ctDNA Levels Research Articles

Exploring the biology of ctDNA release in colorectal cancer

BackgroundCirculating tumor DNA (ctDNA) has emerged as a promising tool for early cancer detection and minimal residual disease monitoring. However, the biology underlying ctDNA release and its variation across cancer types and histologies remains poorly understood. This study investigated the biology behind ctDNA shedding in colorectal cancer. MethodsThe study included a local cohort of 747 stage I-III colorectal cancer patients. All patients had ctDNA measurement prior to treatment and extensive clinical data. Primary tumor RNA sequencing and whole exome sequencing was performed in 95 and 652 patients respectively. Additionally, the study evaluated 89 non-small cell lung cancer patients from the TRACERx cohort, comprising primary tumor RNA sequencing and ctDNA measurement. ResultsWe found tumor size and proliferative capacity to be key factors associated with ctDNA shedding in colorectal cancer. Furthermore, we found that the secretory and CMS3 colorectal cancer subtypes exhibited lower ctDNA shedding, while microsatellite instability (MSI) tumors had higher levels of ctDNA. Mutational analysis did not reveal any genes or pathways associated with ctDNA shedding in colorectal cancer. A comparison of transcriptomic profiles across multiple cancer types demonstrated that colorectal cancer and lung squamous cell carcinoma tumors shared a high-proliferative ctDNA shedding phenotype, while lung adenocarcinoma tumors displayed a distinct low-proliferative subgroup. Additionally, proliferation levels correlated with ctDNA detection sensitivity across multiple cancer types. ConclusionThese findings suggest that tumor size and proliferative capacity are drivers of ctDNA release in colorectal cancer and provide insights into the biology of ctDNA shedding on a pan-cancer level.

Evaluation of the diagnostic and prognostic clinical values of circulating tumor DNA and cell-free DNA in pancreatic malignancies: a comprehensive meta-analysis.

The diagnostic and prognostic clinical value of circulating tumor DNA (ctDNA) and cell-free DNA (cfDNA) in pancreatic malignancies are unclear. Herein, we aimed to perform a meta-analysis to evaluate ctDNA and cfDNA as potential diagnostic and prognostic biomarkers. PRISMA reporting guidelines were followed closely for conducting the current meta-analysis. The PubMed/Medline, Scopus, and Web of Science (WoS) databases were scanned in detail to identify eligible papers for the study. A quality assessment was performed in accordance with the REMARK criteria. The risk ratios (RRs) of the diagnostic accuracy of ctDNA compared to that of carbohydrate antigen 19.9 (CA 19.9) in all disease stages and the hazard ratios (HRs) of the prognostic role of ctDNA in overall survival (OS) were calculated with 95% confidence intervals (CIs). A total of 18 papers were evaluated to assess the diagnostic accuracy and prognostic value of biomarkers related to pancreatic malignancies. The pooled analysis indicated that CA19.9 provides greater diagnostic accuracy across all disease stages than ctDNA or cfDNA (RR = 0.64, 95% CI: 0.50-0.82, p < 0.001). Additionally, in a secondary analysis focusing on prognosis, patients who were ctDNA-positive were found to have significantly worse OS (HR = 2.00, 95% CI: 1.51-2.66, p < 0.001). The findings of this meta-analysis demonstrated that CA19-9 still has greater diagnostic accuracy across all disease stages than KRAS mutations in ctDNA or cfDNA. Nonetheless, the presence of detectable levels of ctDNA was associated with worse patient outcomes regarding OS. There is a growing need for further research on this topic. https://doi.org/10.37766/inplasy2023.12.0092, identifier INPLASY2023120092.

Circulating tumor DNA kinetics: A future tool for radiation therapy personalization in lung cancer?

Locally advanced non-small cell lung cancer (NSCLC) is a highly diverse disease in terms of its histology, staging and molecular biology, yet chemoradiation treatment paradigms are currently not individualized for these factors. Circulating tumor DNA (ctDNA) in the plasma has clinical utility for several systemic therapies in advanced NSCLC, before, during and after treatment. However, in radiation oncology, the evidence for ctDNA in locally advanced NSCLC is largely limited to minimal residual disease (MRD) detection after treatment. In one study, all post-treatment MRD-positive patients developed disease relapse, compared with just 7% of ctDNA MRD-negative patients. As chemoradiation causes a bolus of tumor cell death with each treatment fraction, it has been posited that ctDNA levels fluctuate as well on a per-fraction basis. Indeed, four preliminary studies reveal a subgroup of patients with a transient elevation of ctDNA levels after the first radiotherapy fraction, followed by an overall ctDNA drop. To follow-up on these data suggesting an early ctDNA spike during chemoradiation, there is a need for larger and more systematic inter-fraction ctDNA studies, which if successful, could form the basis for more personalized and efficacious radiotherapy treatment paradigms.

Early monitoring of plasma KRAS G12C with digital PCR predicts antitumor response to immunotherapy or sotorasib in advanced NSCLC: A brief report

BackgroundThe frontline management of non-oncogene addicted non-small cell lung cancer (NSCLC) involves immune-checkpoint inhibitors (ICI) alone or combined with chemotherapy (CT-ICI). The dynamic landscape of KRAS-positive NSCLC presents a spectrum of treatment options, including ICIs, targeted therapy and combination strategies currently under investigation. MethodsWe conducted a prospective project to detect circulating tumor DNA (ctDNA) in patients with KRAS G12C, advanced NSCLC. We included patients undergoing upfront ICIs or subsequent line sotorasib. We planned three-time points: baseline (T0), after 3 months of treatment (T1) and at disease progression (T2). Results24 consecutive patients have been included. The most frequent baseline characteristics were: nonsquamous histology (95.8%), male gender (62.5%), ECOG PS 0–1 (79.2%), <3 metastatic sites (13/24, 54.2%). 18 patients (75%) received ICI-based strategies and 6 patients (25%) sotorasib. Patients with liver metastases (p ​= ​0.01) and those with >3 metastatic sites (p ​= ​0.002) exhibited significantly elevated ctDNA. Median overall survival (OS) was 7.5 months, progression-free survival (PFS) was 4.0 months and the objective response rate (ORR) was 33.3%. Higher AF correlated with an increased risk of death (HR 1.04, p ​= ​0.03), though not progression. The mOS was 7.5 months (95% CI, 1.91-NR) in high-AF group and 11.3 months (95% CI, 6.6-NR) in low-AF group (p ​= ​0.38). Notably, a reduction in plasma DNA levels was significantly associated with objective response (p ​= ​0.01). Two patients received a T2 dosage showing increased ctDNA levels after a previous reduction associated with response. ConclusionEarly monitoring with ctDNA may offer potential benefits in the evolving scenario of KRAS G12C NSCLC treatment.

