Tumor Tissue DNA Research Articles

Construction of store-operated calcium entry-related gene signature for predicting prognosis and indicates immune microenvironment infiltration in stomach adenocarcinomas

Gastric adenocarcinoma (STAD) is the most prevalent malignancy of the human digestive system and the fourth leading cause of cancer-related death. Calcium pools, especially Ca2+ entry (SOCE) for storage operations, play a crucial role in maintaining intracellular and extracellular calcium balance, influencing cell activity, and facilitating tumor progression. Nevertheless, the prognostic and immunological value of SOCE in STAD has not been systematically studied. The objective of this study was to develop a risk model for SOCE signature and to explore its correlation with clinical characteristics, prognosis, tumor microenvironment (TME), as well as response to immunotherapy, chemotherapy, and targeted drugs. We used the TCGA, GEO (GSE84437 and GSE159929), cBioPortal and TIMER databases to acquire mRNA expression data for STAD, along with patient clinical indicators, single-cell sequencing data, genomic variation information, and correlations of immune cell infiltration. An analysis of SOCE genes based on tumor vs. normal tissue comparisons, pan-cancer dimension, single-cell sequencing, DNA mutation, and copy number variation revealed that SOCE genes significantly impact the survival of STAD patients and are differentially involved in the immune response. SOCE co-expressed genes were identified by Pearson analysis, and subsequently protein-protein interaction (PPI) and gene function enrichment analysis indicated that coexpressed genes were associated with multicellular pathways. Based on TCGA and GSE84437 datasets, a multifactor Cox proportional hazard regression analysis was conducted to identify SOCE co-expressed genes associated with overall survival in STAD patients. Several mRNA prognostic genes, including PTPRJ, GPR146, LTBP3, FBLN1, EFEMP2, ADAMTS7 and LBH, were identified, which could be used as effective prognostic predictors for STAD patients. In both training and test datasets, receiver operating characteristic (ROC) curves were utilized to evaluate and illustrate the predictive capability of this characteristic in forecasting overall survival of STAD patients. The qPCR and human protein atlas (HPA) were employed to assess mRNA expression and protein levels. Furthermore, the ESTIMATE, TIMER, CIBERSORT, QUANTISEQ, MCPCOUNTER, xCell and EPIC algorithms were utilized to perform immune score and analyze immune cell infiltration. It effectively revealed the difference in prognosis and immune cell infiltration in TME between high-risk and low-risk groups based on the risk signature associated with SOCE. Notably, significant differences in tumor immune dysfunction and rejection (TIDE) scores between the two groups, suggesting that patients in the low-risk group may exhibit a more favorable response to ICIS treatment. The GDSC database and R packages for predictive analysis were utilized to analyze responses to chemotherapy and targeted drugs in high-risk and low-risk groups. In summary, the 7-gene signature associated with SOCE serves as a significant biomarker for evaluating the TME and predicting the prognosis of STAD patients. In addition, it may provide valuable insights for developing effective immunotherapy and chemotherapy regiments for patients with STAD.

High Prevalence of Chromosomal Rearrangements and LINE Retrotranspositions Detected in Formalin-Fixed, Paraffin-Embedded Colorectal Cancer Tissue

Structural variants (SVs) caused by chromosomal rearrangements in common fragile sites (CFS) or LINE retrotranspositions are highly prevalent in colorectal cancer (CRC). However, methodology for targeted detection of these SVs is lacking. We here report the use of formalin-fixed paraffin-embedded targeted locus capture (FFPE-TLC) sequencing as a novel technology for targeted detection of tumor-specific SVs. Analysis of 29 FFPE colorectal tumor and 8 matched normal samples revealed tumor-specific SVs in 24 patients (83%) with a median of 2 SVs per patient (range 1-21). 104 SVs were found in the CFS-associated genes MACROD2, PRKN, FHIT and WWOX in 18 patients (62%) and 39 SVs caused by three LINE transposable elements were found in 15 patients (52%). Tumor-specificity of SVs was independently verified by droplet digital PCR of tumor tissue DNA and their applicability as plasma circulating tumor DNA biomarkers was demonstrated. We conclude that FFPE-TLC sequencing enables the detection of tumor-specific SVs caused by chromosomal rearrangements and LINE retrotranspositions in FFPE tissue. Therefore, FFPE-TLC sequencing facilitates the investigation of the biological and clinical impact of SVs using FFPE material from (retrospective) cohorts of cancer patients and has potential clinical applicability to detect SV biomarkers in the routine molecular diagnostics setting.

OncoGPT: An AI assistant for genomic-driven precision oncology.

