Publications by authors named "Giulia Siravegna"

51 Publications

FGFR2 Extracellular Domain In-Frame Deletions are Therapeutically Targetable Genomic Alterations that Function as Oncogenic Drivers in Cholangiocarcinoma.

Cancer Discov 2021 Apr 29. Epub 2021 Apr 29.

Department of Medical Oncology, Dana-Farber Cancer Institute.

We conducted next generation DNA sequencing on 335 biliary tract cancers and characterized the genomic landscape by anatomic site within the biliary tree. In addition to frequent FGFR2 fusions among patients with intrahepatic cholangiocarcinoma (IHCC), we identified FGFR2 extracellular domain in-frame deletions (EIDs) in 5 of 178 (2.8%) patients with IHCC, including two patients with FGFR2 p.H167_N173del. Expression of this FGFR2 EID in NIH3T3 cells resulted in constitutive FGFR2 activation, oncogenic transformation, and sensitivity to FGFR inhibitors. Three patients with FGFR2 EIDs were treated with Debio 1347, an oral FGFR-1/2/3 inhibitor, and all showed partial responses. One patient developed an acquired L618F FGFR2 kinase domain mutation at disease progression and experienced a further partial response for 17 months to an irreversible FGFR2 inhibitor, futibatinib. Together, these findings reveal FGFR2 EIDs as an alternative mechanism of FGFR2 activation in IHCC that predict sensitivity to FGFR inhibitors in the clinic.
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http://dx.doi.org/10.1158/2159-8290.CD-20-1669DOI Listing
April 2021

Minimal Residual Disease Detection using a Plasma-Only Circulating Tumor DNA Assay in Colorectal Cancer Patients.

Clin Cancer Res 2021 Apr 29. Epub 2021 Apr 29.

Division of Hematology/Oncology, Massachusetts General Hospital.

Purpose: Detection of persistent circulating tumor DNA (ctDNA) after curative-intent surgery can identify patients with minimal residual disease (MRD) who will ultimately recur. Most ctDNA MRD assays require tumor sequencing to identify tumor-derived mutations to facilitate ctDNA detection, requiring tumor and blood. We evaluated a plasma-only ctDNA assay integrating genomic and epigenomic cancer signatures to enable tumor-uninformed MRD detection.

Experimental Design: 252 prospective serial plasma specimens from 103 colorectal cancer (CRC) patients undergoing curative intent surgery were analyzed and correlated with recurrence.

Results: Of 103 patients, 84 (stage I (9.5%), II (23.8%), III (47.6%), IV (19%)) had evaluable plasma drawn post-completion of definitive therapy, defined as surgery only (n=39) or completion of adjuvant therapy (n=45). In "landmark" plasma drawn one-month (median 31.5 days) post-definitive therapy and >1 year follow up, 15 patients had detectable ctDNA, and all 15 recurred (positive predictive value (PPV) 100%, hazard ratio 11.28 (p<0.0001)). Of 49 patients without detectable ctDNA at the landmark timepoint, 12 (24.5%) recurred. Landmark recurrence sensitivity and specificity were 55.6% and 100%. Incorporating serial longitudinal and surveillance (drawn within 4-months of recurrence) samples, sensitivity improved to 69% and 91%. Integrating epigenomic signatures increased sensitivity by 25-36% versus genomic alterations alone. Notably, standard serum carcinoembryonic antigen (CEA) levels did not predict recurrence (hazard ratio 1.84 (p=0.18); PPV=53.9%).

Conclusions: Plasma-only MRD detection demonstrated favorable sensitivity and specificity for recurrence, comparable to tumor-informed approaches. Integrating analysis of epigenomic and genomic alterations enhanced sensitivity. These findings support the potential clinical utility of plasma-only ctDNA MRD detection.
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http://dx.doi.org/10.1158/1078-0432.CCR-21-0410DOI Listing
April 2021

Clinical acquired resistance to KRASG12C inhibition through a novel KRAS switch-II pocket mutation and polyclonal alterations converging on RAS-MAPK reactivation.

Cancer Discov 2021 Apr 6. Epub 2021 Apr 6.

