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PubMed2026

Tumor-Intrinsic Blood and Imaging Correlatives in Advanced Prostate Cancer Treated with Combination Radiopharmaceutical Therapy and Immunotherapy.

The PRINCE trial showed the clinical activity for 177Lu-PSMA-617 in combination with pembrolizumab for metastatic castration-resistant prostate cancer. To refine patient selection and improve response monitoring strategies to this combination, we investigated candidate tumor-intrinsic biomarkers of treatment response and resistance. Methods: We performed circulating tumor DNA (ctDNA), circulating tumor cell (CTC), and PET imaging analyses at baseline, 12 wk on-treatment, and disease progression in participants enrolled in PRINCE (n = 37). We performed targeted sequencing for ctDNA quantification and genomic analysis of more than 70 prostate cancer genes. CTC enumeration was performed on the EpicSciences platform and was combined with selective single-cell whole-genome sequencing. PET imaging included serial PSMA PET as well as 18F-FDG PET imaging at baseline. Results: A low baseline ctDNA fraction and high PSMA avidity in metastatic lesions were linked to superior treatment responses and may have composite biomarker value. Genomic alterations in tumor suppressor genes TP53, RB1, or PTEN were associated with higher 18F-FDG avidity and metabolic tumor volume on 18F-FDG PET imaging and worse prognosis. At 12-wk on-treatment, both ctDNA detection and PSMA PET imaging were strong indicators of response depth and durability. At disease progression, PSMA expression on PET imaging was lower compared with baseline and supported by subclonal remodeling of ctDNA and CTC copy number profiles and by clonal expansions of tumor suppressor gene mutations. Conclusion: We provide the first integrated molecular and imaging insights into determinants of response and resistance to combined radiopharmaceutical therapy and immunotherapy in prostate cancer and propose biomarker strategies to inform future clinical development.

177Lu-PSMA-617↗

PubMed2026

The role of circulating tumor DNA (ctDNA) to detect minimal residual disease in locally advanced gastroesophageal carcinoma: the BUTTERFLY study.

BACKGROUND: Despite advances in perioperative and neoadjuvant strategies, patients with locally advanced gastroesophageal cancers remain at high risk of recurrence after curative intent treatment. No validated biomarkers are available to detect minimal residual disease (MRD) or to guide post-operative risk-adapted management. Circulating tumor DNA (ctDNA) has emerged as a noninvasive tool for disease monitoring; single-parameter or tumor-informed assays, however, may lack sensitivity in low-tumor burden settings. Multimodal, tumor-agnostic approaches may overcome these limitations. METHODS: The BUTTERFLY study is a prospective, multicenter observational study enrolling patients with stage II-III gastric, gastroesophageal junction, or esophageal cancer treated with perioperative chemotherapy or neoadjuvant chemoradiotherapy followed by surgery. It evaluates the diagnostic performance and prognostic value of an academic, tumor-agnostic, multimodal ctDNA assay for MRD detection and prognostic stratification. Serial plasma samples are collected from baseline through post-operative follow-up and at relapse. Cell-free DNA is analyzed using the Agnostic Liquid Biopsy Multimodal Advancement (ALMA) platform, integrating tumor fraction estimation, somatic copy number alterations, fragmentomic features, single-nucleotide variants, and whole-genome methylation profiling. Multimodal features are combined with clinical variables using machine learning-based models to enhance MRD detection and relapse risk stratification. The primary endpoint includes sensitivity and specificity of ALMA-defined ctDNA/MRD status at the 4-8 weeks after surgery landmark, whereas secondary endpoints assess diagnostic performance at other time points and associations between ctDNA status and dynamics with disease-free survival, overall survival, treatment response, and lead time to recurrence. FUTURE PERSPECTIVES: If validated, this tumor-agnostic, multimodal ctDNA approach may enable earlier molecular relapse detection and support personalized post-operative management strategies.

circulating tumor DNA (ctDNA)↗

PubMed2026

Prospective Evaluation of Circulating Tumor DNA in Metastatic Hormone-Sensitive Prostate Cancer.