160 Background: Cancer patient’s unique genomic profile can help oncologists select a course of precise personalized treatment for the subject. High throughput next-generation sequencing (NGS) technology allows us to identify genomic alterations simultaneously within a patient’s tumor tissue and blood-circulating tumor DNA (ctDNA) in a single test, however, robust tool for accessing mutation-treatment matching is limited. Methods: OncoGPT was built on a cloud-based elastic computing platform. The NGS data analytical module consists of a cascade of computational algorithms for NGS data processing and gene variant calling. The interactive and univariate Cox proportional hazards models were used for mutation-treatment matching and prognostic effect analysis, respectively. Machine learning algorithms including decision tree, random forest, and neural network were trained and tested with novel features for tissue-of-origin (TO) classification across 8 caner types. Results: We built an AI-driven NGS data analytical platform by integrating computational models, matching algorithms and variant annotation databases to highly accurate achieve cancer-related gene mutations, copy number variation, and structure variants using NGS data from 35,122 tumors across 8 cancer types from three institutions. Next, an AI-driven TO classifier was developed and achieved a weighted F1 score of 0.926 for high confidence predictions (≥ 0.9) on tumor samples. Furthermore, augmented AI matching algorithms were applied to match the optimal personalized treatment and provide prognostic prediction for cancer patients with significantly bett survival outcomes (hazard ratio (HR) = 0.326; 95% confidence interval (CI) = 0.213–0.565; P = 2.52×10−5). Conclusions: We have successfully developed an innovative intelligent system (OncoGPT) with AI capabilities to help accurately find actionable targets from patient tumor or blood ctDNA NGS sequencing data and precisely match individualized therapeutic and clinical trial options for patients. In addition, OncoGPT classified primary tumor sites across 8 different cancer types with high confidence predictions. We believe that OncoGPT would help clinicians make optimal treatment decisions for cancer patients through genomic-driven precision oncology.

Comprehensive genomic profiling by liquid biopsy captures tumor heterogeneity and identifies cancer vulnerabilities in patients with RAS/BRAFV600E wild-type metastatic colorectal cancer in the CAPRI 2-GOIM trial

Emerging evidence supports tumor tissue-based comprehensive genomic profiling (CGP) in metastatic colorectal cancer (mCRC). Data on liquid biopsy-based circulating tumor DNA (ctDNA) CGP are scarce and mainly retrospective. Prospective comparison between the two tests is not currently available. The CAPRI 2-GOIM trial investigates efficacy and safety of ctDNA-driven, cetuximab-based, sequence of three treatment lines in patients with RAS/BRAFV600E wild type (WT) mCRC, as determined by local laboratory. Before first-line therapy, CGP is performed with FoundationOne (F1) CDx and F1 Liquid (F1L) CDx (324 genes) on tumor tissue DNA and plasma ctDNA, respectively. For 2/207 (0.96%) patients, no ctDNA was detected by F1L CDx. No patient displayed tumor fraction (TF) below 1%, whereas elevated ctDNA (TF≥10%) was detected among 140/205 (68.3%) patients. 1013 genomic variants were identified. F1L CDx found KRAS, NRAS or BRAFV600E alterations in 19 patients, whose tumors were classified as RAS/BRAFV600E WT by local laboratory. Both F1 CDx and F1L CDx were available for 164/205 (80%) patients. Concordance of 61.4% between the two tests was observed. Concordance increased to 72.7% for F1L CDx with TF ≥10%. Concordance for genes potentially involved in anti-epidermal growth factor receptor (EGFR) resistance was found in 137/164 (83%) patients, increasing to 91.5% for F1L CDx with TF ≥10%. A higher number of genomic alterations was detected by F1L CDx compared with F1 CDx, including 6 cases with KRAS and NRAS alterations. Overall, 109/205 (53.2%) patients displayed at least one actionable genomic alteration (I to IIIB), according to the ESMO Scale for Clinical Actionability of Molecular Targets (ESCAT). Baseline liquid biopsy-based CGP is feasible, it has high concordance with tumor tissue-based CGP, it could better recapitulate tumor heterogeneity, and it is clinically informative by identifying additional actionable genomic alterations in approximately half of RAS/BRAFV600E WT mCRC patients.

KRAS Exon 2 Mutations in Patients with Sporadic Colorectal Cancer: Prevalence Variations in Mexican and Latin American Populations.

We searched for the prevalence of actionable somatic mutations in exon 2 of the KRAS gene in western Mexican patients with CRC. Tumor tissue DNA samples from 150 patients with sporadic CRC recruited at the Civil Hospital of Guadalajara were analyzed. Mutations in exon 2 of the KRAS gene were identified using Sanger sequencing, and the data were analyzed considering clinical-pathological characteristics. Variants in codon 12 (rs121913529 G>A, G>C, and G>T) and codon 13 (rs112445441 G>A) were detected in 26 patients (with a prevalence of 17%). No significant associations were found between these variants and clinical-pathological characteristics (p > 0.05). Furthermore, a comprehensive search was carried out in PubMed/NCBI and Google for the prevalence of KRAS exon 2 mutations in Latin American populations. The 17 studies included 12,604 CRC patients, with an overall prevalence of 30% (95% CI = 0.26-0.35), although the prevalence ranged from 13 to 43% across the different data sources. Determining the variation and frequency of KRAS alleles in CRC patients will enhance their potential to receive targeted treatments and contribute to the understanding of the genomic profile of CRC.

The clinical utility of a circulating tumor cell based cerebrospinal fluid assay in the diagnosis and molecular analysis of leptomeningeal disease in patients with metastatic non-small cell lung cancer.

