Circulating Tumor DNA Testing Research Articles

Candidate molecular alterations associated with potential resistance in KRAS G12D gastrointestinal cancers.

3519 Background: KRAS G12D commonly occurs in pancreatic (PDAC) and colorectal (CRC) cancers. Though developing KRAS G12D inhibitors is pertinent, it is expected that primary and acquired resistance will limit efficacy, similar to those seen with KRAS G12C inhibitors. Here, we assessed the prevalence and outcomes of candidate mutations co-occurring with KRAS G12D in PDAC and CRC using liquid biopsy data. Methods: Patients with advanced CRC and PDAC tested with Guardant360 genomic profiling from 2020 to 2023 (~2500 & 3500 samples) were included. Candidate resistance mutations were determined based on mutations reported following KRAS G12C inhibition. Patients with advanced CRC and PDAC tested with Guardant360 at Mayo Clinic (2016-2023) (1158 & 904 samples) were assessed for overall survival (OS). Patients were divided into three groups: KRAS G12D alone, KRAS G12D with candidate resistance alterations, and KRAS G12D not detected (ND). OS was estimated using Kaplan-Meier method. Cox regression was used for multivariable survival analyses. Results: The Guardant360 database reported KRAS G12D in 16.5% of CRC and 40.2% of PDAC samples. The Table below summarizes the most frequent candidate resistance alterations co-occurring with KRAS G12Dincluding point mutations of KRASand PIK3CAand amplifications of EGFR, KRAS, BRAFand MYC. In the Mayo cohort, 8.9% of CRC and 23.5% of PDAC patients had KRAS G12D. In CRC, those with KRAS G12Dand ≥1 candidate resistance alteration had a significantly lower OS (mOS 18.7m) than KRAS G12D alone (30.9m), and ND (37.3m) ( p=0.004). The presence of concurrent candidate resistance alterations with KRAS G12D remained a poor prognostic factor with HR 2.1 (95% CI: 1.3 – 3.2, p=0.001) after adjusting for age and other patient characteristics. Similarly, in PDAC, those with KRAS G12D and ≥1 resistance mutation had significantly lower OS (mOS 8.1m) than KRAS G12D alone (10.5m) and ND (16.1m) (p<0.0001). In multivariable analyses, both KRAS G12D with candidate resistance alterations (HR 2.1, 95% CI: 1.4-3.3, p<0.001) and G12Dalone (HR 1.6; 1.3–2.0, p<0.001) were poor prognostic factors. Among patients with serial Guardant360, treatment response trended with KRAS G12D variant allele frequency. Conclusions: Circulating tumor DNA testing is a useful tool to reveal candidate molecular alterations linked to potential resistance to KRAS G12D targeting in patients with KRAS G12D gastrointestinal cancers. KRAS G12D with these concurrent molecular alterations is a poor prognostic factor in both PDAC and CRC. [Table: see text]

Pan-tumor circulating tumor DNA testing in the community oncology setting.

e14556 Background: Circulating tumor DNA (ctDNA) technology allows for monitoring the genomic profile of cancer over time non-invasively, and in a way that is more representative of existing tumor clones than tissue sampling. The clinical and research applications of this new technology are numerous, and they are potentiated through serial ctDNA testing of individual patients. It is important to identify and characterize real-world data sets that will permit the development of both ctDNA’s clinical and research applications. Methods: This is an observational study of breast, non-small cell lung cancer (NSCLC), colorectal and prostate cancer patients who had ctDNA testing in The US Oncology Network from August 2014 to August 2023. All unique ctDNA reports per patient were collected, along with the report dates and patient characteristics. Rate of change in number of unique reports per month through time was evaluated as well as frequencies of serial testing and median time lapse between diagnosis and date of first ctDNA test by cancer type. Results: Number of new unique ctDNA testing reports per month increased for The US Oncology Network from 2014 through 2018 at a rate of 0.86 (95% CI [0.70, 1.02]). From 2018 to 2023 this rate increased to 5.87 (95% CI [5.16, 6.59]) new reports per month. The total number of unique patients with one of the 4 cancer indications and at least one ctDNA test during the study time period was 10,852. The cancer indication with greatest number of patients with ctDNA testing is NSCLC with 5,503 patients, followed by breast with 2,408, and colorectal and prostate with 1,544 and 1,397 respectively. Black patients were equally represented across all 4 cancers at rates of 13.6% for colorectal, 12.7% for breast, and 12% for NSCLC and prostate. Patients over 65 made up 66% for prostate and NSCLC but only 38% and 32% for colorectal and breast respectively. Most patients presented with a single ctDNA test (n = 9482), but an important proportion presented with 2 serial ctDNA tests or more (n = 1370, 12.6%).The median time between either cancer diagnosis date or date of first visit in The Network and the date of the first ctDNA test report was 39 days for NSCLC, 1,690 days for breast, 377 days for colorectal and 772 days for prostate, and presented with a skewed, long right tailed distribution. Median times were similar for Black and White patients across all cancers. Conclusions: The number of patients with ctDNA testing data available is increasing through time without evidence of plateauing. Although the total number of patients represented is still a very small fraction of the total patient population, the rate of increase in number of new reports through time is equivalent to an exponential increase in the total number of reports. 12.6% of patients presented with two tests or more, potentially allowing for pre and post treatment assessments. There’s an opportunity to better align cancer research and cancer treatment paradigms with this new technology.