PURPOSE: There are few established prognostic biomarkers in metastatic hormone-sensitive prostate cancer (mHSPC). Disease volume and timing of metastases are prognostic and predictive factors but may be inadequate due to heterogeneity. Circulating tumor DNA (ctDNA) provides both circulating volume (tumor fraction [TF]) and genomic data. There are limited data on ctDNA in mHSPC. METHODS: This was a multicenter, prospective study of ctDNA testing in mHSPC. Presented here are the results before androgen-deprivation therapy initiation. The primary objective was to evaluate the association between TF and overall survival (OS) and time to mCRPC (TTCRPC). Secondary analyses included evaluating outcomes in subgroups of interest and key genomic subtypes. RESULTS: Between 2018 and 2024, 85 patients were enrolled, of whom 72 (25% Black) had evaluable baseline ctDNA samples and are included herein. Baseline TF was positive in 46 patients (64%). Compared with patients with negative ctDNA TF, most patients with positive ctDNA TF had de novo (87% v 39%, P < .001) and high-volume disease (80% v 46%, P = .01). At a median follow-up of 20.8 months, median OS was not reached (NR) with those with negative ctDNA TF and 33 months with positive ctDNA TF (hazard ratio [HR], 3.33 [95% CI, 1.1 to 9.9]; P = .03). However, a negative TF at baseline was associated with an undetectable 7-month prostate-specific antigen, a validated OS surrogate. Median TTCRPC was NR versus 13 months (HR, 3.43 [95% CI, 1.5 to 7.9]; P = .004). ctDNA TF was also potentially prognostic in high-volume disease and those who received doublet therapy. CONCLUSION: In this diverse cohort, a positive ctDNA TF at baseline was associated with worse outcomes in mHSPC and may potentially complement current further risk stratification tools.

Humans↗

PubMed2026

Association of ctDNA RAS mutational status and clinical benefits in first-line metastatic colorectal cancer therapy with chemotherapy plus anti-EGFR (overall response rate and progression-free survival): a brief report of systematic review and meta-analysis.

Monitoring RAS mutations in circulating tumor DNA (ctDNA) is increasingly relevant in metastatic colorectal cancer (mCRC). In patients with tissue RAS wild-type (WT) tumors treated with first-line chemotherapy plus anti-epidermal growth factor receptor therapy (1LChT + anti-EGFR), some studies suggest that RAS WT ctDNA is associated with better outcomes, whereas others reported no differences according to ctDNA RAS mutational status. These inconsistencies may be related to small sample sizes, methodological heterogeneity, differences in assay sensitivity and tumor heterogeneity. We performed a systematic review in patients with tissue RAS WT treated with 1LChT + anti-EGFR. PubMed, Web of Science, and Scopus were searched up to April 2026. Risk of bias was assessed using the QUIPS tool, and random-effect models were applied. Fourteen studies met the inclusion criteria (ten non-interventional studies and four clinical trials). Compared with ctDNA RAS mutated tumors, ctDNA RAS WT tumors showed significantly higher overall response rates [ORR: pooled odds ratio (OR) 2.1, 95% confidence interval (CI): 1.3-3.4; P=0.002] and longer progression-free survival [PFS: pooled hazard ratio (HR) 1.6, 95% CI: 1.3-1.9; P<0.001] [non-interventional studies (NIS) + clinical trials (CT) data]. The pooled prevalence of ctDNA RAS mutations was 10.5% (95% CI: 6.2-14.8%). These findings support ctDNA RAS status as a potential biomarker of benefit from anti-EGFR-based therapy in mCRC, although methodological standardization and prospective validation remain necessary.

Circulating tumor DNA (ctDNA)↗

PubMed2026

An alignment-free strategy for circulating tumor DNA detection and tumor fraction estimation from whole-genome sequencing data.

