3104 - Novel Blood Based Circulating Tumor Cell Biomarker For Breast Cancer Detection

Background

There is an unmet need for a blood test to detect breast cancer in women with dense breast tissue or clinically aggressive subtypes that may be missed by mammograms. Cell-free DNA in blood has shown 15-58% sensitivity for breast cancer. We evaluated the performance of a circulating tumor cell (CTC) assay as a complimentary biomarker for detecting breast cancer in an Asian population, which has high incidence of dense breast tissue.

Methods

A single-center, IRB-approved, prospective and blinded clinical study was conducted on 114 Taiwanese females with biopsy-confirmed breast cancer, and 50 healthy controls confirmed by ultrasound or mammogram. Four milliliter of blood was collected prior to imaging and processed using the CellMax biomimetic platform (CMx) which enumerates CTCs utilizing selection criteria based on a set of markers (cytokeratin 18, mammaglobin, CD45), cell morphometry (size, N/C ratio) and nucleus morphology. Logistic regression models for CMx CTC counts and patient age were used to assess the classification performance of the CMx test.

Results

Of the 114 cancer (80% were stage 0∼2), the subtypes were confirmed for 102 (62% ER/PR+ HER2-, 22% HER2+, 16% TNBC). CTC count was a significant predictor of cancer status (Likelihood Ratio P-value = 0.0001). At 90% specificity (exact 95% CI: 78.2%, 95.6%) sensitivity was 56.3% (95% CI: 43.3%, 68.6%) for the most common subtype ER/PR+HER2-, 36.4% (17.2%-59.3%) for HER2+, 43.8% (19.8%- 70.1%) for TNBC, 46.5% (37.1%- 56.1%) overall. Sensitivity was 62.5% (35.4%- 84.8%) for late stage (Stage III/IV cancer) and 43.5% (33.2%- 54.2%) for early stage (Stage 0, I or II cancer) patients. In the subset of 41 individuals with an indeterminate classification of BIRADS 3 (likely benign) or BIRADS 4 (likely malignant) sensitivity was 90% and specificity was 47.6% (95% CI: 25.7%, 70.2%).

Conclusions

In this initial study, CTC was a significant predictor of cancer. The CTC assay can easily be combined with cfDNA to enhance detection rates. Proof-of-concept data suggests potential for a rule out test to avoid unnecessary follow-up/biopsies in BIRADS 3/4 patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

CellMax Life.

Funding

CellMax Life.

Disclosure

F. Lin: Shareholder / Stockholder / Stock options: CellMax Life. J. Wu: Shareholder / Stockholder / Stock options: CellMax Life. H.B. Hsieh: Shareholder / Stockholder / Stock options: CellMax Life. S. Chang: Shareholder / Stockholder / Stock options: CellMax Life. M. Javey: Shareholder / Stockholder / Stock options: CellMax Life. D. Watson: Shareholder / Stockholder / Stock options: CellMax Life. R. Mei: Shareholder / Stockholder / Stock options: CellMax Life. All other authors have declared no conflicts of interest.