Quality and Accessibility of Liquid Biopsy Information

This cross-sectional study evaluates the information on a circulating tumor DNA test available to the public on popular internet resources.

Budget Impact Analysis of Circulating Tumor DNA Testing for Colon Cancer in Commercial Health and Medicare Advantage Plans

In a randomized clinical trial, treatment guided by tumor-informed circulating tumor (ct)DNA testing reduced adjuvant chemotherapy use without compromising recurrence-free survival in patients with stage II colon cancer. The potential effects of adopting ctDNA testing into routine patient care is unknown. To compare the total cost of patient care scenarios with and without the adoption of ctDNA testing. This budget impact analysis was conducted from the perspectives of US commercial health and Medicare Advantage payers. A decision-analytical model was populated with age-specific incidence of colon cancer, use of adjuvant chemotherapy, and use of single-agent or multiagent regimens. Total cost was estimated with the costs of ctDNA testing, drug acquisition, administration, surveillance, and adverse events. The analysis was conducted from September 2023 to January 2024. The adoption of ctDNA testing. The incremental cost in the first year following the adoption of ctDNA testing, where testing will affect patient treatment and costs. In hypothetical plans with 1 million individuals covered, 35 commercial health plan members and 102 Medicare Advantage members aged 75 years and younger were eligible for ctDNA testing. In the base case with a 50% adoption rate, total cost savings were $221 684 (equivalent to $0.02 per member per month [PMPM]) for a commercial payer and $116 720 (equivalent to $0.01 PMPM) for a Medicare Advantage payer. Cost savings were robust to variations in assumptions of all parameters in the commercial population but sensitive to variations in assumptions of adjuvant chemotherapy use rates in the Medicare Advantage population. The number needed to test to avoid 1 patient receiving adjuvant chemotherapy was 4 in the commercial population and 10 in the Medicare Advantage population. The budget-neutral cost for ctDNA testing was $16 202 for a commercial payer and $5793 for a Medicare Advantage payer. Use of tumor-informed ctDNA testing to guide adjuvant chemotherapy in postsurgery patients with stage II colon cancer was projected to result in cost savings for both commercial and Medicare Advantage payers. Adoption of ctDNA testing is therefore advantageous from a budgetary perspective.

Abstract PO5-13-12: Personalized circulating tumor DNA testing for recurrence detection and treatment response monitoring in patients with metastatic invasive lobular carcinoma