Perioperative Modified FOLFIRINOX for Resectable Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant tumor, and durable disease control is rare with the current standard of care, even for patients who undergo surgical resection. To assess whether neoadjuvant modified 5-fluorouracil, leucovorin, oxaliplatin, and irinotecan (mFOLFIRINOX) leads to early control of micrometastasis and improves survival. This open-label, single-arm, phase 2 nonrandomized controlled trial for resectable PDAC was conducted at the Yale Smilow Cancer Hospital from April 3, 2014, to August 16, 2021. Pancreatic protocol computed tomography was performed at diagnosis to assess surgical candidacy. Data were analyzed from January to July 2023. Patients received 6 cycles of neoadjuvant mFOLFIRINOX before surgery and 6 cycles of adjuvant mFOLFIRINOX. Whole blood was collected and processed to stored plasma for analysis of circulating tumor DNA (ctDNA) levels. Tumors were evaluated for treatment response and keratin 17 (K17) expression. The primary end point was 12-month progression-free survival (PFS) rate. Additional end points included overall survival (OS), ctDNA level, tumor molecular features, and K17 tumor levels. Survival curves were summarized using Kaplan-Meier estimator. Of 46 patients who received mFOLFIRINOX, 31 (67%) were male, and the median (range) age was 65 (46-80) years. A total of 37 (80%) completed 6 preoperative cycles and 33 (72%) underwent surgery. A total of 27 patients (59%) underwent resection per protocol (25 with R0 disease and 2 with R1 disease); metastatic or unresectable disease was identified in 6 patients during exploration. Ten patients underwent surgery off protocol. The 12-month PFS was 67% (90% CI, 56.9-100); the median PFS and OS were 16.6 months (95% CI, 13.3-40.6) and 37.2 months (95% CI, 17.5-not reached), respectively. Baseline ctDNA levels were detected in 16 of 22 patients (73%) and in 3 of 17 (18%) after 6 cycles of mFOLFIRINOX. Those with detectable ctDNA levels 4 weeks postresection had worse PFS (hazard ratio [HR], 34.0; 95% CI, 2.6-4758.6; P = .006) and OS (HR, 11.7; 95% CI, 1.5-129.9; P = .02) compared with those with undetectable levels. Patients with high K17 expression had nonsignificantly worse PFS (HR, 2.7; 95% CI, 0.7-10.9; P = .09) and OS (HR, 3.2; 95% CI, 0.8-13.6; P = .07). This nonrandomized controlled trial met its primary end point, and perioperative mFOLFIRINOX warrants further evaluation in randomized clinical trials. Postoperative ctDNA positivity was strongly associated with recurrence. K17 and ctDNA are promising biomarkers that require additional validation in future prospective studies. ClinicalTrials.gov Identifier: NCT02047474.

Circulating Tumor DNA-Guided De-Escalation Targeted Therapy for Advanced Non−Small Cell Lung Cancer

Uninterrupted targeted therapy until disease progression or intolerable toxic effects is currently the routine therapy for advanced non-small cell lung cancer (NSCLC) involving driver gene variations. However, drug resistance is inevitable. To assess the clinical feasibility of adaptive de-escalation tyrosine kinase inhibitor (TKI) treatment guided by circulating tumor DNA (ctDNA) for achieving complete remission after local consolidative therapy (LCT) in patients with advanced NSCLC. This prospective nonrandomized controlled trial was conducted at a single center from June 3, 2020, to July 19, 2022, and included 60 patients with advanced NSCLC with driver variations without radiologically detectable disease after TKI and LCT. The median (range) follow-up time was 19.2 (3.8-29.7) months. Data analysis was conducted from December 15, 2022, to May 10, 2023. Cessation of TKI treatment and follow-up every 3 months. Treatment was restarted in patients with progressive disease (defined by the Response Evaluation Criteria in Solid Tumors 1.1 criteria), detectable ctDNA, or elevated carcinoembryonic antigen (CEA) levels, whichever manifested first, and treatment ceased if all indicators were negative during follow-up surveillance. Progression-free survival (PFS). Secondary end points were objective response rate, time to next treatment, and overall survival. Among the total study sample of 60 participants (median [range] age, 55 [21-75] years; 33 [55%] were female), the median PFS was 18.4 (95% CI, 12.6-24.2) months and the median (range) total treatment break duration was 9.1 (1.5-28.1) months. Fourteen patients (group A) remained in TKI cessation with a median (range) treatment break duration of 20.3 (6.8-28.1) months; 31 patients (group B) received retreatment owing to detectable ctDNA and/or CEA and had a median PFS of 20.2 (95% CI, 12.9-27.4) months with a median (range) total treatment break duration of 8.8 (1.5-20.6) months; and 15 patients (group C) who underwent retreatment with TKIs due to progressive disease had a median PFS of 5.5 (95% CI, 1.5-7.2) months. For all participants, the TKI retreatment response rate was 96%, the median time to next treatment was 29.3 (95% CI, 25.3-35.2) months, and the data for overall survival were immature. The findings of this nonrandomized controlled trial suggest that this adaptive de-escalation TKI strategy for patients with NSCLC is feasible in those with no lesions after LCT and a negative ctDNA test result. This might provide a de-escalation treatment strategy guided by ctDNA for the subset of patients with advanced NSCLC. ClinicalTrials.gov Identifier: NCT03046316.

Neoadjuvant nivolumab (NIVO) + chemotherapy (chemo) vs chemo in patients (pts) with resectable NSCLC: 4-year update from CheckMate 816.