8644 Background: Leptomeningeal disease (LMD) is associated with significant morbidity and mortality for metastatic non-small cell lung cancer (mNSCLC). The standard of care for diagnosing LMD remains magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) cytology, but these have limited sensitivity. CSF-based liquid biopsy is an emerging strategy for dynamic assessments of CSF-derived tumor cells to monitor intracranial responses and CNS clonal evolution during treatment and at progression. However, data for the feasibility and utility of this approach is limited. We describe our clinical experience to evaluate the use of molecular analysis on CSF-derived circulating tumor cells (CTCs) for mNSCLC. Methods: Patients with mNSCLC who had a lumbar puncture for CSF collection as part of routine clinical care to rule out LMD were included in the study. CSF was evaluated for CTCs and cell-free DNA (cfDNA) with a commercially available assay (CNSide) and subsequent molecular profiling was performed to detect actionable mutations. Patients were analyzed for LMD with CSF cytology and MRI imaging. Molecular testing results from sequencing of tumor tissue and plasma cell tumor DNA were available for all patients. Other than copy number amplification detection for MET, the CSF assay allowed for analysis of MET and HER2 expression via fluorescent in situ hybridization (FISH). Results: The study included 22 patients with mNSCLC (77% female; median age 60 years; 95% adenocarcinoma). Sensitizing EGFR mutations were found in 78% of patients and 18% had an atypical EGFR mutation at initial diagnosis. LMD was diagnosed using the CSF CTC assay in thirteen of the 22 patients (59%) patients. CSF cytology was negative for LMD in five of 13 cases (38%) and furthermore, 2 of these cases (15%) had normal MRI brain imaging. There were sufficient CTCs to perform molecular profiling on seven of the 13 patients (54%). The concordance with tissue NGS was 100% and the driver mutation was identified in all 7 patients with the CSF CTC assay. MET expression and HER2 expression via FISH were noted in 11 patients (50%) and 4 patients (18%) respectively. Conclusions: In this single institution study, we detected a higher sensitivity to diagnose LMD with CNSide. This CSF assay identified 38% of LMD cases which were missed by standard CSF cytology and of note, 15% of the cases found with LMD were missed by both CSF cytology and MRI. In addition, CSF molecular testing using this assay demonstrated high concordance with tissue-based molecular testing. The study illustrates that multigene molecular analysis of CSF CTCs can be a useful tool for diagnosis, monitoring of response to therapy, as well as for the identification of therapeutic targets specific to the CSF especially for patients with oncogene-driven mNSCLC.

Real-world tumor BRCA testing patterns and PARP inhibitor use in HER2-negative metastatic breast cancer.

1113 Background: Testing for BRCA1/BRCA2 mutations (BRCAm) aids systemic treatment decisions for patients (pts) with metastatic breast cancer (mBC). This retrospective study explored real-world germline/tumor (g/t) BRCA testing patterns and PARP inhibitor (PARPi) use in US pts with mBC. Methods: Data from pts ≥18 years old diagnosed with HER2-negative mBC from 2014–2022 were captured in the nationwide Flatiron Health electronic health record-derived deidentified database. Patterns and timing of prospective or incidental BRCA testing were compared across mBC subtypes (hormone receptor-positive [HR+ mBC]/triple-negative mBC [mTNBC]) and disease stage (recurrent/ de novo). BRCAm prevalence was compared by testing modality and mBC subtype. PARPi initiation was assessed in pts with mBC diagnosed from 2018 onwards and a positive BRCAm test result. Clinical characteristics were compared by receipt of a BRCA test, testing modality, and PARPi initiation. Real-world overall survival (OS) by PARPi use was estimated using the Kaplan-Meier method. Results: Of 15,006 pts (including 12,349 with HR+ mBC; 1998 with mTNBC), 8178 (54.5%) did not receive any type of BRCA test, 4654 (31.0%) received a gBRCA test, 3075 (20.5%) received a tumor tissue DNA (ttDNA) test, and 1418 (9.4%) received a circulating tumor DNA (ctDNA) test. BRCA testing prevalence was numerically higher in pts with mTNBC (n=1164; 58.3%) than in pts with HR+ mBC (n=5323; 43.1%). As expected, testing prevalence was higher with ttDNA than with ctDNA (mTNBC: n=569 [28.5%] vs n=137 [6.9%]; HR+ mBC: n=2339 [18.9%] vs n=1224 [9.9%]). Over 93% of pts (recurrent and de novo) who received a tBRCA test were tested after an mBC diagnosis, and >1/3 were tested after first-line therapy, with median times from diagnosis to a ttDNA and ctDNA test of 127 and 431 days, respectively. Both gBRCA and tBRCA testing rates increased from 2014–2022, and testing occurred earlier in pts with recurrent than de novo disease. Among pts with tBRCAm, 66.0% had HR+ mBC, and 25.6% had mTNBC. BRCA1 mutations were more common in mTNBC (59.0%) than in HR+ mBC (22.9%) tumors. Of 219 pts with tBRCAm tumors who were diagnosed with mBC from 2018 onwards, PARPi was initiated in 39/74 (52.7%) pts with gBRCAm, 15/71 (21.1%) pts who were gBRCAm-negative, and 19/74 (25.7%) pts with gBRCAm status unknown. Among pts with g or tBRCAm and available OS data, median OS was numerically longer in pts who received PARPi (32.3 months [95% CI: 24.2, 47.4], n=128) versus pts who did not (29.0 months [95% CI: 21.9, 31.9], n=204; median follow-up time 23.2 months). Conclusions: While NCCN guidelines recommend gBRCA testing for all pts with mBC, more than half of pts with HER2-negative mBC (56.9% of pts with HR+ mBC) did not receive any BRCA test. Among pts with tBRCAm, ~2/3 had HR+ disease. Despite the potential benefits of PARPi for pts with BRCAm mBC, utilization remained low from 2018–2022.

