Liquid biopsies for colorectal cancer: a narrative review of ongoing clinical trials and the current use of this technology at a comprehensive cancer center
Review Article

Liquid biopsies for colorectal cancer: a narrative review of ongoing clinical trials and the current use of this technology at a comprehensive cancer center

Sacha P. Broccard1^, Ali Abbaszadeh Kasbi1, Sanjay P. Bagaria1, Jeremy Jones2, Mira Shoudry1, Emmanuel M. Gabriel1

1Section of Surgical Oncology, Mayo Clinic, Jacksonville, FL, USA; 2Division of Oncology, Mayo Clinic, Jacksonville, FL, USA

Contributions: (I) Conception and design: SP Broccard, SP Bagaria, EM Gabriel; (II) Administrative support: SP Broccard, A Abbaszadeh Kasbi, EM Gabriel; (III) Provision of study materials or patients: SP Broccard, SP Bagaria, A Abbaszadeh Kasbi, EM Gabriel; (IV) Collection and assembly of data: SP Broccard, A Abbaszadeh Kasbi; (V) Data analysis and interpretation: SP Broccard, A Abbaszadeh Kasbi, EM Gabriel; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

^ORCID: 0000-0002-1696-6542.

Correspondence to: Sacha P. Broccard, MD; Emmanuel M. Gabriel, MD, PhD. Section of Surgical Oncology, Mayo Clinic, Jacksonville, FL 32224, USA. Email: Broccard.Sacha@mayo.edu; Gabriel.Emmanuel@mayo.edu.

Objective: In this review, we summarize ongoing clinical trials involving liquid biopsies (LB) for colorectal cancer (CRC), outlining the current landscape and the future implementation of this technology. We also describe the current use of LB in CRC treatment at our institution, the Mayo Clinic Enterprise.

Background: The use of LB in CRC treatment merits close attention. Their role is being evaluated in the screening, non-intervention, intervention, and surveillance settings through many active trials. This, coupled with the technique’s rapid integration into clinical practice, creates constant evolution of care.

Methods: Review of ClinicalTrials.gov was performed identifying relevant and active trials involving LB for CRC. “Colorectal cancer” plus other terms including “liquid biopsies” and “ctDNA” were used as search terms, identifying 35 active trials.

Conclusions: LB use for the CRC is actively being investigated and requires close attention. Based on current evidence, Mayo Clinic Enterprise currently uses LB in the non-interventional, interventional and surveillance setting, but not for screening. Results of these trials may further establish the use of LB in the management of CRC.

Keywords: Liquid biopsy; colorectal cancer (CRC); clinical trial

Submitted Aug 04, 2021. Accepted for publication Nov 30, 2021.

doi: 10.21037/jgo-21-470

Introduction

In 1948, Mandel and Metais first described obtaining circulating tumor DNA (ctDNA) from the bloodstream (1). As the technology matured, ctDNA was found to correlate with disease burden. Later, following advances in prenatal testing, the use of tumor specific ctDNA to identify gene mutations was developed. Targeted and untargeted approaches allow for the identification of individual genes or genome wide analysis, respectively (2). Next-generation based high-throughput sequencing substantially reduced costs. At the same time, it generates large amounts of data with unspecified clinical utility. Machine learning and artificial intelligence offer an apparent solution because they have the capacity to analyze a large volume of individual data points provided by a single liquid biopsy (3). As ctDNA allows for mutational analysis in a minimally invasive way, without the need for resection or excision, it can be used to improve early diagnosis, prognosis, therapy monitoring (4). Tumor-uninformed testing includes NGS with probe set to evaluate the standard set of genes and report out variants. Additional sensitivity can be achieved by using methylation signatures (5,6). Conversely, tumor-informed testing involves sequencing to identify specific mutations present in an individual tumor and then testing only for specified previously identified mutations. This affords the ability to identify rare mutations per million base pairs, however new mutations are more difficult to identify compared to tumor-non informed testing (6).

With the rise of and continued move towards personalized medicine, the thirst for the implementation and routine use of these technologies in the clinical setting continues to grow. Data proving benefit of obtaining real-time tumor-specific information throughout the colorectal cancer (CRC) treatment process is not yet available. Therefore, the frequency with which ctDNA meaningfully impacts care remains largely unproven (7,8). Although, up to now, no test based on liquid biopsy is approved for monitoring the response during treatment, several studies have been demonstrated the promising role of ctDNA in monitoring of treatment response, leading to early detection of progressive disease. Accordingly, ctDNA can improve both specificity and sensitivity of monitoring response. Most studies assessing this role have focused on CRC, melanoma, breast cancer, and non-small cell lung cancer (9-12).

