Alternative dialysis access strategies: A case report of a patient with transrenal hemodialysis catheter due to exhausted traditional routes and review of literature.

Vascular access is the primary lifeline for patients with end-stage renal disease. While arteriovenous fistulas and grafts are the conventionally favored methods for dialysis therapy, certain patients may deplete these traditional vascular access options due to various reasons. In the quest for alternatives, unconventional vascular pathways could be considered, including transhepatic, trans-lumbar and trans-renal approaches. We present a case of a 61-year-old male who exhausted all the traditional vascular access options, therefore trans-renal hemodialysis catheter placement was performed. Overall, this case highlights the challenges of securing a reliable vascular access to perform dialysis therapy and implementing unconventional methods whenever regular means are exhausted.

Transrenal DNA detection of Mycobacterium tuberculosis in patients with pulmonary tuberculosis.

Background: Multiple attempts have been made to use biological samples other than sputum to diagnose tuberculosis (TB). Sputum acid-fast bacillus (AFB) microscopy is the fastest, most straightforward, and most inexpensive method for diagnosing pulmonary TB. However, urine can be used in place of sputum owing to its various advantages, such as a noninvasive method of collection, convenient handling and storage, and minimal risk of infection in health-care workers involved in sample collection. In this study, we aimed to assess the suitability of urine as a sample to obtain transrenal DNA (trDNA) to diagnose TB. This study involved several patients with TB undergoing inpatient treatment, whose AFB microscopy showed negative inversion. Methods: Here, 51 urine samples were collected from 40 patients with TB and examined to confirm the presence of trDNA. First, we compared the efficiency of two trDNA extraction methods.An automated magnetic bead-based method and a more efficient anchoring extraction method. Statistical analyses were performed using Excel software (Microsoft Office Professional Plus 2019). Results: Although molecular diagnosis using GeneXpert yielded negative results, a peculiarity was observed. There was no significant difference between GeneXpert findings and our results nor was there any difference in the sequential trDNA samples obtained. However, even when GeneXpert results were negative, trDNA was detected in seven out of ten samples using the anchor extraction method. Conclusions: Further studies are needed to establish biomarkers for the progression of TB treatment.

Utility of cell-free transrenal DNA for the diagnosis of Tuberculous Meningitis: A proof-of-concept study.

Tuberculous Meningitis (TBM) diagnosis remains a grave challenge. We evaluated the utility of extracellular vesicles (EVs) as a source of cell-free transrenal-mycobacterial DNA (cf-Tr-MTB DNA) for TBM diagnosis from urine samples. We developed a qPCR-assay targeting a highly repetitive 36-bp sequence specific to Mycobacterium tuberculosis complex. EVs were isolated from urine samples of suspected TBM groups (n = 44) [categorized using composite reference standard as 'Definite' TBM (n = 8), 'Probable' TBM (n = 15), 'Possible' TBM (n = 21)] and 'Non-TBM' group (n = 26). cf-Tr-MTB DNA-based qPCR assay was applied to DNA isolated from EVs (EV-DNA) and EV-free-fraction (EV-free DNA). ROC-curves were generated using qPCR results of 'Definite' TBM and 'Non-TBM' category in both EV-DNA and EV-free DNA samples and cut-off values were selected to provide 100% (95%CI:69.1-100) specificity. The cf-Tr-MTB DNA assay gave a sensitivity of 54.5% (95%CI:38.8-69.6) for EV-DNA and 77.3% (95%CI:62.1-88.5) for EV-free DNA in the TBM group (n = 44). The combination of EV-DNA and EV-free DNA results (corresponding to performance cf-Tr MTB DNA assay in urine), gave an overall sensitivity of 81.8% (95%CI:67.2-91.8) in the TBM group. Our results confirmed EVs as one of the sources of cf-Tr-MTB DNA and we believe the cf-Tr-MTB DNA-based qPCR assay has a potential application for TBM diagnosis.

Trans-Renal Cell-Free Tumor DNA for Urine-Based Liquid Biopsy of Cancer.