Abstract Introduction Metastatic invasive lobular carcinoma (mILC) presents unique challenges during treatment response monitoring. A higher frequency of metastases to the bone, gastrointestinal tract, uterus, meninges, ovary, and diffuse serosal involvement is observed in mILC. The challenge with mILC is that they can be difficult to detect clinically and radiographically, and consequently clinical progression can be difficult to determine with conventional imaging modalities like CT Scans, thus precluding many patients with mILC from enrolling into clinical trials. Therefore more accurate biomarkers are needed to better assess response to treatment in real time. In this study, we demonstrate the feasibility of longitudinal ctDNA testing for treatment response monitoring in patients with mILC. Methods In this real-world study, longitudinal plasma samples (n=219) from 60 patients with mILC, treated across 52 independent clinics between 7/22/21 and 6/15/23, were analyzed. A personalized, tumor-informed ctDNA assay (SignateraTM bespoke, mPCR-NGS assay) was used for detection and quantification of ctDNA in plasma samples. Results In this cohort, the median patient age at diagnosis of metastatic disease (baseline) was 62.9 years (range: 32.2-79.7). Of the 60 patients, 41 (68%) had ER+PR+HER2-, 7 (12%) ER+PR-HER2-, 4 (7%) ER+PR+HER2+, 2 (3%) ER+PR-HER2+, 1 (2%) triple negative breast cancer; receptor status was not available for 5 (8%) patients. CDH1 (75%) and PIK3CA (42%) were observed to be the top two genes with somatic, nonsynonymous mutations. Mutations in TP53 and TBX3 were observed in 13% of patients, mutations in AKAP9, IGFN1, RBM26, and RFC3 in 10% of patients, and mutations in ESR1 in 6.7% of patients. At variant level, PIK3CA p.H1047R (22%) and RBM26 p.Q701Tfs*23 (10%) were the top two somatic variants identified. The most common CDH1 variant, p.Q23*, was found in 5% of the cases. Of the 60 patients, 37 (61.7%) were ctDNA-positive at all time points while on treatment (chemotherapy/endocrine therapy/targeted therapy) with the first time point collected at a median of 6.7 months (range: 2.5-2307 months) from baseline. Of these 37, imaging/biopsy results after baseline were available for 32 patients, 86% (27/32) of whom progressed. Thirty-two of 37 persistently ctDNA-positive patients had serial ctDNA measurements available, of which 14 (43%) had significant increase in ctDNA levels (average: 47-fold increase, standard deviation: 98) from first to last time points. At some point during their care ctDNA was detectable in all (n=51) patients with evidence of clinical progression. Of the 60 patients, 14 (23.3%) were ctDNA-negative at all time points tested. None of the 14 persistently ctDNA-negative patients had evidence of disease recurrence or progression at the time of initial testing or throughout ctDNA monitoring. The first ctDNA time point was collected at a median of 33.1 months (range: 0.68-92 months) from baseline for these patients,a median of 3 time points was tested per patient (1-12). Of the remaining 9/60 patients, 3 (33%) had sustained ctDNA clearance for a median of 46 days (range: 0-224 days) in response to treatment, and 2 (22%) were initially ctDNA-negative but turned positive 105 and 156 days later, indicating potential resistance to treatment and molecular progression. Additional 4/9 (44%) had ctDNA levels consistently low levels (average: 0.42 mean tumor molecules/mL) while on treatment for a median of 260 days (range: 217-442) and showed no evidence of progression. Conclusions ctDNA status and dynamics correlate well with clinical status of patients with mILC, as determined by conventional monitoring tools such as imaging and biopsy. Our results indicate that personalized, tumor-informed, longitudinal ctDNA testing may serve as a useful tool for detection of progression and monitoring treatment response in mILC patients. Citation Format: Steffi Oesterreich, Antony Tin, Samuel Rivero-Hinojosa, Janie Fielder, Jenifer Ferguson, Ekaterina Kalashnikova, Angel Rodriguez, Minetta Liu, Adrian Lee. Personalized circulating tumor DNA testing for recurrence detection and treatment response monitoring in patients with metastatic invasive lobular carcinoma [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-13-12.

Precision oncology, cutting the edge: a need for developing cost-based global guidelines for circulating tumor DNA testing in the climate/era of economic uncertainty

Precision oncology, cutting the edge: a need for developing cost-based global guidelines for circulating tumor DNA testing in the climate/era of economic uncertainty

Abstract 977: Germline BRCA1/2 mutations detected by circulating tumor DNA testing in breast cancer patients: A retrospective mutiinstitutional analysis