Abstract PO3-23-09: ESR1 mutations drive resistance to CDK4/6 inhibitors in ER+ Breast Cancer

Abstract Mutations in ESR1 (the gene encoding the estrogen receptor, ERα) are major drivers of resistance to antiestrogen therapy in ER+ breast cancer. However, it remains unclear whether ESR1 mutations also drive resistance to CDK4/6 inhibitors (CDK4/6i). We analyzed de-identified next generation sequencing (NGS) data of tumor tissue DNA (n=1,820) and circulating tumor (ct) DNA (n=2,138) from patients with ER+/HER2- metastatic breast cancer. NGS of tumor tissue DNA and ctDNA previously had been performed using the Tempus xT tumor assay (595-648 genes) and Tempus xF liquid biopsy (105-523 genes), respectively. Patients were stratified into treated (xT:1,070; xF:1,885) or untreated (xT:750; xF:253) with CDK4/6i prior to biopsy, and untreated patients were restricted to those biopsied within 30 days of metastatic diagnosis. ESR1 was the only gene for which mutations were significantly enriched in patients who received CDK4/6i vs. those who did not in both xT (32% vs. 4.8%, q< 0.001) and xF (29% vs. 9.5%, q< 0.001) cohorts. To determine whether ESR1 mutations drive resistance to CDK4/6i, we used MCF-7 cells carrying ESR1 wild-type (WT), Y537S, or D538G ‘hotspot’ knock-in mutations to assess cell proliferation upon treatment with the CDK4/6i palbociclib. Cells harboring the Y537S and D538G mutations displayed a 3-fold increase in the IC50 of palbociclib single agent compared to ESR1WT cells. When treated with palbociclib + fulvestrant or palbociclib + estrogen-free medium (mimicking estrogen suppression in patients treated with aromatase inhibitors), cells harboring the Y537S and D538G mutations displayed an 11.2 to 46.9-fold increase in the IC50 of palbociclib. Treatment with palbociclib arrested growth of MCF-7 ESR1WT xenografts established in ovariectomized nude mice whereas MCF-7 ESR1Y537S and MCF-7 ESR1D538G tumors continued to grow. These results suggest that ESR1 mutations enable cell proliferation and tumor growth in the presence of CDK4/6i and the combination of CDK4/6i + antiestrogens. Next, we performed RNA-seq to investigate the mechanisms underlying ESR1 mutation-mediated resistance to CDK4/6i. Gene set enrichment analysis (GSEA) of the RNA-seq data showed significant upregulation of cell cycle-related Hallmark gene signatures such as E2F targets, G2/M checkpoints, and mitotic spindle in ESR1Y537S vs. ESR1WT and ESR1D538G vs. ESR1WT MCF-7 cells upon treatment with palbociclib. Upregulation of these gene signatures in ESR1-mutant vs. WT cells was also observed upon treatment with palbociclib + fulvestrant and palbociclib in estrogen-free media, suggesting that ESR1 mutations hamper the inhibitory effects of CDK4/6i alone or in combination with antiestrogens on cell cycle progression. Additionally, RNA-seq analysis showed that cells expressing either the Y537S or D538G mutation had elevated basal gene signatures (METABRIC_basal, TCGA_basal, and Huper_basal) compared to ESR1WT cells, consistent with previous studies suggesting that ESR1 mutations promote a luminal-to-basal subtype switch in ER+ breast cancers. We are currently investigating whether this lineage reprogramming underlies resistance to CDK4/6i in ESR1-mutant cells. In addition, we will validate our findings by analyzing the tumor tissue transcriptome from the patients included in this study. Conclusions: ESR1 mutations are enriched following treatment with CDK4/6i in a cohort of 3,958 patients with ER+/HER2- metastatic breast cancer. Mutations in ESR1 in ER+ breast cancer cells directly promote resistance to CDK4/6i alone or CDK4/6i + antiestrogens in vitro and in vivo. Citation Format: M Rosario Chica-Parrado, Chang-Ching Lin, Ellen Jaeger, Michelle Harris, Lei Guo, Emmanuel Bikorimana, Fabiana Napolitano, Calvin Chao, Ariella Hanker, Carlos Arteaga. ESR1 mutations drive resistance to CDK4/6 inhibitors in ER+ Breast Cancer [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 PO3-23-09.

Longitudinal Comparative Analysis of Circulating Tumor DNA and Matched Tumor Tissue DNA in Patients with Metastatic Colorectal Cancer Receiving Palliative First-Line Systemic Anti-Cancer Therapy.

This study aimed to compare tumor tissue DNA (ttDNA) and circulating tumor DNA (ctDNA) to explore the clinical applicability of ctDNA and to better understand clonal evolution in patients with metastatic colorectal cancer undergoing palliative first-line systemic therapy. We performed targeted sequencing analysis of 88 cancer-associated genes using germline DNA, ctDNA at baseline (baseline-ctDNA), and ctDNA at progressive disease (PD-ctDNA). The results were compared with ttDNA data. Among 208 consecutively enrolled patients, we selected 84 (41 males; median age, 59 years; range, 35 to 90 years) with all four sample types available. A total of 202 driver mutations were found in 34 genes. ttDNA exhibited the highest mutation frequency (n=232), followed by baseline-ctDNA (n=155) and PD-ctDNA (n=117). Sequencing ctDNA alongside ttDNA revealed additional mutations in 40 patients (47.6%). PD-ctDNA detected 13 novel mutations in 10 patients (11.9%) compared to ttDNA and baseline-ctDNA. Notably, seven mutations in five patients (6.0%) were missense or nonsense mutations in APC, TP53, SMAD4, and CDH1 genes. In baseline-ctDNA, higher maximal variant allele frequency (VAF) values (p=0.010) and higher VAF values of APC (p=0.012), TP53 (p=0.012), and KRAS (p=0.005) mutations were significantly associated with worse overall survival. While ttDNA remains more sensitive than ctDNA, our ctDNA platform demonstrated validity and potential value when ttDNA was unavailable. Post-treatment analysis of PD-ctDNA unveiled new pathogenic mutations, signifying cancer's clonal evolution. Additionally, baseline-ctDNA's VAF values were prognostic after treatment.

