Role of circulating tumor DNA in the management of patients with colorectal cancer

Implementation of a MSRE ddPCR method for the detection of methylated WIF1 and NPY genes in colorectal cancer patients

BACKGROUND

Colorectal cancer is a worldwide leading cause of death accounting for high-rate mortality. Mutations in the epidermal growth factor receptor and RAS/MAPK pathways, as well as altered methylation genes profiles, have been described as molecular mechanisms promoting and sustaining tumour development and progression. Aberrant methylation is a well-known epigenetic mechanism involved in gene regulation; particularly several genes were reported as hypermethylated in CRC. Recently, it was shown that epigenetic alterations in genes such as neuropeptide y, proenkephalin and Wnt inhibitory factor 1 can be used as promising disease biomarkers. Almost all methods developed for the DNA methylation analysis combined next generation sequencing, conventional qRT-PCR or ddPCR with the prior DNA modification with sodium bisulfite.

METHODS AND RESULTS

We implemented a ddPCR method to assess the methylation status of Wnt inhibitory factor 1 and neuropeptide y using the methylation sensitive restriction enzyme approach that does not impact on DNA quality and guarantees the discrimination of DNA methylation independent of bisulfite conversion.

CONCLUSIONS

We showed that this method is robust and sensitive also allowing the monitoring of CRC disease progression when applied to circulating free DNA samples from liquid biopsies, proving to be a fast and easy to implement assay to be used for the monitoring of the methylation pattern of clinically relevant target genes.

The Position of Circulating Tumor DNA in the Clinical Management of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer type worldwide, with over 1.9 million new cases and 935,000 related deaths in 2020. Within the next decade, the incidence of CRC is estimated to increase by 60% and the mortality by 80%. One of the underlying causes of poor prognosis is late detection, with 60 to 70% of the diagnoses occurring at advanced stages. Circulating cell-free DNA (ccfDNA) is probably the most promising tool for screening, diagnosis, prediction of therapeutic response, and prognosis. More specifically, the analysis of the tumor fraction within the ccfDNA (circulating tumor DNA, ctDNA) has great potential to improve the management of CRC. The present review provides an up-to-date and comprehensive overview of the various aspects related to ctDNA detection in CRC.

Management of obstructive colon cancer: Current status, obstacles, and future directions

Approximately 10%–18% of patients with colon cancer present with obstruction at the initial diagnosis. Despite active screening efforts, the incidence of obstructive colon cancer remains stable. Traditionally, emergency surgery has been indicated to treat patients with obstructive colon cancer. However, compared to patients undergoing elective surgery, the morbidity and mortality rates of patients requiring emergency surgery for obstructive colon cancer are high. With the advancement of colonoscopic techniques and equipment, a self-expandable metal stent (SEMS) was introduced to relieve obstructive symptoms, allowing the patient’s general condition to be restored and for them undergo elective surgery. As the use of SEMS placement is growing, controversies about its application in potentially curable diseases have been raised. In this review, the short- and long-term outcomes of different treatment strategies, particularly emergency surgery vs SEMS placement followed by elective surgery in resectable, locally advanced obstructive colon cancer, are described based on the location of the obstructive cancer lesion. Controversies regarding each treatment strategy are discussed. To overcome current obstacles, a potential diagnostic method using circulating tumor DNA and further research directions incorporating neoadjuvant chemotherapy are introduced.

Practices and expectations on the use of circulating tumor DNA in colorectal cancer patients: A bi-national AGEO/AIOM/GERCOR/FFCD/FRENCH survey

BACKGROUND

Increasing evidence shows that circulating tumor DNA (ctDNA) is a valuable tool in providing molecular, prognostic, predictive and dynamic information in colorectal cancer (CRC) patients. This study aimed to make a picture of knowledge, practice, attitudes and expectations about ctDNA in CRC patients.

MATERIAL AND METHODS

An online CRC-ctdna survey was distributed from November 2019 to January 2020 to French and Italian cooperative and scientific groups of Hepato-Gastroenterologists (HGE), Medical Oncologists (MO), Radiotherapists (RT) and Digestive Surgeons (DS).

