Recognition of the organ-specific mutations in metastatic breast cancer by circulating tumor cells isolated in vivo.

The failure to treat and control the growth of metastases is the main cause of death in breast cancer (BC) patients. Compared to the traditional method of analyzing circulating tumor DNA (ctDNA), capturing intact circulating tumor cells (CTCs) allows us to more accurately characterize mutations and identify suitable targeted therapies. We used CellCollector to collect peripheral CTCs. Thirty metastatic breast cancer (MBC) patients were enrolled, and 17 were analyzed with next-generation sequencing (NGS) methods. Clinical characteristics were analyzed along with the CTCs enumeration and detection rates. Whole-genome amplification (WGA) was used to amplify the CTC genomic DNA of 127 genes. Patients younger than 45 years old, with brain metastasis, with three or more metastatic sites, or with HER2-positive had the highest number of CTCs collected. The CTCs detection rate was also correlated to the number of metastasis sites. Different metastasis sites such as the brain, viscus, bone, and soft tissue contained specific high-frequency gene mutations. AKT3, MYC, and NT5C2 mutations were only found in brain metastases. APC, BCL2L11, ESRP1, FLT3 mutations were only in the visceral metastases. KEAP1, KIT, MET were the specific mutation genes in patients with bone and soft tissue metastases. These findings provide evidence that we can detect gene mutation information for obtaining the biological characteristics by CTCs using CellCollector. Different metastasis sites contain specific high-frequency mutation genes, which provide guidance to the accurate gene therapy.