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Background
- CTCs are cells shed from primary tumor and circulate in blood.
- Detection and analysis of CTCs can be used to help guide treatment decisions, evaluate treatment response, and assess residual and recurrent disease.
- Elevated or increasing CTCs may indicate progression and survival outcomes.
- Biocept technology platform allows for CTC enumeration and biomarker characterization.
Circulating Tumor Cells (CTCs) Demonstrate Prediction of Survival
mPC Patients with less than 5 CTCs survived almost twice as long as patients with 5 or more CTCs.1
CTCs may help identify patients that are not benefiting from treatment; CTC increase during first 12 weeks of treatment are associated with worse overall survival, regardless of therapy.2
Preliminary data suggests, decrease in CTCs to zero at week 13 is a stronger indicator of longer term OS than the more widely used PSA50 and serves as a reasonably likely surrogate for OS in clinical trials.3
Biomarker Status of CTCs Provide Insights for Treatment Decisions
CTCs obtained through the Biocept platform can be used to characterize biomarkers on tumor cells and evaluate changes in protein expression with similar techniques done in tissue. Two important biomarkers in prostate cancer are AR-V7 and PTEN.
Patients with AR-V7 positive CTC, survived longer on taxanes. Patients with AR-V7 negative CTC, survived longer on ARS Inhibitors.4
Changes in AR-V7 status during treatment with AR-directed therapies and taxane chemotherapies.5 Patients’ AR-V7 status may change over time with therapy.6 Serial monitoring may be helpful.
Patients with PTEN loss had much shorter survival time.6
How Does it Work?
A liquid biopsy from Biocept is a fast, easy way to establish biomarker status.
Step 1: Order a Biocept blood test. Your patient can get their blood drawn the same day, at any lab. Please contact customer service for Biocept Collection Kit supplies.
Step 2: The sample is sent via Fed-Ex to the Biocept lab. Our CLIA-certified, CAP-accredited lab isolates cancer cells and DNA fragments and uses analytically and clinically validated reagents to look for standard, clinically relevant biomarkers.
Step 3: Biocept will provide your physician the results within 3-5 days for CTC detection, and may require 2-5 days more for additional biomarker testing when the sample is received into our laboratory. In most instances this is faster than results performed on tissue, with the benefit of not having a surgical procedure.
Who pays for a liquid biopsy? Biocept accepts all insurance and will bill on behalf of the patient. In addition, Biocept has a Financial Assistance Program (see Billing Policy), with payment plans available based on the patient’s financial situation. We are committed to excellence and are here to assist with any questions or concerns you may have. Please call 888.332.7729 M-F from 8-5 Pacific Time to discuss individual claims and policies.
References
- de Bono JS, et al. Circulating Tumor Cells Predict Survival Benefit from Treatment In Metastatic Castration-Resistant Prostate Cancer. Clin Cancer Res 2008; 14: 6302–6309.
- Lorente D, et al. Circulating Tumour Cell Increase as a Biomarker of Disease Progression in Metastatic Castration-Resistant Prostate Cancer Patients with Low Baseline CTC Counts. Ann Oncol 2018; 29:1554-1560.
- Scher, H, et al. Assessment Of Circulating Tumor Cell Number as a Transitional Surrogate Endpoint for Survival in Phase II Trials for Metastatic Castration-Resistant Prostate Cancer. J Clin Oncol 37, 2019 (suppl 7S; abstr 143).
- Sher, H, et al. Assessment of the Validity of Nuclear-Localized Androgen Receptor Splice Variant 7 in Circulating Tumor Cells as a Predictive Biomarker for Castration- Resistant Prostate Cancer. JAMA Oncology 2018; 4(9):1179-1186.
- Nakazawa, M, et al. Serial Blood-Based Analysis of AR-V7 in Men with Advanced Prostate Cancer. Ann Oncol 2015; 26:1859-1865.
- Punnoose, E, et al. PTEN Loss in Circulating Tumour Cells Correlates with PTEN Loss in Fresh Tumour Tissue from Castration-Resistant Prostate Cancer Patients. British Journal of Cancer 2015; 113:1225-1233.