Next-generation sequencing (NGS) assays based on plasma cell-free DNA (cfDNA) are increasingly used for clinical trials inclusion. Their optimized limit of detection applied to a large number of ...genes leads to the identification of mutations not confirmed in tissue. It becomes essential to describe the characteristics and consequences of these liquid biopsy-only mutations. In the STING protocol (Gustave Roussy, NCT04932525), 542 patients with advanced solid cancer had cfDNA-based and tissue-based NGS analysis (performed by FoundationOne® Liquid CDx and FoundationOne CDx™, respectively). Mutations identified in the liquid biopsy but not in the paired tissue were considered as liquid biopsy-only mutations irrespective of their variant allelic frequency (VAF). Out of 542 patients, 281 (51.8%) harbored at least one liquid biopsy-only mutation. These patients were significantly older, and more heavily pretreated. Liquid biopsy-only mutations occurring in TP53, and in DDR genes (ATM, CHEK2, ATR, BRCA2, and BRCA1) accounted for 90.8% of all the mutations. The median VAF of these mutations was generally low (0.37% and 0.40% for TP53 and DDR genes respectively). The variant type repartition depended on the gene. Liquid biopsy-only mutations affected hotspot in TP53 codon 273, 125, 195, 176, 237 or 280 and ATM codon 2891 and 3008. In a subset of 37 patients, 75.0%, 53.5% and 83.3% of the liquid biopsy-only mutations occurring respectively in ATM, TP53, and CHEK2 were confirmed in the matching whole blood sample. Although liquid biopsy-only mutations makes the interpretation of liquid biopsy results more complex, they have distinct characteristics making them more easily identifiable.
The main identified function of BCL2 protein is to prevent cell death by apoptosis. Mouse knock-out for Bcl2 demonstrates growth retardation, severe polycystic kidney disease (PKD), grey hair and ...lymphopenia, and die prematurely after birth. Here, we report a 40-year-old male referred to for abdominal and thoracic aortic dissection with associated aortic root aneurysm, PKD, lymphocytopenia with a history of T cell lymphoblastic lymphoma, white hair since the age of 20, and learning difficulties. PKD, which was also detected in the father and sister, was related to an inherited PKD1 mutation. The combination of PKD with grey hair and lymphocytopenia was also reminiscent of Bcl2-/- mouse phenotype. BCL2 gene transcript and protein level were observed to be dramatically decreased in patient peripheral blood T-cells and in his aorta vascular wall cells, which was not detected in parents and sister T-cells, suggesting an autosomal recessive inheritance. Accordingly, spontaneous apoptosis of patient T-cells was increased and could be rescued through stimulation with an anti-CD3 antibody. Direct sequencing of BCL2 gene exons, promoter and 3'UTR region as well as BCL2 mRNA sequencing failed in identifying any pathogenic variant. Array-CGH was also normal and whole exome sequencing of the patient, parents and sister DNA did not detect any significant variant in genes encoding BCL2-interacting proteins. miRNA array identified an up-regulation of miR-181a, which is a known regulator of BCL2 expression. Altogether, miR-181a-mediated decrease in BCL2 gene expression could be a modifying factor that aggravates the phenotype of a PKD1 constitutive variant.
The cytidine analogues azacytidine and 5-aza-2'-deoxycytidine (decitabine) are commonly used to treat myelodysplastic syndromes, with or without a myeloproliferative component. It remains unclear ...whether the response to these hypomethylating agents results from a cytotoxic or an epigenetic effect. In this study, we address this question in chronic myelomonocytic leukaemia. We describe a comprehensive analysis of the mutational landscape of these tumours, combining whole-exome and whole-genome sequencing. We identify an average of 14±5 somatic mutations in coding sequences of sorted monocyte DNA and the signatures of three mutational processes. Serial sequencing demonstrates that the response to hypomethylating agents is associated with changes in DNA methylation and gene expression, without any decrease in the mutation allele burden, nor prevention of new genetic alteration occurence. Our findings indicate that cytosine analogues restore a balanced haematopoiesis without decreasing the size of the mutated clone, arguing for a predominantly epigenetic effect.