Department of Medicine, Harvard Medical School

Mutant-selective KRASG12C inhibitors, such as MRTX849 (adagrasib) and AMG 510 (sotorasib), have demonstrated efficacy in KRASG12C-mutant cancers including non-small cell lung cancer (NSCLC). However, mechanisms underlying clinical acquired resistance to KRASG12C inhibitors remain undetermined. To begin to define the mechanistic spectrum of acquired resistance, we describe a KRASG12C NSCLC patient who developed polyclonal acquired resistance to MRTX849 with the emergence of 10 heterogeneous resistance alterations in serial cell-free DNA spanning four genes (KRAS, NRAS, BRAF, MAP2K1), all of which converge to reactivate RAS-MAPK signaling. Notably, a novel KRASY96D mutation affecting the switch-II pocket, to which MRTX849 and other inactive-state inhibitors bind, was identified that interferes with key protein-drug interactions and confers resistance to these inhibitors in engineered and patient-derived KRASG12C cancer models. Interestingly, a novel, functionally distinct tri-complex KRASG12C active-state inhibitor RM-018 retained the ability to bind and inhibit KRASG12C/Y96D and could overcome resistance.
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http://dx.doi.org/10.1158/2159-8290.CD-21-0365DOI Listing
April 2021

Genome-wide Copy-number Alterations in Circulating Tumor DNA as a Novel Biomarker for Patients with High-grade Serous Ovarian Cancer.

Clin Cancer Res 2021 May 15;27(9):2549-2559. Epub 2020 Dec 15.

Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy.

Purpose: High-grade serous epithelial ovarian cancer (HGS-EOC) is defined by high levels of somatic copy-number alterations (SCNA) with marked spatial and temporal tumor heterogeneity. Biomarkers serving to monitor drug response and detect disease recurrence are lacking, a fact which reflects an unmet clinical need.

Experimental Design: A total of 185 plasma samples and 109 matched tumor biopsies were collected from 46 patients with HGS-EOC, and analyzed by shallow whole-genome sequencing (sWGS). The percentage of tumor fraction (TF) in the plasma was used to study the biological features of the disease at the time of diagnosis (T0) and correlated with patients' survival. Longitudinal analysis of TF was correlated with CA-125 levels and radiological images to monitor disease recurrence.

Results: Gain in the clonal regions, and , was observed in the 87.8% and 78.05% of plasma samples, suggesting that plasma sWGS mirrors solid biopsies. At T0, multivariate analysis revealed that plasma TF levels were an independent prognostic marker of relapse ( < 0.022). After platinum (Pt)-based treatment, circulating tumor DNA (ctDNA) analysis showed a change in the heterogeneous pattern of genomic amplification, including an increased frequency of amplification, compared with before Pt-based treatment in the and regions. TF in serially collected ctDNA samples outperformed CA-125 in anticipating clinical and radiological progression by 240 days (range, 37-491).

Conclusions: Our results support the notion that sWGS is an inexpensive and useful tool for the genomic analysis of ctDNA in patients with HGS-EOC to monitor disease evolution and to anticipate relapse better than serum CA-125, the routinely used clinical biomarker..
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http://dx.doi.org/10.1158/1078-0432.CCR-20-3345DOI Listing
May 2021

Cancer-Associated Fibroblasts: Versatile Players in the Tumor Microenvironment.

Cancers (Basel) 2020 Sep 17;12(9). Epub 2020 Sep 17.

Division of Surgical Oncology, Department of Surgery, UT Southwestern (University of Texas Southwestern Medical Center), Dallas, TX 75390, USA.

Cancer-associated fibroblasts (CAFs) are indispensable architects of the tumor microenvironment. They perform the essential functions of extracellular matrix deposition, stromal remodeling, tumor vasculature modulation, modification of tumor metabolism, and participation in crosstalk between cancer and immune cells. In this review, we discuss our current understanding of the principal differences between normal fibroblasts and CAFs, the origin of CAFs, their functions, and ultimately, highlight the intimate connection of CAFs to virtually all of the hallmarks of cancer. We address the remarkable degree of functional diversity and phenotypic plasticity displayed by CAFs and strive to stratify CAF biology among different tumor types into practical functional groups. Finally, we summarize the status of recent and ongoing trials of CAF-directed therapies and contend that the paucity of trials resulting in Food and Drug Administration (FDA) approvals thus far is a consequence of the failure to identify targets exclusive of pro-tumorigenic CAF phenotypes that are mechanistically linked to specific CAF functions. We believe that the development of a unified CAF nomenclature, the standardization of functional assays to assess the loss-of-function of CAF properties, and the establishment of rigorous definitions of CAF subpopulations and their mechanistic functions in cancer progression will be crucial to fully realize the promise of CAF-targeted therapies.
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http://dx.doi.org/10.3390/cancers12092652DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564346PMC
September 2020

Long-term Clinical Outcome of Trastuzumab and Lapatinib for HER2-positive Metastatic Colorectal Cancer.

