Circulating Tumor Cells and Circulating Tumor DNA Detection in Potentially Resectable Metastatic Colorectal Cancer: A Prospective Ancillary Study to the Unicancer Prodige-14 Trial

Gravity-based microfiltration reveals unexpected prevalence of circulating tumor cell clusters in ovarian and colorectal cancer

BACKGROUND

Circulating tumor cells (CTCs) are rare (a few cells per milliliter of blood) and mostly isolated as single-cell CTCs (scCTCs). CTC clusters (cCTCs), even rarer, are of growing interest, notably because of their higher metastatic potential, but very difficult to isolate.

METHOD

We introduce gravity-based microfiltration (GµF) for facile isolation of cCTCs using in-house fabricated microfilters and 3D printed cartridges. Optimal flow rate and pore size for cCTC isolation are determined by GµF of cultured ovarian single cells and cell clusters spiked in healthy blood. We perform GµF of blood from orthotopic ovarian cancer mouse models and characterize the morphological features of scCTCs and cCTCs, and the expression of molecular markers for aggressiveness. Finally, we analyze blood from 17 epithelial ovarian cancer patients with either localized or metastatic disease, and from 13 colorectal cancer liver metastasis patients.

RESULTS

Here, we show that GµF optimized for cell cluster isolation captures cCTCs from blood while minimizing unwanted cluster disaggregation, with ~85% capture efficiency. We detect cCTCs in every patient, with between 2-100+ cells. We find cCTCs represent between 5-30% of all CTC capture events, and 10-80% of the CTCs are clustered; remarkably, in 10 patients, most CTCs are circulating not as scCTCs, but as cCTCs.

CONCLUSIONS

GµF uncovers the unexpected prevalence and frequency of cCTCs including sometimes very large ones in epithelial ovarian cancer patients, and motivates additional studies to uncover their properties and role in disease progression.

A prospective study of methylated ctDNA in patients undergoing treatment for liver metastases from colorectal cancer

BACKGROUND

Decision regarding local treatment of colorectal liver metastases (CRLM) is a multidisciplinary assessment, and liver intervention should be performed when the metastases are deemed resectable. There is no standard biomarker to aid neither this decision nor the postoperative treatment decisions. The present prospective, observational study aimed to investigate the potential clinical utility of a combined tumor-specific and organ-specific methylated circulating DNA assay in the perioperative setting of CRLM.

MATERIAL AND METHODS

The study included 56 cases with CRLM. Blood samples were drawn preoperatively and postoperatively. Multiplex methylation analysis of the markers NPY, KANK1, and GAL3ST3 (meth-ctDNA) was performed using droplet digital PCR.

RESULTS

The assay detected preoperative and postoperative meth-ctDNA in 37 % and 46 % of patients, respectively. Patients with negative preoperative meth-ctDNA had a longer median PFS compared to those with positive preoperative meth-ctDNA (HR = 2.2, 95 % CI 1.2-3.9, p < 0.01). In a multivariate analysis, preoperative negative meth-ctDNA was identified as a strong independent predictor of PFS (HR = 3.3, 95 % CI 1.5-7.2, p < 0.01). Similarly, patients with negative postoperative meth-ctDNA had longer median PFS (HR = 3.0, 95 % CI = 1.6-5.6, p < 0.001) and OS (HR = 4.1, 95 % CI 1.9-9.1, p < 0.001) compared to those with positive postoperative meth-ctDNA.

CONCLUSION

Preoperative meth-ctDNA may serve as an important biomarker to inform the multidisciplinary assessment and treatment planning of CRLM. Negative meth-ctDNA may indicate the optimal timing for liver intervention, whereas positive meth-ctDNA may indicate initiation or re-orientation of chemotherapy, or immediate local intervention. Our results confirm postoperative negative meth-ctDNA as a strong prognostic marker of survival.

Circulating Tumor DNA for Prediction of Complete Pathological Response to Neoadjuvant Radiochemotherapy in Locally Advanced Rectal Cancer (NEORECT Trial)

BACKGROUND/OBJECTIVES

Locally advanced rectal cancer is treated with neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision (TME). As this approach achieves complete pathologic remissions (pCR) in approximately 30% of patients, it raises the question of whether surgery is always necessary. Non-surgical strategies, such as "watch and wait" (W&W), have shown similarly promising outcomes. However, there is an unmet need for reliable biomarkers predicting pCR. Analysis of circulating tumor DNA (ctDNA) has shown potential for monitoring treatment response and detecting minimal residual disease. We hypothesized that monitoring ctDNA changes during nCRT might facilitate the identification of individuals who achieve pCR.

METHODS

In the prospective single-center NEORECT trial, the plasma of forty rectal cancer patients was collected before, during, and after nCRT and before TME. Informative somatic mutations were identified in tissue biopsies by NGS and subsequently used for ctDNA quantification by dPCR.

RESULTS

The results identified three distinct ctDNA patterns: increase, decrease, and absence. Remarkably, undetectable DNA was observed in good responders, while a tenfold ctDNA increase was associated with the emergence of new metastases. Despite these insights, ctDNA alone demonstrated low specificity, with no significant correlation to pCR or long-term prognosis. A multimodal approach incorporating routinely available clinical parameters remains inadequate for accurately predicting pCR prior to TME.

CONCLUSIONS

In conclusion, the NEORECT trial establishes the feasibility of ctDNA-based personalized monitoring for rectal cancer patients undergoing nCRT. However, the utility of ctDNA in enhancing pCR prediction for a W&W strategy warrants further investigation. Larger studies integrating multi-gene analyses and expanded clinical datasets are essential in the future.

Clinical value of sequential circulating tumor DNA analysis using next-generation sequencing and epigenetic modifications for guiding thermal ablation for colorectal cancer metastases: a prospective study

INTRODUCTION

While thermal ablation is now a standard treatment option for oligometastatic colorectal cancer patients, selecting those who will benefit most from locoregional therapies remains challenging. This proof-of-concept study is the first to assess the feasibility of routine testing of ctDNA before and after thermal ablation with curative intent, analyzed by next-generation sequencing (NGS) and methylation specific digital droplet PCR (ddPCR). Our prospective study primary objective was to assess the prognostic value of ctDNA before thermal ablation.

METHODS

This single-center prospective study from November 2021 to June 2022 included colorectal cancer patients referred for curative-intent thermal ablation. Cell-free DNA was tested at different time points by next-generation sequencing and detection of WIF1 and NPY genes hypermethylation using ddPCR. The ctDNA was considered positive if either a tumor mutation or hypermethylation was detected; recurrence-free survival was used as the primary endpoint.

RESULTS

The study enrolled 15 patients, and a total of 60 samples were analyzed. The median follow-up after ablation was 316 days, and median recurrence-free survival was 250 days. CtDNA was positive for 33% of the samples collected during the first 24 h. The hazard ratio for progression according to the presence of baseline circulating tumor DNA was estimated at 0.14 (CI 95%: 0.03-0.65, p = 0.019). The dynamics are provided, and patients with no recurrence were all negative at H24 for ctDNA.

DISCUSSION

This study shows the feasibility of routine testing of ctDNA before and after thermal ablation with curative intent. We report that circulating tumor DNA is detectable in patients with low tumor burden using 2 techniques. This study emphasizes the potential of ctDNA for discerning patients who are likely to benefit from thermal ablation from those who may not, which could shape future referrals. The dynamics of ctDNA before and after ablation shed light on the need for further research and larger studies.

Exploring the diagnostic and prognostic significance of circulating tumor cells in stage II-IV colorectal cancer using a nano-based detection method

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer mortality globally, underscoring the urgency for a noninvasive and effective biomarker to enhance patient prognosis. Circulating tumor cells (CTCs), a potential marker for real-time tumor monitoring, are limited in clinical utility due to the low sensitivity of existing detection methods. Previously, we introduced a novel nano-based CTCs detection method that relies on the electrical properties of cell surfaces, thus eliminating the need for specific molecular biomarkers. In this study, we used this technique to evaluate the diagnostic and prognostic value of CTCs in stage II-IV CRC.