Cancer biomarkers are a promising tool for cancer detection, personalization of therapy, and monitoring of treatment response or recurrence. "Liquid biopsy" commonly refers to minimally invasive or non-invasive sampling of a bodily fluid (i.e., blood, urine, saliva) for detection of cancer biomarkers such as circulating tumor cells or cell-free tumor DNA (ctDNA). These methods offer a means to collect frequent tumor assessments without needing surgical biopsies. Despite much progress with blood-based liquid biopsy approaches, there are limitations-including the limited amount of blood that can be drawn from a person and challenges with collecting blood samples at frequent intervals to capture ctDNA biomarker kinetics. These limitations are important because ctDNA is present at extremely low levels in plasma and there is evidence that measuring ctDNA biomarker kinetics over time can be useful for clinical prediction. Additionally, blood-based assays require access to trained phlebotomists and often a trip to a healthcare facility. In contrast, urine is a body fluid that can be self-collected from a patient's home, at frequent intervals, and mailed to a laboratory for analysis. Multiple reports indicate that fragments of ctDNA pass from the bloodstream through the kidney's glomerular filtration system into the urine, where they are known as trans-renal ctDNA (TR-ctDNA). Accumulating studies indicate that the limitations of blood based ctDNA approaches for cancer can be overcome by measuring TR-ctDNA. Here, we review current knowledge about TR-ctDNA in urine as a cancer biomarker approach, and discuss its clinical potential and open questions in this research field.

Correlation of transrenal DNA with non-small-cell lung cancer in noninvasive disease monitoring.

Background: The study aims to use noninvasive transrenal DNA in advanced non-small-cell lung cancer (NSCLC) patients for treatment monitoring and prognosis. Methods: Urine specimens were collected longitudinally for 103 late-stage NSCLC patients. Detection of targetable mutations in transrenal DNA was achieved by digital droplet PCR. Patients' overall survival outcomes were correlated with levels of transrenal DNA. Results: Corresponding patients' matched tumor results demonstrated concordance rate of 95.6% with transrenal DNA. A significant decline in levels was observed after treatment initiation. We observed changes in transrenal DNA levels to be significantly associated with survival for patients (p < 0.0001). Conclusion: Our results demonstrated strong predictive values of transrenal DNA to better identify patients with poorer survival outcomes and may further complement disease management.

Characterizing the molecular composition and diagnostic potential of Mycobacterium tuberculosis urinary cell-free DNA using next-generation sequencing.

BACKGROUND: Urine cell-free DNA (cfDNA) is an attractive target for diagnosing pulmonary Mycobacterium tuberculosis (MTB) infection, but has not been thoroughly characterized as a biomarker. METHODS: This study was performed to investigate the size and composition of urine cfDNA from tuberculosis (TB) patients with minimal bias using next-generation sequencing (NGS). A combination of DNA extraction and single-stranded sequence library preparation methods demonstrated to recover short, highly degraded cfDNA fragments was employed. Urine cfDNA from 10 HIV-positive patients with pulmonary TB and two MTB-negative controls was examined. RESULTS: MTB-derived cfDNA was identifiable by NGS from all MTB-positive patients and was absent from negative controls. MTB cfDNA was significantly shorter than human cfDNA, with median fragment lengths of ≤19-52 bp and 42-92 bp, respectively. MTB cfDNA abundance increased exponentially with decreased fragment length, having a peak fragment length of ≤19 bp in most samples. In addition, we identified a larger fraction of short human genomic cfDNA, ranging from 29 to 53 bp, than previously reported. Urine cfDNA fragments spanned the MTB genome with relative uniformity, but nucleic acids derived from multicopy elements were proportionately over-represented. CONCLUSIONS: TB urine cfDNA is a potentially powerful biomarker but is highly fragmented, necessitating special procedures to maximize its recovery and detection.

Detection of KRAS mutations in circulating tumour DNA from plasma and urine of patients with colorectal cancer.