LBA8010 Background: The phase 3 CheckMate 816 study established neoadjuvant NIVO + chemo as a standard of care for eligible pts with resectable NSCLC. Here, we report the 4-year survival update from this study, representing the longest follow-up among all global phase 3 studies evaluating neoadjuvant or perioperative immunotherapy-based treatments. Methods: Adults with stage IB (≥ 4 cm)–IIIA (per AJCC v7) resectable NSCLC, ECOG PS ≤ 1, and no known EGFR/ ALK alterations were randomized 1:1 to receive NIVO 360 mg + chemo Q3W or chemo alone Q3W for 3 cycles, followed by surgery. Event-free survival (EFS) and pathologic complete response (pCR; both per blinded independent review) were primary endpoints and were both statistically significant. Overall survival (OS) was a key secondary endpoint. Exploratory analyses included efficacy by pCR status and extent of resection. Results: At the 23 Feb 2024 database lock (median follow-up, 57.6 mo), NIVO + chemo continued to improve EFS vs chemo (median, 43.8 mo vs 18.4 mo; HR [95% CI], 0.66 [0.49–0.90]); 4-year EFS rates were 49% vs 38%. EFS favored NIVO + chemo vs chemo regardless of whether pts had lobectomy or pneumonectomy (Table), with 56%–57% vs 40%–43% of pts without disease recurrence at 4 years. NIVO + chemo also continued to show OS improvement vs chemo (HR [98.36% CI], 0.71 [0.47–1.07]; P = 0.0451; median OS was not reached [NR] in both arms, and the significance boundary was not met at this interim analysis). An OS improvement of 13% was sustained over time for NIVO + chemo vs chemo; 4-year OS rates were 71% vs 58%. Pts in the NIVO + chemo arm who had pCR continued to have improved OS vs those who did not (HR [95% CI], 0.08 [0.02–0.34]); 4-year OS rates, 95% vs 63%); a similar trend was seen in the chemo arm, although few pts had pCR with chemo (n = 4). No new safety signals were observed at this update. Additional survival analyses in pt subgroups and by ctDNA levels will be presented. Conclusions: In this 4-year analysis from CheckMate 816, neoadjuvant NIVO + chemo sustained EFS and OS separation vs chemo over time and demonstrated the long-term survival benefit of having pCR in pts with resectable NSCLC. These data provide the first understanding of the long-term benefits of neoadjuvant immunotherapy when added to chemo, reinforcing neoadjuvant NIVO + chemo as a standard of care, and providing a benchmark to assess the benefits of all perioperative immunotherapy-based treatments. Clinical trial information: NCT02998528 . [Table: see text]

A randomized study evaluating tailoring of advanced/metastatic colorectal cancer (mCRC) therapy using circulating tumor DNA (ctDNA): TACT-D.

LBA3557 Background: Identifying non-responders to expensive salvage therapies with modest benefits and substantial treatment related adverse events (TRAEs) (e.g. regorafenib [Reg] or TAS102 [Tas] in mCRC) is key to precision care. Retrospective studies suggest that ctDNA changes at timepoints (4-10 weeks [wks] into therapy) before radiographic assessment may predict treatment outcomes. However, prospective studies assessing early ctDNA changes are lacking and clinical utility remains uncertain. Methods: TACT-D is a randomized study to validate early dynamic changes in ctDNA (ΔctDNA: change in either maximum variant allele frequency (maxVAF) or mean VAF in predicting treatment response/resistance. Patients (pts) with mCRC clinically eligible for Reg/Tas were randomly assigned 2:1 to either standard of care (SOC) or ctDNA arm. All pts had ctDNA sequencing by Guardant360 CDx assay on cycle 1 day 1 (C1D1) and C1D15. On SOC arm, pts were restaged at 8 wks. On ctDNA arm, ΔctDNA (C1D15 - C1D1) was run in real-time and increase in ctDNA (ΔctDNA &gt; 0) triggered early radiographic restaging. Therapy was continued for responders (RECISTv1.1 stable disease/response) and stopped for progression (non-responders). Co-primary endpoints were: 1) comparison of TRAEs among study arms and 2) association of ΔctDNA and objective response rate (RR). Key secondary endpoints were progression free (PFS) and overall (OS) survival. Study was powered (82%; 2-sided α = .05) to detect 30% decrease in toxicity. Results: Between 4/2019 and 8/2023, 100 pts were randomized; 80 evaluable had median age of 56 years, 46% were females, 44% and 56% received Tas and Reg, respectively. Baseline ctDNA levels (ρ 0.90) and ΔctDNA (ρ 0.68) using maxVAF (reported below) and mean VAF showed strong correlation (P &lt; .001). Median ΔctDNA for entire cohort was -47% with no significant difference by treatment arms (SOC -45% v Exp -58%, P = .79) and therapy (Tas -71 v Reg -44, P = .19). ΔctDNA increased in 18% pts. Grade 3/4 TRAEs (32% v 40%, P = .62) did not differ significantly between arms. No significant association was seen between ΔctDNA and RR (OR .88, P = 1.0), PFS (HR .99, P = .88) and OS (HR 1.00, P = .64). Notably, higher baseline maxVAF was strongly associated with response (median maxVAF: 21.8% in non-responders v 3.4% in responders), PFS (HR 1.02) and OS (HR 1.03) (all P &lt; .001). After adjusting for baseline maxVAF, ΔctDNA was found to be associated with both PFS (HR 1.87, P = .038) and OS (HR 3.55, P = .001). Conclusions: In the first prospective study of clinical utility of monitoring ctDNA in mCRC, baseline ctDNA was strongly prognostic for clinical benefit from salvage therapies in mCRC. Adjusted for this prognostic impact, ΔctDNA between C1D1 and C1D15 was predictive of clinical outcomes. Efforts are needed to establish novel signatures, optimal cutoffs/intervals for assessing ctDNA response in mCRC, tailored to pts and their therapy. Clinical trial information: NCT03844620 .

Personalized ctDNA for Monitoring Disease Status in Head and Neck Squamous Cell Carcinoma.