Role of plasma EBV-DNA load and EBER status on newly diagnosed peripheral T-cell lymphoma.

To explore the prognostic and therapeutic role of Epstein-Barr Virus (EBV) on peripheral T-cell lymphoma (PTCL). Totally 262 newly diagnosed PTCL patients who were hospitalized from January 2014 to December 2022 were retrospectively enrolled. Molecular analysis included 31 eligible patients. EBV-encoded RNA (EBER) presence in tumor tissue and EBV DNA levels in patients at baseline (DNA1) and after 4 cycles of chemotherapy (DNA4) were assessed. Our findings revealed that the EBER-positive cohort exhibited significant differences compared to counterparts in overall survival (OS, P = 0.047) and progression-free survival (PFS, P = 0.009). Both DNA1 and DNA4 were significantly associated with inferior OS. Multivariate analysis demonstrated that DNA4 independently affected PTCL prognosis for OS (hazard ratio = 5.1617; 95% confidence interval 1.1017-24.1831; P = 0.037). Treatment with the cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus azacytidine regimen showed a better OS compared to CHOP or CHOP plus etoposide for patients with partially positive EBER and EBER positive statuses (P = 0.192), although the improvement was not statistically significant. This study delineated the genetic paradigm of PTCL, comparing genetic differences by EBV status and found that EBER partially positive plus positive patients were more likely to have DNMT3A (P = 0.002), RHOAG17V (P = 0.023), and TET2 mutations (P = 0.032). EBER, DNA1, and DNA4 emerged as sensitive markers for prognosis. CHOP plus azacytidine might present a preferable option for PTCL patients with DNA methylation due to EBV infection.

Abstract CT202: CSFctDNA as a surrogate for tumor tissue DNA in BC pts with CNS metastases: First results from the Brainstorm program (Oncodistinct 006)

Abstract Background: Central nervous system (CNS) metastases display molecular alterations that differ from primary tumors and metastatic sites, which might confer special CNS sensitivity for targeted treatments. Brain biopsies are an invasive approach and liquid biopsies (LB) are therefore being investigated as a potential tool for detecting these molecular alterations in cerebrospinal fluid (CSF) ctDNA. Methods: The BrainStorm program (NCT04109131) is an international, prospective, interventional study aiming to build a large clinico-pathological database to investigate the development of CNS metastases: (A) before the diagnosis; (B) at diagnosis; and (C) after the diagnosis of CNS metastases. Molecular landscape of CSFctDNA was analyzed and explored as a surrogate for CNS tumor tissue DNA using large next-generation sequencing panels in tumor tissue and tumor-informed targeted gene panels in LB (OncoDEEP®/OncoFOLLOW®) for patients (pts) included in Part (B). Results: As of October 2023, CSF was available for 30 out of 67 pts included in Part (B) of the study and analyses were performed for 12 matched extra-CNS tumor, plasma and CSF samples. The 12 cases were derived from pts with breast cancer (BC) (luminal n=6; triple negative (TN) n=2; HER2-positive n=4) and among them 4 pts were diagnosed with leptomeningeal metastases (LM). CSFctDNA was detectable in 7 out of the 12 CSF samples (58%) and in 3 out of 4 pts with LM (75%). In pts with detectable CSFctDNA, detection rate for known pathogenic molecular alterations was 80% (Table 1). No safety concerns from lumbar puncture were identified. Conclusion: The use of CSFctDNA as a surrogate for tumor tissue DNA in CNS metastases appears to be a feasible and safe approach. Clinically actionable alterations have been identified in CSFctDNA of pts with BC. Further results will be presented at a later stage. TABLE 1: NAND Table 1: Pathogenic molecular alterations in matched tumor, plasma and CSF from pts with detectable CSFctDNA Tumor type Extra-CNS tumor tissue Plasma CSF TNBC PIK3Ca pH1047R PIK3Ca pH1047R PIK3Ca pH1047R Luminal BC PIK3Ca Q546R PIK3Ca Q546R PIK3Ca Q546R Luminal (LM) None KRAS pG13D None Luminal BC BRCA2 p.Y1655, PIK3CA pE545K BRCA2 pY1655, PIK3CA pE545K BRCA2 pY1655, PIK3CA pE545K TNBC (LM) None None None Luminal (LM) ESR1 D538G, PIK3CA H1047R ESR1 D538G, PIK3CA H1047R ESR1 D538G, PIK3CA H1047R HER2-positive BC ErbB2 amplification None None Citation Format: Nuria Kotecki, Diogo Martins-Branco, Guilherme Nader-Marta, Andrea Gombos, Philippe Barthelemy, Anthony Gonçalves, Edith Borcoman, Florian Clatot, Stéphane Holbrechts, Eleonora Stephane de Maio D’Esposito, Claire Cheymol, Vincent Vanhaudenarde, François Duhoux, Caroline Duhem, Paul Clement, Lore Decoster, Hannelore Denys, Florence Lefranc, Jean-Luc Canon, Joseph Gligorov, Luca Arecco, Nadège Kindt, Ahmad Awada. CSFctDNA as a surrogate for tumor tissue DNA in BC pts with CNS metastases: First results from the Brainstorm program (Oncodistinct 006) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT202.