Clin Colorectal Cancer 2020 12 27;19(4):256-262.e2. Epub 2020 Jun 27.

Niguarda Cancer Center, Grande Ospedale Metropolitano Niguarda, Milan, Italy; Dipartimento di Oncologia ed Emato-Oncologia, Università degli Studi di Milano, Milan, Italy. Electronic address:

Background: ERBB2 amplification occurs in 5% of RAS wild-type metastatic colorectal cancer (mCRC) and it has been shown to be a target for treatment with 2 HER2-directed combinations of trastuzumab and lapatinib or trastuzumab and pertuzumab. We present long-term clinical results of trastuzumab and lapatinib (HERACLES-A trial) at 6.7 years (82 months) follow-up and focus on central nervous system (CNS) recurrences.

Patients And Methods: Patients had histologically confirmed KRAS exon 2 (codons 12 and 13) wild-type and HER2-positive mCRC. HER2 positivity was assessed by immunohistochemistry and in situ hybridization HERACLES diagnostic criteria. Patients were treated with intravenous trastuzumab 4 mg/kg loading dose, then 2 mg/kg once per week, and oral lapatinib 1000 mg per day until disease progression or toxicity. Patients who presented with symptoms or signs of CNS disease received brain computed tomography scan or magnetic resonance imaging.

Results: A total of 35 patients received trastuzumab and lapatinib and 32 were evaluable for response. One patient (3%) achieved complete response (CR), 8 (25%) partial response, and 13 (41%) stable disease. Therefore, response rate was 28%. Median progression-free survival was 4.7 months (95% confidence interval [CI] 3.7-6.1). Median overall survival was 10.0 months (95% CI 7.9-15.8). One patient achieved sustained CR still maintained at 7 years of follow-up. Progression in the central nervous system (CNS) occurred in 6 (19%) of 32 patients.

Conclusions: Long-term (6.7 years) follow-up analysis of HERACLES-A supports using of trastuzumab and lapatinib as treatment reference for KRAS wild-type, chemorefractory HER2-positive mCRC. In this subset of patients, prolongation of survival is accompanied by CNS recurrences that will require diagnostic and therapeutic attention in future studies. Clinicaltrials. Gov identifier: NCT 03225937.
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http://dx.doi.org/10.1016/j.clcc.2020.06.009DOI Listing
December 2020

Liquid biopsy, a paradigm shift in oncology: what interventional radiologists should know.

Eur Radiol 2020 Aug 19;30(8):4496-4503. Epub 2020 Mar 19.

Department of Interventional Radiology, MD Anderson Cancer Center, The University of Texas, Houston, TX, USA.

The acquisition of adequate tumor sample is required to verify primary tumor type and specific biomarkers and to assess response to therapy. Historically, invasive surgical procedures were the standard methods to acquire tumor samples until advancements in imaging and minimally invasive equipment facilitated the paradigm shift image-guided biopsy. Image-guided biopsy has improved sampling yield and minimized risk to the patient; however, there are still limitations, such as its invasive nature and its consequent limitations to longitudinal tumor monitoring. The next paradigm shift in sampling technique will need to address these issues to provide a more reliable and less invasive technique. Recently, liquid biopsy (LB) has emerged as a non-invasive alternative to tissue sampling. This technique relies on direct sampling of blood or other bodily fluids in contact with the tumor in order to collect circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and circulating RNAs-in particular microRNA (miRNAs). Clinical applications of LB involve different steps of cancer patient management including screening, detection of disease recurrence, and evaluation of acquired resistance. With any paradigm shift, old techniques are often relegated to a secondary option. Although image-guided biopsies may appear as a passive spectator on the rapid advancement of LB, the two techniques may well be codependent. Interventional radiology may be integral to directly sample the liquid surrounding or draining from the tumor. In addition, LB may help to correctly select the patients for image-guided loco-regional treatments, to determine its treatment endpoint, and to early detect recurrence. KEY POINTS: • Liquid biopsy is a novel technology with potential high impact in the management of patients undergoing image-guided procedures. • Interventional radiology procedures may increase liquid biopsy sensitivity through direct fluid sampling. • Liquid biopsy techniques may provide a venue for improving patients' selection and enhance outcomes of interventional loco-regional therapies performed by interventional radiologists.
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http://dx.doi.org/10.1007/s00330-020-06700-4DOI Listing
August 2020

Whole exome sequencing analysis of urine trans-renal tumour DNA in metastatic colorectal cancer patients.

