Liquid Biopsy in Metastatic Breast Cancer: Current Role of Circulating Tumor Cells and Circulating Tumor DNA

Monitoring response to neoadjuvant chemotherapy in triple negative breast cancer using circulating tumor DNA

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive subtype with poor prognosis. We aimed to determine whether circulating tumor DNA (ctDNA) and circulating tumor cell (CTC) could predict response and long-term outcomes to neoadjuvant chemotherapy (NAC).

METHODS

Patients with TNBC were enrolled between 2017-2021 at The University of Texas MD Anderson Cancer Center (Houston, TX). Serial plasma samples were collected at four timepoints: pre-NAC (baseline), 12-weeks after NAC (mid-NAC), after NAC/prior to surgery (post-NAC), and one-year after surgery. ctDNA was quantified using a tumor-informed ctDNA assay (SignateraTM, Natera, Inc.) and CTC enumeration using CellSearch. Wilcoxon and Fisher's exact tests were used for comparisons between groups and Kaplan-Meier analysis used for survival outcomes.

RESULTS

In total, 37 patients were enrolled. The mean age was 50 and majority of patients had invasive ductal carcinoma (34, 91.9%) with clinical T2, (25, 67.6%) node-negative disease (21, 56.8%). Baseline ctDNA was detected in 90% (27/30) of patients, of whom 70.4% (19/27) achieved ctDNA clearance by mid-NAC. ctDNA clearance at mid-NAC was significantly associated with pathologic complete response (p = 0.02), whereas CTC clearance was not (p = 0.52). There were no differences in overall survival (OS) and recurrence-free survival (RFS) with positive baseline ctDNA and CTC. However, positive ctDNA at mid-NAC was significantly associated with worse OS and RFS (p = 0.0002 and p = 0.0034, respectively).

CONCLUSIONS

Early clearance of ctDNA served as a predictive and prognostic marker in TNBC. Personalized ctDNA monitoring during NAC may help predict response and guide treatment.

Correlation between plasma ccfDNA, mtDNA changes, CTCs, and epithelial-mesenchymal transition in breast cancer patients undergoing NACT

Background/aim

Breast cancer is the most prevalent cancer in women, emphasizing need for noninvasive blood biomarkers to aid in treatment selection. Previous studies have demonstrated elevated levels of plasma circulating cell-free DNA (ccfDNA) in breast cancer patients. Both ccfDNA and mitochondrial DNA (mtDNA) are fragments released into the bloodstream. In this study, we investigated effectiveness of ccfDNA and mtDNA as indicators of treatment response and explored their potential as monitoring biomarkers. Additionally, we compared these markers with circulating tumor cell (CTC) data and assessed their relationship with epithelial-mesenchymal transition (EMT).

Materials and methods

Thirty-six female breast cancer patients and 21 healthy females were included in the study. Quantitative polymerase chain reaction (qPCR) was performed on plasma samples to measure levels of ND1, ND4, ALU115, ALU247, and GAPDH, and DNA integrity was determined by calculating ratios of ALU247/ALU115 and ND4/ND1.

Results

After treatment, patients had a significant decrease in ccfDNA levels and a significant increase in mtDNA copy number (mtDNAcn). However, there was no significant change in ccfDNA and mtDNA integrity. When comparing all groups, patients exhibited higher levels of ALU115 and ALU247 compared to controls. Moreover, patients demonstrated significantly lower ccfDNA integrity than controls.

Conclusion

This study represents the first comprehensive investigation of plasma ccfDNA levels, mtDNAcn, and integrities collectively. Furthermore, it is the first study to explore the relationship between these markers and CTCs, cancer stem cell markers, treatment response, and metastatic status. Our findings suggest that plasma ccfDNA and mtDNA may serve as potential biomarkers for assessing chemotherapy response and can be employed alone or in combination with other biomarkers to monitor treatment efficacy in breast cancer patients.

Applications of Liquid Biopsy for Surgical Patients With Cancer: A Review

Importance

Liquid biopsy is an emerging tool with the potential to change oncologic care practices. Optimal clinical applications for its use are currently undefined for surgical patients.