Abstract Background: The use of circulating tumor (ct) DNA testing allows to detect resistant and actionable somatic alterations and it could be associated with the incidental identification of germline mutations. An univocal variant allele frequency (VAF) threshold to distinguish germinal form somatic mutations has not been assessed yet. We aimed to correlate BRCA1/2 ctdNA detected mutations with germline mutational status to determine potential VAF cutoff. Materials and methods:We retrospectively analyzed the incidence of both somatic (s) and germinal (g) BRCA1/2 alterations in a multiinstitutional retrospective breast cancer (BC) cohort to assess the VAF threshold for the likelihood of germline mutations’ detection by ctDNA next-generation sequencing (Guardant 360) testing. Clinical variables were analyzed using descriptive analyses and receiving operating characteristic (ROC) curves were generated to determine the VAF cutoff. Results: Two hundred and fourteen patients (pts) with sBRCA1/2 mutations (including variant of uncertain significant and synonymous) detected by ctDNA testing, referred to the enrolling centers between January 2015 to May 2023 were included in the analysis. The median age at diagnosis was 50 years old (Interquartile range (IQR)43,5-61.5), 43% had a family history of cancer. Hormone receptor positive/HER2 negative was the most represented subtype (68%) followed by the HER2 positive (16%) and triple negative (16%) ones. At ctDNA baseline, 95.8% of pts had a metastatic disease; the main sites of metastases were bone (67.4%) and visceral (59.3%). Ninetyfour (43.9%) and 137 (64%) pts had a sBRCA1 and sBRCA2 alterations respectively, while 17 (7.9%) had a co-mutation in BRCA1 and BRCA2. The mean VAF value for sBRCA1 alterations was 10.1% (standard deviation (SD) 19.5%, range [0.04%-84.3%]) while for sBRCA2 alterations was 10.8% (SD 18.9%, range [0.21%-80.3%]). The germinal testing, performed per standard of care, was available for 100 pts (46.7%). Among these, 42 (42%) had at least a pathogenic variant detected. A gBRCA1 mutation was present in 11 (11%) pts while 25 (25%) had a gBRCA2 mutation. Comparing the somatic and germinal testing, 9/100 pts had a concordance for BRCA1 detection, the 2 discordant cases had both a low allele frequency sBRCA2 alterations; the concordance for BRCA2 detection was instead 100%. An optimal cutoff of 38.4% (AUC 0.98) for BRCA1 and 19.5% (AUC 0.96) for BRCA2 was assessed by ROC analysis as the likelihood of a germline meaning of a somatic mutation detected by ctDNA analysis. Conclusion: The identification of BRCA1/2 alterations in ctDNA could guide the use of germline testing. The VAF cutoff identified for the likelihood of a germinal mutation is lower than expected, suggesting that a wider population should be screened for germinal mutation with relevant impact on the therapeutic choices and family screening. Citation Format: Letizia Pontolillo, Carolina Reduzzi, Andrew A. Davis, Arielle J. Medford, Annika Putur, Lorenzo Gerratana, Katherine Clifton, Whitney L. Hensing, Marko Velimirovic, Surbhi Warrior, Mara S. Serafini, Eleonora Nicolò, Laura Munoz-Arcos, Jeannine Donahue, Charles S. Dai, Jennifer C. Keenan, Amir Behdad, William J. Gradishar, Diana Giannarelli, Emilio Bria, Cynthia X. Ma, Aditya Bardia, Massimo Cristofanilli. Germline BRCA1/2 mutations detected by circulating tumor DNA testing in breast cancer patients: A retrospective mutiinstitutional analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 977.

Abstract 6559: Clinical validity of post-surgery circulating tumor DNA testing in stage III colon cancer patients treated with adjuvant chemotherapy: The PROVENC3 study