As there are different mechanisms by which different tumors release various amount of ctDNA into the blood, most studies have been focused on patients with metastatic cancers (13). Understanding the strengths and limitations of this technology, as well as how and when to implement it, is currently being examined in multiple ongoing trials. In this review, we focus specifically on the active clinical trials that show promise to continue pushing the forefront of ctDNA and its utility in the management of CRC. We divide the intended and desired clinical utility of ctDNA into four settings: screening, non-interventional (prognostication), interventional (treatment decision-making), and surveillance. Each of these settings can be further divided into multiple independent clinical applications. In the screening setting, ctDNA is under investigation as a tool for early detection of colorectal malignant and precancerous lesions. ctDNA is accepted as a method of detecting persistent micro-metastatic disease following definitive treatment, referred to as minimal residual disease (MRD) in some disease states but remains unproven in others. In the non-interventional setting, MRD shows promise as a tool for prognostication, while ctDNA allows identification of mutated genes such as KRAS, NRAS, BRAF, APC, when tumor tissue is not available. To evaluate MRD, ctDNA can be obtained from both plasma or urine. However, detecting ctDNA in urine less sensitive and less specific than plasma because of significantly lower levels. Thus, ctDNA may detect the micro metastasis or MRD earlier than image-based diagnosis. In the interventional setting, MRD is being evaluated to guide the use of adjuvant chemotherapy (ACT). Additionally, during active treatment ctDNA may aid in detecting therapy resistance, adjusting treatment and de-escalation. In the surveillance setting, ctDNA is being evaluated as a method of detecting recurrence. Taken together, this technique has the potential to impact care throughout the diagnosis and treatment of CRC (11,12,14,15). The purpose of this review is to outline the currently ongoing active clinical trials investigating liquid biopsies (LB) for CRC. We present the following article in accordance with the Narrative Review reporting checklist (available at https://jgo.amegroups.com/article/view/10.21037/jgo-21-470/rc).

Methods

For the identification of trials that would be discussed in this review, ClinicalTrials.gov was used. “Colorectal cancer” was used as the search term under “Condition or disease” “liquid biopsies” and “ctDNA” were used as the search terms for “Other terms”. This identified 35 trials; 7 trials were excluded either due to premature termination secondary to inadequate accrual, uncertain status, or lack of relevance with current review. This resulted in 28 trials meeting criteria for inclusion.

Results

Current clinical trials of LB in CRC

LB for screening

The following trials in Table 1 explore the use of ctDNA for CRC screening. With recent studies demonstrating promising levels of sensitivity and specificity for detecting cancerous lesions, large multisite population-based trials are currently enrolling patients. One major limitation is the inability to achieve adequate sensitivity for detecting precancerous lesions such as small adenomas. The benefit of LB for screening will likely be in high risk populations and in combination with other tools to calculate risk and determine timing for endoscopic evaluation. While LB will play a role as an addition to standard screening practices, it will likely not serve as a replacement.

Table 1

Active trails regarding LB for screening

Study Country Type/technique Summary/intervention Study protocol Accrual target Primary outcome Secondary outcome
NCT02665299 USA ctDNA LB as a screening tool in asymptomatic patients Peripheral blood draw before colonoscopy 206 Correlations between plasma ctDNA and colonoscopy Rate of CRC
Patient contacted yearly for up to
5 years to learn whether they have been found to have a dx of colon cancer
NCT03688906

AI-EMERG		 USA ctDNA, cfRNA, protein (Freenome test) LB for screening (CRC) in average risk patients and comparison to patients with CRC Blood and stool samples collected in 3 groups: 3,275 Clinical annotation of LB in patients with diagnosis of CRC or advanced adenoma n/a
Group A: patients aged 50–84 with CRC cancer or strong clinical suspicion
Group B: patients aged 50–84 undergoing screening colonoscopy
Group C: patients aged 18 or older with a diagnosis of CRC cancer or strong clinical suspicion
NCT04369053 PREEMT (CRC) USA ctDNA, cfRNA, proteins (Freenome test) LB for screening and detection of (CRC) in average risk patients who will undergo colonoscopy Detection of CRC by collecting blood samples from average-risk participants who will undergo a routine screening colonoscopy 25,000 Sensitivity and specificity of Freenome test for (CRC) detection n/a
NCT04136002 ECLIPSE USA ctDNA (LUNAR-2) LB for screening and detection of CRC in average risk Blood draw prior to the patient undergoing the standard of care colonoscopy and retrospectively compare the performance characteristics of the LUNAR-2 test with the findings of the index colonoscopy 10,000 Sensitivity and specificity for (CRC) detection PPV, NPV, sensitivity and specific of adenoma detection

LB, liquid biopsies; ctDNA, circulating tumor DNA; CRC, colorectal cancer.