Circulating tumor DNA (ctDNA) is emerging as a promising biomarker for postoperative monitoring of cancer patients. Precise estimation of circulating tumor fraction is crucial for evaluating treatment effects and timely detection of disease recurrence. All current ctDNA detection methods that utilize whole-genome sequencing (WGS) data rely on the reference genome alignment of sequencing reads and often apply separate tools for detecting different variant types. However, various bioinformatic analysis confounders and the application of external variant calling tools could be avoided by analyzing k-mers from unaligned sequencing reads. While k-mer-based methods have successfully been applied for somatic variant validation and detection, the potential of k-mer-based ctDNA detection is unexplored. We have developed a tumor-informed alignment-free ctDNA detection tool called ctDNAmer that detects tumor-specific somatic variation directly from unaligned sequencing data by identifying k-mers unique to the tumor DNA. ctDNAmer detects variant information across the genome by comparing the primary tumor and germline WGS data and accounts for sample-specific germline variability and technical noise in the same framework. We tested the utility of ctDNAmer for tumor fraction estimation on postoperative plasma cfDNA WGS data (mean sequencing depth ~ 28x) from 90 stage III colorectal cancer patients with three years of follow-up. The tumor fraction (TF) estimates agreed with the available clinical information and ctDNA was detected in 77% (17/22) of recurring patients with a median lead time of 8 months compared to radiological imaging. We further validated ctDNAmer's tumor fraction estimates based on a comparison with the mean cfDNA allele frequencies of somatic clonal SNVs identified from aligned primary tumor sequencing data. The TF estimates showed a strong Pearson correlation of 0.897 with the mean allele frequencies and improved ctDNA detection results across samples with an AUC of 0.79 compared to 0.75 if the mean allele frequency of clonal mutations is used.

Circulating Tumor DNA↗

PubMed2025

Liquid Biopsy in Hematologic Malignancies: Advances, Challenges, and Future Directions.

Hematologic malignancies are cancers that affect the bone marrow, lymphatic system, and hematopoietic cells, resulting in various cancer subtypes and clinical manifestations. Currently, tissue biopsy in hematological malignancies is typically performed for genomic profiling and has limitations such as invasiveness, lengthy procedures, and high expense. On the other hand, liquid biopsy serves as an emerging tool used for examining the blood or other bodily fluids of patients, for the purpose of identifying genetic mutations, biomarkers, or cancer-related substances. Liquid biopsy biomarkers include circulating tumor DNA (ctDNA), microRNA (miRNA), and exosomes. In the context of hematological malignancies, these biomarkers offer valuable insights into disease etiology, enabling effective disease monitoring and guiding treatment decisions owing to their differential expression patterns. This review critically examines the recent advancements and effectiveness of liquid biopsy biomarkers in the areas of diagnosis, therapy, and monitoring. The challenges and future directions of liquid biopsy for hematological malignancies are also discussed.

Humans↗

PubMed2026

Identification of candidate variants in plasma associated with early versus late disease progression under anti-PD-1 therapy in metastatic NSCLC.

BACKGROUND: Immune checkpoint inhibitors (ICIs), including anti-programmed cell death protein 1 (anti-PD-1) antibodies, have significantly improved outcomes in patients with metastatic non-small cell lung cancer (mNSCLC). However, substantial heterogeneity exists in clinical benefit, with some patients exhibiting early progression (EP) and others late progression (LP). To date, no biomarkers of EP versus LP disease have been implemented in clinical practice. Circulating tumor DNA (ctDNA) analysis represents a minimally invasive strategy for identifying such biomarkers. In this proof-of-concept study, we evaluated the performance of the TruSight Oncology 500 ctDNA (TSO500 ctDNA) panel and explored its feasibility to identify candidate variants associated with early and late disease progression under anti-PD-1 therapy. METHODS: Baseline ctDNA from eight mNSCLC patients treated with pembrolizumab was extracted and sequenced using the TSO500 ctDNA assay, a 523-gene targeted next-generation sequencing panel. Patients were classified according to their response as LP or EP. Variant calling was performed using the DRAGEN Bio-IT platform, and variants were annotated and clinically interpreted using the Clinical Genomics Workspace (CGW; PierianDx) according to Association for Molecular Pathology (AMP)/American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines. Survival outcomes were assessed using Kaplan-Meier and log-rank tests. Performance of ctDNA variants was evaluated using receiver operating characteristic (ROC) curve analysis, and multi-gene models were assessed using leave-one-out cross-validation with penalized logistic regression. RESULTS: All patients harbored detectable variants, including SNVs (100%), MNVs (87.5%), deletions (75%), and insertions (62.5%). Tier I variants were identified in 37.5% of patients, while all cases showed tier II and multiple tier III alterations. TP53 variants were associated with poorer outcomes under anti-PD-1 therapy. Individual gene alterations in TP53, ERBB3, SMC1A or LATS1 showed moderate discriminatory performance between LP and EP patients; however, combination of mutated genes improved apparent discrimination. Notably, specific two-gene combinations (SMC1A + LATS1 or ERBB3 + LATS1) showed the highest discriminatory performance between LP and EP patients in this exploratory cohort. CONCLUSIONS: This study demonstrates the feasibility and analytical performance of the TSO500 ctDNA panel and provides hypothesis-generating evidence that plasma gene variants may be useful to evaluate early versus late disease progression in patients with mNSCLC receiving immunotherapy.