Observations

Liquid biopsy analytes such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have been the most clinically studied assays and were initially limited to advanced-stage disease. In the metastatic setting, CTCs and ctDNA levels are prognostic. Although their levels correlate with treatment response, CTC-guided systemic regimen switches for nonresponders have not been shown to improve clinical outcomes. ctDNA genomic profiling has succeeded, and there are now multiple plasma-based assays approved by the US Food and Drug Administration that can detect actionable mutations to guide systemic therapy. Technological advancements in assay sensitivity have expanded the use of ctDNA to early-stage and resectable disease, allowing for detection of minimal residual disease. Postoperative ctDNA levels are a strong predictor of disease recurrence, and ctDNA detection often precedes serum carcinoembryonic antigen elevation and radiographic changes. However, its use for surveillance has not been shown to improve clinical outcomes. A promising application of ctDNA is for adjuvant therapy escalation and de-escalation. A phase 2 clinical trial demonstrated that treatment de-escalation for patients with high-risk stage II colorectal cancer and negative postoperative ctDNA had similar recurrence-free survival as patients receiving standard-of-care chemotherapy. These results suggest that ctDNA may help select patients who will benefit from adjuvant chemotherapy, and multiple clinical trials are actively underway.

Conclusions and Relevance

Although uncertainties regarding the optimal use of liquid biopsy remain, it has the potential to significantly improve care for patients with cancer at all stages of disease. It is critical that surgeons understand how to use and interpret these assays, and they should be active participants in clinical trials to advance the field.

Biology of breast cancer brain metastases and novel therapies targeting the blood brain barrier: an updated review

Brain metastasis (BM) is a critical cause of morbidity and mortality in patients with breast cancer (BC). Compared with other cancer cells, BC cells (BCs) exhibit special features in the metastatic process. However, the underlying mechanisms are still unclear, especially the crosstalk between tumour cells and the microenvironment. To date, novel therapies for BM, including targeted therapy and antibody‒drug conjugates, have been developed. Due to an improved understanding of the blood‒brain barrier (BBB) and blood-tumour barrier (BTB), the development and testing of therapeutic agents in clinical phases have substantially increased. However, these therapies face a major challenge due to the low penetration of the BBB or BTB. As a result, researchers have increasingly focused on finding ways to promote drug penetration through these barriers. This review provides an updated overview of breast cancer brain metastases (BCBM) and summarizes the newly developed therapies for BCBM, especially drugs targeting the BBB or BTB.

Oncotherapeutic Strategies in Early Onset Colorectal Cancer

Early onset colorectal cancer (EOCRC), defined as colorectal cancers in patients aged less than 50 years, is becoming an increasingly common issue, globally. Since 1994, the incidence of this condition has been rising by 2% annually. Approximately one in five patients under 50 years of age diagnosed with colorectal cancer have an underlying genetic predisposition syndrome. The detection of cancer among the other 80% of patients poses a considerable task, as there is no family history to advocate for commencing early screening in this group. Patients with EOCRC have distinct social, spiritual, fertility, and financial needs from their older counterparts that need to be addressed. This review discusses the risk factors associated with the development of EOCRC and current best practice for the management of this disease.

The Role of Cell-Free DNA in Cancer Treatment Decision Making

The aim of this review is to evaluate the present status of the use of cell-free DNA and its fraction of circulating tumor DNA (ctDNA) because this year July 2022, an ESMO guideline was published regarding the application of ctDNA in patient care. This review is for clinical oncologists to explain the concept, the terms used, the pros and cons of ctDNA; thus, the technical aspects of the different platforms are not reviewed in detail, but we try to help in navigating the current knowledge in liquid biopsy. Since the validated and adequately sensitive ctDNA assays have utility in identifying actionable mutations to direct targeted therapy, ctDNA may be used for this soon in routine clinical practice and in other different areas as well. The cfDNA fragments can be obtained by liquid biopsy and can be used for diagnosis, prognosis, and selecting among treatment options in cancer patients. A great proportion of cfDNA comes from normal cells of the body or from food uptake. Only a small part (<1%) of it is related to tumors, originating from primary tumors, metastatic sites, or circulating tumor cells (CTCs). Soon the data obtained from ctDNA may routinely be used for finding minimal residual disease, detecting relapse, and determining the sites of metastases. It might also be used for deciding appropriate therapy, and/or emerging resistance to the therapy and the data analysis of ctDNA may be combined with imaging or other markers. However, to achieve this goal, further clinical validations are inevitable. As a result, clinicians should be aware of the limitations of the assays. Of course, several open questions are still under research and because of it cfDNA and ctDNA testing are not part of routine care yet.