Neuroblastoma has a very diverse clinical behaviour: from spontaneous regression to a very aggressive malignant progression and resistance to chemotherapy. This heterogeneous clinical behaviour might ...be due to the existence of Cancer Stem Cells (CSC), a subpopulation within the tumor with stem-like cell properties: a significant proliferation capacity, a unique self-renewal capacity, and therefore, a higher ability to form new tumors. We enriched the CSC-like cell population content of two commercial neuroblastoma cell lines by the use of conditioned cell culture media for neurospheres, and compared genomic gains and losses and genome expression by array-CGH and microarray analysis, respectively (in CSC-like versus standard tumor cells culture). Despite the array-CGH did not show significant differences between standard and CSC-like in both analyzed cell lines, the microarray expression analysis highlighted some of the most relevant biological processes and molecular functions that might be responsible for the CSC-like phenotype. Some signalling pathways detected seem to be involved in self-renewal of normal tissues (Wnt, Notch, Hh and TGF-β) and contribute to CSC phenotype. We focused on the aberrant activation of TGF-β and Hh signalling pathways, confirming the inhibition of repressors of TGF-β pathway, as SMAD6 and SMAD7 by RT-qPCR. The analysis of the Sonic Hedgehog pathway showed overexpression of PTCH1, GLI1 and SMO. We found overexpression of CD133 and CD15 in SIMA neurospheres, confirming that this cell line was particularly enriched in stem-like cells. This work shows a cross-talk among different pathways in neuroblastoma and its importance in CSC-like cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
2516
Background: ctDNA shed is a promising biomarker for cancer immunotherapy, with patients (pts) having higher concentration of plasma ctDNA being reported to have poorer outcome. Its role in the ...maintenance setting with immune checkpoint inhibitors remains unexplored. In SAFIR02-Lung, advanced NSCLC pts were enrolled to receive a platinum-based chemotherapy. After 4 cycles, if stable or in response, pts with no targetable alterations were oriented to the immunotherapy sub-study and randomized between maintenance durvalumab or Standard of Care (SoC) (PMID 35802649). Durvalumab prolonged survival only in the PD-L1 ≥ 1% subgroup. Here we explored Tumor Fraction (TF) as determined by Low-Pass Whole Genome Sequencing as a biomarker for immunotherapy irrespective of PD-L1. Methods: SAFIR02-Lung (NCT02117167) is a multicentric, randomized phase 2 clinical trial. Plasma samples were obtained at randomization, just before maintenance treatment initiation. DNA was extracted using the Maxwell RSC ccfDNA Plasma Kit (Promega, AS1840). Sequencing libraries were prepared using the Low Input SureSelectXT protocol (Agilent, G9916A). Pooled libraries were sequenced on a NovaSeq 6000 platform (Illumina) as 2 × 150 bp paired-end reads (NovaSeq 6000 SP Reagent Kit v1.5). Genomic copy number aberrations and TF were investigated using the ichorCNA (V0.2.0) tool. TF ≥ 2% was considered positive. For the survival analyses, a landmark approach was performed, by considering the randomization date as the landmark time. Progression Free Survival (PFS) was the primary endpoint, defined as the time from randomization until the date of objective radiological disease progression, clinical progression or death. The secondary endpoint was Overall Survival (OS). Results: 50 out of 121 plasma samples from pts randomized to durvalumab were analyzed for the feasibility part. 34 pts (68%) were < 65 years, 33 (66%) were male. PD-L1 expression was available for 18 pts and 39% of them had PD-L1 ≥ 1%. Median TF was 1.1%, 8 pts (16%) had a TF ≥ 2%, ranging from 2.2% to 23.3%. TF at randomization was marginally correlated with the presence of liver metastases (p 0.063) and with the sum of target lesions (p 0.081). No significant correlation was observed with PD-L1 positivity. Pts with TF ≥ 2% had lower median PFS 1.7months (m) (95% CI 1.2 – 4.2) vs 5.8m (95% CI 2.9 – 7.5) for those with TF < 2%, p 0.0003. Similarly, median OS was lower for pts with TF > 2% 10.4m (95% CI 4.2 – 18.7) vs 25.9m (95% CI 18.2 – NR) for those with TF < 2%, p 0.0002. Data will be presented on the whole cohort, including control group receiving SoC, to discriminate between a prognostic or a predictive value of TF. Conclusions: TF was positive in 16% of pts randomized to durvalumab in the SAFIR02-Lung trial. This population seems to have a limited benefit from maintenance durvalumab after induction chemotherapy. Clinical trial information: NCT02117167 .