METHODS

A total of 194 participants were included, consisting of 136 CRC patients and 58 healthy individuals. The peripheral blood of the participants was collected, and CTC enumeration was performed utilizing the nano-based detection method that we newly developed. The receiver operating characteristic (ROC) curve and multivariate Cox proportional-hazards analysis were used to assess the effectiveness of CTCs for diagnosing CRC and predicting patient prognosis.

RESULTS

The nano-based method demonstrated an ability to differentiate CRC patients from healthy individuals with a sensitivity of 84.6% and a specificity of 94.8%. Furthermore, baseline CTC levels were predictive of progression-free survival (PFS) in CRC patients, with lower levels associated with longer PFS compared to higher levels (4.5 vs 8.0 months at 15 CTCs/mL, p = 0.016; 4.4 vs 8.0 months at 20 CTCs/mL, p = 0.028). We also explored the dynamic changes in the number of CTCs after 1 to 5 cycles of chemotherapy. Patients with increasing CTC levels typically experienced disease progression (PD), while those with decreasing levels often achieved a partial response (PR) or maintained stable disease (SD). These findings suggest that the dynamic fluctuations in CTC counts are closely tied to the clinical course of the disease.

CONCLUSION

Our study indicates the potential of nano-based CTCs detection in diagnosing and predicting outcomes for patients with stage II-IV CRC.

A panorama of colon cancer in the era of liquid biopsy

Colon cancer (CC) is one of the most frequent cancers worldwide being responsible for over 500 thousand deaths in 2022. Its financial and human burden is expected to increase in the next decades accompanying the growing and aging of the global population. Much of this burden could be alleviated considering that the lethality of CC is mostly due to its late diagnosis and failure in the individualized management of patients. Coordinated government actions and implementation of better diagnostic tools capable of detecting CC earlier and of tracking tumoral evolution are mandatory to achieve a reduction in CC's social impact. CtDNA-based liquid biopsy (LB) has great potential to contribute to patients' screening adhesion, CC earlier detection, and to longitudinal tumor follow-up. In this review, we will discuss the latest epidemiological data on CC disease, diagnostic, subtypes, genetics, and treatment management focusing on the advantages and limitations of ctDNA-based LB, including important bottlenecks and solutions necessary for its clinical translation. The latest ctDNA-directed CC clinical trials will also be examined.

Pre-hepatectomy dynamic circulating tumor DNA to predict pathologic response to preoperative chemotherapy and post-hepatectomy recurrence in patients with colorectal liver metastases

OBJECTIVE

To evaluate the predictive value of pre-hepatectomy dynamic circulating tumor DNA (ctDNA) on pathologic response to preoperative chemotherapy and recurrence after liver resection for colorectal liver metastases (CRLM).

BACKGROUND

Pathologic response is a predictor of clinical outcomes for patients undergoing hepatectomy for CRLM. Postoperative ctDNA has been proven to be sensitive for recurrence detection. However, few studies investigate the impact of pre-hepatectomy ctDNA on pathologic response and recurrence.

METHODS

Patients with potential resectable CRLM underwent preoperative chemotherapy and hepatectomy between 2018 and 2021 was considered for inclusion. Plasma ctDNA was collected before and after preoperative chemotherapy. Pathologic response was analyzed for all patients after liver resection. Recurrence free survival was compared between patients with different ctDNA status and different pathologic response. The relation between ctDNA and pathologic response was also analyzed.

RESULTS

A total of 114 patients were included. ctDNA was detectable in 108 of 114 patients (94.7%) before chemotherapy, in 56 of 114 patients (49.1%) after chemotherapy. Patients with ctDNA positive at baseline and negative after chemotherapy had significantly longer RFS (median RFS 17 vs 7 months, p = 0.001) and HRFS (median HRFS unreached vs 8 months, p < 0.001) than those with ctDNA persistently positive after chemotherapy. Two patients (1.6%) had a pathologic complete response and 56 patients (45.2%) had a pathologic major response. Post-chemotherapy ctDNA- was associated with improved major pathologic response (53.4% vs 32.1%, p = 0.011). In the multivariable analysis, ctDNA- after chemotherapy (HR 0.51, 95% CI 0.28-0.93), major pathologic response (HR 0.34, 95% CI 0.19-0.62) and surgery combined with radiofrequency ablation (HR 2.62, 95% CI 1.38-5.00) were independently associated with RFS (all p < 0.05).

CONCLUSIONS

Pre-hepatectomy dynamic monitoring of ctDNA could predict pathologic response to preoperative chemotherapy and post-hepatectomy recurrence in CRLM patients. Negative ctDNA after preoperative chemotherapy was associated with better tumor regression grade and recurrence-free survival, which might be used to guide pre-hepatectomy chemotherapy and predict prognosis.

Investigating surface proteins and antibody combinations for detecting circulating tumor cells of various sarcomas

Circulating tumor cells (CTCs) have gathered attention as a biomarker for carcinomas. However, CTCs in sarcomas have received little attention. In this work, we investigated cell surface proteins and antibody combinations for immunofluorescence detection of sarcoma CTCs. A microfluidic device that combines filtration and immunoaffinity using gangliosides 2 and cell surface vimentin (CSV) antibodies was employed to capture CTCs. For CTC detection, antibodies against cytokeratins 7 and 8 (CK), pan-cytokeratin (panCK), or a combination of panCK and CSV were used. Thirty-nine blood samples were collected from 21 patients of various sarcoma subtypes. In the independent samples study, samples were subjected to one of three antibody combination choices. Significant difference in CTC enumeration was found between CK and panCK + CSV, and between panCK and panCK + CSV. Upon stratification of CK+ samples, those of metastatic disease had a higher CTC number than those of localized disease. In the paired samples study involving cytokeratin-positive sarcoma subtypes, using panCK antibody detected more CTCs than CK. Similarly, for osteosarcoma, using panCK + CSV combination resulted in a higher CTC count than panCK. This study emphasized deliberate selection of cell surface proteins for sarcoma CTC detection and subtype stratification for studying cancers as heterogeneous as sarcomas.

Prospects of liquid biopsy in the prognosis and clinical management of gastrointestinal cancers

Gastrointestinal (GI) cancers account for one-fourth of the global cancer incidence and are incriminated to cause one-third of cancer-related deaths. GI cancer includes esophageal, gastric, liver, pancreatic, and colorectal cancers, mostly diagnosed at advanced stages due to a lack of accurate markers for early stages. The invasiveness of diagnostic methods like colonoscopy for solid biopsy reduces patient compliance as it cannot be frequently used to screen patients. Therefore, minimally invasive approaches like liquid biopsy may be explored for screening and early identification of gastrointestinal cancers. Liquid biopsy involves the qualitative and quantitative determination of certain cancer-specific biomarkers in body fluids such as blood, serum, saliva, and urine to predict disease progression, therapeutic tolerance, toxicities, and recurrence by evaluating minimal residual disease and its correlation with other clinical features. In this review, we deliberate upon various tumor-specific cellular and molecular entities such as circulating tumor cells (CTCs), tumor-educated platelets (TEPs), circulating tumor DNA (ctDNA), cell-free DNA (cfDNA), exosomes, and exosome-derived biomolecules and cite recent advances pertaining to their use in predicting disease progression, therapy response, or risk of relapse. We also discuss the technical challenges associated with translating liquid biopsy into clinical settings for various clinical applications in gastrointestinal cancers.

Predicting early recurrence after resection of initially unresectable colorectal liver metastases: the role of baseline and pre-surgery clinical, radiological and molecular factors in a real-life multicentre experience

BACKGROUND

Advances in surgical techniques and systemic treatments have increased the likelihood of achieving radical surgery and long-term survival in metastatic colorectal cancer (mCRC) patients with initially unresectable colorectal liver metastases (CRLMs). Nonetheless, roughly half of the patients resected after an upfront systemic therapy experience disease relapse within 6 months from surgery, thus leading to the question whether surgery is actually beneficial for these patients.

MATERIALS AND METHODS

A real-world dataset of mCRC patients with initially unresectable liver-limited disease treated with conversion chemotherapy followed by radical resection of CRLMs at three high-volume Italian institutions was retrospectively assessed with the aim of investigating the association of baseline and pre-surgical clinical, radiological and molecular factors with the risk of relapse within 6 or 12 months from surgery.