Non-interventional LB (i.e., prognostication)

Eleven trials (Table 2) evaluate the pathophysiology and biochemical characteristics of ctDNA throughout CRC treatment: including surgery, chemotherapy, radiation therapy and immunotherapy. Understanding how and when to collect samples, and correlating them to different stages in treatment allows determination of their prognostic value. These trials highlight the importance of establishing institutional protocols for collecting and storing specimens as well as for multi-institutional data comparison.

Table 2

Active trails regarding non-interventional LB

Study Country Type/technique Summary/intervention Study protocol Accrual target Primary outcome Secondary outcome
NCT03776591 Norway ctDNA Compare surgical technique of open D33 vs. Lap CME for right sided CRC Patients ≤85 years with tumor localized in the right colon included. Blood samples for analysis of ctDNA/CTCs collected preoperatively, 3–10th postoperative day, at 3 months, and at each check the next five years at six months intervals. Sample times correlated to surveillance CEA and CT 218 Complications Prognostic significance of ctDNA
NCT04726800 CITCCA Norway, Sweden ctDNA Feasibility of profiling ctDNA in stage I–III CRC Blood draw before surgery (baseline), after surgery at 4–6 weeks, 3-, 6-, 12- and 24 months postoperatively to measure ctDNA in plasma 300 Rate of post-op ctDNA+, rate of ctDNA+ conversion to ctDNA-negative following surgery n/a
NCT04108481 iRE-C USA ctDNA Feasibility and safety of Y90 with immunotherapy in MCRC MSS Analyze changes in the expression profile and in levels of ctDNA in blood pre- and post- treatment with Y90-radioembolization 18 Maximum tolerated Y90 dose in combination with immunotherapy ctDNA levels pre- and post-treatment, adverse events, response rate
NCT03284684 Periop ctDNA France ctDNA Determine kinetics of perioperative ctDNA testing in CRC, breast and prostate Analyze the kinetics of perioperative circulating DNA in breast, prostate, and colon cancer 30 ctDNA concentration, ctDNA integrity, ctDNA proportion Plasma concentration of KDRA, ACTB
NCT03546569 CISMO Denmark ctDNA Determine ctDNA levels following colonic stenting in malignant

obstruction in CRC 		Base line blood samples to determine the level of ctDNA, cfDNA, and CTC are drawn prior to SEMS placement 20 ctDNA levels in relation to colonic stenting Immune response, metastatic ability of cancer cells
NCT04354064 USA ctDNA Describe ctDNA levels in solid tumors undergoing treatment Not provided 3,362 Freedom from progression Post treatment ctDNA detection, DFS, OS
NCT04491929 Denmark ctDNA Describe tumor specific mutations using ctDNA in patients undergoing Y90 for refractory MCRC Total cell free DNA level will be quantified in all samples. The samples will be analyzed for tumor specific mutations such as the KRAS, BRAF and NRAS oncogenes 30 Feasibility Response rate, PFS, OS
NCT03841799 COLON-IM France ctDNA Describe local tissue microenvironment of patients with CRC Blood and stool samples at surgery, at month 3 post surgery and at month 6 post surgery 80 Characterize local microenvironment Describe ctDNA, lymphocyte infiltrate, cytokine environment
NCT03975491 EXACT USA ctDNA Evaluate relationship between exercise

and recurrence in post treatment CRC 		Exercise intervention consists of moderate-intensity (50–70% age-predicted maximum heart rate) treadmill walking. Examine the effect of 12 week aerobic exercise on systemic inflammation, CRP, IL-6, insulin resistance quantified using an oral glucose tolerance test, and ctDNA. 60 Levels of CRP, IL-6 Proportion of ctDNA, TNF, insulin resistance
NCT03702309 LIBERATE Canada ctDNA, cfRNA Develop LB protocol Peripheral blood samples collected serially for DNA extraction for 5 years. 2,500 Collection and annotation of biospecimens n/a
NCT04853017 AMPLIFY-201 USA ctDNA Phase 1/2 safety and efficacy of adjuvant immunotherapy for NRAS mutated solid tumors with MRD Post-surgical LB will guide a molecular adjuvant treatment as follows: (I) ctDNA+ patients will receive CAPOX for 3 months; (II) ctDNA− patients will receive CAPE for 6 months but will be retested after 1 cycle, and if found ctDNA+ will be switched to CAPOX treatment 159 Maximum tolerated dose, safety, relapse compared to observation ctDNA clearance rate, relapse free survival, OS

LB, liquid biopsies; ctDNA, circulating tumor DNA; CRC, colorectal cancer; SEMS, self-expanding metal stent; MRD, minimal residual disease; CAPE, capecitabine.