Abstract Introduction: Surgery followed by adjuvant chemotherapy (ACT) is standard of care in stage III colon cancer. However, only 15-20% of patients benefit from ACT, as half of patients are cured by surgery, and 25-30% still experience a recurrence. Detection of circulating tumor DNA (ctDNA) after resection of the primary tumor is a strong prognostic biomarker in non-metastatic colon cancer and offers a promising approach to better stratify stage III colon cancer patients for ACT treatment decisions. Aim: The PROVENC3 study aims to determine the clinical validity of post-surgery ctDNA detection in patients with stage III colon cancer treated with ACT. Methods: Blood was collected pre-surgery, post-surgery and post-ACT for stage III colon cancer patients treated with ACT. Tumor-informed detection of ctDNA was performed through integrated whole genome sequencing (WGS) analyses of formalin-fixed paraffin-embedded tumor tissue DNA (80x), germline DNA (40x), and plasma cell-free DNA (30x). The primary outcome was time to recurrence (TTR). Results: Results from 209 patients (median follow up: 40 months) show that ctDNA-positive patients post-surgery (n=28) had a higher risk of developing a recurrence than ctDNA-negative patients (HR: 6.3, [95%CI: 3.5-11.3], P<10−8). 38% of patients with a recurrence within 3 years were ctDNA-positive post-surgery. Combination of post-surgery ctDNA status with established clinicopathological risk classification of low-risk (T1-3 and N1) and high-risk (T4 and/or N2) resulted in a 3-year cumulative recurrence risk of 82% for clinical high-risk ctDNA-positive patients compared to 7% for clinical low-risk ctDNA-negative patients (HR 28.9 [95%CI: 10.6-78.2]; P<10−10). Results from 170 patients with post-ACT blood available showed that post-ACT ctDNA-positive patients (n=24) were at a higher risk of developing a recurrence (HR 7.9 [95%CI: 3.5-15.9]; P<10−8) than ctDNA-negative patients. The patients experiencing a recurrence had higher aggregate ctDNA variant allele frequencies than patients not experiencing a recurrence post-surgery or post-ACT (P<0.001 and P<0.001, respectively). Conclusion: Post-surgery ctDNA detection by tumor-informed WGS is a strong prognostic biomarker in stage III colon cancer patients, and improves the current risk stratification. Importantly, the post-surgery ctDNA-positive patients who did not experience a recurrence were likely cured by ACT. These data enable the design of clinical practice-changing ctDNA-guided interventional trials in stage III colon cancer to personalize adjuvant treatment decisions. Citation Format: Carmen Rubio Alarcon, Andrew Georgiadis, Ingrid A. Franken, Haoyue Wang, Sietske C. van Nassau, Suzanna J. Schraa, Dave E. van der Kruijssen, Karlijn van Rooijen, Theodora C. Linders, Pien Delis-van Diemen, Maartje Alkemade, Anne Bolijn, Marianne Tijssen, Margriet Lemmens, Lana Meiqari, Steven L. Ketelaars, Adria Closa Mosquera, Miranda M. van Dongen, Mirthe Lanfermeijer, Birgit I. Lissenberg-Witte, Linda J. Bosch, Teunise Bisschop-Snetselaar, Bregje Adriaans, Amy Greer, David Riley, James R. White, Christopher Greco, Liam Cox, Jesse Fox, Kaitlin Victor, Catherine Leech, Samuel V. Angiuoli, Niels F. Kok, Cornelis J. Punt, Daan van den Broek, Miriam Koopman, Gerrit A. Meijer, Victor E. Velculescu, Jeanine M. Roodhart, Veerle M. Coupé, Mark Sausen, Geraldine R. Vink, Remond J. Fijneman. Clinical validity of post-surgery circulating tumor DNA testing in stage III colon cancer patients treated with adjuvant chemotherapy: The PROVENC3 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6559.

A scenario-drafting study to explore potential future implementation pathways of circulating tumor DNA testing in oncology.

Circulating tumor DNA (ctDNA) detection has multiple promising applications in oncology, but the road toward implementation in clinical practice is unclear. We aimed to support the implementation process by exploring potential future pathways of ctDNA testing. To do so, we studied four ctDNA-testing applications in two cancer types and elicited opinions from 30 ctDNA experts in the Netherlands. Our results showed that the current available evidence differed per application and cancer type. Tumor profiling and monitoring treatment response were found most likely to be implemented in non-small cell lung cancer (NSCLC) within 5 years. For colorectal cancer, applications of ctDNA testing were found to be at an early stage in the implementation process. Demonstrating clinical utility was found a key aspect for successful implementation, but there was no consensus regarding the evidence requirements. The next step toward implementation is to define how clinical utility of biomarkers should be evaluated. Finally, these data indicate that specific challenges for each clinical application and tumor type should be appropriately addressed in a deliberative process involving all stakeholders to ensure implementation of ctDNA testing and timely access for patients.

Associations Among Optimal Lung Cancer Treatment, Clinical Outcomes, and Health Care Utilization in Patients Who Underwent Comprehensive Genomic Profiling.

Although immune checkpoint inhibitor immunotherapies are contraindicated as first-line treatment of advanced non-small cell lung cancer (NSCLC) in patients with ALK rearrangement and EGFR mutation, many receive them. The purpose of this study was to examine the association between optimal first-line treatment in this population and clinical outcomes. Claims and genomic data from patients with advanced or metastatic NSCLC were extracted from a nationally representative GuardantINFORM dataset. Patients who had their first claim mentioning advanced or metastatic NSCLC between March 2019 and February 2020 and had ALK rearrangement or EGFR mutation detected by comprehensive genomic profiling were included in this study. Patients were classified as having received optimal or suboptimal first-line treatment. Claims were reviewed to determine real-world time to next treatment, real-world time to discontinuation, and health services utilization (emergency department, inpatient, and outpatient) in the 12 months following first-line treatment initiation. Survival analyses were conducted using Kaplan-Meier plots and Cox proportional hazard models. Health services utilization was compared between the groups using t tests and negative binomial models. Of the 359 patients included, 280 (78.0%) received optimal first-line treatment. Optimally treated patients had longer median real-world time to next treatment (11.2 vs 4.4 months; P<.01) and real-world time to discontinuation (10.4 vs 1.9 months; P<.01). The optimal group had significantly fewer emergency department presentations (0.76 vs 1.27; P<.01) and outpatient visits (22.9 vs 42.7; P<.01) than the suboptimal group but did not significantly differ in inpatient utilization. Adjusted utilization analysis yielded similar findings. Patients with NSCLC who received optimal treatment, as determined by comprehensive genomic profiling using next-generation sequencing-based circulating tumor DNA testing (Guardant360), had significantly superior clinical and utilization outcomes, reinforcing existing guidelines recommending profiling at the onset of treatment.

