Biomarkers of minimal residual disease and treatment

Minimal residual disease (MRD) has been defined as a very small numbers of cancer cells that remain in the body after curative treatment. Its presence or absence will ultimately determine prognosis. With the introduction of new technologies the presence of MRD in patients with solid tumours can be detected and characterized. As MRD predicts future relapse, be it early or late treatment failure, in an otherwise asymptomatic patient its treatment and when to start treatment remains to be determined. Thus the concepts of personalized medicine using different biomarkers to classify the biological properties of MRD maybe come possible. Based on this determinations it may be possible to use targeted therapies rather than all patients with the same type of cancer receiving a standard treatment. However, it is important to understand the limitations of the different technologies, what these techniques are detecting and how they may help in the treatment of patients with cancer. The majority of published studies are in patients with metastatic cancer and there are few reports in patients with MRD. In this chapter the concept of MRD, the methods used to detect it and what treatments may be effective based on the biological characteristics of the tumour cells as determined by different biomarkers is reviewed. MRD depends on the phenotypic properties of the tumour cells to survive in their new environment and the anti-tumour immune response. This is a dynamic process and changes with time in the wake of immunosuppression caused by the tumour cells and/or the effects of treatment to select resistant tumour cells. With the use of biomarkers to typify the characteristics of MRD and the development of new drugs a personalized treatment can be designed rather than all patients given the same treatment. Patients who are initially negative for MRD may not require further treatment with liquid biopsies used to monitor the patients during follow-up in order to detect those patients who may become MRD positive. The liquid biopsy used during the follow up of MRD positive patients can be used to detect changes in the biological properties of the tumour cells and thus may need treatment changes to overcome tumour cell resistance.

Circulating tumor cells in peripheral blood as a diagnostic biomarker of breast cancer: A meta-analysis

Purpose

Studies have reported that breast cancer (BC) patients' circulating tumor cells (CTCs) have varying results for their diagnostic role. Thus, we conducted a meta-analysis to systematically assess the accuracy of CTCs in the diagnosis of BC.

Methods

A meta-analysis was conducted to evaluate the overall accuracy of CTC detection. A pooled analysis of sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic advantage ratio (DOR) was used to measure diagnostic accuracy. In addition, the area under the summary receiver operating characteristic curve (AUC) was used to discriminate BC from non-BC. An analysis of the threshold effect was calculated using the Spearman correlation coefficient. We calculated the Q and I2 statistics to determine whether the studies were heterogeneous. Sensitivity analysis was performed by removing studies one by one. Publication bias was assessed by Deeks' funnel plot asymmetry test.

Results

Studies from the PubMed, Cochrane Library, Embase, Web of Science, Wanfang, Vip, and CNKI databases were collected for diagnosing BC from January 2000 to April March 2023. Finally, 8 publications were retrieved in total containing 2014 cases involved in the study. Based on a random-effects model, it was found that the pooled SEN was 0.69 (0.55 - 0.80), SPE was 0.93 (0.60 - 0.99), PLR was 9.5 (1.4 - 65.9), NLR was 0.33 (0.23 - 0.48), DOR was 29 (4 - 205) and the AUC of the summary receiver operating characteristic (SROC) curve was 0.81 (0.77 - 0.84). Some heterogeneity was found in the article, but there was no threshold effect to account for it (P = 0.27). Deek's funnel plot asymmetry test indicated that no publication bias was observed in this meta-analysis (P = 0.52).

Conclusion

The results of this meta-analysis confirmed that CTCs were an important component of noninvasive methods of confirming BC with SEN of 0.69 (0.55 - 0.80), SPE of 0.93 (0.60 - 0.99) and AUC of 0.81 (0.77 - 0.84).

Bioplatforms in liquid biopsy: advances in the techniques for isolation, characterization and clinical applications

Tissue biopsy analysis has conventionally been the gold standard for cancer prognosis, diagnosis and prediction of responses/resistances to treatments. The existing biopsy procedures used in clinical practice are, however, invasive, painful and often associated with pitfalls like poor recovery of tumor cells and infeasibility for repetition in single patients. To circumvent these limitations, alternative non-invasive, rapid and economical, yet sturdy, consistent and dependable, biopsy techniques are required. Liquid biopsy is an emerging technology that fulfills these criteria and potentially much more in terms of subject-specific real-time monitoring of cancer progression, determination of tumor heterogeneity and treatment responses, and specific identification of the type and stages of cancers. The present review first briefly revisits the state-of-the-art technique of liquid biopsy and then proceeds to address in detail, the advances in the potential clinical applications of four major biological agencies present in liquid biopsy samples (circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), exosomes and tumor-educated platelets (TEPs)). Finally, the authors conclude with the limitations that need to be addressed in order for liquid biopsy to effectively replace the conventional invasive biopsy methods in the clinical settings.