Interventional LB

Ten trials (Table 3) are aimed at identifying LB as tool for guiding therapy and for triggering modifications in treatment. The growing understanding of MRD and its implications position LB to make a significant impact on adjuvant therapy. Patients receiving care at Mayo Clinic benefit from information gained with post-resection LB. Interventional LB trials constitute a growing proportion of trials, a trend that will continue as non-interventional LB trials increase our understanding of the specific relationships between malignancy and ctDNA.

Table 3

Active trials regarding interventional LB

Study Country Type/technique Summary/intervention Study protocol Accrual target Primary outcome Secondary outcome
NCT04259944 PEGASUS Italy ctDNA (LUNAR1) LB to guide the post-treatment therapy in high-risk CRC (chemo vs. targeted vs. observation) Not provided 140 Positive cases following interventional LB DFS, OS, ctDNA seroconversion
NCT04089631 CIRCULATE Germany ctDNA LB to guide the post-treatment therapy in stage II CRC (chemo vs. observation) 4 to 8 weeks after resection, the patient is randomized: ctDNA+ patients are randomized (2:1) in “chemotherapy” (with capecitabine) or “follow-up”, ctDNA− patients are randomized (1:4) in “follow-up” or “off study” (follow-up will be organized within the routine clinical practice) 4,812 DFS in ctDNA pos OS, DFS in ctDNA neg
NCT04068103 COBRA USA ctDNA (LUNAR-1) LB to guide the post-treatment therapy in patients with stage IIa CRC (chemo vs. observation) Patients are randomized to 1 of 2 arms: 1,408 Rate ctDNA clearance, RFS in ctDNA+ ctDNA prevalence following resection
Arm I (blood stored and tested for ctDNA later): patients undergo active surveillance
Arm II (blood tested for ctDNA at baseline): patients are assigned to 1 of 2 groups
Group I (ctDNA detected): patients will undergo chemotherapy
Group II (ctDNA not detected): patients undergo active surveillance
After completion of study treatment, patients are followed up at 12 months and then every 6 months for 2 years
NCT04120701 France ctDNA LB to guide the post-treatment therapy in stage II CRC (chemo vs. observation) Not provided 1,980 DFS in ctDNA+ n/a
NCT04264702 BESPOKE USA ctDNA (SIGNATERATM) LB to guide post-treatment therapy in stage II/III CRC Blood sample from patients who have undergone surgery for stage I to IV CRC are drawn. Patients will be followed for up to two years with periodic whole blood collection 1,000 Impact of ctDNA on adjuvant therapy, ctDNA detected recurrence Molecular residual disease, rate of metastatic resection
NCT03803553 USA CtDNA (LUNAR-1) LB to guide post-treatment therapy in MCRC (chemo vs. targeted vs. immune vs. observation) Patients with stage III CRC following resection assigned into 1 of 3 groups based on ctDNA results: 500 DFS for ctDNA+ receiving additional treatment compared to ctDNA+ who are observed, ctDNA clearance rate OS, DFS
ctDNA+: FOLFIRI
ctDNA+: active surveillance
ctDNA−: active surveillance
NCT02997241 CCTDRP China ctDNA Determine relationship between change in gene copies and recurrence Phase I component: predict recurrence through OncocareTM 500 Rate of treatment of chemo based on standard of care vs. with ctDNA
Phase II component: patients placed into four groups on the basis of genetic risk judged by OncocareTM and clinical risk judged by clinical routine method
NCT04775862 Saudi Arabia ctDNA LB to evaluate RAS status and guide rechallenge with anti-EGFR in advanced CRC RAS wild type and left sided primary disease receive standard chemotherapy with an anti EGFR mAb. Upon progression of disease, second line systemic chemotherapy ± anti-VEGF antibody will be given as per standard of care. With progression, patients will be enrolled into the study as per inclusion criteria, and a cfDNA blood test will be drawn, and RAS status will be examined. If RAS is wildtype, then the investigator will decide whether to re-challenge with an anti EGFR antibody, or give standard of care third line chemotherapy 60 Response rate, PFS Rate of RAS wt after progressions using ctDNA
NCT03436563 USA ctDNA Evaluate immunotherapy for MSI-H unresectable MCRC and ctDNA+ patients Patients receive M7824 IV over 1 hour on days 1 and 15. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity or for six doses in patients with detectable ctDNA following resection of all known liver metastases 74 Response rate, clearance of ctDNA PFS, OS, DFS, adverse events
NCT03765736 COLOMATE USA ctDNA LB to identify genetic mutations in MCRC or unresectable CRC Screens patients with colon or rectal cancer that has spread to other places in the body (metastatic) or cannot be removed by surgery (unresectable) for genetic mutations via blood samples for recommendation to a molecularly assigned therapy 500 Proportion of patients with actionable genomic profile n/a
NCT04670588 USA ctDNA Determine the feasibility of tumor response assessment by ctDNA in patients with locally advanced rectal cancer undergoing total neoadjuvant therapy Peripheral blood sample obtained 4 weeks before neoadjuvant therapy. For patients with 16 and 8 week therapy respectively, 3 and 2 blood samples for ctDNA are obtained. Tumor response rate assessed by ctDNA will be compared with the response rate assessed by the standard method to explore if a significant correlation exists between these two response assessment methods 30 Mean serum ctDNA concentration Response based on serum ctDNA level, and standard clinical assessments

