(41 days)
The CellSearch™ Circulating Tumor Cell Kit is intended for the enumeration of circulating tumor cells (CTC) of epithelial origin (CD45-, EpCAM+ and cytokeratin 8 & 18+, and/or cytokeratin 19+) in whole blood in conjunction with the CellTracks® AutoPrep System, the CellSpotter® Analyzer or CellTracks® Analyzer II, and the CellSearch™ Circulating Tumor Cell Control Kit.
The presence of CTC in the peripheral blood, as detected by the CellSearch™ Circulating Turnor Cell Kit, is associated with decreased progression free survival and decreased overall survival in patients treated for metastatic breast cancer. A CTC count of 5 or more per 7.5 mL of blood generally is predictive of shorter progression free survival and shorter overall survival.
Epithelial cells are immunomagnetically labeled by targeting the Epithelial Cell Adhesion Molecule (EpCAM) antigen. Anti-EpCAM monoclonal antibodies conjugated to ferrofluid particles are colloidal and, when mixed with a sample containing the target epithelial cells, bind to the EpCAM antigen associated with the epithelial cells. After immunomagnetic selection of epithelial cells from 7.5 mL of blood. Fluorescent reagents are added at this time to discriminate between the immunomagnetically selected cells. Anti-Cytokeratin - Phycoerythrin (CK-PE) stains the intracellular cytoskeleton cytokeratin proteins expressed in cells of epithelial origin, anti-CD45-Allophycocyan (CD45-APC) stains leukocytes and DAPI stains DNA present in the cell nucleus. A strong magnetic field is applied to the processed reagent/sample mixture that causes the labeled target cells to move to the cartridge surface. The cartridge is then placed on the CellTracks® Analyzer II for data acquisition and analysis. The CellTracks® Analyzer II acquires images of PE, APC and DAPI fluorescence staining of the entire viewing surface.
After data acquisition is completed, the images are analyzed for any event where cytokeratin-PE and DAPI are within a specified space in the cartridge, i.e. indicating the possible presence of a cell with a nucleus that expresses cytokeratin. Images from each fluorescent color as well as a composite image of the cytokeratin staining (green) and the nuclear staining (purple) are presented to the user in a gallery for final cell classification. A cell is classified as a tumor cell when it its EpCAM+ (i.e., it is captured), CK+, DAPI+ and CD45-. A check mark placed by the operator next to the composite images classifies the event as a Circulating Tumor Cell (CTC) and the software tallies all the checked boxes to obtain the CTC count.
Our data demonstrate that metastatic breast cancer patients with 5 or more CTC/per 7.5 mL of blood have a significantly greater probability for shorter progression free and overall survival than patients who have fewer than 5 CTC per 7.5 mL of blood.
Response:
1. Table of Acceptance Criteria and Reported Device Performance
| Test | Acceptance Criteria (Predicate Device K031588 Performance) | Reported Device Performance (CellSearch™ Circulating Tumor Cell Kit K050245) |
|---|---|---|
| Non-Clinical Studies | ||
| Recovery | Slope of 0.85, intercept of 5.6, r=0.997 | Regression equation: Y=0.93x + 3.87, R²=0.999 (93% recovery) |
| Linearity/Reportable Range | Slope of 0.99, intercept of 5.7, r²=0.99 over 4 to 1022 CTCs | Slope of 1.007, intercept of 3.0, r=0.99, r²=0.995 over 0 to 1238 CTCs |
| Limits of Detection | 1.28 cells sensitivity | Approximately 1 cell in the sample chamber (effective 1 CTC per 7.5 mL blood) |
| Reproducibility (Control Samples) | Total %CV of 9.4% (high control, mean 258); 15.8% (low control, mean 47) | Total %CV of 5% (high control, mean 969); 18% (low control, mean 48) |
| System Reproducibility (Patient Specimens) | N/A (Comparison to predicate device's preclinical study, not patient data) | Regression equation: Y=0.98x + 0.67, R²=0.9978 (n=163 duplicates) for patient samples |
| Interfering Substances | No interference stated for predicate (implied through substantial equivalence) | No significant differences with various cancer/OTC drugs, Intralipid, hemolysis, icterus, HAMA. Doxorubicin caused aberrant staining, but identifiable. |
| Clinical Studies | ||
| Expected Values (Control Subjects) | N/A (New device establishes its own expected values) | 1 out of 345 healthy subjects/non-malignant disease patients had >5 CTC/7.5 mL |
| Progression-Free Survival (PFS) - Baseline CTC | N/A (New device establishes its own clinical correlation) | Median PFS 30.3 weeks for 80 weeks for 80 weeks for |
§ 866.6020 Immunomagnetic circulating cancer cell selection and enumeration system.
(a)
Identification. An immunomagnetic circulating cancer cell selection and enumeration system is a device that consists of biological probes, fluorochromes, and other reagents; preservation and preparation devices; and a semiautomated analytical instrument to select and count circulating cancer cells in a prepared sample of whole blood. This device is intended for adjunctive use in monitoring or predicting cancer disease progression, response to therapy, and for the detection of recurrent disease.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Immunomagnetic Circulating Cancer Cell Selection and Enumeration System.” See § 866.1(e) for availability of this guidance document.