ESMO Open 2019 11;4(6)

University of Turin, Department of Oncology, Candiolo (TO), Italy

Background: The analysis of circulating free tumour DNA (ctDNA) in blood, commonly referred as liquid biopsy, is being used to characterise patients with solid cancers. Tumour-specific genetic variants can also be present in DNA isolated from other body fluids, such as urine. Unlike blood, urine sampling is non-invasive, can be self-performed, and allows recurrent longitudinal monitoring. The features of tumour DNA that clears from the glomerular filtration barrier, named trans-renal tumour DNA (trtDNA), are largely unexplored.

Patients And Methods: Specimens were collected from 24 patients with or mutant metastatic colorectal cancer (mCRC). Driver mutations were assessed by droplet digital PCR (ddPCR) in ctDNA from plasma and trtDNA from urine. Whole exome sequencing (WES) was performed in DNA isolated from tissue, plasma and urine.

Results: Out of the 24 CRC cases, only four had sufficient DNA to allow WES analyses in urine and plasma. We found that tumour alterations primarily reside in low molecular weight fragments (less than 112 bp). In patients whose trtDNA was more than 2.69% of the urine derived DNA, cancer-specific molecular alterations, mutational signatures and copy number profiles identified in urine DNA are comparable with those detected in plasma ctDNA.

Conclusions: With current technologies, WES analysis of trtDNA is feasible in a small fraction of mCRC patients. Tumour-related genetic information is mainly present in low molecular weight DNA fragments. Although the limited amounts of trtDNA poses analytical challenges, enrichment of low molecular weight DNAs and optimised computational tools can improve the detection of tumour-specific genetic information in urine.
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http://dx.doi.org/10.1136/esmoopen-2019-000572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001107PMC
November 2019

Serial ctDNA Monitoring to Predict Response to Systemic Therapy in Metastatic Gastrointestinal Cancers.

Clin Cancer Res 2020 04 15;26(8):1877-1885. Epub 2020 Jan 15.

Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.

Purpose: ctDNA offers a promising, noninvasive approach to monitor therapeutic efficacy in real-time. We explored whether the quantitative percent change in ctDNA early after therapy initiation can predict treatment response and progression-free survival (PFS) in patients with metastatic gastrointestinal cancer.

Experimental Design: A total of 138 patients with metastatic gastrointestinal cancers and tumor profiling by next-generation sequencing had serial blood draws pretreatment and at scheduled intervals during therapy. ctDNA was assessed using individualized droplet digital PCR measuring the mutant allele fraction in plasma of mutations identified in tumor biopsies. ctDNA changes were correlated with tumor markers and radiographic response.

Results: A total of 138 patients enrolled. A total of 101 patients were evaluable for ctDNA and 68 for tumor markers at 4 weeks. Percent change of ctDNA by 4 weeks predicted partial response (PR, < 0.0001) and clinical benefit [CB: PR and stable disease (SD), < 0.0001]. ctDNA decreased by 98% (median) and >30% for all PR patients. ctDNA change at 8 weeks, but not 2 weeks, also predicted CB ( < 0.0001). Four-week change in tumor markers also predicted response ( = 0.0026) and CB ( = 0.022). However, at a clinically relevant specificity threshold of 90%, 4-week ctDNA change more effectively predicted CB versus tumor markers, with a sensitivity of 60% versus 24%, respectively ( = 0.0109). Patients whose 4-week ctDNA decreased beyond this threshold (≥30% decrease) had a median PFS of 175 days versus 59.5 days (HR, 3.29; 95% CI, 1.55-7.00; < 0.0001).

Conclusions: Serial ctDNA monitoring may provide early indication of response to systemic therapy in patients with metastatic gastrointestinal cancer prior to radiographic assessments and may outperform standard tumor markers, warranting further evaluation.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-3467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7165022PMC
April 2020

Liquid versus tissue biopsy for detecting acquired resistance and tumor heterogeneity in gastrointestinal cancers.

Nat Med 2019 09 9;25(9):1415-1421. Epub 2019 Sep 9.

Cancer Center, Massachusetts General Hospital, Boston, MA, USA.

