Fragmentation patterns of cell-free DNA and somatic mutations in the urine of metastatic breast cancer patients

BACKGROUND

Urinary cell-free deoxyribonucleic acid (DNA) (ucfDNA) holds promise as a biomarker; however, its potential remains largely unexplored. We examined the fragmentation pattern of ucfDNA and identified somatic mutations within urine samples from metastatic breast cancer (MBC) patients.

METHODS

Urine and blood specimens were collected before treatment from 45 MBC patients and posttreatment urine samples from 16 of the 45 patients at the China National Cancer Center. Somatic mutations and tumor mutational burden (TMB) in the urine and plasma of 10 patients were analyzed by next-generation sequencing (NGS). Fragmentation patterns of cfDNA were displayed using electropherograms. Differences in the extracted amount of cfDNA, length of cfDNA fragments, and TMB between urine and plasma were compared using a Wilcoxon test.

RESULTS

The fragmentation patterns of ucfDNA were categorized as follows: (1) profile A (n = 26) containing a short peak (100-200 bp) and a long peak (>1500 bp); (2) profile B (n = 8) containing only a long peak; and (3) profile C (n = 11) containing flat pattern. For profile A patients, the short-peaked ucfDNA circulating in the bloodstream was much shorter compared with plasma cfDNA (149 vs. 171 bp, Wilcoxon test, P = 0.023). The fragmentation patterns in lung metastasis patients exhibited a higher propensity toward profile C ( P = 0.002). After treatment, 87.5% of the patients exhibited consistent fragmentation patterns. The concordance rate for somatic mutations in the plasma and urine was 30%, and the median TMB of urine and plasma was not significantly different.

CONCLUSIONS

This study established a fragmentation pattern for ucfDNA and detected somatic mutations in the urine of MBC patients. These results suggest the potential application of ucfDNA as a biomarker for MBC.

Monitoring of urothelial cancer disease status after treatment by digital droplet PCR liquid biopsy assays

OBJECTIVES

Real-time monitoring of disease status would be beneficial for timely decision making in the treatment of urothelial cancer (UC), and may accelerate the evaluation of clinical trials. Use of cell free tumor DNA (cftDNA) as a biomarker in liquid biopsy is minimally invasive and its successful use has been reported in various cancer types, including UC. The objective of this study was to evaluate the use of digital droplet PCR (ddPCR)-based assays to monitor UC after treatment.

METHOD AND MATERIALS

Blood, urine and matching formalin fixed, paraffin embedded diagnostic specimens were collected from 20 patients diagnosed with stage T1 (n = 2) and T2/T3 (n = 18) disease. SNaPshot assays, Sanger sequencing and whole exome sequencing were used to identify tumor-specific mutations, and somatic mutation status was confirmed using patient-matched DNAs extracted from buffy coats and peripheral blood mononucleocytes. The ddPCR assays of the tumor-specific mutations were used to detect the fractional abundance of cftDNA in plasma and urine.

RESULTS

SNaPshot and Sanger sequencing identified point mutations in 70% of the patients that were assayable by ddPCR. Cases of remission and relapse monitored by assays for PIK3CA E542K and TP53 Y163C mutations in plasma and urine concurred with clinical observations up to 48 months from the start of chemotherapy. A new ddPCR assay for the telomerase reverse transcriptase (TERT) promoter (-124) mutation was developed. The TERT assay was able to detect mutations in cases below the limit of detection by SNaPshot. Whole exome sequencing identified a novel mutation, CNTNAP4 G727*. A ddPCR assay designed to detect this mutation was able to distinguish mutant from wild-type alleles.

CONCLUSIONS

The study demonstrated that ddPCR assays could be used to detect cftDNA in liquid biopsy monitoring of the post-therapy disease status in patients with UC. Overall, 70% of the patients in our study harbored mutations that were assayable by ddPCR.

Urine biopsy technologies: Cancer and beyond

Since the discovery of circulating tumor cells in 1869, technological advances in the study of biomarkers from liquid biopsy have made it possible to diagnose disease in a less invasive way. Although blood-based liquid biopsy has been used extensively for the detection of solid tumors and immune diseases, the potential of urine-based liquid biopsy has not been fully explored. Advancements in technologies for the harvesting and analysis of biomarkers are providing new opportunities for the characterization of other disease types. Liquid biopsy markers such as exfoliated bladder cancer cells, cell-free DNA (cfDNA), and exosomes have the potential to change the nature of disease management and care, as they allow a cost-effective and convenient mode of patient monitoring throughout treatment. In this review, we addressed the advancement of research in the field of disease detection for the key liquid biopsy markers such as cancer cells, cfDNA, and exosomes, with an emphasis on urine-based liquid biopsy. First, we highlighted key technologies that were widely available and used extensively for clinical urine sample analysis. Next, we presented recent technological developments in cell and genetic research, with implications for the detection of other types of diseases, besides cancer. We then concluded with some discussions on these areas, emphasizing the role of microfluidics and artificial intelligence in advancing point-of-care applications. We believe that the benefits of urine biopsy provide diagnostic development potential, which will pave opportunities for new ways to guide treatment selections and facilitate precision disease therapies.