Serial Circulating Tumor DNA Analysis with a Tumor-Naïve Next-Generation Sequencing Panel Detects Minimal Residual Disease and Predicts Outcome in Ovarian Cancer.

In ovarian cancer, serial circulating tumor DNA testing is a highly predictive marker of patient survival, with a significantly improved recurrence detection lead time compared with conventional monitoring tools.

The Perceived Value of Liquid Biopsy: Results From a Canadian Validation Study of Circulating Tumor DNA T790M Testing—Patient’s Willingness-to-Pay: A Brief Report

IntroductionLiquid biopsy is recommended to diagnose molecular resistance to targeted therapy in patients with lung cancer. Nevertheless, not all jurisdictions provide funding and patient access. We report patients’ perceived value of liquid biopsy in targeted therapy resistance. MethodsCanadian patients participating in a national EGFR T790M liquid biopsy validation study completed structured interviews measuring perceived value and willingness-to-pay for plasma circulating tumor DNA testing as an alternative to tumor biopsy using open-ended and iterative bidding approaches. ResultsA total of 60 patients with advanced lung cancer participated with a median age of 64 years (range: 31–87 y); 69% were Asian and 45% female. All had received prior EGFR tyrosine kinase inhibitor; 17% also received chemotherapy. All patients preferred to have plasma testing over repeat tumor biopsy. In the context of the Canadian publicly funded system, patients estimated that a median of 300 (interquartile range: 150–800) Canadian dollars was a reasonable price to pay for liquid biopsy. Patients were personally willing to pay a median 100 (interquartile range: 33–350) Canadian dollars. ConclusionsIn a system that covers the cost of standard diagnostic tests, patients with lung cancer indicated high willingness-to-pay out-of-pocket for liquid biopsy in the setting of acquired targeted therapy resistance. Patients have high perceived value of plasma genotyping and prefer it to repeat tumor biopsy.

Tumor-Agnostic Circulating Tumor DNA Testing for Monitoring Muscle-Invasive Bladder Cancer

Circulating tumor DNA (ctDNA) has recently emerged as a real-time prognostic and predictive biomarker for monitoring cancer patients. Here, we aimed to ascertain whether tumor-agnostic ctDNA testing would be a feasible strategy to monitor disease progression and therapeutic response in muscle-invasive bladder cancer (MIBC) patients after radical cystectomy (RC). Forty-two MIBC patients who underwent RC were prospectively included. Blood samples from these patients were collected at different follow-up time points. Two specific mutations (TERT c.1-124C&gt;T and ATM c.1236-2A&gt;T) were analyzed in the patients’ plasma samples by droplet digital PCR to determine their ctDNA status. During a median follow-up of 21 months, 24% of patients progressed in a median of six months. ctDNA status was identified as a prognostic biomarker of tumor progression before RC and 4 and 12 months later (HR 6.774, HR 3.673, and HR 30.865, respectively; p &lt; 0.05). Lastly, dynamic changes in ctDNA status between baseline and four months later were significantly associated with patient outcomes (p = 0.045). In conclusion, longitudinal ctDNA analysis using a tumor-agnostic approach is a potential tool for monitoring MIBC patients after RC. The implementation of this testing in a clinical setting could improve disease management and patients’ outcomes.

"I just wanted more": Hereditary cancer syndromes patients' perspectives on the utility of circulating tumour DNA testing for cancer screening.

Hereditary cancer syndromes (HCS) predispose individuals to a higher risk of developing multiple cancers. However, current screening strategies have limited ability to screen for all cancer risks. Circulating tumour DNA (ctDNA) detects DNA fragments shed by tumour cells in the bloodstream and can potentially detect cancers early. This study aimed to explore patients' perspectives on ctDNA's utility to help inform its clinical adoption and implementation. We conducted a qualitative interpretive description study using semi-structured phone interviews. Participants were purposively sampled adult HCS patients recruited from a Canadian HCS research consortium. Thirty HCS patients were interviewed (n = 19 women, age range 20s-70s, n = 25 were white). Participants were highly concerned about developing cancers, particularly those without reliable screening options for early detection. They "just wanted more" than their current screening strategies. Participants were enthusiastic about ctDNA's potential to be comprehensive (detect multiple cancers), predictive (detect cancers early) and tailored (lead to personalized clinical management). Participants also acknowledged ctDNA's potential limitations, including false positives/negatives risks and experiencing additional anxiety. However, they saw ctDNA's potential benefits outweighing its limitations. In conclusion, participants' belief in ctDNA's potential to improve their care overshadowed its limitations, indicating patients' support for using ctDNA in HCS care.