Abstract 2425: Pairwise analysis of plasma cell-free DNA before and after paclitaxel plus ramucirumab treatment in patients with metastatic gastric cancer

Abstract Background: Plasma cell-free DNA (cfDNA) analysis has emerged as an appealing alternative to detect somatic mutations. This study compared cfDNA at baseline (baseline-cfDNA) and progressive disease (PD-cfDNA) and tumor tissue DNA (ttDNA) in patients with metastatic gastric cancer who underwent palliative second-line paclitaxel+ramucirumab treatment. Methods: We conducted targeted sequencing of 106 cancer-related genes using germline DNA, baseline-cfDNA, and PD-cfDNA samples. The results were then compared with conventional cancer panel results using ttDNA. Results: Of 76 consecutively enrolled patients who received paclitaxel+ramucirumab treatment, 46 patients (27 males; median age 57.5 [range, 32-73] years) with access to all three samples were analyzed along with their ttDNA data. A total of 138, 145, and 80 mutations were detected in baseline-cfDNA, PD-cfDNA, and ttDNA respectively. Combined analysis of baseline-cfDNA and ttDNA revealed that TP53 (56.5%) was the most frequently mutated gene, followed by CDH1 (26.1%), KRAS (21.7%), and APC (13.5%). For the top four genes, the sensitivity and positive predictive value of baseline-cfDNA compared with ttDNA were 71.8% and 51.9%, respectively. Compared with ttDNA alone, 32 patients (70.0%) benefited from baseline-cfDNA in detecting novel mutations. When combined with baseline-cfDNA and PD-cfDNA, novel mutations were discovered in 34 patients (73.9%). Of note, PD-cfDNA analysis detected 9 novel pathogenic mutations in TP53, APC, PIK3CA, CDH1, RNF43, CTNNB1, and BRCA2 genes in 8 patients (17.4%) after treatment. In baseline-cfDNA, patients with a circulating ttDNA fraction concentration at 110-160 bp of >4.3777 ng/µL had significantly shorter progression-free survival (PFS) (median 3.5 vs. 5.3 months, P=0.016). In addition, maximal variant allele frequency (VAF) values of >0.1045 (median 3.4 vs. 5.2 months, P=0.022) and the sum of VAF values of >0.2071 (median 3.4 vs. 5.2 months, P=0.028) were significantly associated with shorter PFS. In patients with TP53 mutations, those with TP53 VAF values of >0.1014 significantly had worse PFS (median 4.6 vs. 6.4 months, P=0.022). Conclusions: Although cfDNA could not entirely take over the role of ttDNA, cfDNA analysis identified additional somatic mutations that were otherwise missed by ttDNA alone. Moreover, PD-cfDNA analysis detected novel pathogenic mutations that developed during treatment, implicating the clonal evolution of cancer. In addition, baseline cfDNA predicted PFS of patients receiving paclitaxel+ramucirumab therapy. Citation Format: Ji-Won Kim, Dong Soo Kyung, Won Yeong Ko, Hwang-Phill Kim, Sung-Hyun Hwang, Kui-Jin Kim, Ju Hyun Lee, Jeongmin Seo, Minsu Kang, Eun Hee Jung, Koung Jin Suh, Se Hyun Kim, Jin Won Kim, Yu Jung Kim, Jee Hyun Kim, Keun-Wook Lee. Pairwise analysis of plasma cell-free DNA before and after paclitaxel plus ramucirumab treatment in patients with metastatic gastric cancer [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 2425.

Abstract 966: Longitudinal comparative analysis of circulating tumor DNA and matched tumor tissue DNA in patients with metastatic colorectal cancer receiving palliative first-line systemic anti-cancer therapy

Abstract Background: Plasma circulating tumor DNA (ctDNA) analysis has become an attractive method for precision oncology. This study compared mutational landscapes of ctDNA with matched tumor tissue DNA (ttDNA) to explore clinical applicability and to better understand clonal evolution in patients with metastatic colorectal cancer receiving palliative first-line systemic anti-cancer therapy (SACT). Methods: We performed unique molecular identifier-based targeted sequencing of 88 cancer-associated genes using the following samples: ttDNA, germline DNA, ctDNA at baseline (baseline-ctDNA), and ctDNA at progressive disease (PD-ctDNA). Results: Of the 208 consecutively enrolled patients, 84 were selected (41 males; median age 59, ranging from 35 to 90) with access to all four samples. Excluding duplicated mutations, a total of 202 driver mutations were discovered in 34 genes. ttDNA exhibited the highest occurrence of mutations (N=232), followed by baseline-ctDNA (N=155) and PD-ctDNA (N=117). Genotype concordance for the ten most mutated genes was highest between baseline-ctDNA and PD-ctDNA, at 94.3%, while the concordance rates for ttDNA were 85.5% with baseline-ctDNA and 83.6% with PD-ctDNA. Overall, 40 of the 84 patients (47.6%) benefited from sequencing ctDNA in addition to ttDNA as it identified additional mutations. Compared to ttDNA and baseline-ctDNA, PD-ctDNA identified 13 novel mutations in ten patients (11.9%). Notably, 7 mutations in five patients (6.0%) were missense or nonsense mutations in APC, TP53, SMAD4, and CDH1 genes. In baseline-ctDNA, patients with maximal variant allele frequency (VAF) values of >0.059 showed significantly worse progression-free survival (median 10.5 vs. 17.1 months, P=0.036) and overall survival (median 18.1 vs. 40.3 months, P=0.010). Moreover, overall survival was significantly worse in those with higher VAF values of APC (median 18.1 vs. 36.8 months, P=0.012), TP53 (median 24.7 vs. 40.3 months, P=0.012), and KRAS (median 13.7 vs. 27.6 months, P=0.005) mutations. Conclusions: While ttDNA remains more sensitive than ctDNA, our unique molecular identifier-based ctDNA platform demonstrated the validity and potential value when ttDNA was unavailable. Furthermore, post-SACT analysis of PD-ctDNA revealed new pathogenic mutations, indicating the clonal evolution of cancer. In addition, the VAF values of baseline-ctDNA predicted prognosis after SACT. Citation Format: Ji-Won Kim, Seung-been Lee, Hong-Geun Kim, Sung-Hyun Hwang, Kui-Jin Kim, Ju Hyun Lee, Jeongmin Seo, Minsu Kang, Eun Hee Jung, Koung Jin Suh, Se Hyun Kim, Jin Won Kim, Yu Jung Kim, Jee Hyun Kim, Nak-Jung Kwon, Keun-Wook Lee. Longitudinal comparative analysis of circulating tumor DNA and matched tumor tissue DNA in patients with metastatic colorectal cancer receiving palliative first-line systemic anti-cancer therapy [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 966.