RESULTS

Overall, 268 patients were included in the analysis and 207 (77%) experienced recurrence. Ninety-six (46%) of them had disease relapse within 6 months after CRLM resection and in spite of several variables associated with early recurrence at univariate analyses, only primary tumour resection at diagnosis [odds ratio (OR) 0.53, 95% confidence interval (CI) 0.32-0.89, P = 0.02] remained significant in the multivariable model. Among patients with resected primary tumours, pN+ stage was associated with higher risk of disease relapse within 6 months (OR 3.02, 95% CI 1.23-7.41, P = 0.02). One hundred and forty-nine patients (72%) had disease relapse within 12 months after CRLMs resection but none of the analysed variables was independently associated with outcome.

CONCLUSIONS

Clinical, radiological and molecular factors assessed before and after conversion chemotherapy do not reliably predict early recurrence after secondary resection of initially unresectable CRLMs. While novel markers are needed to optimize the cost/efficacy balance of surgical procedures, CRLM resection should be offered as soon as metastases become resectable during first-line chemotherapy to all patients eligible for surgery.

Multimodal Management of Colorectal Liver Metastases: State of the Art

Liver is the most common site of colorectal cancer (CRC) metastases. Treatment of CRC liver metastases (CRLM) includes different strategies, prevalently based on the clinical and oncological intent. Valid approaches in liver-limited or liver-prevalent disease include surgery, percutaneous ablative procedures (radiofrequency ablation, microwave ablation), intra-arterial perfusional techniques (chemo-embolization, radio-embolization) as well as stereotactic radiotherapy. Systemic treatments, including chemotherapy, immunotherapy and other biological agents, are the only options for patients with no chance of locoregional approaches. The use of chemotherapy in other settings, such as neoadjuvant, adjuvant or conversion therapy of CRLM, is commonly accepted in the clinical practice, although data from several clinical trials have been mostly inconclusive. The optimal integration of all these strategies, when applicable and clinically indicated, should be ever considered in patients affected by CRLM based on clinical evidence and multidisciplinary experience. Here we revised in detail all the possible therapeutic approaches of CRLM focusing on the current evidences, the studies still in progress and the often contradictory data.

[Liquid Biopsy - A new diagnostic concept in oncology]

The analysis of tumor cells circulating in the blood or of products of tumor cells circulating in other body fluids has gained increasing attention in recent years and is summarized under the term liquid biopsy (LB). LB includes the analysis of circulating tumor cells, cell-free circulating tumor-associated nucleic acids, extracellular vesicles, proteins, or other products that are released into the peripheral bloodstream by the primary or metastatic tumor. For a huge number of solid tumor entities, LB has already been successfully applied in preclinical and clinical studies for the detection, risk stratification, treatment monitoring and relapse detection. LB provides valuable real-time information on tumor cell development, therapeutic targets, and mechanisms of therapy resistance using a non-invasive peripheral blood test. In this article, the most important LB analytes and the current state of research are presented. In addition, the remaining obstacles and the diverse efforts to implement LB in clinical routine are critically discussed.

Molecular response assessment using circulating tumor DNA (ctDNA) in advanced solid tumors

The therapeutic landscape for patients with advanced malignancies has changed dramatically over the last twenty years. The growing number of targeted therapies and immunotherapeutic options available have improved response rates and survival for a subset of patients, however determining which patients will experience clinical benefit from these therapies in order to avoid potential toxicities and reduce healthcare costs remains a clinical challenge. Cell-free circulating tumor DNA (ctDNA) is shed by tumor cells into systemic circulation and is already an integral part of routine clinical practice for the non-invasive tumor genotyping in advanced non-small cell lung cancer as well as other malignancies. The short half-life of ctDNA offers a unique opportunity to utilize early on-treatment changes in ctDNA for real-time assessment of therapeutic response and outcome, termed molecular response. Here, we provide a summary and review of the use of molecular response for the prediction of outcomes in patients with advanced cancer, including the current state of science, its application in clinic, and next steps for the development of this predictive tool.

Circulating tumor cells participate in the formation of microvascular invasion and impact on clinical outcomes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor worldwide. Although the treatment strategies have been improved in recent years, the long-term prognosis of HCC is far from satisfactory mainly due to high postoperative recurrence and metastasis rate. Vascular tumor thrombus, including microvascular invasion (MVI) and portal vein tumor thrombus (PVTT), affects the outcome of hepatectomy and liver transplantation. If vascular invasion could be found preoperatively, especially the risk of MVI, more reasonable surgical selection will be chosen to reduce the risk of postoperative recurrence and metastasis. However, there is a lack of reliable prediction methods, and the formation mechanism of MVI/PVTT is still unclear. At present, there is no study to explore the possibility of tumor thrombus formation from a single circulating tumor cell (CTC) of HCC, nor any related study to describe the possible leading role and molecular mechanism of HCC CTCs as an important component of MVI/PVTT. In this study, we review the current understanding of MVI and possible mechanisms, discuss the function of CTCs in the formation of MVI and interaction with immune cells in the circulation. In conclusion, we discuss implications for potential therapeutic targets and the prospect of clinical treatment of HCC.

Evaluation of cell surface vimentin positive circulating tumor cells as a prognostic biomarker for stage III/IV colorectal cancer

Currently, little is known about the phenotypes of circulating tumor cells (CTCs), particularly epithelial and mesenchymal phenotypes, and their impact on the prognosis of colorectal cancer (CRC) patients. This study aims to investigate the CTC phenotypes and their prognostic implications in stage III/IV CRC. Patients who were diagnosed with CRC and underwent CTC detection at two hospitals were included. CTCs were detected using a mesenchymal CTC kit, and the clinical and pathological characteristics of CTCs were compared with those of cell surface vimentin-positive CTCs (CSV-CTCs). Disease-free survival (DFS) was assessed and used as an indicator of CTC phenotype-related prognosis. Univariate and multivariate Cox regression analyses were made to identify risk factors, and nomogram models were employed for prognostic prediction. A total of 82 patients were enrolled, with a CTC detection rate of 86.6%. Among the detected CTCs, 60% were CSV-CTCs. The CSV-CTC count showed a positive correlation with the T-stage, the M-stage, and the location of the primary tumor (P = 0.01, P = 0.014, and P = 0.01, respectively). Kaplan-Meier survival analysis revealed that CSV-CTCs were associated with worse DFS in patients receiving first-line oxaliplatin chemotherapy (hazard ratio (HR) = 3.78, 95% CI 1.55-9.26, p = 0.04). When the cut-off value of the CSV-CTC count was 3, the optimal prognostic prediction was achieved. Compound models considering CSV-CTCs, TNM staging, the site of the primary tumor and the Ras gene status yielded the best results in both the receiver operating characteristic (ROC) analysis and the decision curve analysis (DCA). This study indicates that CSV-CTCs predominate in CTCs of CRC patients, and a count of CSV-CTCs ≥ 3 is an independent risk factor for worse prognosis.

Circulating Tumour DNA as Biomarker for Colorectal Liver Metastases: A Systematic Review and Meta-Analysis

Circulating tumour DNA (ctDNA) is a potential biomarker that could contribute to more judicious patient selection for personalised treatment. This review and meta-analysis gives an overview of the current knowledge in the literature investigating the value of ctDNA in patients with colorectal liver metastases (CRLM). A systematic search was conducted in electronic databases for studies published prior to the 26th of May 2023. Studies investigating the association between ctDNA and oncological outcomes in patients undergoing curative-intent local therapy for CRLM were included. Meta-analyses were performed to pool hazard ratios (HR) for the recurrence-free survival (RFS) and overall survival (OS). A total of eleven studies were included and nine were eligible for meta-analyses. Patients with detectable ctDNA after surgery experienced a significantly higher chance of recurrence (HR 3.12, 95% CI 2.27-4.28, p < 0.000010) and shorter OS (HR 5.04, 95% CI 2.53-10.04, p < 0.00001) compared to patients without detectable ctDNA. A similar association for recurrence was found in patients with detectable ctDNA after the completion of adjuvant therapy (HR 6.39, 95% CI 2.13-19.17, p < 0.0009). The meta-analyses revealed no association between detectable ctDNA before surgery and the RFS and OS. These meta-analyses demonstrate the strong association between detectable ctDNA after treatment and oncological outcomes in CRLM patients.