Many patients with locoregionally advanced human papillomavirus-negative head and neck squamous cell carcinoma (HNSCC) relapse. ctDNA has the potential to identify minimal residual disease, but its clinical utility for virus-negative HNSCC is not well understood. We retrospectively evaluated a personalized, commercial ctDNA assay (Signatera, Natera) during clinical care of patients treated for predominantly newly diagnosed human papillomavirus-negative HNSCC. Signatera utilizes 16-plex PCR from matched tumor and blood. Objectives were to understand ctDNA detectability and correlate changes posttreatment with disease outcomes. Testing was successful in 100/116 (86%) patients (median age: 65 years, 68% male, 65% smokers); testing failed in 16 (14%) because of insufficient tissue. Oral cavity (55, 47%) tumors were most common; most had stage III to IV disease (82, 71%), whereas 17 (15%) had distant metastases. Pretreatment, 75/100 patients with successful testing (75%) had detectable ctDNA (range: 0.03-4049.69 mean tumor molecules/mL). No clinical features predicted ctDNA detectability or levels (multivariate analysis). At a median follow-up of 5.1 months (range: 0.2-15.1), 55 (55%) had >1 test result (range: 1-7; 194 samples). Of 55 patients, 17 (31%) remained ctDNA positive after starting treatment. Progression-free survival was significantly worse for patients who were ctDNA positive versus ctDNA negative posttreatment (HR, 7.33; 95% confidence interval, 3.12-17.2; P < 0.001); 1-year overall survival was 89.1% versus 100%, respectively (HR, 7.46; 95% confidence interval, 0.46-119.5; P = 0.155). Tumor-informed ctDNA testing is feasible in nonviral HNSCC. ctDNA positivity is an indicator of disease progression and associated with inferior survival. Further research is warranted to understand whether ctDNA may be leveraged to guide therapy in HNSCC.

Correlation of ctDNA and LDH levels in patients with soft tissue sarcoma: A single-center experience.

e23535 Background: Our study aims to examine the relationship between the presence of circulating tumor DNA (ctDNA) and lactate dehydrogenase (LDH) in patients diagnosed with soft tissue sarcoma (STS). There is emerging yet limited data on the applicability of ctDNA in STS. LDH is a cheaper readily available test that has been associated with unfavorable overall survival in different malignancies. This research aims to understand the correlation between ctDNA and LDH as a tool to assess its utility as indirect markers of response to treatment in STS. Methods: This was a single-center retrospective chart review on patients diagnosed with STS. Eligibility criteria included a confirmed diagnosis and available measurements of both ctDNA and LDH levels. Correlation was compared between Non-hispanic whites (NHW) and Hispanics (H). Data was sourced from our electronic medical record and Signatera™ assay to obtain the primary endpoints. Specimens were standardized in accordance to Natera’s™ specifications. Study endpoints included the correlation coefficients between ctDNA and LDH levels. A two-stage study design was applied for a robust analysis. Spearman's rank correlation coefficient (denoted as r) was employed for statistical analysis, assessing the strength and direction of the monotonic relationship between ctDNA and LDH levels. Marker values were treated as continuous variables in these analyses. All analyses were executed in GraphPad Prism software. Results: The cohort comprised 33 patients with STS (14 NHW, 19 H). The median LDH in H was 189 (interquartile range (IQR) = 184) vs 184 (IQR = 105) in NHW. Comparatively, the median ctDNA in H was 0 (IQR = 39.3) and also 0 (IQR = 11.1) in NHW. The overall correlation between ctDNA and LDH levels was moderate positive (r = 0.5, p = 0.002), indicating a consistent, though not necessarily linear, relationship. Subgroup analysis showed r = 0.19 (p = 0.52) in NHW and r = 0.43 (p = 0.1) in H groups, suggesting ethnic variability in the ctDNA-LDH correlation. These findings were statistically significant within the predefined confidence limits and probability values. Conclusions: Our study demonstrated a significant correlation between ctDNA levels and LDH in STS patients, implying that higher ctDNA may be associated with higher LDH levels. This association can lead clinicians in monitoring LDH more frequently as an indirect marker of response to treatment in STS. This correlation suggests an increased tumor burden with a higher inflammatory response, with variations across different racial groups. The wider availability of LDH testing compared to ctDNA in many centers highlights LDH's potential as an indirect marker for STS. Further research with larger prospective cohorts is essential to confirm LDH's role paired with ctDNA in guiding treatment decisions in STS, enhancing its utility in clinical practice.

Differences in baseline ctDNA value between Hispanic and non-Hispanic White patients with soft tissue sarcoma (STS): A single-center retrospective analysis.

e23533 Background: Circulating tumor DNA (ctDNA) has shown promise as a biomarker for cancer detection and tracking in multiple malignancies like melanoma, colon and lung. Due to the heterogeneity of sarcoma, there has been limited research on ctDNA as a tool for measuring minimal residual disease (MRD). Differences in baseline in ctDNA for STS in racial minorities have been poorly studied. To identify potential racial differences in the efficacy of this tool, this study compares the quantitative values of baseline ctDNA between non-Hispanic white (NHW) and Hispanic (H) patients with soft tissue sarcoma (STS). Methods: The medical records of 33 STS patients who had ctDNA analysis from Natera™ were examined retrospectively at Dignity Health Cancer Institute.There were 19 H patients and 14 NHW patients in the group. All Black (B), Asian (A), and Other (O) racial groups were excluded due to lower numbers. GraphPad Prism software was used to examine the baseline ctDNA levels. Using continuous measures for statistical analysis, we conducted descriptive statistics and determined the mean, standard deviation, and median ctDNA levels for each group. The ctDNA levels were compared between groups using a two-tailed t-test with a significance level of p &lt; 0.05. Results: The average ctDNA levels were 416.675 (standard deviation = 1349.394) in NHW and 300.305 (standard deviation = 1000.543) in H. The median levels were 0 for both groups. The statistical analysis showed that there was no significant differences in the baseline ctDNA levels between the two groups (p = 0.73). Furthermore, the gender distribution among NHW and Hs in the cohort was comparable, with a p-value of 1.00. Conclusions: This study establishes that there is no substantial differences in baseline levels of ctDNA between H and NHW patients with STS. These findings indicate that ctDNA levels in these populations can be equally utilized for diagnostic and monitoring reasons in clinical settings. Nevertheless, to gain a comprehensive understanding of the racial disparities in ctDNA utility and its implications in customized treatment for STS, it is necessary to conduct more extensive research with larger sample sizes and incorporate additional variables.

A phase II trial of TAS-102 in patients with colorectal cancer with ctDNA-defined minimal residual disease post-adjuvant therapy compared to synthetic control cohort: Results from the MD Anderson INTERCEPT program.

