Circulating tumor cell analysis in metastatic triple-negative breast cancers

Area of Science:

• Oncology
• Biomarker Discovery
• Translational Research

Background:

• Rare-cell technologies have advanced, enabling detection, enumeration, and genomic profiling of circulating tumor cells (CTCs).
• Accurate enumeration of CTCs is crucial for monitoring treatment response and predicting outcomes in metastatic cancers.

Purpose of the Study:

• To evaluate and compare two distinct methods for enumerating CTCs in patients with metastatic triple-negative breast cancer (TNBC).
• To assess the correlation of CTC counts with treatment outcomes, including time-to-progression (TTP) and overall survival (OS).

Main Methods:

• Prospective evaluation of the CellSearch system (FDA-cleared) and an immunomagnetic enrichment/flow cytometry method (IE/FC) for CTC enumeration.
• Blood samples from patients with metastatic TNBC were analyzed at baseline and 7-14 days post-therapy initiation (cetuximab ± carboplatin) in a phase II trial.
• Correlation analysis between CTC counts from both methods and clinical endpoints (TTP, OS).

Main Results:

• CTC enumeration by CellSearch and IE/FC methods showed significant correlation at baseline (r=0.62) and post-therapy (r=0.53).
• While baseline CTCs did not correlate with TTP, post-therapy CTCs were significantly associated with TTP for both assays (P=0.02-0.03).
• CTCs at both time points were significantly correlated with OS (P<0.0001-0.0086) for both methods.

Conclusions:

• CTC enumeration using CellSearch and IE/FC assays demonstrated high concordance in patients with metastatic TNBC.
• Both assays provided prognostic information, correlating significantly with TTP and OS.
• The IE/FC method offers the additional advantage of isolating viable CTCs for downstream genomic profiling.