Analytical validation of the CellMax platform for early detection of cancer by enumeration of rare circulating tumor cells

The CellMax (CMx®) platform was developed to enrich for epithelial circulating tumor cells (CTCs) in the whole blood. This report provides assay performance data, including accuracy, linearity, limit of blank, limit of detection (LOD), specificity, and precision of enumeration of cancer cell line cells (CLCs) spiked in cell culture medium or healthy donor blood samples. Additionally, assay specificity was demonstrated in 32 young healthy donors and clinical feasibility was demonstrated in a cohort of 47 subjects consisting of healthy donors and patients who were colonoscopy verified to have colorectal cancer, adenomas, or a negative result. The CMx platform demonstrated high accuracy, linearity, and sensitivity for the enumeration of all CLC concentrations tested, including the extremely low range of 1 to 10 cells in 2 mL of blood, which is most relevant for early cancer detection. Theoretically, the assay LOD is 0.71 CTCs in 2 mL of blood. The analytical specificity was 100% demonstrated using 32 young healthy donor samples. We also demonstrated precision across multiple days and multiple operators, with good reproducibility of recovery efficiency. In a clinical feasibility study, the CMx platform identified 8 of 10 diseased subjects as positive (80% clinical sensitivity) and 4 of 5 controls as negative (80% clinical specificity). We also compared processing time and transportation effects for similar blood samples from two different sites and assessed an artificial intelligence-based counting method. Finally, unlike other platforms for which captured CTCs are retained on ferromagnetic beads or tethered to the slide surface, the CMx platform's unique airfoam-enabled release of CTCs allows captured cells to be transferred from a microfluidic chip to an Eppendorf tube, enabling a seamless transition to downstream applications such as genetic analyses and live cell manipulations.

Application of Circulation Tumor Cells Detection in Diagnosis and Treatment of Breast Tumors

In recent years, the clinical application of circulating tumor cell (CTCs) detection has become one of the research hotspots in the field of precision medicine. CTCs detection is noninvasive, easy to obtain, can be repeatedly collected, and highly repeatable with other advantages. It not only can be a real-time comprehensive monitoring of cancer treatment but also can have a large number of applications, including early diagnosis of tumor, timely evaluation of efficacy, condition monitoring, resistance factor analysis, prognosis judgment, individualized treatment of tumors, drug guidance, and so on. At present, many large-scale clinical studies at home and abroad run through all stages of breast cancer diagnosis and treatment. For different treatment stages of breast cancer, the application value of CTCs detection is different. Compared with traditional detection methods, CTCs have advantages in dynamic monitoring of disease changes and efficacy evaluation in real-time. In the era of breast cancer classificational and individualized treatment, CTCs detection can provide patients with the most timely and optimized treatment plan.

Circulating Tumor Cells: Applications in Cytopathology

Circulating tumor cells (CTCs) are rare tumor cells found in the blood of patients with cancer that can be reliably detected by CTC technologies to provide prognostic, predictive, and diagnostic information. CTC sampling reflects intratumoral and intertumoral heterogeneity better than targeted biopsy. CTC samples are minimally invasive and amenable to repeated sampling, allowing real-time evaluation of tumor in response to therapy-related pressures and possibly early detection. Cytology is the most natural arena for integration of CTC testing. CTC technology may also be deployed to enhance and facilitate the practice of cytology and surgical pathology.

Molecular analysis of circulating tumors cells: Biomarkers beyond enumeration

Advances in our molecular understanding of cancer biology have paved the way to an expanding compendium of molecularly-targeted therapies, accompanied by the urgent need for biomarkers that enable the precise selection of the most appropriate therapies for individual cancer patients. Circulating biomarkers such as circulating tumor cells (CTCs) are poised to fill this need, since they are "liquid biopsies" that can be performed non-invasively and serially, and may capture the spectrum of spatial and temporal tumor heterogeneity better than conventional tissue biopsies. Increasing evidence suggests that moving beyond the enumeration of CTCs towards more sophisticated molecular analyses can provide actionable data that may predict and potentially improve clinical outcomes. In this review, we discuss the potential of molecular CTC analyses to serve as prognostic and predictive biomarkers to guide cancer therapy and early cancer detection. As technologies to capture and analyze CTCs continue to increase in sophistication, we anticipate that the potential clinical applications of CTCs will grow exponentially in the coming years.