Abstract
In this work, we aimed at analyzing genome-wide gene expression and DNA gains and losses in neuroblastoma cell lines and in neurospheres containing stem-like cells. SKNDZ and SIMA ...neuroblastoma cell lines were grown in DMEM cell culture medium, and in DMEM-F12 selective serum free medium (with EGF, bFGF and B27; to induce the neurosphere-forming phenotype). After RNA and genomic DNA extractions from the 4 cell lines (2 standard, 2 neurosphere-forming cell lines), expression microarrays and array-CGH analyses were performed (Aligent Technologies). Array-CGH did not show any significant differences between standard and neurosphere-forming cell lines, both in SKNDZ and in SIMA. Microarray expression analysis demonstrated a total of 425 upregulated and 170 downregulated genes in neurosphere-forming cell lines. The differentially expressed genes were classified using the PANTHER classification system (www.pantherdb.org). As a result, apoptosis, cell adhesion, cell communication, cell cycle, and immune system processes appeared upregulated and downregulated in neurospheres. Some of those genes participate in pathways related with cancer (Table 1). In conclusion, the stem-like phenotype does not seem to be linked to anatomic changes at the level of deletions/gains of DNA, but to changes in expression of genes, like those of the TGF-beta, Notch and Sonic Hedgehog pathways. Those pathways, specially TGF-beta, widely described as an important therapeutic target against cancer, should be further studied to determine their real implication in the neurosphere-formation process in neuroblastoma, and therefore, as candidate targets for the treatment of neuroblastoma stem-like cells.
Citation Format: {Authors}. {Abstract title} abstract. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 413. doi:1538-7445.AM2012-413
Abstract
Liquid biopsies are a minimally invasive sampling approach to overcome the heterogeneity of tumors and represent a valuable source of circulating tumor DNA (ctDNA) for oncological biomarker ...analysis. ctDNA measurements require a highly sensitive and reliable detection technology to quantify often low-level genetic aberrations within a high background of wild-type sequences. Digital PCR emerged as a powerful technology for the next-generation analysis of liquid biopsies. Stilla Technologies' 6-color naica® system is an ultrasensitive, easy-to-use digital PCR platform capable of simultaneously and precisely quantifying high numbers of biomarkers in a single reaction.
Non-small cell lung cancer (NSCLC) is a leading cause of cancer mortality worldwide. Epidermal growth factor receptor (EGFR) is frequently mutated in NSCLC. A handful of anti-EGFR Tyrosine Kinase Inhibitor therapies are approved by the FDA; however, most patients develop resistance over time to these treatments. Both monitoring primary EGFR mutations to predict treatment response and precociously detecting resistance mutations to adapt treatments promptly through ctDNA analysis stand to improve the effectiveness of NSCLC patient management.
Stilla has developed a highly multiplexed 6-color Crystal Digital PCR EGFR kit detecting more than 90% of EGFR mutations described in NSCLC from ctDNA. The assay detects 32 common and rare somatic EGFR mutations in exons 18, 19, 20, and 21, including both activating and resistant mutations.
In this work, we evaluated the sensitivity, precision and specificity of the EGFR 6-color Crystal Digital PCR assay highly specific and sensitive for the detection of EGFR mutations, with a Limit of Detection in a high background of wild-type DNA ranging from 0.30 to 0.46 cp/μL (with observed MAFs ranging from 0.06 to 0.09%). Moreover, a high concordance was observed between those EGFR results obtained for NSCLC ctDNA samples using 6-color Crystal Digital PCR and other technologies. With a rapid time to results and straightforward ctDNA analysis workflow, Crystal Digital PCR on the naica system promises ultrasensitive, highly multiplexed 6-color mutation detection, maximizing the information obtained from precious samples.
Citation Format: Cécile Jovelet, Myrtille Remy, Noémie Pata-Merci, Damien Vasseur, Ludovic Lacroix, Claudia Labrador-Rached, Allison C. Mallory. Highly multiplexed EGFR mutation detection from liquid biopsy samples using the 6-color Crystal Digital PCR™ abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 75.