Novel Clinical Tool to Estimate Risk of False-Negative KRAS Mutations in Circulating Tumor DNA Testing.

In metastatic colorectal cancer, the detection of RAS mutations by circulating tumor DNA (ctDNA) has emerged as a valid and noninvasive alternative approach to determining RAS status. However, some RAS mutations may be missed, that is, false negatives can occur, possibly compromising important treatment decisions. We propose a statistical model to assess the probability of false negatives when performing ctDNA testing for RAS. Cohorts of 172 subjects with tissue and multipanel ctDNA testing from MD Anderson Cancer Center and 146 subjects from Massachusetts General Hospital were collected. We developed a Bayesian model that uses observed frequencies of reference mutations (the maximum of APC and TP53) to provide information about the probability of KRAS false negatives. The model was alternatively trained on one cohort and tested on the other. All data were collected on Guardant assays. The model suggests that negative KRAS findings are believable when the maximum of APC and TP53 frequencies is at least 8% (corresponding posterior probability of false negative <5%). Validation studies demonstrated the ability of our tool to discriminate between false-negative and true-negative subjects. Simulations further confirmed the utility of the proposed approach. We suggest clinicians use the tool to more precisely quantify KRAS false-negative ctDNA results when at least one of the reference mutations (APC, TP53) is observed; usage may be especially important for subjects with a maximum reference frequency of <8%. Extension of the methodology to predict false negatives of other genes is possible. Additional reference genes can also be considered. Use of personal training data sets is supported. An open-source R Shiny application is available for public use.

Circulating tumour DNA testing in metastatic breast cancer: Integration with tissue testing.

Breast cancer biomarker profiling predominantly relies on tissue testing (surgical and/or biopsy samples). However, the field of liquid biopsy, particularly the analysis of circulating tumour DNA (ctDNA), has witnessed remarkable progress and continues to evolve rapidly. The incorporation of ctDNA-based testing into clinical practice is creating new opportunities for patients with metastatic breast cancer (MBC). ctDNA offers advantages over conventional tissue analyses, as it reflects tumour heterogeneity and enables multiple serial biopsies in a minimally invasive manner. Thus, it serves as a valuable complement to standard tumour tissues and, in certain instances, may even present a potential alternative approach. In the context of MBC, ctDNA testing proves highly informative in the detection of disease progression, monitoring treatment response, assessing actionable biomarkers, and identifying mechanisms of resistance. Nevertheless, ctDNA does exhibit inherent limitations, including its generally low abundance, necessitating timely blood samplings and rigorous management of the pre-analytical phase. The development of highly sensitive assays and robust bioinformatic tools has paved the way for reliable ctDNA analyses. The time has now come to establish how ctDNA and tissue analyses can be effectively integrated into the diagnostic workflow of MBC to provide patients with the most comprehensive and accurate profiling. In this manuscript, we comprehensively analyse the current methodologies employed in ctDNA analysis and explore the potential benefits arising from the integration of tissue and ctDNA testing for patients diagnosed with MBC.

Association of Circulating Tumor DNA Testing Before Tissue Diagnosis With Time to Treatment Among Patients With Suspected Advanced Lung Cancer