3623 Background: Circulating tumor DNA (ctDNA) has emerged as a novel marker with high specificity and positive predictive value for identifying radiographically occult minimal residual disease (MRD) in colorectal cancer (CRC) patients (pts). A widely acknowledged unmet need is the development of therapeutic strategies to eradicate MRD and increase the cure rate of the disease. Ongoing trials are evaluating MRD as a biomarker for determining the intensity of post-operative adjuvant therapy. However, the feasibility and efficacy of therapy in pts who are MRD+ during surveillance (after all curative intent treatments including adjuvant chemotherapy) is unknown. Methods: In this phase II study, pts with stages II-IV CRC noted to be MRD+ during surveillance (ctDNA+ but no radiographic evidence of disease on imaging in last 30 days) received 6 months (m) of TAS-102. Pts were identified through the MD Anderson INTERCEPT program that integrates MRD testing with a tissue informed assay (Signatera) into standard of care for CRC pts. The primary endpoint was 6-m ctDNA clearance and secondary endpoints included 3-m ctDNA clearance, and disease-free survival (DFS). For comparison, a synthetic cohort (SC) was retrospectively created through the MD Anderson INTERCEPT Program of MRD+ pts not enrolled in MRD trials. Pts in the SC were matched by stage, BRAFmt status, MSI-H status, and treatment history. Results: Between 7/22/22 and 11/7/23, 15 MRD+ pts were enrolled and received TAS-102. Baseline characteristics included a median age of 62 (range: 37-73), resected Stage IV (80%), MSS (100%), BRAF wildtype (100%) and neoadjuvant therapy (87%). 30 pts were included in the SC and baseline characteristics included median age of 57 (range: 32-79), resected stage IV (80%), MSS (100%), BRAF wildtype (100%) and neoadjuvant therapy (90%). At data cutoff, 14 pts receiving TAS-102 had 3-m ctDNA levels. 7 pts (50%) had undetectable ctDNA levels at 3-m compared to 2 pts (6.7%) in the SC (p=0.0022). 12 had a decrease in their ctDNA level (86%) compared to 5 (17%) in the SC (p&lt;0.0001). At 6-m, 82% of pts on trial had ctDNA levels at or below prior levels. 5 pts (45%) maintained undetectable ctDNA at 6-m compared to 2 pts (6.7%) in the SC (p=0.0096). Median DFS was 9.4-m with TAS-102 compared to 5.8-m in the SC. Conclusions: It is possible to identify MRD+ pts through screening during surveillance and enroll them onto therapeutic trials. Preliminary results suggest that treatment with TAS-102 is effective in inducing ctDNA clearance in the short term, and in doing so, may prolong DFS for pts receiving additional therapy compared to the SC. However, without evidence of persistent clearance this is unlikely to result in an increased cure fraction. Updated results, including survival data, will be presented. Clinical trial information: NCT05343013 .

A phase IV trial to confirm the efficacy of olaparib in combination with bevacizumab as maintenance frontline treatment of HRD-positive ovarian tumours (IOlanTHe).

TPS5628 Background: PAOLA-1/ENGOT-ov25 trial demonstrated that Olaparib (O) plus Bevacizumab (B) determined a significant survival benefit in patients (pts) with advanced, high-grade, epithelial ovarian, peritoneal and/or fallopian-tube cancer (HEOC) presenting defects of homologous recombination repair system (HRD+) in clinical response after first-line platinum-based chemotherapy (CT) plus B. Methods: IOLANTHE is a multicenter Italian phase IV trial (sponsored by the MaNGO group, Protocol Number IRFMN-OVA-8542) aiming to confirm in a setting close to clinical practice the efficacy of this combination in pts with HRD+HEOC. As the study includes a consistent translational component, all suspicious advanced cases will be considered for study enrollment. Pts with a confirmed pathological diagnosis of HEOC will be included in the step 1 of the trial which main inclusion criteria are the following: -availability of formalin-fixed, paraffin-embedded samples for the central testing of HRD status (performed by Myriad Mychoice CDx Plus assay) - suitability to receive CT + B. Only HRD+ pts responding to first line CT plus at least one cycle of B will be enrolled in the step 2 of the trial and will be treated with B 15 mg/kg every 3 weeks plus O 300 mg twice daily. Considering the PAOLA-1 median progression free survival (PFS) of 37.2 months (mo) in the B-O arm, with a sample size of 90 pts followed for 24 months and setting a one-side error of 5%, we will have a statistical power of 80% to demonstrate a PFS-24mo≥64% with an upper critical value of 61%. In order to have 90 patients eligible for the step 2 of the study, 190 pts are needed to be enrolled in the step 1 of the clinical study (as approximately 80% of pts with HEOC will respond to CT and out of these, 60% will be HRD+). The translational subproject 1 will consist of the analysis of circulating-tumor (ctDNA), using whole genome sequencing aiming - to correlate residual tumour after surgery and ctDNA levels - to anticipate the diagnosis of progression - to monitor the mutational status of HR-related genes and other genes such as Tp53BP1, POLQ, REV7 probably involved in PARPi resistance during the maintenance therapy. The translational subproject 2 will be developed to compare pts’ response to therapy with that of cancer cells, tested by organotypic model treated with the combination. These models will be generated using fresh tumor tissue and ascitic fluid for the isolation of the tumor cells and macroscopically healthy omentum for the isolation of the mesothelial cells and fibroblasts. Eight centers have been activated and other 6 are waiting for the activation with 19 patients registered and 3 screening failures. The enrollment is continuing, according to protocol timeline (12 months for enrollment, 6 months for surgery and CT and 24 months for maintenance treatment). Clinical trial information: NCT06121401 .