Neuroblastoma has a very diverse clinical behaviour: from spontaneous regression to a very aggressive malignant progression and resistance to chemotherapy. This heterogeneous clinical behaviour might ...be due to the existence of Cancer Stem Cells (CSC), a subpopulation within the tumor with stem-like cell properties: a significant proliferation capacity, a unique self-renewal capacity, and therefore, a higher ability to form new tumors. We enriched the CSC-like cell population content of two commercial neuroblastoma cell lines by the use of conditioned cell culture media for neurospheres, and compared genomic gains and losses and genome expression by array-CGH and microarray analysis, respectively (in CSC-like versus standard tumor cells culture). Despite the array-CGH did not show significant differences between standard and CSC-like in both analyzed cell lines, the microarray expression analysis highlighted some of the most relevant biological processes and molecular functions that might be responsible for the CSC-like phenotype. Some signalling pathways detected seem to be involved in self-renewal of normal tissues (Wnt, Notch, Hh and TGF- beta ) and contribute to CSC phenotype. We focused on the aberrant activation of TGF- beta and Hh signalling pathways, confirming the inhibition of repressors of TGF- beta pathway, as SMAD6 and SMAD7 by RT-qPCR. The analysis of the Sonic Hedgehog pathway showed overexpression of PTCH1, GLI1 and SMO. We found overexpression of CD133 and CD15 in SIMA neurospheres, confirming that this cell line was particularly enriched in stem-like cells. This work shows a cross-talk among different pathways in neuroblastoma and its importance in CSC-like cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Introduction Circulating tumor DNA (ctDNA) detection has not been reported yet in ALK-positive anaplastic large cell lymphoma (ALK+ALCL), a rare aggressive non-Hodgkin lymphoma with a peak incidence ...in children, adolescents and young adults. In this study, we aimed to evaluate whether ctDNA can be detected, characterized and used to monitor minimal residual disease (MRD) in ALK+ALCL. Patients and Methods Plasma samples were collected from 23 French patients diagnosed with ALK+ALCL between November 2020 and March 2023. Based on cell-free DNA (cfDNA) extracted from plasma, we performed shallow whole genome sequencing (shWGS) and a comprehensive genomic profiling (CGP) of more than 500 genes covered at a median depth of over 3000 unique reads to assess ctDNA content. In this study, we defined samples as positive if they had a tumor fraction over 3%, evaluated by shWGS analysis, or if ALK rearrangements were identified using CGP. Additionally, ALK rearrangement genomic breakpoint were defined by CGP analysis. For each patient, specific digital droplet PCR (ddPCR) assays were designed based on the identified breakpoints to monitor ctDNA content during the ALK+ALCL disease follow-up. Results The median age of patients at the time of diagnosis was 13 years (range: 4-54). Sixteen patients, (69.6%) received at least one ALK tyrosine kinase inhibitor (TKI). A total of 80 plasma samples were collected at various time points from the 23 patients, with a median of 3 samples per patient (range: 1 - 20). Four samples failed for DNA extraction, resulting in 76 samples available for molecular analysis Of the 76 samples, 43 (56.6%) were analyzed using shWGS, 19 (25%) using CGP among which, 14 were analyzed using both techniques. CGP was found to be a more sensitive method for detecting ctDNA in ALK+ALCL compared to shWGS, with 12 out of 14 samples (85.7%) tested positive with CGP, compared to 5 out of 14 samples (35.7%) with shWGS (p<0.01). Of the 19 samples tested with CGP, ALK rearrangement was identified in 14 samples (73.7%), with NPM1:: ALK fusion detected in 11 samples, and ATIC:: ALK, TRAF1:: ALK and EEF1G:: ALK detected in one sample each. The average tumor mutational burden was low, with 5.3 mutations per megabase (mut/Mb) (range: 0-14.5 mut/Mb). No microsatellite instability was detected. Amplification of MDM4 and MYC genes was observed in three patients each. ANKRD26 was the most frequently mutated gene in the study, with four patients affected. LRP1B, epigenetic modifiers such as EP300 and KMT2A, and TP53 were mutated in three patients each. Interestingly, CGP allowed the identification of the ALK:c.3520T>C;p.(Phe1174Leu) mutation in a plasma sample collected during disease progression while the patient was on long lasting crizotinib therapy. Finally, we monitored MRD, based on ctDNA detection in 49 samples from 12 patients using ddPCR assays. Our results were compared with the established gold standard for MRD monitoring in ALK+ALCL, i.e. RT-PCR on circulating cells performed on the same samples. The ddPCR assay showed a 87% sensitivity, 100% specificity, 100% positive predictive value, and 83% negative predictive value. However, four samples had false-negative results due to pre-analytical sampling issues. These samples had been stored at room temperature without undergoing centrifugation for more than 24 hours. Conclusion To date, this study is the first to report on the feasibility and clinical value of ctDNA for the management of ALK+ALCL patients. CGP demonstrated high sensitivity in detecting ctDNA, identifying the genomic breakpoint within the ALK gene and, for the first time in ALK+ALCL, detecting resistance mutations to ALK TKI. Additionally, our unique patient-specific ddPCR approach was proven to be a cost-effective method for MRD monitoring. Altogether, these findings serve as a proof-of-concept for the development of ctDNA techniques in the clinical management of ALK+ALCL.
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