LB, liquid biopsies; ctDNA, circulating tumor DNA; CRC, colorectal cancer.

LB for surveillance

These four trials (Table 4) depict a future role of LB in the setting of surveillance and early identification of recurrence or relapse. The consistent use over the last half century of carcinoembryonic antigen (CEA) and the acknowledged limitations of this blood test exemplify the persistent interest in blood tests with the ability identify disease prior to radiologic visualization. Tumor informed tests, using patient/tumor specific sequencing, currently play a role in surveillance at Mayo Clinic and other institutions.

Table 4

Active trails regarding LB for surveillance

Study Country Type/technique Summary/intervention Study protocol Accrual target Primary outcome Secondary outcome
NCT03883802 NeoFox Spain ctDNA Tolerability and effect

of Foxy-5 in neo-adjuvant setting for

CRC		 The level of ctDNA in plasma as a surrogate for disease recurrence in patients with Wnt-5a low colon cancer treated with Foxy-5. 100 Adverse events, ctDNA as marker for disease free period OS, DFS, RFI
NCT04084249 IMPROVE-IT2 Denmark ctDNA LB to guided post-treatment surveillance Patients with stage III or high-risk stage II assigned into two groups 254 Fraction of patient with recurrence receiving curative intent treatment OS, time to clinical recurrence
Experimental: ctDNA guided surveillance
No intervention: standard Danish follow-up program
NCT03484195 China ctDNA Evaluate the efficacy of NAC FOLFOXIRI in locally advanced colon CA Patients with locally advanced colon cancer treated with 4 cycles of neoadjuvant chemotherapy followed by surgical resection. PET-CT scanning performed before and after the neoadjuvant chemotherapy to assess SUV max changes. The ctDNA in peripheral blood before and after each cycle of neoadjuvant chemotherapy will be detected 30 Rate of tumor downstaging Relationship between ctDNA and survival, DFS, OS
NCT04046445 KISIMA-01 USA ctDNA Phase Ib for ATP128 alone or with BI 754091 for stage IV CRC MSS anti PD-1 non-responders Patients with CRC stage IV assigned in one of the following groups: 32 Safety and tolerability Detect early signal of relapse by ctDNA
Cohort 1a: 6 patients with stage IV CRC
Cohort 1b: 6 patients with stage IV MSS/MMRp CRC with progression
Cohort 2a: 5 patients with stage IV MSS/MMRp CRC with progression
Cohort 2b: 15 patients with stage IV MSS/MMRp with liver-limited CRC
Cohort 2c: 19 patients with stage IV MSS/MMRp CRC with progression
NCT03615170 China ctDNA Application of ctDNA test in the diagnosis

and treatment of patients with advanced rectal cancer		 Not provided 200 Disease free survival n/a

LB, liquid biopsies; ctDNA, circulating tumor DNA; CRC, colorectal cancer.

The current Mayo Clinic practice (16)

As there are limited publications on the actual clinical use, liquid biopsy-based technologies are far from reaching their full potential. Centers across North America, including our own, have begun integrating ctDNA to clinical practice to aid in the care of patients with CRCs. We report our institutional practice with LB as it pertains to the screening, non-interventional (prognostication), interventional (treatment decision-making), and surveillance settings. Our current standards of practice are based on interpretation of published (not ongoing) studies and are not intended to be institutional evidence-based recommendations (16).