During cancer therapy, tumor heterogeneity can drive the evolution of multiple tumor subclones harboring unique resistance mechanisms in an individual patient. Previous case reports and small case series have suggested that liquid biopsy (specifically, cell-free DNA (cfDNA)) may better capture the heterogeneity of acquired resistance. However, the effectiveness of cfDNA versus standard single-lesion tumor biopsies has not been directly compared in larger-scale prospective cohorts of patients following progression on targeted therapy. Here, in a prospective cohort of 42 patients with molecularly defined gastrointestinal cancers and acquired resistance to targeted therapy, direct comparison of postprogression cfDNA versus tumor biopsy revealed that cfDNA more frequently identified clinically relevant resistance alterations and multiple resistance mechanisms, detecting resistance alterations not found in the matched tumor biopsy in 78% of cases. Whole-exome sequencing of serial cfDNA, tumor biopsies and rapid autopsy specimens elucidated substantial geographic and evolutionary differences across lesions. Our data suggest that acquired resistance is frequently characterized by profound tumor heterogeneity, and that the emergence of multiple resistance alterations in an individual patient may represent the 'rule' rather than the 'exception'. These findings have profound therapeutic implications and highlight the potential advantages of cfDNA over tissue biopsy in the setting of acquired resistance.
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http://dx.doi.org/10.1038/s41591-019-0561-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6741444PMC
September 2019

TAS-120 Overcomes Resistance to ATP-Competitive FGFR Inhibitors in Patients with FGFR2 Fusion-Positive Intrahepatic Cholangiocarcinoma.

Cancer Discov 2019 08 20;9(8):1064-1079. Epub 2019 May 20.

Gastrointestinal Oncology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York.

ATP-competitive fibroblast growth factor receptor (FGFR) kinase inhibitors, including BGJ398 and Debio 1347, show antitumor activity in patients with intrahepatic cholangiocarcinoma (ICC) harboring activating gene fusions. Unfortunately, acquired resistance develops and is often associated with the emergence of secondary kinase domain mutations. Here, we report that the irreversible pan-FGFR inhibitor TAS-120 demonstrated efficacy in 4 patients with 2 fusion-positive ICC who developed resistance to BGJ398 or Debio 1347. Examination of serial biopsies, circulating tumor DNA (ctDNA), and patient-derived ICC cells revealed that TAS-120 was active against multiple FGFR2 mutations conferring resistance to BGJ398 or Debio 1347. Functional assessment and modeling the clonal outgrowth of individual resistance mutations from polyclonal cell pools mirrored the resistance profiles observed clinically for each inhibitor. Our findings suggest that strategic sequencing of FGFR inhibitors, guided by serial biopsy and ctDNA analysis, may prolong the duration of benefit from FGFR inhibition in patients with fusion-positive ICC. SIGNIFICANCE: ATP-competitive FGFR inhibitors (BGJ398, Debio 1347) show efficacy in -altered ICC; however, acquired kinase domain mutations cause drug resistance and tumor progression. We demonstrate that the irreversible FGFR inhibitor TAS-120 provides clinical benefit in patients with resistance to BGJ398 or Debio 1347 and overcomes several FGFR2 mutations in ICC models..
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http://dx.doi.org/10.1158/2159-8290.CD-19-0182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6677584PMC
August 2019

A Genomic Analysis Workflow for Colorectal Cancer Precision Oncology.

Clin Colorectal Cancer 2019 06 7;18(2):91-101.e3. Epub 2019 Mar 7.

Candiolo Cancer Institute, FPO-IRCCS, Candiolo (TO), Italy; University of Turin, Department of Oncology, Candiolo (TO), Italy. Electronic address:

Background: The diagnosis of colorectal cancer (CRC) is routinely accomplished through histopathologic examination. Prognostic information and treatment decisions are mainly determined by TNM classification, first defined in 1968. In the last decade, patient-specific CRC genomic landscapes were shown to provide important prognostic and predictive information. Therefore, there is a need for developing next generation sequencing (NGS) and bioinformatic workflows that can be routinely used for the assessment of prognostic and predictive biomarkers.

Materials And Methods: To foster the application of genomics in the clinical management of CRCs, the IDEA workflow has been built to easily adapt to the availability of patient specimens and the clinical question that is being asked. Initially, IDEA deploys ad-hoc NGS assays to interrogate predefined genomic target sequences (from 600 kb to 30 Mb) with optimal detection sensitivity. Next, sequencing data are processed through an integrated bioinformatic pipeline to assess single nucleotide variants, insertions and deletions, gene copy-number alterations, and chromosomal rearrangements. The overall results are gathered into a user-friendly report.