RESULTS

Overall, 307 physicians completed the survey (57% Italian; 43% French). Most of them were MO (62%) and HGE (24%). Affiliations were University Hospital (48%), Cancer Center (21%), General Hospital (21%) and Private Hospital (10%). Notably, half of respondents declared to have access to ctDNA in their daily practice. Of them, 53% uses ctDNA to assess RAS/BRAF status only, 46% for RAS/BRAF with other mutations and 1% only for other mutations. MO and HGE identified quick RAS profiling (P = 0.031) as the main reason of interest in the use of ctDNA. Physicians from University Hospitals and Cancer Centers prescribed more ctDNA (P < 0.001) and more often in house (P < 0.001). The main future expectations concerning ctDNA were to guide therapeutic strategies in metastatic (78%) and adjuvant (73%) settings, and to better/quicker profile disease at baseline (56%).

CONCLUSION

Half of participants can order ctDNA in their daily practice. Molecular profiling of metastatic patients remains the main goal of ctDNA use and ctDNA-based therapeutic strategies are an expectation for the future in both adjuvant and metastatic settings.

Human Epidermal Growth Factor Receptor 2 (HER2) in Advanced Gastric Cancer: Current Knowledge and Future Perspectives

The discovery of human epidermal growth factor receptor 2 (HER2) overexpression in 15-20% of gastric adenocarcinomas has been a key advance in the global care of this disease. Validated by the ToGA trial in the first-line setting of advanced HER2-positive (+) gastric cancer (GC), trastuzumab, an anti-HER2 monoclonal antibody (mAb), was the first therapeutic agent to significantly improve the prognosis of these patients. Since these results, many attempts have been made to improve the clinical outcomes of patients with HER2+ GC. However, all the other HER2-targeting molecules have failed to show a survival benefit in large phase III studies. The value of continuing trastuzumab after disease progression has been suggested by several retrospective studies. However, recent results of a randomized phase II trial showed no benefit from this strategy. On the other hand, novel therapeutic methods, such as immunotherapy, are emerging as new tools in the strategy of care of advanced GC, even if their benefit in the specific HER2+ population remains undetermined. Furthermore, substantial progress has been made in the understanding of the mechanisms leading to resistance to anti-HER2 therapies, and in the screening methods to detect them, thus opening new perspectives. The aim of this review was firstly to summarize the existing data on the specific strategy of care of HER2+ advanced GC, and secondly, to describe current knowledge regarding the potential mechanisms of resistance to HER2-targeting therapies. Lastly, we report the prospects for overcoming these potential obstacles, from future therapeutic strategies to new detection methods.

Evaluation of Antineoplasic Activity of Zingiber Officinale Essential Oil in the Colorectal Region of Wistar Rats

INTRODUCTION

Aberrant Crypt (AC) and Aberrant Crypt Focus (ACF) are considered pre-neoplasic lesions, ranging from hyperplasia to different degrees of dysplasia in the colon. This work aimed to evaluate and quantify the chemopreventive activity of Zingiber officinale essential oil in the colorectal region of Wistar rats.

MATERIALS AND METHODS

We extracted the essential oil from ginger rhizomes and carried out ACF induction, in rats, with 1.2 Dimethylhydrazine (DMH) at a 20 mg/kg dose. The experimental groups were GI (negative control); GII (positive induction control); GIII (DMH + essential oil); GIV (DMH +5-Florouracil) and GV (essential oil). The histological techniques used were methylene blue, hematoxylin-eosin (HE) dyeing, and immunohistochemistry (IHQ).

RESULTS

The major essential oil compounds were citral (17.25%), δ-citral (10.25%), camphene (9.55%), α-zingiberene (7.57%), nerol (6.37%) and plelandrene (6.83%). For the presence of AC or ACF, we did not observe them in GI and GV, while in GII and GIII, they were observed, in high values, in both regions, but only in the distal region, there was a significant difference between them. For GIV, for both regions, there were significant lower numbers of AC when compared to GIII. As observed, with HE, there were hyperplastic and dysplastic ACF in the proximal and distal portions of the colon. For IHQ analyses, there were positively PCNA antibody marked cells in all experimental groups. Yet, there was no significant correlation of mitotic index among them. Moreover, the results of GIII compared to GIV were very similar.

CONCLUSION

In this sense, the Zingiber officinale essential oil has good antioxidant potential because it presents a mixture of monoterpene and sesquiterpene compounds. Thus, it is able to develop a chemoprotective effect, as it presented similar results to the standard drug, showing cell proliferation control.