  • In the screening setting (Table 1), Mayo Clinic does not use LB as part of routine care.
  • In the non-interventional setting (Table 2), LB is performed for patients with stage IV disease. This has potential benefits, including establishment of baseline ctDNA characteristics that may be compared to levels following treatment, correlation of ctDNA with the primary tumor characteristics, and obtaining material for analysis if tissue biopsy is not feasible.
  • In the interventional setting (Table 3), LB-guided therapy alteration is occurring at Mayo Clinic.
  • For patients with stage IV disease who are receiving systemic treatment, LB is used when disease resistance is identified radiologically and there is concern for mutation. For example, LB potentially guides discontinuation of an EGFR inhibitor when a new KRAS/RAS mutation is identified on ctDNA.
  • Post-surgical LB to evaluate MRD following resection is selectively used to identify patients who have a higher risk of recurrence. This information can occasionally help guide adjuvant therapy discussions; however, we would caution against its routine use in clinical practice until prospective trials show a benefit from early detection and treatment.

In our view, ctDNA should not be used as a decision point for de-escalation of ACT until fully studied in prospective trials given the relatively poor sensitivities for these tests (generally less than 50% sensitive for single time point). LB is provided by independent companies (e.g., Natera Inc., San Carlos, CA, USA) and is selectively used for surveillance with sequential LBs at progressive intervals in combination with traditional biochemical tests (i.e., serum CEA levels). The tests used are primarily tumor non-informed (i.e., Guardant360) at initiation and during treatment while tumor informed (i.e., Natera) are used for detecting recurrence (16).

Discussion

These active LB trials reveal the broad investigation of the many possible uses of LB as well as its pathophysiology. By breaking down the setting of LB use in current ongoing clinical trials, we can better understand the focus and desired integration of this technology. Of the 29 clinical trials, four are evaluating LBs in the screening setting, eleven are looking at non-interventional LB use, ten are focused on interventional LB, and four in the surveillance setting. Multiple recent in-depth reviews (2,16-20). have extensively outlined the potential impacts of LBs on clinical practice and the theoretical benefits of early detection, improved prognostication, ACT escalation, ACT de-escalation, LB guided ACT adjustments, and earlier identification of recurrence. Moreover, it can be used as a reliable biomarker for treatment response monitoring (21). However, the standardization of protocols and assays across institutions, has not kept up with the strong desire to include ctDNA within clinical trials or clinical care.

The National Cancer Institute’s recent publication and recommendation to address implementation barriers for the use of ctDNA in CRC merits attention (8). This NCI paper accepts ctDNA as a viable marker for MRD. For patients without tumor tissue available, recommendations state ctDNA provides reliable tumor material for analysis. They endorse next-generation sequencing-based multigene assays as the superior technique as opposed to the PCR-based assays. Noting the variability of the ctDNA assays and pre-analytical variables, the NCI stresses the importance of standardization of practices. Proactive collaboration in creating high-quality databases that allow for subsequent pooled analysis is essential for establishing clinical utility. Overall, the NCI task force simply recommends the continued evaluation of these technologies with emphasis on collaborative initiatives (8).

Though the current NCI recommendations do not entirely guide LB use, their conclusions for achieving cohesive and reproducible results are actionable. Certain settings for LB use, such as surveillance, have lower barriers for entrance into clinical practice (22,23). There are a few active LB trials that are promising across each setting. In the screening setting, AL EMERGE Trial in CRC (NCT03688906) evaluated 3,275 asymptomatic patients. Dr. Putcha et al. (24) reported 94% sensitivity and specificity rate in screening for stage I/II CRC. The follow-up trial, PREEMT CRC (NCT04369053) is actively recruiting patients with a goal of 25,000. In the non-interventional LB setting, CITCCA (Scandinavia), is one of the larger trials with a goal of 300 patients evaluating perioperative ctDNA and its role in prognostication. In the interventional LB setting, the CIRCULATE trial out of Germany randomized 4,812 patients with stage II CRC with ctDNA+ to ACT or follow-up. In the surveillance setting, the IMPROVE-IT2 trial out of Denmark randomizes CRC patients to ctDNA surveillance or standard Danish follow-up. One of the more valuable trials that is directly in line with NCI recommendations comes from Canada. Though it is not immediately impactful, the LIBERATE trial aims to establish an institution wide LB protocol.