TruSight Oncology 500↗

PubMed2025

From Diagnosis, Therapy Decision-Making to Genetic Risk Assessment: The Impact of ctDNA Testing on Comprehensive Cancer Management-A Case Report.

Circulating tumor DNA (ctDNA) testing is a minimally invasive alternative to tissue biopsy and is ideal for inaccessible tumors or limited samples. It captures tumor heterogeneity over time and different anatomic locations, unlike the static snapshot provided by a biopsy. In this report, we describe a 68-year-old female with an initial diagnosis of metastatic pancreatic adenocarcinoma (a pancreas head mass with multiple bilateral lung nodules). Mutation profiling of the pancreatic mass biopsy using a comprehensive cancer next-generation sequencing (NGS) panel was unsuccessful due to insufficient tissue. Consequently, ctDNA testing using a pan-cancer NGS panel was performed, and an EGFR p.L858R variant at 2.15% was identified. Interestingly, this activating variant is highly specific to non-small cell lung cancer (NSCLC), which raised the possibility of a synchronous tumor unrelated to the pancreatic mass. Immunohistochemistry showed the EGFR variant in station 7 lymph nodes but not in pancreatic biopsy tissue, supporting the inference that the variant originated from the lung mass. Droplet digital PCR on the limited pancreatic biopsy identified a KRAS p.Q61 variant, which was absent by ctDNA testing, suggesting a pancreatic primary with low ctDNA levels. In addition to diagnosing a primary lung cancer, ctDNA testing guided treatment decisions. With a primary EGFR p.L858R-mutant NSCLC, osimertinib was administered, resulting in a partial response within 10 months. In addition, given the synchronous primary pancreatic adenocarcinoma, germline testing was performed, revealing a CDKN2A p.I49T variant consistent with melanoma-pancreatic cancer syndrome, prompting comprehensive cancer surveillance and familial testing. This case illustrates how ctDNA testing enabled a comprehensive evaluation by clarifying the diagnosis, identifying actionable biomarkers, and facilitating genetic risk assessment, ultimately having a significant impact on the patient's clinical management.

Humans↗

PubMed2026

Current Evidence for Circulating Tumor DNA in Sarcoma: Challenges and Opportunities for Clinical Application.

Sarcomas represent a diverse group of mesenchymal tumors with high rates of recurrence after resection. While recent technical advances have enabled the detection of rare circulating tumor DNA (ctDNA) in other malignancies, the complexity and heterogeneity of sarcoma genomics have historically limited ctDNA in these cancers. This narrative review highlights the rapidly evolving evidence supporting potential clinical applications of ctDNA in common sarcoma subtypes including gastrointestinal stromal tumor, leiomyosarcoma, rhabdomyosarcoma, osteosarcoma, and Ewing sarcoma.

Humans↗

PubMed2025

ctDNA can detect minimal residual disease in curative treated non-small cell lung cancer patients using a tumor agnostic approach.

BACKGROUND: Circulating tumor DNA (ctDNA) has the potential to become a reliable biomarker for identifying minimal residual disease (MRD) and predicting recurrence in patients with non-small cell lung cancer (NSCLC) following curative treatment. However, there is a lack of studies that investigate the clinical validity of ctDNA using a tumor-agnostic approach, which can provide significant clinical benefits. METHODS: We analyzed samples from 45 NSCLC patients recruited in a prospective national multicenter study, all of whom had undergone curative treatment. A total of 38 pre-treatment plasma samples and 76 post-treatment plasma samples were examined using a commercially available cancer personalized profiling by deep sequencing (CAPP-seq) strategy, and a tumor-agnostic approach. Post-treatment samples were collected at two distinct landmark time points: Follow-up 1 (0.5-4.5 months post-treatment) and Follow-up 2 (4.5-7.5 months post-treatment). RESULTS: Detectable ctDNA post-treatment was significantly associated with increased risk of tumor recurrence and shorter recurrence-free survival (RFS). Using only a single blood sample taken from Follow-up 2, we correctly identified MRD in 50% of the patients who later experienced recurrence. However, subgroup analysis further revealed that in patients treated with radiotherapy or chemoradiotherapy (CRT), ctDNA detection was significantly linked to shorter RFS in the MRD analysis from Follow-up 2, but not in the MRD analysis from Follow-up 1. CONCLUSION: These findings suggest that post-treatment ctDNA, detected using a tumor-agnostic approach, is a reliable biomarker for predicting recurrence in NSCLC patients following curative treatment. However, the optimal timing for blood sampling to detect MRD appears to depend on the type of curative treatment received.