Characterization of circulating tumor cells in newly diagnosed breast cancer

Identification of circulating tumor cells (CTCs) by surface marker expression and ploidy analysis [immunostaining-fluorescence in situ hybridization (iFISH)] has been shown to be a highly sensitive method in the identification of certain solid cancers. In the present study, iFISH analysis was performed to identify CTCs in 184 patients with newly diagnosed non-metastatic breast cancer, and the distribution of CTC subtypes was characterized based on cytokeratin (CK) expression and ploidy status. It was revealed that CTCs of non-metastatic, aneuploid breast cancers, independent of CK expression profile, can be detected with high sensitivity (90.76%) by the iFISH system. Higher CTC counts and sensitivity were observed in patients with increased tumor size burden and unfavorable hormone receptor status. Investigation of CTC subtypes based on ploidy analysis indicated that triploid CTCs constituted the majority of CTCs evaluated. While CK-positive CTCs were detected in a small cohort of patients, an overall low rate of CK expression was observed in the 18 patient samples evaluated. Of note, CK expression was rare in CTCs detected in patients with Herceptin 2 (Her2)-positive or triple-negative [estrogen receptor (ER)-, progesterone receptor (PR)- and Her2-negative], indicating that lack of ER and PR may result in promotion of epithelial-mesenchymal transition and enhancement of tumor aggression.

Circulating tumor cells and microemboli can differentiate malignant and benign pulmonary lesions

The presence of circulating tumor cells (CTC) or microemboli (CTM) in the peripheral blood can theoretically anticipate malignancy of solid lesions in a variety of organs. We aimed to preliminarily assess this capability in patients with pulmonary lesions of suspected malignant nature.

We used a cell-size filtration method (ScreenCell) and cytomorphometric criteria to detect CTC/CTM in a 3 mL sample of peripheral blood that was taken just before diagnostic percutaneous CT-guided fine needle aspiration (FNA) or core biopsy of the suspicious lung lesion.

At least one CTC/CTM was found in 47 of 67 (70%) patients with final diagnoses of lung malignancy and in none of 8 patients with benign pulmonary nodules. In particular they were detected in 38 (69%) of 55 primary lung cancers and in 9 (75%) of 12 lung metastases from extra-pulmonary cancers. Sensitivity of CTC/CTM presence for malignancy was 70.1% (95%CI: 56.9-83.1%), specificity 100%, positive predictive value 100% and negative predictive value 28.6% (95%CI: 11.9-45.3%). Remarkably, the presence of CTC/CTM anticipated the diagnosis of primary lung cancer in 3 of 5 patients with non-diagnostic or inconclusive results of FNA or core biopsy, whereas CTC/CTM were not observed in 1 patient with sarcoidosis and 1 with amarthocondroma.

These results suggest that presently, due to the low sensitivity, the search of CTC/CTM cannot replace CT guided percutaneous FNA or core biopsy in the diagnostic work-up of patients with suspicious malignant lung lesions. However, the high specificity may as yet indicate a role in cases with non-diagnostic or inconclusive FNA or core biopsy results that warrants to be further investigated.

Liquid Biopsy for Cancer: Circulating Tumor Cells, Circulating Free DNA or Exosomes?

Precision medicine and personalized medicine are based on the development of biomarkers, and liquid biopsy has been reported to be able to detect biomarkers that carry information on tumor development and progression. Compared with traditional 'solid biopsy', which cannot always be performed to determine tumor dynamics, liquid biopsy has notable advantages in that it is a noninvasive modality that can provide diagnostic and prognostic information prior to treatment, during treatment and during progression. In this review, we describe the source, characteristics, technology for detection and current situation of circulating tumor cells, circulating free DNA and exosomes used for diagnosis, recurrence monitoring, prognosis assessment and medication planning.

The promise of circulating tumor cells for precision cancer therapy

The rapidly growing array of therapeutic options in cancer requires informative biomarkers to guide the rational selection and precision application of appropriate therapies. Circulating biomarkers such as circulating tumor cells have immense potential as noninvasive, serial 'liquid biopsies' that may be more representative of the complete spectrum of a patient's individual malignancy than spatially and temporally restricted tumor biopsies. In this review, we discuss the current state-of-the-art in the isolation and molecular characterization of circulating tumor cells as well as their utility in a wide range of clinical applications such as prognostics, treatment monitoring and identification of novel therapeutic targets and resistance mechanisms to enable real-time adjustments in the clinical management of cancer.