BACKGROUND: Circulating tumour DNA (ctDNA) is very useful for purposes of cancer genetics; however, it has some limitations. Recently, ctDNA in body fluids, such as urine, sputum, and pleural effusion, has been investigated. The aim of this study was to evaluate the quantity of ctDNA derived from urine (trans-renal ctDNA) and the accuracy of KRAS mutation detection in relation to disease stage in colorectal cancer. METHODS: Urine, plasma, and tissue samples were collected from consecutively resected colorectal cancer patients. DNA was extracted from each sample and the quantity was determined. From each DNA sample, KRAS mutations were detected using droplet digital PCR. RESULTS: 200 patients participated and KRAS mutations were detected in 84 patients (42.0%) from tumour tissue. The concentration of trans-renal ctDNA (trtDNA) was significantly lower than that of plasma; however, there was no significant difference between the sensitivity using ctDNA and that using trtDNA (29.8% VS 33.3%, p = 0.62). Concordance between these two tests was only 17.5%. Combination analysis (ctDNA + trtDNA) improved the sensitivity to 53.6%, and sensitivity was significantly higher than that of corresponding single assays (p = 0.003). In early cancer stages, trtDNA had greater sensitivity for detecting KRAS mutations than ctDNA (37.7% vs. 21.3%, p = 0.047). Conversely, it was less useful for advanced cancer stages (21.7% vs. 52.2%, p = 0.07). Notably, KRAS mutations were detected using ctDNA or trtDNA in 12 of 116 (10.3%) patients who had no KRAS mutations in their tissue samples. CONCLUSIONS: trtDNA and ctDNA have equal potential and combination analysis significantly improved the sensitivity.

Diagnosing Pulmonary Tuberculosis by Using Sequence-Specific Purification of Urine Cell-Free DNA.

Transrenal urine cell-free DNA (cfDNA) is a promising tuberculosis (TB) biomarker, but is challenging to detect because of the short length (<100 bp) and low concentration of TB-specific fragments. We aimed to improve the diagnostic sensitivity of TB urine cfDNA by increasing recovery of short fragments during sample preparation. We developed a highly sensitive sequence-specific purification method that uses hybridization probes immobilized on magnetic beads to capture short TB cfDNA (50 bp) with 91.8% average efficiency. Combined with short-target PCR, the assay limit of detection was ≤5 copies of cfDNA in 10 ml urine. In a clinical cohort study in South Africa, our urine cfDNA assay had 83.7% sensitivity (95% CI: 71.0 to 91.5%) and 100% specificity (95% CI: 86.2 to 100%) for diagnosis of active pulmonary TB when using sputum Xpert MTB/RIF as the reference standard. The detected cfDNA concentration was 0.14 to 2,804 copies/ml (median 14.6 copies/ml) and was inversely correlated with CD4 count and days to culture positivity. Sensitivity was nonsignificantly higher in HIV-positive (88.2%) compared to HIV-negative patients (73.3%), and was not dependent on CD4 count. Sensitivity remained high in sputum smear-negative (76.0%) and urine lipoarabinomannan (LAM)-negative (76.5%) patients. With improved sample preparation, urine cfDNA is a viable biomarker for TB diagnosis. Our assay has the highest reported accuracy of any TB urine cfDNA test to date and has the potential to enable rapid non-sputum-based TB diagnosis across key underserved patient populations.

Metagenomic analysis of mycobacterial transrenal DNA in patients with HIV and tuberculosis coinfection.

The existence of "transrenal" DNA (tr-DNA), i.e. cell-free DNA that has distributed through the renal barrier to the urine, was first shown from a pathogen in 2000 (Botezatu et al., 2000). However, a targeted search for tr-DNA from Mycobacterium tuberculosis (MBT) started relatively recently (Cannas et al., 2008; Green et al., 2009). While other MBT cellular components found in the urine, e.g. lipoarabinomannan, have been used as an enhanced diagnostic tool, tr-DNA has the potential for strain specific identification or a more persistent biomarker during treatment of active disease. We therefore sought to identify by high-throughput next generation sequencing (NGS) MBT genome fragments in the urine of people with human immunodeficiency virus and tuberculosis (HIV-TB) co-infection living in a co-epidemic setting, and to evaluate whether these DNA targets are suitable for the development a quantitative TaqMan polymerase chain reaction with real-time detection (rt-PCR). Selection and mapping to the reference MBT genome of strain H37Rv (NC_000962) revealed 158 fragments of mycobacterial DNA with length from 19 to 44 base pairs (bp) repeated in different DNA samples. Five targets were chosen for design of rt-PCR primers and probes. Comparative analysis of the newly developed tests that were based on the results of NGS did not reveal a significant increase in sensitivity and specificity relative to the previous empirically designed targets. Howver, highly reproducible NGS reads of mycobacterial tr-DNA were obtained. rt-PCR test development suitable for more practical clinical use was likely limited by the small size of the secreted DNA fragments. It is necessary to develop further molecular approaches for the detection of mycobacterial tr-DNA or rely on NGS techniques with inherent bioinformatics requirements.