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.

It was not possible to detect BRAF V600E mutation in circulating cell-free DNA from patients with ameloblastoma: A diagnostic accuracy study.

The objective of this study is to evaluate the diagnostic accuracy of plasma-based liquid biopsy for the detection of the BRAF V600E mutation in circulating cell-free DNA from patients with ameloblastoma. This is a prospective diagnostic accuracy study conducted based on the Standards for Reporting Diagnostic Accuracy recommendations. The index test was the plasma-based liquid biopsy, whereas the reference standard was the conventional tissue biopsy. The target condition was the detection of BRAF V600E mutation. The study population consisted of individuals with ameloblastoma recruited from three tertiary hospitals from Brazil. A negative control group composed of three individuals with confirmed wild-type BRAF lesions were included. The participants underwent plasma circulating cell-free DNA and tumor tissue DNA isolation, and both were submitted to using competitive allele-specific TaqMan™ real-time polymerase chain reaction technology mutation detection assays. Sensitivity and specificity measures and positive and negative predictive values were calculated. Twelve patients with conventional ameloblastoma were included. BRAF V600E mutation was detected in 11/12 (91.66%) ameloblastoma tissue samples. However, the mutation was not detected in any of the plasma-based liquid biopsy circulating cell-free DNA samples in both ameloblastomas and negative control group. The sensitivity and specificity of plasma-based liquid biopsy for the detection of the BRAF V600E mutation in circulating cell-free DNA was 0.0 and 1.0, respectively. The agreement between index test and reference standard results was 26.66%. Plasma-based liquid biopsy does not seem to be an accurate method for the detection of the BRAF V600E mutation in circulating circulating cell-free DNA from patients with ameloblastoma, regardless of tumor size, anatomic location, recurrence status, and other clinicopathological features.

Targeting of G-quadruplex DNA with 99mTc(I)/Re(I) Tricarbonyl Complexes Carrying Pyridostatin Derivatives.

The main goal of this work was to elucidate the potential relevance of (radio)metal chelates of 99mTc and Re targeting G-quadruplex structures for the design of new tools for cancer theranostics. 99mTc provides the complexes with the ability to perform single-photon-emission computed tomography imaging studies, while the Re complexes should act as anticancer agents upon interaction with specific G4 DNA or RNA structures present in tumor tissues. Towards this goal, we have developed isostructural 99mTc(I) and Re(I) tricarbonyl complexes anchored by a pyrazolyl-diamine (Pz) chelator carrying a pendant pyridostatin (PDS) fragment as the G4-binding motif. The interaction of the PDF-Pz-Re (8) complex with different G4-forming oligonucleotides was studied by circular dichroism, fluorescence spectroscopy and FRET-melting assays. The results showed that the Re complex retained the ability to bind and stabilize G4-structures from different DNA or RNA sequences, namely those present on the SRC proto-oncogene and telomeric RNA (TERRA sequence). PDF-Pz-Re (8) showed low to moderate cytotoxicity in PC3 and MCF-7 cancer cell lines, as typically observed for G4-binders. Biodistribution studies of the congener PDF-Pz-99mTc (12) in normal mice showed that the complex undergoes a fast blood clearance with a predominant hepatobiliary excretion, pointing also for a high in vitro stability.

Digital RNA sequencing using unique molecular identifiers enables ultrasensitive RNA mutation analysis

Mutation analysis is typically performed at the DNA level since most technical approaches are developed for DNA analysis. However, some applications, like transcriptional mutagenesis, RNA editing and gene expression analysis, require RNA analysis. Here, we combine reverse transcription and digital DNA sequencing to enable low error digital RNA sequencing. We evaluate yield, reproducibility, dynamic range and error correction rate for seven different reverse transcription conditions using multiplexed assays. The yield, reproducibility and error rate vary substantially between the specific conditions, where the yield differs 9.9-fold between the best and worst performing condition. Next, we show that error rates similar to DNA sequencing can be achieved for RNA using appropriate reverse transcription conditions, enabling detection of mutant allele frequencies <0.1% at RNA level. We also detect mutations at both DNA and RNA levels in tumor tissue using a breast cancer panel. Finally, we demonstrate that digital RNA sequencing can be applied to liquid biopsies, analyzing cell-free gene transcripts. In conclusion, we demonstrate that digital RNA sequencing is suitable for ultrasensitive RNA mutation analysis, enabling several basic research and clinical applications.