Correlation of ctDNA with hematologic ratios (NLR, MLR, PLR, ELR) in predicting disease progression in soft tissue sarcomas among non-Hispanic Whites and Hispanics: Single-center experience.

e23536 Background: Circulating tumor DNA (ctDNA) has gained prominence as a potential indirect marker for minimal residual disease (MRD) in various cancers, including soft tissue sarcomas (STS). Previous studies have suggested that indirect hematologic ratios – such as Neutrophil-Lymphocyte Ratio (NLR), Monocyte-Lymphocyte Ratio (MLR), Platelet-Lymphocyte Ratio (PLR), and Eosinophil-Lymphocyte Ratio (ELR) may correlate with worse outcomes. We sought to evaluate the correlation of NLR, MLR, PLR and ELR in a real world cohort of Non-Hispanic Whites (NHW) and Hispanics (H) with advanced STS. Methods: We performed a retrospective chart review at Dignity Health Cancer institute using our Electronic Medical Records (EMR) and Signatera™ assay to obtain our data points. Inclusion criteria were STS patients of all ages and stages of disease with complete records. We reviewed 33 patient charts, 14 NHW and 19 H patients. Of the NHW population, 11 were male (M) and 3 females (F). For the H population, 14 were M, and 5 were F. We utilized Spearman's rank correlation coefficient to assess monotonic relationships between ct-DNA levels and the hematologic ratios. ct-DNA was quantified through standardized assays per Protocol, with the resultant values treated as continuous variables in our statistical analyses. Power considerations, based on expected effect sizes and type I error rate adjustments were performed. Results: The Spearman’s correlation coefficients and p-values indicated varied associations across ethnic groups. For NHW, the correlations were generally weak and non-significant (NLR: r = 0.18, p = 0.54; MLR: r = -0.04, p = 0.89; PLR: r = 0.35, p = 0.21; ELR: r = 0.001, p = 1.00). Conversely, in the Hispanic cohort, stronger and statistically significant correlations were observed, particularly with NLR (r = 0.78, p &lt; 0.0001) and MLR (r = 0.70, p &lt; 0.001). Overall, the correlations across the entire study population did not reach statistical significance. Conclusions: This study revealed notable racial variations, particularly in the H population, in the relationship between ctDNA levels and hematologic ratios. The noteworthy associations found with NLR (r = 0.78, p &lt; 0.0001) and MLR (r = 0.70, p &lt; 0.001) highlight the possible usefulness of these ctDNA and these indirect biomarkers in assessing disease status in STS. These findings suggest the possibility of using hematologic ratios, particularly in the Hispanic population, as markers of disease progression similar as ctDNA. Hematologic ratios are more easily accessible to the general population compared to ctDNA in many underserved countries and communities. Future studies with larger cohorts are need to further analyze its validity.

On-treatment (tx) dynamic circulating tumor DNA changes (∆ctDNA) associated with progression-free survival (PFS) and overall survival (OS) of patients (pts) with HR+/HER2− advanced breast cancer (ABC) in MONALEESA-3 (ML-3).

1012 Background: In ML-3, ribociclib (RIB) demonstrated a significant PFS/OS benefit over placebo (PBO) in pts with HR+/HER2− ABC. We report associations of on-tx ∆ctDNA with OS/PFS and tumor size and of ctDNA detectability with radiological progression. Methods: Pts were randomized 2:1 to RIB or PBO + fulvestrant as 1st- or 2nd-line tx. ctDNA levels were measured by NGS at cycle 1 day 1 (C1D1), C4D1, C8D1, and every 8 cycles until end of tx. Analyses included: Wilcoxon rank sum text to compare ∆ctDNA from C1D1 to C4D1; Kaplan-Meier method to visualize relationship of ctDNA with PFS/OS; Cox proportional hazards model for associations of ctDNA and tumor metrics (objective response rate, best % change, % change at 1st tumor evaluation); Fisher’s exact test to compare ctDNA detectability between arms; and ∆ctDNA across time points to assess lead time between ctDNA level-based and radiological progression. Results: Overall, 534/726 (73.6%) pts had paired C1/C4 measurements. Rates of detectable (+) and undetectable (−) ctDNA at C1 and C4 were: C1+/C4+, 33.0%; C1+/C4−, 34.5%; C1−/C4−, 27.5%; and C1−/C4+, 5.1%. RIB vs PBO had a larger % decrease in ctDNA level from C1 to C4 (P=0.003). Pts with better best overall response also had larger ctDNA decreases from C1 to C4 (P&lt;0.0001). On-tx ∆ctDNA from C1 to C4 correlated with PFS/OS (P&lt;0.0001; Table). C1-/C4-, C1+/C4-, and C1+/C4+ strongly correlated with PFS within response categories (PR, SD, NCRNPD). C1-to-C4 % ∆ctDNA was only moderately correlated with tumor size change (best % change, r=0.41; change at 1st evaluation, r=0.32; both P&lt;0.001). Univariate/multivariate analyses showed significant correlations between ctDNA metrics (% change, detection pattern at C4D1) and PFS/OS. ctDNA detection and % change generally remained significantly associated with PFS/OS even after adjusting for change in tumor size. In a longitudinal analysis of pts who cleared ctDNA at C4D1 (C4–), the median lead time between ctDNA progression and radiological progression was 8.2 mo (IQR 4.5–15.6). Conclusions: On-tx ∆ctDNA from C1 to C4 was correlated with PFS/OS even after adjusting for tumor size changes, suggesting that ctDNA and tumor dynamics capture distinct aspects of tumor tx responses. Decreases in ctDNA were greater with RIB vs PBO, mirroring ML-3 efficacy readouts but at a much earlier timepoint. This longitudinal analysis of ctDNA in ML-3 suggests that detecting ∆ctDNA is a sensitive way to monitor progression and may be a potential surrogate for efficacy in HR+/HER2− ABC. Clinical trial information: NCT02422615 . [Table: see text]

Personalized cell-free tumor DNA analysis for patients with HNSCC: Liquid biopsy for minimal residual disease detection in head and neck squamous cell carcinoma (LIONESS).