Circulating Tumor DNA as a Prognostic Factor in Patients With Resectable Hepatic Metastases of Uveal Melanoma

OBJECTIVE

We report here the results of a prospective study of circulating tumor DNA (ctDNA) detection in patients undergoing uveal melanoma (UM) liver metastases resection (NCT02849145).

BACKGROUND

In UM patients, the liver is the most common and often only site of metastases. Local treatments of liver metastases, such as surgical resection, have a likely benefit in selected patients.

METHODS

Upon enrollment, metastatic UM patients eligible for curative liver surgery had plasma samples collected before and after surgery. GNAQ / GNA11 mutations were identified in archived tumor tissue and used to quantify ctDNA by droplet digital polymerase chain reaction which was then associated with the patient's surgical outcomes.

RESULTS

Forty-seven patients were included. Liver surgery was associated with a major increase of cell-free circulating DNA levels, with a peak 2 days after surgery (∼20-fold). Among 40 evaluable patients, 14 (35%) had detectable ctDNA before surgery, with a median allelic frequency of 1.1%. These patients experienced statistically shorter relapse-free survival (RFS) versus patients with no detectable ctDNA before surgery (median RFS: 5.5 vs 12.2 months; hazard ratio=2.23, 95% CI: 1.06-4.69, P =0.04), and had a numerically shorter overall survival (OS) (median OS: 27.0 vs 42.3 months). ctDNA positivity at postsurgery time points was also associated with RFS and OS.

CONCLUSIONS

This study is the first to report ctDNA detection rate and prognostic impact in UM patients eligible for surgical resection of their liver metastases. If confirmed by further studies in this setting, this noninvasive biomarker could inform treatment decisions in UM patients with liver metastases.

Clinical application of circulating tumour DNA in colorectal cancer

Liquid biopsies that detect circulating tumour DNA (ctDNA) have the potential to revolutionise the personalised management of colorectal cancer. For patients with early-stage disease, emerging clinical applications include the assessment of molecular residual disease after surgery, the monitoring of adjuvant chemotherapy efficacy, and early detection of recurrence during surveillance. In the advanced disease setting, data highlight the potential of ctDNA levels as a prognostic marker and as an early indicator of treatment response. ctDNA assessment can complement standard tissue-based testing for molecular characterisation, with the added ability to monitor emerging mutations under the selective pressure of targeted therapy. Here we provide an overview of the evidence supporting the use of ctDNA in colorectal cancer, the studies underway to address some of the outstanding questions, and the barriers to widespread clinical uptake.

The potential role of minimal/molecular residual disease in colorectal cancer: curative surgery, radiotherapy and beyond

Detection of minimal/molecular residual disease (MRD) based on ctDNA assay develops from hematological malignancies to solid tumors. Generally, there are two mainstream assays in MRD testing technology: tumor-informed and tumor-agnostic. For colorectal cancer (CRC), MRD is used not only to monitor recurrence and predict prognosis, but also to help in clinical decision making and assessment of clinical efficacy in the settings of curative surgery, radiotherapy, chemotherapy and surveillance. Accumulated clinical trials are exploring roles of MRD in early or advanced stages of CRC. Here, we give an overview of how MRD is and will be used in CRC.

Circulating tumour DNA at baseline for individualised prognostication in patients with chemotherapy-naïve metastatic colorectal cancer. An AGEO prospective study

PURPOSE

Baseline circulating tumour DNA (ctDNA) is a potential prognostic marker in metastatic colorectal cancer (mCRC) patients. However, few studies have compared ctDNA with the usual prognostic factors, and no ctDNA cut-off has been proposed for daily use in clinical practice.

PATIENTS AND METHODS

Chemotherapy-naive patients with mCRC were prospectively included. Plasma samples were collected at diagnosis and analysed centrally by both NGS and methylation digital PCR. Baseline patient and disease characteristics, treatment regimens, and secondary surgeries were collected. The restricted cubic spline method was used to define the optimal cut-off of ctDNA mutated allelic frequency (MAF). Prognostic values were assessed on overall survival (OS) using Cox models.

RESULTS

From July 2015 to December 2016, 412 patients were included. ctDNA was undetectable in 83 patients (20%). ctDNA was an independent prognostic marker for OS considering the whole study population. The optimal cut-off for ctDNA MAF was 20% with median OS of 16.0 and 35.8 months for patients with MAF ≥20% and<20%, respectively (hazard ratio = 0.40; 95% confidence intervals: 0.31-0.51; P < 0.0001). The independent prognostic value of ctDNA MAF at 20% was confirmed in subgroups defined by RAS/BRAF status or resectability of metastases. Combining ctDNA MAF and carcinoembryonic antigen levels allowed us to define three different prognostic groups with median OS of 14.2, 21.1, and 46.4 months (P < 0.0001).

CONCLUSION

ctDNA with a MAF cut-off of 20% improves prognostication of chemotherapy-naïve mCRC patients and may be useful in the future for individualised therapeutic decisions and as a stratification factor in clinical trials.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT02502656.

Recurrence Prediction by Circulating Tumor DNA in the Patient with Colorectal Liver Metastases After Hepatectomy: A Prospective Biomarker Study

BACKGROUND

The recurrence rate after hepatic resection of colorectal liver metastases (CRLM) remains high. This study aimed to investigate postoperative circulating tumor DNA (ctDNA) based on ultra-deep next-generation sequencing (NGS) to predict patient recurrence and survival.

METHODS

Using the high-throughput NGS method tagged with a dual-indexed unique molecular identifier, named the CRLM-specific 25-gene panel (J25), this study sequenced ctDNA in peripheral blood samples collected from 134 CRLM patients who underwent hepatectomy after postoperative day 6.

RESULTS

Of 134 samples, 42 (31.3%) were shown to be ctDNA-positive, and 37 resulted in recurrence. Kaplan-Meier survival analysis showed that disease-free survival (DFS) in the ctDNA-positive subgroup was significantly shorter than in the ctDNA-negative subgroup (hazard ratio [HR], 2.96; 95% confidence interval [CI], 1.91-4.6; p < 0.05). When the 42 ctDNA-positive samples were further divided by the median of the mean allele frequency (AF, 0.1034%), the subgroup with higher AFs showed a significantly shorter DFS than the subgroup with lower AFs (HR, 1.98; 95% CI, 1.02-3.85; p < 0.05). The ctDNA-positive patients who received adjuvant chemotherapy longer than 2 months showed a significantly longer DFS than those who received treatment for 2 months or less (HR, 0.377; 95% CI, 0.189-0.751; p < 0.05). Uni- and multivariable Cox regression indicated two factors independently correlated with prognosis: ctDNA positivity and no preoperative chemotherapy.

CONCLUSION

The study demonstrated that ctDNA status 6 days postoperatively could sensitively and accurately predict recurrence for patients with CRLM using the J25 panel.

ctDNA as a prognostic biomarker in resectable CLM: Systematic review and meta-analysis

Cell-free circulating tumor DNA (ctDNA) is synthesized by tumor cells, including metastatic tumors, and circulates in the bloodstream. Evidence suggests that ctDNA is a potential predictive and prognostic biomarker for colorectal cancer (CRC), but its predictive efficacy in detecting CRC liver metastasis (CLM) remains unclear. Additionally, its utility in the clinical setting needs further investigation. We conducted a meta-analysis to determine the utility of ctDNA as a biomarker for predicting the prognosis of CLM and investigate the relationship between CLM and ctDNA positivity. A literature search was performed in electronic databases to identify relevant studies published up to March 19, 2022. We retrieved data on overall survival (OS), disease-free survival (DFS), and recurrence-free survival (RFS) for both ctDNA-positive and ctDNA-negative colorectal liver metastasis (CLM) patients from the selected articles. Hazard ratios (HRs) were also calculated for these survival outcomes analysis was also performed. The stability of the combined meta-analysis was verified by sensitivity analysis and publication bias evaluation. Ten trials were included, and 615 patients were evaluated. In patients with CLM, pooled HRs revealed a substantial link between ctDNA positivity and RFS/DFS. Subgroup analysis revealed that ctDNA had a prospective detection value. Sensitivity analysis and publication bias evaluation indicated stable results. Although the results on pooled HR for OS suggested that ctDNA-positive patients had a shorter survival time, their pooled HRs had a relatively evident heterogeneity, and sensitivity analysis and publication bias evaluation indicated that pooled HRs were extremely unstable. In conclusion, our results demonstrate that ctDNA appears to be a prognostic biomarker for resectable CLM patients.