Liquid biopsy has emerged as a complement to tumor tissue profiling for advanced non-small cell lung cancer (NSCLC). The optimal way to integrate liquid biopsy into the diagnostic algorithm for patients with newly diagnosed advanced NSCLC remains unclear. To evaluate the use of circulating tumor DNA (ctDNA) genotyping before tissue diagnosis among patients with suspected advanced NSCLC and its association with time to treatment. This single-group nonrandomized clinical trial was conducted among 150 patients at the Princess Margaret Cancer Centre-University Health Network (Toronto, Ontario, Canada) between July 1, 2021, and November 30, 2022. Patients referred for investigation and diagnosis of lung cancer were eligible if they had radiologic evidence of advanced lung cancer prior to a tissue diagnosis. Patients underwent plasma ctDNA testing with a next-generation sequencing (NGS) assay before lung cancer diagnosis. Diagnostic biopsy and tissue NGS were performed per standard of care. The primary end point was time from referral to treatment initiation among patients with advanced nonsquamous NSCLC using ctDNA testing before diagnosis (ACCELERATE [Accelerating Lung Cancer Diagnosis Through Liquid Biopsy] cohort). This cohort was compared with a reference cohort using standard tissue genotyping after tissue diagnosis. Of the 150 patients (median age at diagnosis, 68 years [range, 33-91 years]; 80 men [53%]) enrolled, 90 (60%) had advanced nonsquamous NSCLC. The median time to treatment was 39 days (IQR, 27-52 days) for the ACCELERATE cohort vs 62 days (IQR, 44-82 days) for the reference cohort (P < .001). Among the ACCELERATE cohort, the median turnaround time from sample collection to genotyping results was 7 days (IQR, 6-9 days) for plasma and 23 days (IQR, 18-28 days) for tissue NGS (P < .001). Of the 90 patients with advanced nonsquamous NSCLC, 21 (23%) started targeted therapy before tissue NGS results were available, and 11 (12%) had actionable alterations identified only through plasma testing. This nonrandomized clinical trial found that the use of plasma ctDNA genotyping before tissue diagnosis among patients with suspected advanced NSCLC was associated with accelerated time to treatment compared with a reference cohort undergoing standard tissue testing. ClinicalTrials.gov Identifier: NCT04863924.

Postoperative circulating tumor DNA testing based on tumor naïve strategy after liver metastasis surgery in colorectal cancer patients.

There is still a lack of highly sensitive methods for monitoring recurrence of colorectal cancer patients after liver metastasis surgery. The aim of this study was to evaluate the prognostic value of tumor-naive ctDNA detection after resection of colorectal liver metastases (CRLM). Patients with resectable CRLM were prospectively enrolled. Based on the tumor-naive strategy, NGS panels containing 15 colorectal cancer hotspot mutated genes were used to detect ctDNA 3-6 weeks after surgery. A total of 67 patients were included in the study, and the positive rate of postoperative ctDNA was 77.6% (52/67). Patients with positive ctDNA had a significantly higher risk of recurrence after surgery (HR 3.596, 95% CI 1.479 to 8.744, P = 0.005), and a higher proportion relapsed within 3 months after surgery (46.7% vs 3.8%). The C-index of postoperative ctDNA in predicting recurrence was higher than that of CRS and postoperative CEA. The nomogram combining CRS and postoperative ctDNA can improve the accuracy of recurrence prediction. Tumor-naive ctDNA detection can detect molecular residual lesions in patients with colorectal cancer after liver metastasis, and its prognostic value is superior to conventional clinical factors.

High-resolution circulating tumor DNA testing predicts survival in metastatic lung cancer clinical trials.

High-resolution circulating tumor DNA testing predicts survival in metastatic lung cancer clinical trials.

Locally performed postoperative circulating tumour DNA testing performed during routine clinical care to predict recurrence of colorectal cancer.

Identifying patients at high risk for colorectal cancer recurrence is essential for improving prognosis. In the postoperative period, circulating tumour DNA (ctDNA) has been demonstrated as a significant prognostic indicator of recurrence. These results have been obtained under the strict rigours of clinical trials, but not validated in a real-world setting using in-house testing. We report the outcomes of locally performed postoperative ctDNA testing conducted during routine clinical care and the association with the recurrence of colorectal cancer. We recruited 36 consecutive patients with newly diagnosed colorectal cancer between 2018 and 2020. Postoperative plasma samples were collected at the first outpatient review following resection. Tumour-informed ctDNA analysis was performed using droplet digital polymerase chain reaction or targeted next-generation sequencing. At the time of surgery, there were 24 patients (66.7%) with localized cancer, nine (25%) with nodal spread, and three (8.3%) with metastatic disease. The median time from surgery to plasma sample donation was 22 days (IQR 20-28 days). At least one somatic mutation was identified in primary tumour tissue for 28 (77.8%) patients. Postoperative ctDNA was detected in five patients (13.9%). The median duration of follow-up was 32.0months (IQR 27.2-38.1months). Two patients (5.56%) developed metastatic recurrence. However, neither had detectable postoperative ctDNA. There were no instances of loco-regional recurrence. Analysis of postoperative ctDNA testing can be performed locally, however this study did not reproduce the adverse association between detectable postoperative ctDNA and the development of colorectal cancer recurrence seen in clinical trials.