative predictive value 97% and 83%, respectively. In all 15 discrepant cases identical plasma cfDNA samples were tested using an alternative cfDNA BRAF mutation PCRbased method (BEAMing, Sysmex Inostics, Baltimore, MD), which yielded 100% agreement with the Idylla platform. Longitudinally collected plasma samples were available in 13 patients (appendiceal, n = 2; colorectal, n = 2; melanoma, n = 4; papillary thyroid cancer, n = 2; other, n = 3) with plasma BRAF V600 mutations treated with predominantly BRAF targeting combinations and changes in the amount of BRAF-mutant cfDNA tracked changes in tumor markers and disease burden visualized via imaging. Conclusions: Detecting V600 BRAF mutations in cfDNA from plasma using the Idylla platform and BRAF V600 mutation prototype cartridges is a fast and noninvasive alternative to mutation testing of tumor tissue with an acceptable level of concordance and sensitivity, and should be investigated further for testing and monitoring of BRAF mutation status in patients with cancer.