Prospective Study of Perioperative Circulating Tumor DNA Dynamics in Patients Undergoing Hepatectomy for Colorectal Liver Metastases

OBJECTIVE

To evaluate the association of perioperative ctDNA dynamics on outcomes after hepatectomy for CLM.

SUMMARY BACKGROUND DATA

Prognostication is imprecise for patients undergoing hepatectomy for CLM, and ctDNA is a promising biomarker. However, clinical implications of perioperative ctDNA dynamics are not well established.

METHODS

Patients underwent curative-intent hepatectomy after preoperative chemotherapy for CLM (2013-2017) with paired prehepatectomy/postoperative ctDNA analyses via plasma-only assay. Positivity was determined using a proprietary variant classifier. Primary endpoint was recurrence-free survival (RFS). Median follow-up was 55 months.

RESULTS

Forty-eight patients were included. ctDNA was detected before and after surgery (ctDNA+/+) in 14 (29%), before but not after surgery (ctDNA+/-) in 19 (40%), and not at all (ctDNA-/-) in 11 (23%). Adverse tissue somatic mutations were detected in TP53 (n = 26; 54%), RAS (n = 23; 48%), SMAD4 (n = 5; 10%), FBXW7 (n = 3; 6%), and BRAF (n = 2; 4%). ctDNA+/+ was associated with worse RFS (median: ctDNA+/+, 6.0 months; ctDNA+/-, not reached; ctDNA-/-, 33.0 months; P = 0.001). Compared to ctDNA+/+, ctDNA+/- was associated with improved RFS [hazard ratio (HR) 0.24 (95% confidence interval (CI) 0.1-0.58)] and overall survival [HR 0.24 (95% CI 0.08-0.74)]. Adverse somatic mutations were not associated with survival. After adjustment for prehepatectomy chemotherapy, synchronous disease, and ≥2 CLM, ctDNA+/- and ctDNA-/- were independently associated with improved RFS compared to ctDNA+/+ (ctDNA+/-: HR 0.21, 95% CI 0.08-0.53; ctDNA-/-: HR 0.21, 95% CI 0.08-0.56).

CONCLUSIONS

Perioperative ctDNA dynamics are associated with survival, identify patients with high recurrence risk, and may be used to guide treatment decisions and surveillance after hepatectomy for patients with CLM.

[Liquid Biopsy - A new diagnostic concept in oncology]

The analysis of tumor cells circulating in the blood or of products of tumor cells circulating in other body fluids has gained increasing attention in recent years and is summarized under the term liquid biopsy (LB). LB includes the analysis of circulating tumor cells, cell-free circulating tumor-associated nucleic acids, extracellular vesicles, proteins, or other products that are released into the peripheral bloodstream by the primary or metastatic tumor. For a huge number of solid tumor entities, LB has already been successfully applied in preclinical and clinical studies for the detection, risk stratification, treatment monitoring and relapse detection. LB provides valuable real-time information on tumor cell development, therapeutic targets, and mechanisms of therapy resistance using a non-invasive peripheral blood test. In this article, the most important LB analytes and the current state of research are presented. In addition, the remaining obstacles and the diverse efforts to implement LB in clinical routine are critically discussed.

Utilization of Circulating Tumor Cells in the Management of Solid Tumors

Circulating tumor cells (CTCs) are tumor cells shed from the primary tumor into circulation, with clusters of CTCs responsible for cancer metastases. CTC detection and isolation from the bloodstream are based on properties distinguishing CTCs from normal blood cells. Current CTC detection techniques can be divided into two main categories: label dependent, which depends upon antibodies that selectively bind cell surface antigens present on CTCs, or label-independent detection, which is detection based on the size, deformability, and biophysical properties of CTCs. CTCs may play significant roles in cancer screening, diagnosis, treatment navigation, including prognostication and precision medicine, and surveillance. In cancer screening, capturing and evaluating CTCs from peripheral blood could be a strategy to detect cancer at its earliest stage. Cancer diagnosis using liquid biopsy could also have tremendous benefits. Full utilization of CTCs in the clinical management of malignancies may be feasible in the near future; however, several challenges still exist. CTC assays currently lack adequate sensitivity, especially in early-stage solid malignancies, due to low numbers of detectable CTCs. As assays improve and more trials evaluate the clinical utility of CTC detection in guiding therapies, we anticipate increased use in cancer management.

The role of tumour biological factors in technical anatomical resectability assessment of colorectal liver metastases following induction systemic treatment: An analysis of the Dutch CAIRO5 trial

BACKGROUND

Large inter-surgeon variability exists in technical anatomical resectability assessment of colorectal cancer liver-only metastases (CRLM) following induction systemic therapy. We evaluated the role of tumour biological factors in predicting resectability and (early) recurrence after surgery for initially unresectable CRLM.

METHODS

482 patients with initially unresectable CRLM from the phase 3 CAIRO5 trial were selected, with two-monthly resectability assessments by a liver expert panel. If no consensus existed among panel surgeons (i.e. same vote for (un)resectability of CRLM), conclusion was based on majority. The association of tumour biological (sidedness, synchronous CRLM, carcinoembryonic antigen and RAS/BRAF^V600E mutation status) and technical anatomical factors with consensus among panel surgeons, secondary resectability and early recurrence (<6 months) without curative-intent repeat local treatment was analysed by uni- and pre-specified multivariable logistic regression.

RESULTS

After systemic treatment, 240 (50%) patients received complete local treatment of CRLM of which 75 (31%) patients experienced early recurrence without repeat local treatment. Higher number of CRLM (odds ratio 1.09 [95% confidence interval 1.03-1.15]) and age (odds ratio 1.03 [95% confidence interval 1.00-1.07]) were independently associated with early recurrence without repeat local treatment. In 138 (52%) patients, no consensus among panel surgeons was present prior to local treatment. Postoperative outcomes in patients with and without consensus were comparable.

CONCLUSIONS

Almost a third of patients selected by an expert panel for secondary CRLM surgery following induction systemic treatment experience an early recurrence only amenable to palliative treatment. Number of CRLM and age, but no tumour biological factors are predictive, suggesting that until there are better biomarkers; resectability assessment remains primarily a technical anatomical decision.

Circulating tumour cells in gastrointestinal cancers: food for thought?

Gastrointestinal (GI) cancers account for 35% of cancer-related deaths, predominantly due to their ability to spread and generate drug-tolerant metastases. Arising from different locations in the GI system, the majority of metastatic GI malignancies colonise the liver and the lungs. In this context, circulating tumour cells (CTCs) are playing a critical role in the formation of new metastases, and their presence in the blood of patients has been correlated with a poor outcome. In addition to their prognostic utility, prospective targeting of CTCs may represent a novel, yet ambitious strategy in the fight against metastasis. A better understanding of CTC biology, mechanistic underpinnings and weaknesses may facilitate the development of previously underappreciated anti-metastasis approaches. Here, along with related clinical studies, we outline a selection of the literature describing biological features of CTCs with an impact on their metastasis forming ability in different GI cancers.

Predicting early extrahepatic recurrence after local treatment of colorectal liver metastases

BACKGROUND

Patients who develop early extrahepatic recurrence (EHR) may not benefit from local treatment of colorectal liver metastases (CRLMs). This study aimed to develop a prediction model for early EHR after local treatment of CRLMs using a national data set.

METHODS

A Cox regression prediction model for EHR was developed and validated internally using data on patients who had local treatment for CRLMs with curative intent. Performance assessment included calibration, discrimination, net benefit, and generalizability by internal-external cross-validation. The prognostic relevance of early EHR (within 6 months) was evaluated by landmark analysis.