Toward Informed Selection and Interpretation of Clinical Genomic Tests in Prostate Cancer.

Clinical genomic testing of patient germline, tumor tissue, or plasma cell-free DNA can enable a personalized approach to cancer management and treatment. In prostate cancer (PCa), broad genotyping tests are now widely used to identify germline and/or somatic alterations in BRCA2 and other DNA damage repair genes. Alterations in these genes can confer cancer sensitivity to poly (ADP-ribose) polymerase inhibitors, are linked with poor prognosis, and can have potential hereditary cancer implications for family members. However, there is huge variability in genomic tests and reporting standards, meaning that for successful implementation of testing in clinical practice, end users must carefully select the most appropriate test for a given patient and critically interpret the results. In this white paper, we outline key pre- and post-test considerations for choosing a genomic test and evaluating reported variants, specifically for patients with advanced PCa. Test choice must be based on clinical context and disease state, availability and suitability of tumor tissue, and the genes and regions that are covered by the test. We describe strategies to recognize false positives or negatives in test results, including frameworks to assess low tumor fraction, subclonal alterations, clonal hematopoiesis, and pathogenic versus nonpathogenic variants. We assume that improved understanding among health care professionals and researchers of the nuances associated with genomic testing will ultimately lead to optimal patient care and clinical decision making.

Differences in Genomic Alterations and Accumulations of Heavy Metals Between Advanced Non-small Cell Lung Cancer Patients with and without Bone Metastasis.

Purpose: Bone metastasis (BoM) has been closely associated with increased morbidity and poor survival outcomes in patients with non-small cell lung cancer (NSCLC). Given its significant implications, this study aimed to systematically compare the biological characteristics between advanced NSCLC patients with and without BoM. Methods: In this study, the genomic alterations from the tumor tissue DNA of 42 advanced NSCLC patients without BoM and 67 patients with BoM and were analyzed by a next-generation sequencing (NGS) panel. The serum concentrations of 18 heavy metals were detected by inductively coupled plasma emission spectrometry (ICP-MS). Results: A total of 157 somatic mutations across 18 mutated genes and 105 somatic mutations spanning 16 mutant genes were identified in 61 out of 67 (91.05%) patients with BoM and 37 of 42 (88.10%) patients without BoM, respectively. Among these mutated genes, NTRK1, FGFR1, ERBB4, NTRK3, and FGFR2 stood out exclusively in patients with BoM, whereas BRAF, GNAS, and AKT1 manifested solely in those without BoM. Moreover, both co-occurring sets of genes and mutually exclusive sets of genes in patients with BoM were different from those in patients without BoM. In addition, the serum concentrations of Cu and Sr in patients with BoM were significantly higher than in patients without BoM. One of our aims was to explore how these heavy metals associated with BoM interacted with other heavy metals, and significant positive correlations were observed between Cu and Co, between Cu and Cr, between Sr and Ba, and between Sr and Ni in patients with BoM. Given the significant impacts of molecular characteristics on patients' prognosis, we also observed a noteworthy negative correlation between EGFR mutations and Co, alongside a significant positive correlation between TP53 mutations and Cd. Conclusions: The genomic alterations, somatic interactions, key signaling pathways, functional biological information, and accumulations of serum heavy metals were markedly different between advanced NSCLC patients with and without BoM, and certain heavy metals (e.g., Cu, Sr) might have potentials to identify high-risk patients with BoM.

Reliable detection of genetic alterations in cyst fluid DNA for the diagnosis of brain tumors.

Liquid biopsy of cyst fluid in brain tumors has not been extensively studied to date. The present study was performed to see whether diagnostic genetic alterations found in brain tumor tissue DNA could also be detected in cell-free DNA (cfDNA) of cyst fluid in cystic brain tumors. Cyst fluid was obtained from 22 patients undergoing surgery for a cystic brain tumor with confirmed genetic alterations in tumor DNA. Pathological diagnoses based on WHO 2021 classification and diagnostic alterations in the tumor DNA, such as IDH1 R132H and TERT promoter mutation for oligodendrogliomas, were detected by Sanger sequencing. The same alterations were analyzed by both droplet digital PCR (ddPCR) and Sanger sequencing in cyst fluid cfDNA. Additionally, multiplex ligation-dependent probe amplification (MLPA) assays were performed to assess 1p/19q status, presence of CDKN2A loss, PTEN loss and EGFR amplification, to assess whether differentiating between astrocytomas and oligodendrogliomas and grading is possible from cyst fluid cfDNA. Twenty-five genetic alterations were found in 22 tumor samples. All (100%) alterations were detected in cyst fluid cfDNA by ddPCR. Twenty of the 25 (80%) alterations were also detected by Sanger sequencing of cyst fluid cfDNA. Variant allele frequency (VAF) in cyst fluid cfDNA was comparable to that of tumor DNA (R = 0.62, Pearson's correlation). MLPA was feasible in 11 out of 17 (65%) diffuse gliomas, with close correlation of results between tumor DNA and cyst fluid cfDNA. Cell-free DNA obtained from cyst fluid in cystic brain tumors is a reliable alternative to tumor DNA when diagnosing brain tumors.