Perioperative changes in cell-free DNA for patients undergoing surgery for colon cancer

Assessment of cfDNA release dynamics during colorectal cancer surgery

Approximately two-thirds of patients with colorectal cancer (CRC) undergo resection with curative intent; however, 30% to 50% of these patients experience recurrence. The concentration of cell-free DNA (cfDNA) before and after surgery may be related to the prognosis of patients with CRC, but there is limited information regarding cfDNA levels at the time of surgery. Here, we analyzed surgical cfDNA release using plasma samples from 30 colorectal cancer patients at three key points during surgery: preoperative (immediately before surgery), intraoperative (during surgery), and postoperative (at the end of surgery). Automated electrophoresis was used to analyze cfDNA concentrations and fragment sizes, which were then correlated with clinical variables. Our findings indicate a significant increase in cfDNA release during and after surgery (2.8- and 2.2-fold higher respectively, p < 0.01). Characteristic fragments of cfDNA (<400 bp) predominated at all surgical stages; however, the release of genomic material (>400 bp) was also observed. We found that cfDNA concentration increases during and after surgery in patients over 60 years old (2.9-fold higher intraoperatively than preoperatively and 2.3 folds higher postoperatively than preoperatively, p < 0.01); in patients with comorbidities (3.0-fold higher intraoperatively and 2.3-fold higher postoperatively, p < 0.01); and in patients with CEA levels >5 ng/mL (3.1-fold higher intraoperatively and 1.3-fold higher postoperatively, p < 0.01). Interestingly, cfDNA release during surgery is significantly higher in patients with adverse clinical characteristics. Patients bearing locally advanced tumors or metastasis had a 3.1-fold increase in cfDNA release intraoperatively and 2.4-fold increase postoperatively, p < 0.01. cfDNA concentration also increases intraoperatively in patients with a high score of tumor buds (2.6 folds higher, p < 0.02), patients with perineural invasion (3.4-fold higher, p < 0.02) and in patients with lymphovascular invasion (3.1-fold higher, p < 0.05). Furthermore, we observed that cfDNA concentration may rise in correlation with the duration of the surgery, highlighting its potential as a marker of surgical quality. Taken together, our results suggest that in addition to physiological age, comorbidities and unfavorable clinical traits, intense surgical manipulation from the tumor's extent, may result in greater tissue damage and elevated cfDNA release.

Post-surgery sequelae unrelated to disease progression and chemotherapy revealed in follow-up of patients with stage III colon cancer

BACKGROUND

We studied the poorly-known dynamics of circulating DNA (cir-nDNA), as monitored prospectively over an extended post-surgery period, in patients with cancer.

METHODS

On patients with stage III colon cancer (N = 120), using personalised molecular tags we carried out the prospective, multicenter, blinded cohort study of the post-surgery serial analysis of cir-nDNA concentration. 74 patients were included and 357 plasma samples tested.

FINDINGS

During post-operative follow-up, the patients' median cir-nDNA concentration was greater (P < 0.0001 in the [43-364 days range]) than both the median value in healthy individuals and the pre-surgery value. These cir-nDNA levels were highly associated with NETs markers (P-value associating MPO and cir-nDNA, and NE and cir-nDNA are 6.6 x 10-17, and 1.9 x 10-7), in accordance with previous reports which indicate that cir-nDNA are NETs by-products. Unexpectedly, in 34 out of 50 patients we found that NETs continued to be formed for an extended duration post-surgery, even in patients without disease progression. Given that this phenomenon was observed in patients without adjuvant CT, and in patients >18 months post-surgery, the data suggest that the persistence of NETs formation is not due to the adjuvant CT.

INTERPRETATION

(1), Given the inter-patient heterogeneity, the post-surgery cir-nDNA level cannot be considered a reliable value, and caution must be exercised when determining mutation allele frequency or the mutation status; and (2), specific studies must be undertaken to investigate the possible clinical impact of the persistent, low-grade inflammation resulting from elevated NETs levels, such as observed in these post-surgery patients, given that such levels are known to potentially induce adverse cardiovascular or thrombotic events.

FUNDING

This work was supported by the H2020 European ERA-NET grant on Translational Cancer Research (TRANSCAN-2).

DSBSO-Based XL-MS Analysis of Breast Cancer PDX Tissues to Delineate Protein Interaction Network in Clinical Samples

Protein-protein interactions (PPIs) are fundamental to understanding biological systems as protein complexes are the active molecular modules critical for carrying out cellular functions. Dysfunctional PPIs have been associated with various diseases including cancer. Systems-wide PPI analysis not only sheds light on pathological mechanisms, but also represents a paradigm in identifying potential therapeutic targets. In recent years, cross-linking mass spectrometry (XL-MS) has emerged as a powerful tool for defining endogenous PPIs of cellular networks. While proteome-wide studies have been performed in cell lysates, intact cells and tissues, applications of XL-MS in clinical samples have not been reported. In this study, we adopted a DSBSO-based in vivo XL-MS platform to map interaction landscapes from two breast cancer patient-derived xenograft (PDX) models. As a result, we have generated a PDX interaction network comprising 2,557 human proteins and identified interactions unique to breast cancer subtypes. Interestingly, most of the observed differences in PPIs correlated well with protein abundance changes determined by TMT-based proteome quantitation. Collectively, this work has demonstrated the feasibility of XL-MS analysis in clinical samples, and established an analytical workflow for tissue cross-linking that can be generalized for mapping PPIs from patient samples in the future to dissect disease-relevant cellular networks.

Bioinformatics analysis and experimental validation of tumorigenic role of PPIA in gastric cancer

Gastric cancer (GC) is a malignant tumor with high incidence rate and mortality. Due to the lack of effective diagnostic indicators, most patients are diagnosed in late stage and have a poor prognosis. An increasing number of studies have proved that Peptidylprolyl isomerase A (PPIA) can play an oncogene role in various cancer types. However, the precise mechanism of PPIA in GC is still unclear. Herein, we analyzed the mRNA levels of PPIA in pan-cancer. The prognostic value of PPIA on GC was also evaluated using multiple databases. Additionally, the relationship between PPIA expression and clinical factors in GC was also examined. We further confirmed that PPIA expression was not affected by genetic alteration and DNA methylation. Moreover, the upstream regulator miRNA and lncRNA of PPIA were identified, which suggested that LINC10232/miRNA-204-5p/PPIA axis might act as a potential biological pathway in GC. Finally, this study revealed that PPIA was negatively correlated with immune checkpoint expression, immune cell biomarkers, and immune cell infiltration in GC.

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.

Liquid biopsy for early detection and therapeutic monitoring of hepatocellular carcinoma

Advances in our knowledge of the molecular characteristics of hepatocellular carcinoma (HCC) have enabled significant progress in the detection and therapeutic prediction of HCC. As a non-invasive alternative to tissue biopsy, liquid biopsy examines circulating cellular components such as exosomes, nucleic acids, and cell-free DNA found in body fluids (e.g., urine, saliva, ascites, and pleural effusions) and provides information about tumor characteristics. Technical advances in liquid biopsy have led to the increasing adoption of diagnostic and monitoring applications for HCC. This review summarizes the various analytes, ongoing clinical trials, and case studies of United States Food and Drug Administrationapproved in vitro diagnostic applications for liquid biopsy, and provides insight into its implementation in managing HCC.