RESULTS

During a median follow-up of 35 months, 557 of the 1077 patients had EHR and 249 died. Median overall survival was 19.5 (95 per cent c.i. 15.6 to 23.0) months in patients with early EHR after CRLM treatment, compared with not reached (45.3 months to not reached) in patients without an early EHR. The EHR prediction model included side and stage of the primary tumour, RAS/BRAFV600E mutational status, and number and size of CRLMs. The range of 6-month EHR predictions was 5.9-56.0 (i.q.r. 12.9-22.0) per cent. The model demonstrated good calibration and discrimination. The C-index through 6 and 12 months was 0.663 (95 per cent c.i. 0.624 to 0.702) and 0.661 (0.632 to 0.689) respectively. The observed 6-month EHR risk was 6.5 per cent for patients in the lowest quartile of predicted risk compared with 32.0 per cent in the highest quartile.

CONCLUSION

Early EHR after local treatment of CRLMs can be predicted.

Molecular assessment of endoscopically collected pancreatic juice and duodenal fluid from patients with pancreatic diseases

One concern associated with pancreatic diseases is the poor prognosis of pancreatic cancer. Even with advances in diagnostic modalities, risk stratification of premalignant lesions and differentiation of pancreatic cysts are challenging. Pancreatic lesions of concern include intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, serous cystadenomas, pseudocysts, and retention cysts, as well as cystic degeneration of solid tumors such as solid pseudopapillary neoplasms and pancreatic neuroendocrine neoplasms. Pancreatic juice obtained during endoscopic retrograde cholangiopancreatography has previously been used for the detection of KRAS mutation. Recently, duodenal fluid, which can be obtained during the relatively minimally invasive procedures of endoscopic ultrasound (EUS) and esophagogastroduodenoscopy, and cyst fluid collected by EUS-guided fine-needle aspiration (FNA) were used for molecular biological analysis. Furthermore, advanced analytic methods with high sensitivity were used for the detection of single and multiple markers. Early detection of malignant pancreatic tumors and risk stratification of premalignant tumors can be performed using duodenal fluid samples with a single marker with high sensitivity. Technological advances in simultaneous detection of multiple markers allow for the differentiation of cystic pancreatic tumors. One thing to note is that the clinical guidelines do not recommend pancreatic cyst fluid and pancreatic juice (PJ) sampling by EUS-FNA and endoscopic retrograde cholangiopancreatography, respectively, in actual clinical practice, but state that they be performed at experienced facilities, and duodenal fluid sampling is not mentioned in the guidelines. With improved specimen handling and the combination of markers, molecular markers in PJ samples may be used in clinical practice in the near future.

Clinical Applications of Liquid Biopsy in Colorectal Cancer Screening: Current Challenges and Future Perspectives

Colorectal cancer (CRC) represents the third most prevalent cancer worldwide and a leading cause of mortality among the population of western countries. However, CRC is frequently a preventable malignancy due to various screening tests being available. While failing to obtain real-time data, current screening methods (either endoscopic or stool-based tests) also require disagreeable preparation protocols and tissue sampling through invasive procedures, rendering adherence to CRC screening programs suboptimal. In this context, the necessity for novel, less invasive biomarkers able to identify and assess cancer at an early stage is evident. Liquid biopsy comes as a promising minimally invasive diagnostic tool, able to provide comprehensive information on tumor heterogeneity and dynamics during carcinogenesis. This review focuses on the potential use of circulating tumor cells (CTCs), circulating nucleic acids (CNAs) and extracellular vesicles as emerging liquid biopsy markers with clinical application in the setting of CRC screening. The review also examines the opportunity to implement liquid biopsy analysis during everyday practice and provides highlights on clinical trials researching blood tests designed for early cancer diagnosis. Additionally, the review explores potential applications of liquid biopsies in the era of immunotherapy.

Advances in the Biology, Detection Techniques, and Clinical Applications of Circulating Tumor Cells

Circulating tumor cells (CTCs) play a crucial role in tumor recurrence and metastasis, and their early detection has shown remarkable benefits in clinical theranostics. However, CTCs are extremely rare, thus detecting them in the blood is very challenging. New CTC detection techniques are continuously being developed, enabling deeper analysis of CTC biology and potential clinical application. This article reviews current CTC detection techniques and their clinical application. CTCs have provided, and will continue to provide, important insights into the process of metastasis, which could lead to development of new therapies for different cancers.

Liquid Biopsies in Colorectal Liver Metastases: Towards the Era of Precision Oncologic Surgery

Tumor mutational analysis has been incorporated into the management of patients with CRLM since it can provide valuable prognostic information as well as guide peri-operative systemic treatment. Unlike tumor biopsy, liquid biopsy has emerged as a promising, non-invasive alternative that can detect cell-derived markers from a variety of body fluids and might better characterize all subclones present at a specific time point and allow sequential monitoring of disease evolution. Although not currently considered standard of care, an increasing number of cancer centers are nowadays routinely using liquid biopsies in the treatment of CRLM patients with promising results. The current review provides an overview of liquid biopsies in cancer therapeutics and focuses on the application of this relatively new approach on patients with CRLM.

Diagnostic and prognostic biomarkers in colorectal cancer and the potential role of exosomes in drug delivery

Colorectal cancer (CRC) is third most common cancer with second most common cause of death worldwide. One fourth to one fifth of the CRC cases are detected at advance stage. Early detection of colorectal cancer might help in decreasing mortality and morbidity worldwide. CRC being a heterogeneous disease, new non-invasive approaches are needed to complement and improve the screening and management of CRC. Reliable and early detectable biomarkers would improve diagnosis, prognosis, therapeutic responses, and will enable the prediction of drug response and recurrence risk. Over the past decades molecular research has demonstrated the potentials of CTCs, ctDNAs, circulating mRNA, ncRNAs, and exosomes as tumor biomarkers. Non-invasive screening approaches using fecal samples for identification of altered gut microbes in CRC is also gaining attention. Exosomes can be potential candidates that can be employed in the drug delivery system. Further, the integration of in vitro, in vivo and in silico models that involve CRC biomarkers will help to understand the interactions occurring at the cellular level. This review summarizes recent update on CRC biomarkers and their application along with the nanoparticles followed by the application of organoid culture in CRC.

Circulating Tumor Cells as an Indicator of Treatment Options for Hepatocellular Carcinoma Less Than or Equal to 3 cm in Size: A Multi-Center, Retrospective Study

Background

The status of circulating tumor cells (CTCs) is related to the recurrence of hepatocellular carcinoma (HCC), which is also one of the reasons for the poor prognosis of HCC. The purpose of this study was to explore whether CTCs can help guide the choice of treatment methods for HCC.

Methods

This study is a multicenter retrospective study, including 602 patients with HCC. CTCs were detected in the overall cohort before operation. There were 361 patients in the training cohort and 241 patients in the validation cohort. Patients were divided into CTC-negative group (CTCs = 0/5 mL) and the CTC-positive group (CTCs ≥ 1/5 mL) according to CTCs status. Subgroup analysis was performed according to CTCs status. We compared overall survival, and recurrence outcomes for HCC patients with different CTC statuses after undergoing radiofrequency ablation (RFA) or surgical resection (SR).

Results

There was no significant difference in overall survival (OS) and recurrence-free survival (RFS) between the RFA group and SR group for CTC-negative patients in both the training cohort and the validation cohort (P > 0.05). However, among CTC-positive patients, the clinical outcome of patients in the SR group was significantly better than those in the RFA group. CTC-positive patients who underwent RFA had increased early recurrence compared to those who underwent SR. RFA is an independent risk factor for survival and recurrence in CTC-positive HCC patients.

Conclusions

The CTC status could serve as an indicator to guide the choice between surgical resection or radiofrequency ablation for early hepatocellular carcinoma. Surgical resection is recommended for CTC-positive patients.

Guiding Value of Circulating Tumor Cells for Preoperative Transcatheter Arterial Embolization in Solitary Large Hepatocellular Carcinoma: A Single-Center Retrospective Clinical Study

Background

Large hepatocellular carcinoma (LHCC) is highly malignant and prone to recurrence, leading to a poor long-term prognosis for patients. There is an urgent need for measures to intervene in postoperative recurrence. Preoperative Transcatheter Arterial Embolization (TACE) is an effective treatment. However, there is a lack of reliable preoperative indicators to guide the application of preoperative TACE. We, therefore, investigated whether the preoperative status of circulating tumor cells (CTCs) could be used to guide preoperative TACE for HCC treatment.

