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

Abstract

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.

Liquid Biopsies: Applications for Cancer Diagnosis and Monitoring

“…For example, urinary ctDNA has been detected in bladder [23,37,58] and other urothelial cancers [23]. Moreover, transrenal DNA, resulting from the clearance of bloodstream cfDNA by the kidneys, has also been detected in non-urological tumors, such as NSCLC [28] and CRC [39,52]. Notably, urinary ctDNA also presents cancer-specific mutations [23], CNVs and methylation al-terations [58] that are highly concordant with the ones found in tumor tissues [39,47,52].…”

“…Both the quantity [17,21,22,26,39,47,52] and the integrity [21,22,26] of cfDNA in circulation have shown the ability to distinguish cancer patients from healthy individuals. The total levels of cfDNA tend to be higher in cancer patients than in healthy subjects [17,21,22,26,39,47,52], and seem to increase with stage [17] and metastasis [55]. The increased concentration of cfDNA in these patients is thought to reflect the additional release of genetic material from tumor cells, but it could also be a result of the defective clearance of circulating DNA by phagocites [79].…”

“…Importantly, these (epi)genetic alterations seem to be highly concordant in blood ctDNA and in corresponding tumor tissues in a variety of cancers, including lung [17,29,42], breast [35], colorectal [17,44,50,52], pancreatic [32], liver [57], esophageal [17], gastric [6,43], and ovarian [17] cancers. In this sense, these minimallyinvasive and less risky liquid biopsies [57] could be used as an alternative to tissue biopsies in cases in which the latter cannot be performed [24,39,49] or when these do not gather enough high-quality DNA [17,39]. In fact, since 2016, non-small cell lung cancer (NSCLC) patients who are unable to provide tumor specimens can be tested for EGFR mutations in plasma, using the U.S. Food and Drug Administration (FDA)-approved cobas EGFR Mutation Test v2 [80].…”

“…Besides blood, other biofluids, such as urine [7,23,28,37,39,47,52], cerebrospinal fluid (CSF) [60], and gastric washes [54], have been shown to harbor ctDNA. Depending on the type of cancer, tumors might more closely contact with different fluids that, consequently, might contain higher ctDNA concentrations than blood [23].…”

Markers of metastatic colorectal cancer

“…Saliva has been suggested as preferable to blood in terms of technical simplicity and potential diagnostic usefulness, demonstrated for assessment of miRNA: miR-21 [22,25]. Preliminary urinary tests have also been performed, showing urinary ctDNA to be 90% concordant with tissue testing [26]. This compares favourably to blood testing and may open a new perspective in studies on CRC markers.…”