Search

Background This is a pilot proof-of-concept study to evaluate the utility of a custom 15-gene circulating tumor DNA (ctDNA) panel as a potential companion molecular next-generation sequencing (NGS) assay for identifying somatic single nucleotide variants and indels in non-small-cell lung cancer (NSCLC) patients. The custom panel covers the hotspot mutations in EGFR, KRAS, NRAS, BRAF, PIK3CA, ERBB2, MET, KIT, PDGFRA, ALK, ROS1, RET, NTRK1, NTRK2 and NTRK3 genes which serve as biomarkers for guiding treatment decisions in NSCLC patients. Method The custom 15-gene ctDNA NGS panel was designed using ArcherDX Assay Designer. A total of 20 ng or 50 ng input ctDNA was used to construct the libraries. The analytical performance was evaluated using reference standards at different allellic frequencies (0.1%, 1%, 5% and parental). The clinical performance was evaluated using plasma samples collected from 10 treatment naïve advanced stage III or IV NSCLC patients who were tested for tissue EGFR mutations. The bioinformatics analysis was performed using the proprietary Archer Analysis Software. Results For the analytical validation, we achieved 100% sensitivity and specificity for the detection of known mutations in the reference standards. The limit of detection was 1% allelic frequency. Clinical validation showed that the clinical sensitivity and specificity of the assay for detecting EGFR mutation were 83.3% and 100% respectively. In addition, the NGS panel also detected other mutations of uncertain significance in 6 out of 10 patients. Conclusion This preliminary analysis showed that the custom 15-gene ctDNA NGS panel demonstrated good analytical and clinical performances for the EGFR mutation. Further studies incorporating the validation of other candidate gene mutations are warranted.

We report the first case of epidermal-growth-factor-receptor (EGFR) mutation-positive lung adenocarcinoma with acrometastasis in a 51-year-old woman who presented with a swelling on her right hand. Magnetic resonance imaging revealed an expansile lesion at the base of the 5th metacarpal bone of her right hand with cortical erosion and patchy enhancement suggestive of a malignant transformation of a giant-cell tumor. A core needle biopsy of this lesion showed a metastatic adenocarcinoma on histopathological examination which was immunoreactive to cytokeratin (CK) 7 and thyroid transcription factor (TTF)-1 but not to CK20 suggesting a lung primary. A chest radiograph and computed tomography (CT) scan revealed a right upper lobe lung mass. Fluoro-deoxyglucose hypermetabolism was noted in the lung mass and the right 5th metacarpal bone lesion but not elsewhere on positron-emission-tomography/CT scan. Needle biopsy of the lung mass showed adenocarcinoma with histopathological and immunohistochemical features similar to that of the right 5th metacarpal bone lesion. Both the primary lung adenocarcinoma and the acrometastatic lesion were tested positive for EGFR mutation in exon 21 (L858R substitution). She underwent R0 resection of her right upper and middle lobes with systematic mediastinal lymph nodes resection and wide excision of the metacarpal metastasis followed by cytotoxic chemotherapy. A curative approach with complete resection of the primary tumor and oligometastastic site in Stage IV non-small cell lung carcinoma (NSCLC) followed by additive cytotoxic chemotherapy has not been reported to date and as such there is still no data on disease-free survival with this approach.