Humans↗

PubMed2026

Longitudinal ctDNA tracking in early and recurrent breast cancer using an ultrasensitive structural variant-based assay: an extended analysis from the TRACER study.

BACKGROUND: Detection of circulating tumor DNA (ctDNA) following curative-intent therapy is prognostic of disease recurrence in early-stage breast cancer (EBC). An ultrasensitive structural variant (SV)-based ctDNA assay was evaluated previously in a 100-patient EBC cohort treated with neoadjuvant therapy, demonstrating high sensitivity, specificity, and a long lead-time to relapse. The stability of primary tumor-specific SVs at and after metastatic recurrence and their utility for longer-term ctDNA monitoring had not been established. PATIENTS AND METHODS: An updated retrospective analysis of ctDNA dynamics was conducted in an expanded cohort of 121 patients with EBC treated with neoadjuvant therapy. Plasma samples were collected at key clinical timepoints and serially in several patients who experienced metastatic recurrence. Clinical variables were abstracted from medical records. Associations between ctDNA detection, dynamics, and clinical outcomes were evaluated in the early-stage and metastatic settings. RESULTS: Thirty of 121 patients experienced clinical recurrence (28 distant, 2 local) over a median follow-up of 4.2 years (range 0.5-8.8; 25 ctDNA evaluable with adjuvant timepoints). All patients with detectable ctDNA in the adjuvant setting developed metastatic recurrence (22/22). Median lead time from ctDNA detection to metastatic recurrence was 346 days (range 0-1937). Among recurrent cases, 79% of primary tumor-specific SVs (n = 17 patients, tumor fraction ≥0.1%) remained detectable in plasma [range 7% (1/14 SV)-100% (15/15); median: 92%]. ctDNA dynamics in the recurrent metastatic setting demonstrated a strong relationship with radiographic outcomes in evaluable patients (n = 9). CONCLUSION: This SV-based digital PCR assay provided ultrasensitive ctDNA detection in an expanded EBC cohort, maintaining 100% positive predictive value for metastatic recurrence. In patients with recurrence, ctDNA dynamics were concordant with radiographic outcomes. Prospective studies evaluating the clinical utility of longitudinal ctDNA monitoring are warranted.

MRD↗

PubMed2026

Circulating Tumor DNA in Breast Cancer: A Liquid Biopsy Revolution for Non-Invasive Genomic Profiling and Clinical Decision-Making.

Breast cancer remains the most frequently diagnosed cancer and a leading cause of cancer-related mortality among women worldwide, underscoring the need for accurate, minimally invasive biomarkers to support precision oncology. Conventional tissue biopsy remains the standard for molecular characterization but is limited by its invasiveness, inability to capture spatial and temporal tumor heterogeneity, and challenges in serial monitoring. Circulating tumor DNA (ctDNA), a tumor-derived fraction of cell-free DNA, has emerged as a promising liquid biopsy biomarker capable of providing real-time genomic information throughout disease progression. This narrative review examines recent advances in ctDNA biology, analytical technologies, clinical applications, current limitations, and future directions in breast cancer management. A structured literature search of PubMed/MEDLINE, Scopus, Embase, Web of Science, and Google Scholar identified relevant English-language publications from 2015 to 2026. Current evidence indicates that highly sensitive platforms, including digital PCR, BEAMing, and next-generation sequencing, can detect clinically actionable alterations in genes such as PIK3CA, ESR1, TP53, ERBB2, AKT1, and BRCA1/2. ctDNA has demonstrated particular utility in identifying minimal residual disease, monitoring therapeutic response, detecting emerging resistance mechanisms, and guiding targeted treatment selection in advanced breast cancer. However, applications in early cancer detection, population screening, and artificial intelligence-assisted clinical decision-making remain investigational. Widespread clinical implementation is constrained by low ctDNA abundance in early-stage disease, analytical variability, limited assay standardization, and cost considerations. Continued technological innovation, prospective multicenter validation, standardized testing protocols, and evidence-based clinical guidelines are essential to fully integrate ctDNA into routine precision breast cancer care.