Potential use of transrenal DNA for non-invasive monitoring and prognosis of colorectal cancer.

Background: Anti-EGFR mAb are recommended treatment for metastatic colorectal cancer (mCRC). Accurate mutation profiling and disease monitoring are challenging. The current study investigates the potential use of transrenal DNA as a biomarker for disease management. Methods: Agreement between archival tissue specimens and transrenal DNA extracted from 200 post-treated mCRC patients was determined. Total DNA concentrations were measured and mutations within the KRAS and EGFR genes were profiled for each specimen. To ascertain therapy resistance; patients were serially monitored monthly. Results: Concordance measurement with matched tissues at baseline was remarkably high (92%) for EGFR and KRAS mutations. Sensitivity and specificity were 98.4% and 89.1% respectively. Newly detectable mutations for a subgroup of patients with initial wildtype characteristics were evident after 4 months of anti-EGFR mAb therapy. Survival analysis using adjusted estimates showed that patients detected by transrenal DNA for key mutations or had higher mutant DNA content had poorer outcome. Conclusion: Transrenal DNA offers new options to follow clinical treatment in mCRC. It demonstrates the ability to capture newly acquired mutations that has strong associative links to therapy resistance. Patients with these mutations fared poorly for survival outcomes and indicated possible prognostic value for transrenal DNA detection.

Whole exome sequencing analysis of urine trans-renal tumour DNA in metastatic colorectal cancer patients.

BACKGROUND: The analysis of circulating free tumour DNA (ctDNA) in blood, commonly referred as liquid biopsy, is being used to characterise patients with solid cancers. Tumour-specific genetic variants can also be present in DNA isolated from other body fluids, such as urine. Unlike blood, urine sampling is non-invasive, can be self-performed, and allows recurrent longitudinal monitoring. The features of tumour DNA that clears from the glomerular filtration barrier, named trans-renal tumour DNA (trtDNA), are largely unexplored. PATIENTS AND METHODS: Specimens were collected from 24 patients with KRAS or BRAF mutant metastatic colorectal cancer (mCRC). Driver mutations were assessed by droplet digital PCR (ddPCR) in ctDNA from plasma and trtDNA from urine. Whole exome sequencing (WES) was performed in DNA isolated from tissue, plasma and urine. RESULTS: Out of the 24 CRC cases, only four had sufficient DNA to allow WES analyses in urine and plasma. We found that tumour alterations primarily reside in low molecular weight fragments (less than 112 bp). In patients whose trtDNA was more than 2.69% of the urine derived DNA, cancer-specific molecular alterations, mutational signatures and copy number profiles identified in urine DNA are comparable with those detected in plasma ctDNA. CONCLUSIONS: With current technologies, WES analysis of trtDNA is feasible in a small fraction of mCRC patients. Tumour-related genetic information is mainly present in low molecular weight DNA fragments. Although the limited amounts of trtDNA poses analytical challenges, enrichment of low molecular weight DNAs and optimised computational tools can improve the detection of tumour-specific genetic information in urine.

Urinary measurement of circulating tumor DNA for treatment monitoring and prognosis of metastatic colorectal cancer patients.