3010 Background: Early relapse and development of metastatic disease are some of the primary reasons for the poor prognosis of patients with head and neck squamous cell carcinoma (HNSCC). We conducted LIONESS, a single-center prospective cohort study to assess ctDNA in plasma and saliva from 76 patients with HNSCC receiving primary surgery with curative intent. Our objectives were to determine whether postoperative ctDNA detection can act as a biomarker for surgical tumor clearance and detection of molecular residual disease (MRD) and to evaluate the potential of tumor-informed ctDNA analysis for early molecular-level detection of relapse or prior to clinically confirmed recurrence. Methods: Plasma and saliva samples from 76 HNSCC patients (37% stage I/II, 63% stage III/IV; 93% p16-negative) were collected pre- and postoperatively and during clinical follow-up. Whole exome sequencing was performed on FFPE tumor tissue. Tumor-specific variants for personalized assay design (RaDaR, NeoGenomics Laboratories) were selected and used in the analysis of serial samples for evidence of MRD. ctDNA levels were correlated to tumor volumes from staging CT, as well as pathological and other clinical parameters. Results: 617 longitudinal plasma and 128 saliva samples were collected pre- and postoperatively and during clinical follow-up (median follow-up time of 805 days). In plasma, ctDNA was detected at a median estimated variant allele frequency (eVAF) of 0.036% (0.000327% - 18.43%). 34% of positive samples had ctDNA levels detected at an eVAF of ≤0.01%. Increased plasma ctDNA levels were detected postoperatively in 96% of cases with confirmed clinical recurrences (21/22) with a median lead time of 160 days (6 – 763 days). Of the remaining 54 patients with no clinically confirmed relapse, ctDNA was detected immediately postop in 7 of them. In 5 patients, adjuvant therapy resulted in persistent ctDNA clearance, while 2 patients are deceased. ctDNA was also detected in baseline saliva samples from patients with HNSCC of various anatomical locations with a 74% overlap with the corresponding plasma ctDNA profiles. There was a strong linear correlation between larger tumor volumes and higher eVAF and a trend towards higher eVAF in cases with regional and distant recurrences in comparison to local relapse. Pathological tumor stage and lymph node involvement were both strongly correlated with preoperative ctDNA shedding. Conclusions: The use of ctDNA detection in surgically treated patients with HNSCC has significant potential to guide treatment decisions, improve disease outcome and potentially spare patients unnecessary, partially invasive interventions during clinical follow-up. Our work demonstrates the feasibility of tumor-informed ctDNA assays for detection of MRD postoperatively and for monitoring for early detection of relapse.

Updated results and biomarker analyses from the phase 2 trial of nab-paclitaxel plus sintilimab as second-line therapy for advanced or metastatic gastric/gastroesophageal junction adenocarcinoma (G/GEJA).

4037 Background: Sintilimab plus Nab-paclitaxel (nab-PTX) has exhibited promising efficacy and safety in the second line (2L) treatment of PD-1/PD-L1 inhibitor naïve advanced G/GEJA (ZC Jiang et al 2022 ASCO GI). This update presents the latest findings on efficacy, survival outcomes and exploration of biological markers. Methods: We collected blood samples from the advanced G/GEJA patients (pts) who were enrolled in our Phase 2 clinical trial and treated with sintilimab plus nab-PTX. Target-capture deep sequencing of 1,021 genes was conducted to identify somatic variants in circulating tumor DNA (ctDNA) from the baseline plasma samples (N=55) and disease progression samples of the pts with PFS &gt;4 months (N=17). And T cell repertoire sequencing was performed on pretreatment samples (N=55) as well as on paired blood samples obtained during the first tumor evaluation (N=45). Results: From Nov 2019 to Sep 2022, 58 pts were enrolled, with a median follow-up of 20.9 months (95% CI 17.04-24.76) until July 10, 2023. The objective response rate (ORR) and disease control rate (DCR) were 44.8% and 79.3%, respectively. The median progression free survival (mPFS) and median overall survival (mOS) were 4.8 months (95%CI 3.06-6.54) and 11.8 months (95%CI 10.43-13.17). Analysis of baseline ctDNA revealed a notably higher prevalence of EPHB1 mutation in non-responders (PD+increased SD) compared to responders (CR+PR+decreased SD) (21.43% vs. 0%, P=0.022). Pts with EPHB1 mutation showed a significantly increased risk of disease progression (HR 3.86, 95% CI 0.43-34.41, p=0.013) and death (HR 4.49, 95% CI 0.43-46.93, p=0.005) compared to wild-type EPHB1 pts. In contrast to high ctDNA level (mean tumor molecules [MTM] per mL of plasma, cutoff value=2999.7), low ctDNA level demonstrated a significantly reduced risk of disease progression (HR 1.88, 95% CI 1.05-3.37, p=0.034). Dynamic T cell receptor (TCR) diversity analysis during baseline and the initial tumor assessment showed a significant post-treatment increase in the Shannon index within the responder group (P=0.045, median Shannon index change: responder 0.43 vs. non-responder -0.49). An increased Shannon index was correlated with significantly prolonged mPFS (HR 0.44, 95% CI 0.22-0.91, P=0.009), while no significant difference was observed in mOS (HR 0.74, 95% CI 0.36-1.54, P=0.399). A negative correlation between the Shannon index and MTM was observed (R=-0.37, P=0.009). Conclusions: 2L-treatment with sintilimab plus nab-PTX maintains favorable efficacy in advanced G/GEJA pts without prior PD-1/PD-L1 inhibitor treatment. EPHB1 mutation and dynamic change of TCR could serve as potential predictive factors. Further investigation is warranted. Clinical trial information: NCT04140318 .

Personalized circulating tumor DNA for minimal residual disease and dynamic assessment in patients undergoing neoadjuvant chemotherapy for breast cancer: Preliminary analysis from MSK-LINC.

3049 Background: Identification of minimal residual disease (MRD) with circulating tumor DNA (ctDNA) in pts with early-stage breast cancer holds promise to identify risk of relapse. MSK-LINC is prospective ctDNA plasma analysis of breast cancer pts. This pilot study evaluated the utility of serial ctDNA assessment as a biomarker for monitoring MRD and recurrence prediction in clinical stage II-III breast cancer pts undergoing neoadjuvant chemotherapy (NAC). Methods: 30 pts who underwent NAC across all subtypes were identified from MSK-LINC. The ctDNA analysis was performed at baseline, on-NAC, post-NAC/pre-surgery, within 8 weeks post-surgery, and during follow-up. Personalized ctDNA RaDaR assays were designed using whole exome sequencing data of paired primary tumor and germline samples from each pt. ctDNA levels were quantified as an estimated variant allele fraction (eVAF). Results: ctDNA panels were successfully designed for 29/30 pts (16 Stage II, 13 Stage III), including 6 HR+/HER2-, 12 HER2+, and 11 TNBC, with a median follow up of 4.2 years. The bespoke ctDNA assays targeted a median of 48 variants (21-51), with a median of 43 variants (11-48) passing quality control. A total of 175 plasma samples were analyzed, including 24 baseline and 24 post-surgery. A 100% ctDNA detection rate was observed at baseline in the 24 pts for whom a baseline sample was available (median eVAF 0.33%, range 0.0083% - 8.91%). Pathologic complete response (pCR) was achieved in 11 pts who remained disease free; and of the 18 pts without a pCR, 5 recurred. All patients with a pCR were ctDNA negative post treatment. In 3/5 patients who recurred, MRD detection was achieved, including one patient with persistent ctDNA positivity throughout all timepoints. For the other two pts, ctDNA was first detected in follow-up plasma collected at 4.4 and 9.8 months prior to clinical recurrence. Conclusions: This study demonstrates the potential of ctDNA as a dynamic biomarker for monitoring disease burden in pts with high-risk early-stage breast cancer, highlighting its remarkable sensitivity at baseline and its capability for MRD detection preceding clinical recurrence. These findings suggest the need for further research to fully understand the relationship between ctDNA dynamics during and after NACT with prediction of breast cancer outcomes. ctDNA detection rates in plasma samples across collection timepoints. [Table: see text]