Detection of Circulating Tumor Cells in Cerebrospinal Fluid of Patients with Suspected Breast Cancer Leptomeningeal Metastases: A Prospective Study

BACKGROUND

The diagnosis of breast cancer (BC)-related leptomeningeal metastases (LM) relies on the detection of tumor cells in cerebrospinal fluid (CSF) using conventional cytology (gold standard). However, the sensitivity of this technique is low. Our goal was to evaluate whether circulating tumor cell (CTC) detection in CSF using the CellSearch® system could be used for LM diagnosis.

METHODS

This prospective, monocentric study included adult patients with suspected BC-related LM. The clinical sensitivity and specificity of CTC detection in CSF for LM diagnosis were calculated relative to conventional CSF cytology.

RESULTS

Forty-nine eligible patients were included and 40 were evaluable (CTC detection technical failure: n = 8, eligibility criteria failure: n = 1). Cytology was positive in 18/40 patients. CTCs were detected in these 18 patients (median: 5824 CTC, range: 93 to 45052) and in 5/22 patients with negative cytology (median: 2 CTC, range: 1 to 44). The detection of ≥1 CSF CTC was associated with a clinical sensitivity of 100% (95% CI, 82.4-100) and a specificity of 77.3% (95% CI, 64.3-90.3) for LM diagnosis. HER2+ CTCs were detected in the CSF of 40.6% of patients with HER2- BC (median: 500 CTC, range: 13 to 28 320).

CONCLUSIONS

The clinical sensitivity of CTC detection in CSF with the CellSearch® system for LM diagnosis is higher than that of CSF cytology. CTC detection in patients with negative cytology, however, must be further investigated. The finding of HER2+ CTCs in patients with HER2- BC suggests that the HER2 status of LM should be evaluated to increase the treatment opportunities for these patients.

Potential utility of miRNAs for liquid biopsy in breast cancer

Breast cancer (BC) remains the most prevalent malignancy due to its incidence rate, recurrence, and metastasis in women. Conventional strategies of cancer detection– mammography and tissue biopsy lack the capacity to detect the complete cancer genomic landscape. Besides, they often give false- positive or negative results. The presence of this and other disadvantages such as invasiveness, high-cost, and side effects necessitates developing new strategies to overcome the BC burden. Liquid biopsy (LB) has been brought to the fore owing to its early detection, screening, prognosis, simplicity of the technique, and efficient monitoring. Remarkably, microRNAs (miRNAs)– gene expression regulators seem to play a major role as biomarkers detected in the samples of LB. Particularly, miR-21 and miR-155 among other possible candidates seem to serve as favorable biomarkers in the diagnosis and prognosis of BC. Hence, this review will assess the potential utility of miRNAs as biomarkers and will highlight certain promising candidates for the LB approach in the diagnosis and management of BC that may optimize the patient outcome.

Comparison of sample preparation methods for rare cell isolation in microfluidic devices

The analysis of circulating tumor cells (CTCs) is important for cancer diagnosis and prognosis. Microfluidics has been employed for CTC analysis due to its scaling advantages and high performance. However, pre-analytical methods for CTC sample preparation are often combined with microfluidic platforms because a large sample volume is required to detect extremely rare CTCs. Among pre-analytical methods, Ficoll-Paque™, OncoQuick™, and RosetteSep™ are commonly used to separate cells of interest. To compare their performance, we spiked L3.6pl pancreatic cancer cells into healthy blood samples and then employed each technique to prepare blood samples, followed by using a microfluidic platform to capture and detect L3.6pl cells. We found these three methods have similar performance, though the slight edge of RosetteSep™ over Ficoll-Paque™ is statistically significant. We also studied the effects of the tumor cell concentrations on the performance of the frequently used Ficoll-Paque™ method. Furthermore, we examined the repeatability and variability of each pre-analytical technique and the microfluidics-enabled detection. This study will provide researchers and clinicians with comparative data that can influence the choice of sample preparation method, help estimate CTC loss in each pre-analytical method, and correlate the results of clinical studies that employ different techniques.