Reimbursement plays an important role in the clinical adoption of these technologies as the evidence regarding their utility unfolds. As the evidence continues to emerge, reimbursement will likely impact the clinical adoption of these technologies. The cost, though continually dropping, must be factored into decision-making as the potential for sequential LB in numerous cancers could significantly impact the cost of cancer care. A recent JNCCN review described the specifics of ctDNA reimbursement from Medicare and more than 200 commercial payers between 2015 and 2019 (25,26). The variation in insurance policy structures, indications for testing, coverage by test type, and the documentation required for approval of testing creates an exceedingly confusing landscape for all parties involved. While ctDNA coverage has expanded from a previously near-exclusive use in NSCLC to pan-cancer use, its coverage remains significantly (27) limited. Solid tumor analysis for non-specified gene (i.e., Grardant360) was covered in 4 policies (14%) of private payers and in 4 Medicare policies. Although sequential LB throughout treatment provides more accurate and more actionable data, most payers cover one-time tests for treatment selection. Only 11% of the few payers covering any LB testing, cover sequential ctDNA testing for disease and treatment monitoring (25-27).

Conclusions

The desire to implement and benefit from LB across CRC care continues to grow. Technological innovations, including next-generation sequencing and pooled algorithmic automated analysis, combined with sequential data extraction has led to highly sensitive and specific tests. The intended use of LB throughout the diagnosis, treatment, and surveillance of CRC is actively under investigation. There is broad acceptance that ctDNA can detect MRD and these technologies are selectively being integrated into practice. Mayo Clinic currently uses ctDNA to adjust treatment in stage IV disease, to identify the low-risk stage II patients that may benefit from ACT, and selectively for surveillance. However, the lack of standardization in LB protocols—preanalytical processing, storage, and analytical methods—has prevented acceptable cross study verification. Because of this, NCI recommendations are still broad-based and call for continued collaborative evaluation of LB use. The collaboration of national databases, such as BloodPAC in North America and the European Liquid Biopsy, will be key to further the safe, effective, and clinically useful implementation of LB technologies.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://jgo.amegroups.com/article/view/10.21037/jgo-21-470/rc

Peer Review File: Available at https://jgo.amegroups.com/article/view/10.21037/jgo-21-470/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-21-470/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