Circulating tumor cell free DNA from plasma and urine in the clinical management of colorectal cancer

BACKGROUND

Tissue biopsy remains the conventional technique for tumor genotyping. The main limitations are it is invasive and provides only partial snapshot during disease progression. Liquid biopsy approaches via plasma and urine are possible alternatives, and the current study aims to provide comparative analyses for plasma and urine derived disease genotyping.

METHODS

Blood and urine specimens were collected from 150 individuals with metastatic colorectal cancer (mCRC). Patients had multiple metastases and advanced stages of cancer. Common genetic mutations including KRAS and BRAF genetic abnormalities were evaluated. Patients were also serially monitored and compared.

RESULTS

In all cases, plasma and urine cell free DNA were successfully recovered and were of good quality for genetic analysis. Median recovered DNA from both urine and plasma samples were higher in mCRC patients than healthy volunteers indicating disease associations. Among the identified mutations, matched tumor tissue profiles compared to results from plasma ctDNA was 92%. For urine cell free DNA, the concordance among the identified mutations was 91%. Both sample types were closely matched to reference standards of tissue biopsy and indicated good clinical utility. Serial measurements indicated trends within each patient group that was linked with disease outcome.

CONCLUSIONS

In the current study, our data indicated that both plasma and urine cell free DNA can be utilized to address possible disease progression in colorectal cancer patients. More importantly, this also provide risk stratifications that correlated to disease outcome. This can potentially aid in early clinical intervention for patients with possibly worse outcomes.

Comprehensive characterization of cell-free tumor DNA in plasma and urine of patients with renal tumors

BACKGROUND

Cell-free tumor-derived DNA (ctDNA) allows non-invasive monitoring of cancers, but its utility in renal cell cancer (RCC) has not been established.

METHODS

Here, a combination of untargeted and targeted sequencing methods, applied to two independent cohorts of patients (n = 91) with various renal tumor subtypes, were used to determine ctDNA content in plasma and urine.

RESULTS

Our data revealed lower plasma ctDNA levels in RCC relative to other cancers of similar size and stage, with untargeted detection in 27.5% of patients from both cohorts. A sensitive personalized approach, applied to plasma and urine from select patients (n = 22) improved detection to ~ 50%, including in patients with early-stage disease and even benign lesions. Detection in plasma, but not urine, was more frequent amongst patients with larger tumors and in those patients with venous tumor thrombus. With data from one extensively characterized patient, we observed that plasma and, for the first time, urine ctDNA may better represent tumor heterogeneity than a single tissue biopsy. Furthermore, in a subset of patients (n = 16), longitudinal sampling revealed that ctDNA can track disease course and may pre-empt radiological identification of minimal residual disease or disease progression on systemic therapy. Additional datasets will be required to validate these findings.

CONCLUSIONS

These data highlight RCC as a ctDNA-low malignancy. The biological reasons for this are yet to be determined. Nonetheless, our findings indicate potential clinical utility in the management of patients with renal tumors, provided improvement in isolation and detection approaches.

Monitoring Daily Dynamics of Early Tumor Response to Targeted Therapy by Detecting Circulating Tumor DNA in Urine

Purpose: Noninvasive drug biomarkers for the early assessment of tumor response can enable adaptive therapeutic decision-making and proof-of-concept studies for investigational drugs. Circulating tumor DNA (ctDNA) is released into the circulation by tumor cell turnover and has been shown to be detectable in urine.Experimental Design: We tested the hypothesis that dynamic changes in EGFR activating (exon 19del and L858R) and resistance (T790M) mutation levels detected in urine could inform tumor response within days of therapy for advanced non-small cell lung cancer (NSCLC) patients receiving osimertinib, a second-line third-generation anti-EGFR tyrosine kinase inhibitor.Results: Eight of nine evaluable NSCLC patients had detectable T790M-mutant DNA fragments in pretreatment baseline samples. Daily monitoring of mutations in urine indicated a pattern of intermittent spikes throughout week 1, suggesting apoptosis with an overall decrease in fragment numbers from baselines to day 7 preceding radiographic response assessed at 6 to 12 weeks.Conclusions: These findings suggest drug-induced tumor apoptosis within days of initial dosing. Daily sampling of ctDNA may enable early assessment of patient response and proof-of-concept studies for drug development. The modeling of tumor lysis through the day-to-day kinetics of ctDNA released into the blood and then into the urine is demonstrated in this proof-of-concept study in lung cancer patients receiving anti-EGFR tyrosine kinase inhibitors. This strategy may determine the specific clonal populations of cells which undergo apoptosis within the first week of therapy. This has important implications for developing combinational strategies to address inter- and intralesional heterogeneity and characterizing residual disease after initial drug exposure. Clin Cancer Res; 23(16); 4716-23. ©2017 AACR.