Methods

This study recruited 361 HCC patients and compared recurrence-free survival (RFS) and overall survival (OS) in patients treated with TACE prior to surgery and those not treated with TACE. Patients were divided into CTC-positive group and CTC-negative group according to CTC status, and the effect of preoperative TACE on RFS and OS was compared in each subgroup.

Results

In CTC-positive patients, preoperative TACE reduces early recurrence and improves long-term survival. However, HCC patients did not benefit from preoperative TACE for the overall population and CTC-negative patients.

Conclusions

Preoperative CTC testing is a reliable indicator of whether HCC patients received TACE preoperatively. CTC positivity was associated with early tumor recurrence, and preoperative TACE could reduce early recurrence and long-term prognosis in CTC-positive patients.

The time-dependent changes in serum carcinoembryonic antigen impact on posthepatectomy outcomes of colorectal liver metastasis

BACKGROUND

Only a few studies have examined the impact of carcinoembryonic antigen variation in patients before and after curative resection of colorectal liver metastasis . This study examined the correlation between carcinoembryonic antigen levels and patient prognosis.

METHODS

Patients who underwent curative resection for colorectal liver metastasis between 2000 and 2017 were enrolled. This study examined patients with high preoperative carcinoembryonic antigen levels that normalized after resection of colorectal liver metastasis and the correlation between prognosis and time-dependent changes in carcinoembryonic antigen levels. The similarity in the risk of recurrence in patients with normal preoperative carcinoembryonic antigen levels was evaluated.

RESULTS

A total of 143 consecutive patients were included in the study cohort and classified into the normal preoperative (46 patients), normalized postoperative (57 patients), and elevated preoperative and postoperative (40 patients) carcinoembryonic antigen groups. All clinicopathologic characteristics were comparable between patients grouped according to carcinoembryonic antigen levels. The 5-year disease-free survival and overall survival rates for all patients were 30.4% and 56.0%, respectively. Multivariate analysis confirmed that elevated preoperative and postoperative carcinoembryonic antigen levels (hazard ratio = 1.73, 95% confidence interval: 1.04-2.87) were independently associated with poor disease-free survival; normalization of postoperative carcinoembryonic antigen (hazard ratio = 0.94, 95% confidence interval: 0.57-1.53) was statistically indistinguishable from normal preoperative carcinoembryonic antigen levels. The risk of recurrence was similar to that of patients with normal preoperative carcinoembryonic antigen levels CONCLUSION: Patients with elevated preoperative carcinoembryonic antigen levels that normalized after resection of colorectal liver metastasis were not at risk of poor disease-free survival. Elevated carcinoembryonic antigen levels after surgery are independent prognostic factors for disease-free survival.

Patient-Derived Organoids of Colorectal Cancer: A Useful Tool for Personalized Medicine

Colorectal cancer is one of the most important malignancies worldwide, with high incidence and mortality rates. Several studies have been conducted using two-dimensional cultured cell lines; however, these cells do not represent a study model of patient tumors very well. In recent years, advancements in three-dimensional culture methods have facilitated the establishment of patient-derived organoids, which have become indispensable for molecular biology-related studies of colorectal cancer. Patient-derived organoids are useful in both basic science and clinical practice; they can help predict the sensitivity of patients with cancer to chemotherapy and radiotherapy and provide the right treatment to the right patient. Regarding precision medicine, combining gene panel testing and organoid-based screening can increase the effectiveness of medical care. In this study, we review the development of three-dimensional culture methods and present the most recent information on the clinical application of patient-derived organoids. Moreover, we discuss the problems and future prospects of organoid-based personalized medicine.

Clinical Applications of Liquid Biopsy in Prostate Cancer: From Screening to Predictive Biomarker

Prostate cancer (PC) remains the most common malignancy and the second most common cause of cancer death in men. As a result of highly variable biological behavior and development of resistance to available agents under therapeutic pressure, optimal management is often unclear. Traditional surgical biopsies, even when augmented by genomic studies, may fail to provide adequate guidance for clinical decisions as these can only provide a snapshot of a dynamic process. Additionally, surgical biopsies are cumbersome to perform repeatedly and often involve risk. Liquid biopsies (LB) are defined as the analysis of either corpuscular (circulating tumor cells, extracellular vesicles) or molecular (circulating DNA or RNA) tumor-derived material. LB could more precisely identify clinically relevant alterations that characterize the metastatic potential of tumors, predict response to specific treatments or actively monitor for the emergence of resistance. These tests can potentially be repeated as often as deemed necessary and can detect real-time response to treatment with minimal inconvenience to the patient. In the current review, we consider common clinical scenarios to describe available LB assays in PC as a platform to explore existing evidence for their use in guiding decision making and to discuss current limitations to their adoption in the clinic.

The management of colorectal liver metastases amenable of surgical resection: How to shape treatment strategies according to clinical, radiological, pathological and molecular features

Metastatic colorectal cancer (mCRC) patients have poor chances of long term survival, being < 15% of them still alive after 5 years from diagnosis. Nonetheless, patients with colorectal liver metastases (CRLM) may be eligible for metastases resection thus being able to achieve long-term disease remission and survival. The likelihood for patients with CRLM of being or becoming eligible for liver metastasectomy is increasing, thanks to the evolution of surgical techniques, the availability of active systemic treatments and the widespread diffusion of experienced multidisciplinary boards to manage these patients. However, disease relapse after liver surgery is common and occurs in two-thirds of resected patients. Therefore, adequate radiological staging and risk stratification is crucial for the optimal selection of patients candidate to surgery in order to maximize the benefit-risk ratio of liver metastasectomy and to individualize the treatment strategy. Based on the multidimensional assessment, three possible approaches are available: upfront liver surgery followed by adjuvant chemotherapy, perioperative chemotherapy preceding and following liver surgery, and an upfront systemic treatment including chemotherapy plus a targeted agent, both chosen according to patients' and tumours' characteristics, then followed by liver surgery if indicated. In this review, we describe the most important factors impacting the therapeutic choices in patients with resectable and potentially resectable CRLM, and we discuss the most promising factors that may reshape the future decision-making process of these patients.

Dynamic liquid biopsy components as predictive and prognostic biomarkers in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. The diagnosis, prognosis and therapeutic monitoring of CRC depends largely on tissue biopsy. However, due to tumor heterogeneity and limitations such as invasiveness, high cost and limited applicability in longitudinal monitoring, liquid biopsy has gathered immense attention in CRC. Liquid biopsy has several advantages over tissue biopsy including ease of sampling, effective monitoring, and longitudinal assessment of treatment dynamics. Furthermore, the importance of liquid biopsy is signified by approval of several liquid biopsy assays by regulatory bodies indicating the powerful approach of liquid biopsy for comprehensive CRC screening, diagnostic and prognostics. Several liquid biopsy biomarkers such as novel components of the microbiome, non-coding RNAs, extracellular vesicles and circulating tumor DNA are extensively being researched for their role in CRC management. Majority of these components have shown promising results on their clinical application in CRC including early detection, observe tumor heterogeneity for treatment and response, prediction of metastases and relapse and detection of minimal residual disease. Therefore, in this review, we aim to provide updated information on various novel liquid biopsy markers such as a) oral microbiota related bacterial network b) gut microbiome-associated serum metabolites c) PIWI-interacting RNAs (piRNAs), microRNA(miRNAs), Long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and d) circulating tumor DNAs (ctDNA) and circulating tumor cells (CTC) for their role in disease diagnosis, prognosis, treatment monitoring and their applicability for personalized management of CRC.

Variant allele frequency in baseline circulating tumour DNA to measure tumour burden and to stratify outcomes in patients with RAS wild-type metastatic colorectal cancer: a translational objective of the Valentino study

INTRODUCTION

In patients with metastatic colorectal cancer (mCRC), baseline circulating tumour DNA (ctDNA) variant allele fraction (VAF) might serve as a surrogate of disease burden and should be evaluated in comparison with CEA and RECIST-defined sum of target lesions.