Recent advances in circulating nucleic acids in oncology

Circulating cell-free DNA (cfDNA) is one of the fastest growing and most exciting areas in oncology in recent years. Its potential clinical uses cover now each phase of cancer patient management care (predictive information, detection of the minimal residual disease, early detection of resistance, treatment monitoring, recurrence surveillance, and cancer early detection/screening). This review relates the recent advances in the application of circulating DNA or RNA in oncology building on unpublished or initial findings/work presented at the 10th international symposium on circulating nucleic acids in plasma and serum held in Montpellier from the 20th to the 22nd of September 2017. This year, presenters revealed their latest data and crucial observations notably in relation to (i) the circulating cell-free (cfDNA) structure and implications regarding their optimal detection; (ii) their role in the metastatic or immunological processes; (iii) evaluation of miRNA panels for cancer patient follow up; (iv) the detection of the minimal residual disease; (v) the evaluation of a screening tests for cancer using cfDNA analysis; and (vi) elements of preanalytical guidelines. This work reviews the recent progresses in the field brought to light in the meeting, as well as in the most important reports from the literature, past and present. It proposes a broader picture of the basic research and its potential, and of the implementation and current challenges in the use of circulating nucleic acids in oncology.

The Use of Circulating Tumor DNA to Monitor and Predict Response to Treatment in Colorectal Cancer

Background: Colorectal cancer is one of the most common cancers worldwide and has a high mortality rate following disease recurrence. Treatment efficacy is maximized by providing tailored cancer treatment, ideally involving surgical resection and personalized neoadjuvant and adjuvant therapies, including chemotherapy, radiotherapy and increasingly, targeted therapy. Early detection of recurrence or disease progression results in more treatable disease and is essential to improving survival outcomes. Recent advances in the understanding of tumor genetics have resulted in the discovery of circulating tumor DNA (ctDNA). A growing body of evidence supports the use of these sensitive biomarkers in detecting residual disease and diagnosing recurrence as well as enabling targeted and tumor-specific adjuvant therapies. Methods: A literature search in Pubmed was performed to identify all original articles preceding April 2019 that utilize ctDNA for the purpose of monitoring response to colorectal cancer treatment. Results: Ninety-two clinical studies were included. These studies demonstrate that ctDNA is a reliable measure of tumor burden. Studies show the utility of ctDNA in assessing the adequacy of surgical tumor clearance and changes in ctDNA levels reflect response to systemic treatments. ctDNA can be used in the selection of targeted treatments. The reappearance or increase in ctDNA, as well as the emergence of new mutations, correlates with disease recurrence, progression, and resistance to therapy, with ctDNA measurement allowing more sensitive monitoring than currently used clinical tools. Conclusions: ctDNA shows enormous promise as a sensitive biomarker for monitoring response to many treatment modalities and for targeting therapy. Thus, it is emerging as a new way for guiding treatment decisions-initiating, altering, and ceasing treatments, or prompting investigation into the potential for residual disease. However, many potentially useful ctDNA markers are available and more work is needed to determine which are best suited for specific purposes and for improving specific outcomes.

Cell-Free DNA in the Liquid Biopsy Context: Role and Differences Between ctDNA and CTC Marker in Cancer Management

Liquid biopsy is a new diagnostic concept to investigate the molecular features of solid tumors by blood, saliva, urine, and any other body fluids which show a source of potential biomarkers. In cancer patients, it is a simple and less invasive mean, representing a sustainable alternative to interrogate all tumor cells longitudinally, quantifying and characterizing the biological materials (DNAs, RNAs, proteins) which originate from cancer tissues. Circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) analysis from a simple blood draw received enormous attention for the related clinical research results. A rich scientific literature demonstrates that liquid biopsy is a valid instrument to assess the tumor biomarkers in real time and profile the cancer genotype in diagnostic and prognostic field, as well to quantify minimal residual disease, during patient follow-up. This could be a breakthrough for a companion diagnostic and personalized medicine. Liquid biopsy needs further implementation in the methodological aspects as well as cost-based assessment. The number of new molecular diagnostic assays increases day by day, but the standards for their adoption and clinical validation are still to be achieved.

A practical guide to biomarkers for the evaluation of colorectal cancer

Evaluation of microsatellite instability (MSI) of every colorectal cancer (CRC) is important for prognostic and therapeutic purposes, while molecular testing helps identify actionable targeted therapy for patients with metastatic disease. This review will discuss the biomarkers commonly encountered in the clinical evaluation of CRC, and practical issues regarding MSI screening, reporting, interpretation, molecular test indication, and specimen requirements.