breast cancer↗

PubMed2026

Evidence for the prognostic value of TP53 mutations in circulating tumor DNA across solid malignancies: a systematic review and meta-analysis.

BACKGROUND: The purpose of this meta-analysis study is to provide evidence for the clinical utility of TP53 mutations in circulating tumor DNA (ctDNA) as a prognostic biomarker. METHODS: We searched the PubMed, Embase, Cochrane, and Web of Science databases (last update May 2025) for studies on TP53 mutations in ctDNA or cfDNA as prognosis overall survival and in solid tumors. A total of 21 studies that met the criteria were utilized and data was collected regarding the authors, year of publication, study design, site of the study, number of patients, detection, mutation sample size and outcome measures were collected. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the study, and meta-analysis was done by using STATA 16.0. Effect sizes were in the form of hazard ratios (HR) that had 95% confidence intervals (CI). The models used were fixed-effects and random-effects based on heterogeneity. Funnel plots, and Egger's test was used to measure publication bias, and sensitivity analysis conducted through a leave-one-out method. RESULTS: A total of 21 studies (2,685 TP53-mutated patients, one unreported) showed: Mutated patients had worse progression-free survival (PFS) (HR=2.10, p=0.000; 12 studies, heterogeneity resolved after excluding Yoshida 2023), shorter OS (HR=1.74, p=0.014; 9 studies), and reduced DFS (HR=1.73, p=0.007; 3 studies), but RFS (2 items) showed no statistically significant differences. Subgroup analyses revealed: Prospective studies showed stronger PFS (HR=2.14 vs retrospective 1.90) with Japanese subgroup HR=4.90; Lung/liver cancers had higher HRs than breast. Prospective OS HR=2.25 (lung 3.14, endometrial 0.75). Retrospective DFS HR=1.89 vs Japanese breast RFS HR=4.00. Heterogeneity originated from study design, region, and cancer type variations, with no significant publication bias (Egger's test p>0.05). CONCLUSION: Current evidence suggests that TP53 mutations detected in ctDNA are significantly associated with poor prognosis in various solid tumors, particularly lung cancer. The association is robust for PFS and OS, though high heterogeneity and biological complexity warrant cautious interpretation. These findings support the potential incorporation of ctDNA-based TP53 mutation status into clinical prognostic assessment systems as an adjunctive parameter; however, further standardization of detection protocols, functional annotation of mutation types (e.g., LOF vs. GOF), incorporation of VAF and clonality analysis, and validation in large prospective multicenter cohorts are needed before routine clinical implementation. PROSPERO REGISTRATION NUMBER: CRD420251021095.

Humans↗

PubMed2025

Molecular Residual Disease and Recurrence in Rectal Cancer Patients Undergoing Upfront Surgery: A Prospective Cohort Study.