Prognostic and predictive value of ultrasensitive ctDNA monitoring in a metastatic pan-cancer cohort treated with immune checkpoint inhibitors in the context of phase 1 clinical trials.

2510 Background: Determining which patients will achieve clinical benefit from immune checkpoint inhibition (ICI) therapy remains an open question. Liquid biopsy tests to assess baseline and early dynamics of circulating tumor DNA (ctDNA) may allow clinicians to track response more granularly and predict ICI response or resistance prior to imaging. However, lack of sensitivity may hinder accurate detection of low ctDNA levels in tumors with low shedding rates or during substantial drops and clearance in response. Methods: This study represents a cohort of 175 patients with refractory metastatic tumors from 18 different cancer types, who received 1-3 successive lines of ICI treatment in the context of phase-1 clinical trials. Thus far, 609 plasma samples from 90 stage-IV cancer patients receiving immune checkpoint inhibitor (ICI) treatment have been processed. ctDNA was profiled using the NeXT Personal assay, a liquid biopsy platform that leverages whole-genome sequencing of tumor and normal samples to create custom, patient-specific panels that include up to 1,800 somatic variants. This enables the detection of molecular residual disease (MRD) down to a detection threshold of 1 part per million (PPM) of ctDNA. Results: NeXT Personal assay detected positive levels of ctDNA in 99% (81/82) of plasma baseline samples, with a wide dynamic range, extending from 4.2 PPM (~0.00042% TF) to ~640,000 PPM (~64% TF) (median limit of detection = 2 PPM, 0.0002% TF). Lower ctDNA values at baseline were correlated with increased duration of PFS (log-rank p=0.017, HR=0.57, 95% CI 0.36-0.91) and extended OS (log-rank p=0.002, HR=0.46, 95% CI 0.28-0.75). Early reduction in ctDNA level from baseline to treatment cycle 3 was associated with significant increases in PFS (log-rank p=0.001, HR=0.36, 95% CI 0.19-0.67) and OS (log-rank p=0.015, HR=0.44, 95% CI 0.22-0.87), representing a &gt;3-fold increase in both median PFS and OS. ctDNA clearance resulted in significant improvement in both PFS and OS (PFS: log-rank p=0.002, HR=0.24, 95% CI 0.09-0.62; OS: log-rank p=0.01, HR=0.29, 95% CI 0.1-0.8). All plasma timepoints from periods of durable complete response (CR) assessed via RECIST 1.1 were ctDNA-negative, with a molecular clearance lead time of 277 days over radiographically confirmed CR. Conclusions: We demonstrate that early ctDNA dynamics are predictive of long-term ICI response in the advanced, pan-cancer ECT setting. Even in this refractory advanced cancer cohort, an ultra-sensitive assay was required for accurate MRD status determination, with low ctDNA detections down to 4.2 PPM that might otherwise have been missed. Taken together, these findings suggest a high sensitivity ctDNA assay is crucial for accurate monitoring of ICI response, providing information for more accurate patient management.

CtDNA for clinical decision support in pancreatic cancer.

e16354 Background: Circulating tumor DNA (ctDNA) is increasingly used to inform therapeutic decisions and its applicability to pancreatic cancer is emerging. We explore the adoption of ctDNA profiling in patients presenting to our pancreatic cancer clinic to help guide localized and metastatic pancreatic cancer treatment. Methods: This was an IRB-approved retrospective cohort study of Signatera ctDNA profiling among patients with pancreatic cancer at Northwell Health between October 2021 and September 2023. Patients received ctDNA testing at various treatment timepoints and were categorized according to clinical context: neoadjuvant, adjuvant, surveillance, radiographic relapse, and metastatic. Average ctDNA level and conversion rates were calculated for each group. Results: There were 203 tests completed among 59 patients representing the following clinical contexts: 36% metastatic disease, 27% in the adjuvant setting, 23% during surveillance, 7% prior to surgery, and 6% after relapse. 43 patients had ctDNA tests that were drawn but were cancelled or could not be performed due to inadequate tissue samples, of which 8 had at least one completed test and were included in final analysis. Of all 27 metastatic patients, 8 patients had tests that were never completed. 46% of all tests were positive, which ranged from 0.3 to 8089 MTM/mL, and averaged 196 MTM/mL. 51% of all patients had ctDNA results that remained positive, 34% remained negative, and 15% changed over time from either positive to negative or vice versa. Median ctDNA level was 0.1 MTM/mL or less for patients who were tested prior to surgery or during adjuvant treatment or surveillance and the median ranged from 0.0-67.1 for patients with metastatic disease or relapse. All ctDNA tests sent after radiographic relapse also tested positive. Conclusions: ctDNA testing was most commonly performed in patients with localized disease on adjuvant chemotherapy, and in those with metastatic disease at time of diagnosis, who also had the highest rates of positive tests by stage at diagnosis. Given all patients tested during relapse had positive tests, ctDNA may be an early predictor of disease progression in patients with negative tests on surveillance. When tissue is limited, such as in metastatic patients who are less likely to undergo surgery, production of the ctDNA assay may be hindered. A prospective, larger scale, and more longitudinal study would add greater power and clinical context.