Standard Surveillance vs. Intensive Surveillance in Early Breast Cancer

CA27.29, CEA and CA125 will be measured with the AIA®-CL1200 by TOSOH BIOSCIENCE (TOSOH CORPORATION, Tokyo, Japan). The CL AIA-PACK assays are two-step chemiluminescence enzyme immunoassay kits. CA27.29/CEA/CA125 present in a test sample is bound to the anti- CA27.29/CEA/CA125 mouse monoclonal antibody immobilized on the magnetic microparticles in one cell (Cell-I). After first incubation, the magnetic microparticles are washed and the enzyme-labeled anti- CA27.29/CEA/CA125 mouse monoclonal antibody that has been reconstituted in another cell (Cell-II) is dispensed into Cell-I. After second incubation, the magnetic microparticles are washed again and are incubated with a chemiluminescent substrate, DIFURAT®. The amount of enzyme-labeled antibodies that bind to the magnetic microparticles is directly proportional to the CA27.29/CEA/CA125 concentration in the test sample. A standard curve is constructed, unknown sample concentrations are calculated by using this curve.

CTCs will be analyzed using the CellSearch® System (Menarini Silicon Biosystems). The CellSearch® system is designed to enumerate CTCs of epithelial origin (CD45-, EpCAM+, cytokeratin 8+ / 18+ and/or 19+). The basic principle is linking a magnetic ferrofluid reagent that contains i. a. antibodies targeting the EpCAM antigen to CTCs. After steps of immunomagnetic capture and enrichment as well as addition of fluorescent reagents (that contain anti-CK-PE, DAPI and anti-CD45-APC), the automatic dispersion to a magnetic cartridge holder takes place. Via strong magnetic field, the magnetically labeled epithelial cells are attracted to the surface of the cartridge where they can be scanned automatically. Images of events where CK-PE and DAPI fluorescence are co-located are presented to the user for final classification. An event is classified as a tumor cell when its morphological features are consistent with that of a tumor cell and it exhibits the phenotype EpCAM+, CK+, DAPI+ and CD45-.

Presence of ctDNA will be analyzed centrally at Inivata Inc. using the RaDaRTM assay. Therefore, primary tumor tissue and peripheral blood specimens will be shipped for centralized analysis to Inivata Inc. RaDaRTM is a tumor-informed approach, beginning with whole exome sequencing of a tumor specimen from a patient's biopsy or surgical resection. SNVs and indels identified from the exome sequencing are prioritized to build a patient specific primer panel of up to 48 tumor-specific somatic variants. Patient specific primers are combined with common SNP primers for NGS for quality control purposes. To detect patient specific ctDNA, NGS testing is performed with the RaDaRTM assay using a multiplex PCR based on the InVision® platform.

To ensure the possibility of retrospective studies during and after the ongoing study, a biobank will be implemented.