OBJECTIVE: To evaluate the prognostic utility of postoperative circulating tumor DNA (ctDNA) for recurrence and treatment response in patients with rectal cancer undergoing upfront surgery. BACKGROUND: ctDNA-based molecular residual disease (MRD) testing shows promise in colorectal cancer, but its role in patients with rectal cancer not receiving neoadjuvant therapy is unclear. This study evaluates whether postoperative ctDNA predicts disease-free survival (DFS) and guides adjuvant chemotherapy (ACT) decisions. METHODS: We analyzed ctDNA from patients with stage II to III rectal cancer (N=250) enrolled in the GALAXY study, a multicenter registry in Japan. A clinically validated, personalized, tumor-informed 16-plex PCR next-generation sequencing assay (Signatera) was used to detect and quantify ctDNA. The primary outcome was DFS, defined as the time from landmark to recurrence, death, or the latest radiologic assessment. RESULTS: In the MRD window (2-10 wk postsurgery, before ACT), 14.2% (35/246) of patients were ctDNA-positive and had significantly shorter DFS (HR: 9.96, 95% CI: 5.76-17.2, P <0.0001). Among patients who were ctDNA-positive in the MRD window, a significant benefit from ACT was observed (HR: 0.28, 95% CI: 0.09-0.89, P =0.031), whereas no benefit was seen in ctDNA-negative patients (HR: 0.59, 95% CI: 0.26-1.35, P =0.211). When analyzing ctDNA dynamics from the MRD window to 6 months postsurgery, recurrence risk was higher in patients who converted from ctDNA-negative to positive (HR: 8.22, 95% CI: 1.86-36.32, P =0.0055) and who remained ctDNA-positive (HR: 45.48, 95% CI: 14.31-144.57, P <0.0001) compared with serially ctDNA-negative patients. CONCLUSIONS: Postoperative ctDNA status is a robust biomarker predicting recurrence risk and ACT benefit in patients with rectal cancer undergoing upfront surgery.

Humans↗

PubMed2026

Promises and Pitfalls of ctDNA testing in the Management of Cholangiocarcinoma.

Diagnosis and treatment of cholangiocarcinoma is often limited by the availability of tissue biopsies for genomic analysis. Liquid biopsies using blood circulating tumor DNA (ctDNA) have emerged as a valuable and non-invasive alternative to conventional testing. ctDNA analysis has advanced the treatment paradigm for cholangiocarcinoma (CCA) by identifying targetable mutations and molecular mechanisms of treatment resistance. Additionally, it has shown preliminary promise in stratifying patients for adjuvant systemic therapy and enabling earlier detection of relapse. However, current ctDNA platforms face biological and technical challenges that limit their sensitivity for certain mutation types (i.e. gene fusions and amplifications), which are commonly found in CCA. To overcome these hurdles, new sequencing techniques and analytic methods involving artificial intelligence, epigenetic profiling, and diverse reference genomes are being developed. These advanced technologies underscore the promise of ctDNA testing as an indispensable tool in the management and study of CCAs.

Cholangiocarcinoma↗

PubMed2025

In-depth assessment of BRAF, NRAS, KRAS, EGFR, and PIK3CA mutations on cell-free DNA in the blood of melanoma patients receiving immune checkpoint inhibition.

INTRODUCTION: Circulating tumor DNA (ctDNA) holds promise for guiding immune checkpoint inhibitor (ICI) therapy and stratifying responders from non-responders. While tumor-informed ctDNA detection approaches are sensitive and mutation-inclusive, they require tumor tissue, which limits applicability in real-world settings. Conversely, tumor-agnostic methods often have limited genomic coverage. In this study, we evaluated a tumor-agnostic, broad-panel ctDNA assay in patients with advanced melanoma treated with ICI. METHODS: We conducted a prospective analysis of 241 longitudinal samples from 39 patients with unresectable stage III/IV melanoma using a SYSMEX targeted NGS panel covering 1,114 COSMIC mutations. Plasma samples were collected at baseline and during ICI therapy. The assay's sensitivity reached seven mutant molecules, corresponding to a 0.07% mutation allele frequency (MAF). ctDNA profiles were compared with matched tumor tissue and correlated with clinical features and survival. RESULTS: At baseline, ctDNA was detected in 64.5% of patients. Common mutations included BRAFV600E (43.8%) and NRASG12D (36.4%), followed by KRAS, EGFR, and PIK3CA variants. Overall tissue-plasma concordance was 51.6%, with more extended biopsy-plasma intervals associated with discordance (p = 0.0105). Notably, 12.2% of cases exhibited partial concordance, characterized by shared mutations and additional plasma-only alterations, underscoring the complementary value of blood-based profiling. Persistent or re-emerging ctDNA positivity post-therapy correlated with shorter progression-free survival (PFS, p = 0.003), while ctDNA-negative patients showed significantly improved outcomes. Patients that remained ctDNA-negative had significantly longer progression-free survival (median not reached) compared to those with persistent ctDNA positivity (median 3 months) or those converting to positive (median 7.5 months; p = 0.0073). Early NRAS and KRAS ctDNA levels strongly predicted poor response (p = 0.0069 and p = 0.028). The prognostic impact extended beyond canonical drivers, as non-hotspot variants also correlated with the outcome. Notably, even low-level ctDNA persistence (5-10 MM/mL) carried adverse prognostic implications (p = 0.0054). Concerning a shorter PFS, ctDNA positivity was also associated with elevated S100 levels (p = 0.047). Organ-specific mutation enrichment (e.g., KRASG12D in brain, EGFRG719A in lymph nodes) suggested possible metastatic tropism. CONCLUSION: Broad tumor-agnostic ctDNA analysis effectively identified clinically relevant mutations and predicted outcomes in ICI-treated melanoma patients. This approach enables tissue-independent and real-time ctDNA monitoring and may inform patient selection and therapeutic strategies in future interventional trials.