Background Solid tumor tissue testing is the gold standard for molecular-based assays for metastatic colorectal cancer (mCRC). This poses challenges during treatment monitoring. Total DNA derived from urine specimens offers clear advantages to track the disease dynamics. Our study aims to evaluate the sensitivity for total DNA recovered from urine and its clinical relevance to mCRC. Methods KRAS mutations in urine specimens were examined in 150 mCRC patients. Baseline concordance was established to determined clinical relevance. The total DNA quantities were also prospectively examined in serial samplings during treatment. Results Analysis of the genetic mutations showed good agreement for baseline samples. Matched tumor and urine specimens' molecular profiles were observed to have 90% concordance. Comparing with healthy volunteers, we established a cutoff of 8.15 ng that demonstrated elevated total DNA levels was associated with mCRC patients (sensitivity: 90.7%; specificity: 82.0%). For patients treated with chemotherapy or anti-epidermal growth factor receptor inhibitors, DNA quantity mirrored early treatment response. Survival analysis showed that patients with sustained elevated quantities of KRAS mutations had poorer outcome. Conclusions Total urine DNA offers a viable complement for mutation profiling in mCRC patients, given the good agreement with matched tumor samples. Our study also established that this is specific based on the results from healthy individuals. Serial monitoring of total DNA levels allowed early prediction to treatment response and was effective to identify high risk patients. This is potentially useful to complement current disease management.

In Vitro Evaluation of the Occlusive Properties of the ArtVentive Endoluminal Occlusion System Occlusion Device for Transrenal Ureteral Occlusion.

PURPOSE: Current techniques for percutaneous ureteral occlusion are either technically difficult or not satisfactory because of frequent ureteral recanalization. The purpose of this in vitro study was to evaluate the occlusive properties of an "off the shelf" solution (Endoluminal Occlusion System [EOS™]; ArtVentive Medical Group, Inc., Carlsbad, CA) for transrenal ureteral occlusion. MATERIALS AND METHODS: Both 8 and 11 mm expanded polytetrafluoroethylene-covered ArtVentive EOS devices were used in 10 porcine models. Experiments were performed in explanted porcine ureters to simulate physiologic conditions. EOS devices were deployed in a midureteral position using a transrenal approach. Contrast agent (Iopamidol 300) diluted in saline solution was infused into the renal pelvis under continuous fluoroscopic guidance. Intrapelvic pressure measurements were performed until leakage, plug dislocation, or until pelvic blow out occurred. RESULTS: All EOS devices were deployed effectively and achieved prompt total ureteral occlusion. Ureteral leakage occurred with intraureteral pressures between 60 to 109 cm H2O (8 mm EOS) and between 65 and 125 cm H2O (11 mm EOS). Before leakage, tubular reflux was seen in all cases, pelvic blowout occurred in half of the cases. CONCLUSIONS: The ArtVentive EOS occlusive device is an effective tool for "off the shelf" ureteral occlusion. Both the 8 mm and the 11 mm devices fully occluded ureters at pressure levels that are to be expected in vivo.

Tracking a CAD-ALK gene rearrangement in urine and blood of a colorectal cancer patient treated with an ALK inhibitor.

BACKGROUND: Monitoring response and resistance to kinase inhibitors is essential to precision cancer medicine, and is usually investigated by molecular profiling of a tissue biopsy obtained at progression. However, tumor heterogeneity and tissue sampling bias limit the effectiveness of this strategy. In addition, tissue biopsies are not always feasible and are associated with risks due to the invasiveness of the procedure. To overcome these limitations, blood-based liquid biopsy analysis has proven effective to non-invasively follow tumor clonal evolution. PATIENTS AND METHODS: We exploited urine cell-free, trans-renal DNA (tr-DNA) and matched plasma circulating tumor DNA (ctDNA) to monitor a metastatic colorectal cancer patient carrying a CAD-ALK translocation during treatment with an ALK inhibitor. RESULTS: Using a custom next generation sequencing panel we identified the genomic CAD-ALK rearrangement and a TP53 mutation in plasma ctDNA. Sensitive assays were developed to detect both alterations in urine tr-DNA. The dynamics of the CAD-ALK rearrangement in plasma and urine were concordant and paralleled the patient's clinical course. Detection of the CAD-ALK gene fusion in urine tr-DNA anticipated radiological confirmation of disease progression. Analysis of plasma ctDNA identified ALK kinase mutations that emerged during treatment with the ALK inhibitor entrectinib. CONCLUSION: We find that urine-based genetic testing allows tracing of tumor-specific oncogenic rearrangements. This strategy could be effectively applied to non-invasively monitor tumor evolution during therapy. The same approach could be exploited to monitor minimal residual disease after surgery with curative intent in patients whose tumors carry gene fusions. The latter could be implemented without the need of patient hospitalization since urine tr-DNA can be self-collected, is stable over time and can be shipped at specified time-points to central labs for testing.