METHODS

In this pre-planned analysis of the VALENTINO trial, we included patients with RAS wild-type mCRC receiving upfront FOLFOX/panitumumab with available baseline liquid biopsy. CtDNA was analysed by means of a 14-gene NGS panel. For each patient, the gene with the highest VAF in ctDNA was selected.

RESULTS

The final cohort included 135 patients. The median VAF was 12.6% (IQR: 2.0-45.2%). Higher VAF was observed in patients with liver metastases and with synchronous metastases presentation. Patients with high VAF had poorer median OS compared to those with low VAF (21.8 vs 36.5 months; HR: 1.82, 95%CI: 1.20-2.76; p = 0.005). VAF outperformed baseline CEA and target lesion diameter in the prognostic stratification and remained significantly correlated with OS (p = 0.003) in a multivariate model. VAF was not significantly correlated with dimensional response and PFS.

CONCLUSION

CtDNA measured by VAF is prognostic in patients with RAS wild-type mCRC. Response and PFS after an anti-EGFR-based first-line strategy are independent from initial tumour burden.

Circulating DNA in patients undergoing loco-regional treatment of colorectal cancer metastases: a systematic review and meta-analysis

Background

Loco-regional treatment strategies of colorectal cancer (CRC) metastases are evolving, but biological markers that can benefit patients and assist physicians in clinical decisions are lacking. The primary objective of this systematic review and meta-analysis is to investigate the current knowledge on circulating DNA and its clinical utility in predicting outcomes in patients undergoing loco-regional treatment of CRC metastases.

Methods

A systematic search of PubMed, Embase, and Cochrane Central Register of Controlled Trials was conducted on March 22, 2022. We included studies on patients undergoing loco-regional treatment of CRC metastases reporting the predictive or prognostic value of circulating DNA in the blood. Hazard ratios (HR) were pooled in separate random-effects meta-analyses to investigate if pre- or post-ablation measurements of circulating DNA were associated with survival. The risk of bias was assessed according to the Quality in Prognosis Studies tool.

Results

Twenty-eight studies with 2868 patients were included, of which 16 studies were eligible for meta-analyses. As expected in this new research field, a majority of included studies (n = 21/28) had a high risk of bias in at least one domain. Circulating DNA above the cutoff in a plasma sample taken before loco-regional treatment was associated with a short recurrence-free survival [pooled HR = 2.8, 95% confidence interval (CI) 1.4-5.7, n = 162] and overall survival (pooled HR = 4.7, 95% CI 1.1-20.6, n = 105). Circulating DNA above the cutoff in a plasma sample taken after loco-regional treatment was associated with a short recurrence-free survival (pooled HR = 4.5, 95% CI 3.4-6.1, n = 569) and overall survival (pooled HR = 7.5, 95% CI 2.0-27.3, n = 161). There was limited data on the association between dynamics in circulating DNA and outcome.

Conclusions

Measurements of circulating DNA can be valuable when selecting and monitoring patients undergoing loco-regional treatment of CRC metastases. Studies designed to investigate the true clinical utility of circulating DNA in the context of various ablation modalities are warranted.The review has been registered at PROSPERO (ID: CRD42022320032).

Circulating tumor cells: biology and clinical significance

Circulating tumor cells (CTCs) are tumor cells that have sloughed off the primary tumor and extravasate into and circulate in the blood. Understanding of the metastatic cascade of CTCs has tremendous potential for the identification of targets against cancer metastasis. Detecting these very rare CTCs among the massive blood cells is challenging. However, emerging technologies for CTCs detection have profoundly contributed to deepening investigation into the biology of CTCs and have facilitated their clinical application. Current technologies for the detection of CTCs are summarized herein, together with their advantages and disadvantages. The detection of CTCs is usually dependent on molecular markers, with the epithelial cell adhesion molecule being the most widely used, although molecular markers vary between different types of cancer. Properties associated with epithelial-to-mesenchymal transition and stemness have been identified in CTCs, indicating their increased metastatic capacity. Only a small proportion of CTCs can survive and eventually initiate metastases, suggesting that an interaction and modulation between CTCs and the hostile blood microenvironment is essential for CTC metastasis. Single-cell sequencing of CTCs has been extensively investigated, and has enabled researchers to reveal the genome and transcriptome of CTCs. Herein, we also review the clinical applications of CTCs, especially for monitoring response to cancer treatment and in evaluating prognosis. Hence, CTCs have and will continue to contribute to providing significant insights into metastatic processes and will open new avenues for useful clinical applications.

Circulating tumor cells in colorectal cancer in the era of precision medicine

Colorectal cancer (CRC) is one of the main causes of cancer-related morbidity and mortality across the globe. Although serum biomarkers such as carcinoembryonic antigen (CEA) and carbohydrate antigen 19–9 (CA-199) have been prevalently used as biomarkers in various cancers, they are neither very sensitive nor highly specific. Repeated tissue biopsies at different times of the disease can be uncomfortable for cancer patients. Additionally, the existence of tumor heterogeneity and the results of local biopsy provide limited information about the overall tumor biology. Against this backdrop, it is necessary to look for reliable and noninvasive biomarkers of CRC. Circulating tumor cells (CTCs), which depart from a primary tumor, enter the bloodstream, and imitate metastasis, have a great potential for precision medicine in patients with CRC. Various efficient CTC isolation platforms have been developed to capture and identify CTCs. The count of CTCs, as well as their biological characteristics and genomic heterogeneity, can be used for the early diagnosis, prognosis, and prediction of treatment response in CRC. This study reviewed the existing CTC isolation techniques and their applications in the clinical diagnosis and treatment of CRC. The study also presented their limitations and provided future research directions.

Detection and clinical significance of circulating tumor cells in colorectal cancer

Histopathological examination (biopsy) is the "gold standard" for the diagnosis of colorectal cancer (CRC). However, biopsy is an invasive method, and due to the temporal and spatial heterogeneity of the tumor, a single biopsy cannot reveal the comprehensive biological characteristics and dynamic changes of the tumor. Therefore, there is a need for new biomarkers to improve CRC diagnosis and to monitor and treat CRC patients. Numerous studies have shown that "liquid biopsy" is a promising minimally invasive method for early CRC detection. A liquid biopsy mainly samples circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), microRNA (miRNA) and extracellular vesicles (EVs). CTCs are malignant cells that are shed from the primary tumors and/or metastases into the peripheral circulation. CTCs carry information on both primary tumors and metastases that can reflect dynamic changes in tumors in a timely manner. As a promising biomarker, CTCs can be used for early disease detection, treatment response and disease progression evaluation, disease mechanism elucidation, and therapeutic target identification for drug development. This review will discuss currently available technologies for plasma CTC isolation and detection, their utility in the management of CRC patients and future research directions.

Current and Emerging Applications of Droplet Digital PCR in Oncology: An Updated Review

In the era of personalized medicine and targeted therapies for the management of patients with cancer, ultrasensitive detection methods for tumor genotyping, such as next-generation sequencing or droplet digital polymerase chain reaction (ddPCR), play a significant role. In the search for less invasive strategies for diagnosis, prognosis and disease monitoring, the number of publications regarding liquid biopsy approaches using ddPCR has increased substantially in recent years. There is a long list of malignancies in which ddPCR provides a reliable and accurate tool for detection of nucleic acid-based markers derived from cell-free DNA, cell-free RNA, circulating tumor cells, extracellular vesicles or exosomes when isolated from whole blood, plasma and serum, helping to anticipate tumor relapse or unveil intratumor heterogeneity and clonal evolution in response to treatment. This updated review describes recent developments in ddPCR platforms and provides a general overview about the major applications of liquid biopsy in blood, including its utility for molecular response and minimal residual disease monitoring in hematological malignancies or the therapeutic management of patients with colorectal or lung cancer, particularly for the selection and monitoring of treatment with tyrosine kinase inhibitors. Although plasma is the main source of genetic material for tumor genomic profiling, liquid biopsy by ddPCR is being investigated in a wide variety of biologic fluids, such as cerebrospinal fluid, urine, stool, ocular fluids, sputum, saliva, bronchoalveolar lavage, pleural effusion, mucin, peritoneal fluid, fine needle aspirate, bile or pancreatic juice. The present review focuses on these "alternative" sources of genetic material and their analysis by ddPCR in different kinds of cancers.