  1. Mandel P, Metais P. Nuclear Acids In Human Blood Plasma. C R Seances Soc Biol Fil 1948;142:241-3. [PubMed]
  2. Alix-Panabières C, Pantel K. Liquid Biopsy: From Discovery to Clinical Application. Cancer Discov 2021;11:858-73. [Crossref] [PubMed]
  3. Cario CL, Chen E, Leong L, et al. A machine learning approach to optimizing cell-free DNA sequencing panels: with an application to prostate cancer. BMC Cancer 2020;20:820. [Crossref] [PubMed]
  4. Neumann MHD, Bender S, Krahn T, et al. ctDNA and CTCs in Liquid Biopsy - Current Status and Where We Need to Progress. Comput Struct Biotechnol J 2018;16:190-5. [Crossref] [PubMed]
  5. Luo H, Zhao Q, Wei W, et al. Circulating tumor DNA methylation profiles enable early diagnosis, prognosis prediction, and screening for colorectal cancer. Sci Transl Med 2020;12:eaax7533. [Crossref] [PubMed]
  6. Chen M, Zhao H. Next-generation sequencing in liquid biopsy: cancer screening and early detection. Hum Genomics 2019;13:34. [Crossref] [PubMed]
  7. Zhang Q, Luo J, Wu S, et al. Prognostic and Predictive Impact of Circulating Tumor DNA in Patients with Advanced Cancers Treated with Immune Checkpoint Blockade. Cancer Discov 2020;10:1842-53. [Crossref] [PubMed]
  8. Dasari A, Morris VK, Allegra CJ, et al. ctDNA applications and integration in colorectal cancer: an NCI Colon and Rectal-Anal Task Forces whitepaper. Nat Rev Clin Oncol 2020;17:757-70. [Crossref] [PubMed]
  9. Boonstra PA, Wind TT, van Kruchten M, et al. Clinical utility of circulating tumor DNA as a response and follow-up marker in cancer therapy. Cancer Metastasis Rev 2020;39:999-1013. [Crossref] [PubMed]
  10. Bratman SV, Yang SYC, Iafolla MAJ, et al. Personalized circulating tumor DNA analysis as a predictive biomarker in solid tumor patients treated with pembrolizumab. Nat Cancer 2020;1:873-81. [Crossref] [PubMed]
  11. Wang Y, Yang L, Bao H, et al. Utility of ctDNA in predicting response to neoadjuvant chemoradiotherapy and prognosis assessment in locally advanced rectal cancer: A prospective cohort study. PLoS Med 2021;18:e1003741. [Crossref] [PubMed]
  12. Li J, Jiang W, Wei J, et al. Patient specific circulating tumor DNA fingerprints to monitor treatment response across multiple tumors. J Transl Med 2020;18:293. [Crossref] [PubMed]
  13. Speicher MR, Pantel K. Tumor signatures in the blood. Nat Biotechnol 2014;32:441-3. [Crossref] [PubMed]
  14. Naidoo M, Gibbs P, Tie J. ctDNA and Adjuvant Therapy for Colorectal Cancer: Time to Re-Invent Our Treatment Paradigm. Cancers (Basel) 2021;13:346. [Crossref] [PubMed]
  15. Pellini B, Pejovic N, Feng W, et al. ctDNA MRD Detection and Personalized Oncogenomic Analysis in Oligometastatic Colorectal Cancer From Plasma and Urine. JCO Precis Oncol 2021;5. ePO. [PubMed]
  16. Gabriel E, Bagaria SP. Assessing the Impact of Circulating Tumor DNA (ctDNA) in Patients With Colorectal Cancer: Separating Fact From Fiction. Front Oncol 2018;8:297. [Crossref] [PubMed]
  17. Chakrabarti S, Xie H, Urrutia R, et al. The Promise of Circulating Tumor DNA (ctDNA) in the Management of Early-Stage Colon Cancer: A Critical Review. Cancers (Basel) 2020;12:2808. [Crossref] [PubMed]
  18. Ignatiadis M, Sledge GW, Jeffrey SS. Liquid biopsy enters the clinic - implementation issues and future challenges. Nat Rev Clin Oncol 2021;18:297-312. [Crossref] [PubMed]
  19. Osumi H, Shinozaki E, Yamaguchi K, et al. Clinical utility of circulating tumor DNA for colorectal cancer. Cancer Sci 2019;110:1148-55. [Crossref] [PubMed]
  20. Marcuello M, Vymetalkova V, Neves RPL, et al. Circulating biomarkers for early detection and clinical management of colorectal cancer. Mol Aspects Med 2019;69:107-22. [Crossref] [PubMed]
  21. Henriksen TV, Tarazona N, Reinert T, et al. Circulating tumor DNA analysis for assessment of recurrence risk, benefit of adjuvant therapy, and early relapse detection after treatment in colorectal cancer patients. J Clin Oncol 2021;39:11. [Crossref]
  22. Tie J, Cohen JD, Wang Y, et al. Circulating Tumor DNA Analyses as Markers of Recurrence Risk and Benefit of Adjuvant Therapy for Stage III Colon Cancer. JAMA Oncol 2019;5:1710-7. [Crossref] [PubMed]
  23. Tie J, Wang Y, Tomasetti C, et al. Circulating tumor DNA analysis detects minimal residual disease and predicts recurrence in patients with stage II colon cancer. Sci Transl Med 2016;8:346ra92. [Crossref] [PubMed]
  24. AI-EMERGE: Development and Validation of a Multi-analyte, Blood-based Colorectal Cancer Screening Test 2021. Available online: https://clinicaltrials.gov/ct2/show/NCT03688906
  25. Douglas MP, Gray SW, Phillips KA. Private Payer and Medicare Coverage for Circulating Tumor DNA Testing: A Historical Analysis of Coverage Policies From 2015 to 2019. J Natl Compr Canc Netw 2020;18:866-72. [Crossref] [PubMed]
  26. Felgner S, Ex P, Henschke C. Physicians' Decision Making on Adoption of New Technologies and Role of Coverage with Evidence Development: A Qualitative Study. Value Health 2018;21:1069-76. [Crossref] [PubMed]
  27. IJzerman MJ, de Boer J, Azad A, et al. Towards Routine Implementation of Liquid Biopsies in Cancer Management: It Is Always Too Early, until Suddenly It Is Too Late. Diagnostics (Basel) 2021;11:103. [Crossref] [PubMed]
Cite this article as: Broccard SP, Kasbi AA, Bagaria SP, Jones J, Shoudry M, Gabriel EM. Liquid biopsies for colorectal cancer: a narrative review of ongoing clinical trials and the current use of this technology at a comprehensive cancer center. J Gastrointest Oncol 2022;13(1):438-449. doi: 10.21037/jgo-21-470

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