Humans↗

PubMed2026

High-Sensitivity ctDNA Analysis Uncovers Relevant Signals Missed by NGS in Pancreatic Cancer.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) carries high mortality despite multimodal therapy, and improved biomarkers are needed to guide perioperative care. This study evaluated the prognostic significance of Kirsten rat sarcoma virus (KRAS)-mutant circulating tumor DNA (ctDNA) detected by next-generation sequencing (NGS) and digital droplet PCR (ddPCR) in localized PDAC. EXPERIMENTAL DESIGN: In this prospective cohort study (2020-2024), patients with localized PDAC undergoing neoadjuvant chemotherapy (NAC) were enrolled across multiple sites within Northwestern Medicine. Blood samples for ctDNA were assessed at diagnosis, after NAC, and after resection using tumor-agnostic NGS and ddPCR targeting KRAS G12D/V/R mutations. Overall survival (OS) was assessed using Kaplan-Meier analysis. RESULTS: The cohort included 106 patients. At diagnosis, KRAS ctDNA was detected in 17.2% (17/99) by NGS and 64.9% (63/97) by ddPCR. Detection by both platforms was associated with shorter OS, with the higher-sensitivity ddPCR assay providing greater prognostic discrimination by identifying additional patients with poor outcomes not captured by NGS (NGS median OS 11.2 vs. 30.5 months, P < 0.001; ddPCR median OS 24.7 vs. 70.9 months, P = 0.004). Stratified by detection method, median OS was shortest in patients with ctDNA detected by both NGS and ddPCR (10.9 months), longest in those not detected by either platform (40.7 months), and intermediate in patients detected only by ddPCR (26.9 months; P < 0.001). CONCLUSIONS: In localized PDAC, KRAS-mutant ctDNA detected by NGS or ddPCR was associated with worse survival. ddPCR identified additional patients missed by NGS. Integrating ddPCR with NGS ctDNA measures may improve perioperative risk stratification, although validation is needed before clinical implementation.

Humans↗

PubMed2026

Diagnostic Accuracy of Circulating Tumor DNA to Predict Retroperitoneal Histology in Patients Treated With Retroperitoneal Lymph Node Dissection for Testicular Germ Tumor.

Testicular germ cell tumor (GCT) has survival rates exceeding 90% and thus contemporary research has focused on reducing morbidity. While chemotherapy is efficacious, long-term effects are significant. Primary retroperitoneal lymphadenectomy (P-RPLND) has been offered, and postchemotherapy lymphadenectomy (PC-RPLND) is considered, based on residual node size, to reduce overtreatment. A significant number of patients have necrosis in the retroperitoneum and are thus overtreated. Circulating tumor DNA (ctDNA) may be used to determine which patients would benefit from RPLND. This retrospective analysis sought to determine the performance of ctDNA to detect retroperitoneal GCT only, teratoma only, and GCT/teratoma. All patients had a ctDNA obtained preoperatively and at 3, 6, and 12 months postoperatively. Ninety-two patients underwent P or PC-RPLND. The sensitivity, specificity, and positive predictive values (PPVs) and negative predictive values (NPVs) for detecting active GCT/teratoma in the entire cohort were 60%, 87%, 96%, and 30%, respectively. For GCT only these were 85%, 75%, 73%, and 86%. For teratoma only, these were 31%, 34%, 23%, and 43%. These findings indicate that patients with a positive ctDNA likely harbor active GCT and/or teratoma, as suggested by a PPV of 96%. Future studies may use whole-genome ctDNA assays to improve detection of teratoma and incorporate ctDNA into surveillance protocols.

Humans↗