Mycobacteria-derived biomarkers for tuberculosis diagnosis.

Tuberculosis (TB) remains an escalating problem worldwide. The current diagnostic methods do not always guarantee reliable diagnosis. TB treatment is a time-consuming process that requires the use of several chemotherapeutics, to which mycobacteria are becoming increasingly resistant. This article focuses on the potential utility of biomarkers of mycobacterial origin with potential implications for TB diagnosis. Properly standardized indicators could become new diagnostic tools, improving and streamlining the identification of Mycobacterium tuberculosis infection and the implementation of appropriate therapy. These markers can also potentially provide a quick confirmation of effectiveness of new anti-mycobacterial drugs and TB vaccines, leading to a possible application in practice.

Investigation of transrenal KRAS mutation in late stage NSCLC patients correlates to disease progression.

PURPOSE: Using transrenal DNA to detect KRAS mutations in non-small cell lung cancer (NSCLC), the study addressed the clinical impact for longitudinal monitoring and prognostic value for disease outcome. METHODS: Digital droplet PCR was used to detect the mutant DNA. A total of 200 NSCLC patients were recruited with varying molecular profiles. To ascertain the specificity of transrenal DNA to accurately profile the disease, primary tissues were compared. Subsequently, serial samplings were performed at different treatment cycles to gauge the predictive value. RESULTS: Transrenal DNA was successfully detected in all 200 patients. Overall concordance rate for mutant KRAS DNA within urine specimens and primary tissue biopsies was 95% (k = 0.87; 95% CI: 0.82-0.95). Patients with positive results at baseline had lower median overall survival (OS) than the wildtype group. More importantly, longitudinal monitoring of urine specimens showed an increase in the quantity of transrenal DNA, which were highly associated with disease progression and outcome. CONCLUSIONS: Our study showed a highly associative link to the patient's tumor KRAS profile. Monitoring its variations aided in stratifying patients with worse outcome. Urinary specimens that can be extracted non-invasively presents new opportunities to track patients with KRAS mutation undergoing therapy.

Comparison of MicroRNA Content in Plasma and Urine Indicates the Existence of a Transrenal Passage of Selected MicroRNAs.

MicroRNAs (miRNAs) in urine are examined as potential biomarkers. We examined the urine samples from 70 individuals (45 males, 25 females, mean age 65 years, range 20-84 years). Of the urine donors, 15 were healthy volunteers, 5 were patients with non-cancer diseases, 50 were patients with different stages of bladder cancer. To examine the spectrum of miRNAs in the cell-free fraction of urine, TaqMan Human miRNA Array Card A v.2.1 was used. A set of 30 miRNAs were found that are constantly present in urine supernatants independently of sex, age and health status of the subjects. We compared this set with miRNAs found in plasma, expressed in kidney and genito-urinary tract. Our results indicate that some miRNA could be transferred from the circulation into urine.

Hemodialysis catheter insertion using transrenal approach.

We report a patient suffering from end-stage renal disease (ESRD) because of lupus nephritis presented with exhausted vascular access after multiple arteriovenous grafts creation and hemodialysis catheters insertion. A rare percutaneous transrenal approach was finally used for the insertion of dialysis catheter. After 2 years, this hemodialysis catheter was complicated by blockage but was successfully replaced by a new catheter via the same site. Our report shows that the transrenal route of hemodialysis catheter insertion can provide a glimpse of hope for those ESRD patients with exhausted vascular access.