Results: We provide evidence that IDEA is capable of identifying clinically relevant molecular alterations. When optimized to analyze circulating tumor DNA, IDEA can be used to monitor response and relapse in the blood of patients with metastatic CRC receiving targeted agents. IDEA detected primary and secondary resistance mechanisms to ERBB2 blockade including sub-clonal RAS and BRAF mutations.

Conclusions: The IDEA workflow provides a flexible platform to integrate NGS and bioinformatic tools for refined diagnosis and management of patients with advanced CRC.
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http://dx.doi.org/10.1016/j.clcc.2019.02.008DOI Listing
June 2019

Multisite analysis of high-grade serous epithelial ovarian cancers identifies genomic regions of focal and recurrent copy number alteration in 3q26.2 and 8q24.3.

Int J Cancer 2019 11 26;145(10):2670-2681. Epub 2019 Apr 26.

Department of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri" IRCCS, Milano, Italy.

High-grade serous epithelial ovarian cancer (HGS-EOC) is a systemic disease, with marked intra and interpatient tumor heterogeneity. The issue of spatial and temporal heterogeneity has long been overlooked, hampering the possibility to identify those genomic alterations that persist, before and after therapy, in the genome of all tumor cells across the different anatomical districts. This knowledge is the first step to clarify those molecular determinants that characterize the tumor biology of HGS-EOC and their route toward malignancy. In our study, -omics data were generated from 79 snap frozen matched tumor biopsies, withdrawn before and after chemotherapy from 24 HGS-EOC patients, gathered together from independent cohorts. The landscape of somatic copy number alterations depicts a more homogenous and stable genomic portrait than the single nucleotide variant profile. Genomic identification of significant targets in cancer analysis identified two focal and minimal common regions (FMCRs) of amplification in the cytoband 3q26.2 (region α, 193 kb long) and 8q24.3 (region β, 495 kb long). Analysis in two external databases confirmed regions α and β are features of HGS-EOC. The MECOM gene is located in region α, and 15 genes are in region β. No functional data are yet available for the genes in the β region. In conclusion, we have identified for the first time two FMCRs of amplification in HGS-EOC, opening up a potential biological role in its etiopathogenesis.
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http://dx.doi.org/10.1002/ijc.32288DOI Listing
November 2019

Plasma HER2 () Copy Number Predicts Response to HER2-targeted Therapy in Metastatic Colorectal Cancer.

Clin Cancer Res 2019 05 26;25(10):3046-3053. Epub 2019 Feb 26.

Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Torino, Italy.

Purpose: (HER2) amplification is an emerging biomarker in colon cancer, conferring sensitivity to combination anti-HER2 therapy. Measurement of HER2 copy number is typically performed using surgical specimens, but cell-free circulating tumor DNA (ctDNA) analysis may be a noninvasive alternative. We determined the sensitivity of plasma copy number (pCN) for detecting amplifications and whether pCN correlated with tissue-detected copy number. We also assessed response to HER2-targeted therapy based on pCN and suggest a pCN threshold predictive of response.

Experimental Design: Forty-eight pretreatment and progression plasma samples from 29 HER2-positive patients in the HERACLES A clinical trial were tested using the Guardant360 cfDNA assay. We correlated pCN with progression-free survival (PFS) and best objective response (BOR) and applied an adjustment method based on tumor DNA shedding using the maximum mutant allele fraction as a surrogate for tumor content to accurately determine the pCN threshold predictive of response.

Results: Forty-seven of 48 samples had detectable ctDNA, and 46 of 47 samples were -amplified on the basis of cfDNA [2.55-122 copies; 97.9% sensitivity (95% confidence interval, 87.2%-99.8%)]. An adjusted pCN of ≥25.82 copies correlated with BOR and PFS ( = 0.0347).

Conclusions: cfDNA is a viable alternative to tissue-based genotyping in the metastatic setting. The cfDNA platform utilized correctly identified 28 of 29 (96.6%) of pretreatment samples as -amplified and predicted benefit from HER2-targeted therapy. In this study, an observed pCN of 2.4 and an adjusted pCN of 25.82 copies of are proposed to select patients who will benefit from HER2-targeted therapy.
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http://dx.doi.org/10.1158/1078-0432.CCR-18-3389DOI Listing
May 2019

Retreatment with anti-EGFR monoclonal antibodies in metastatic colorectal cancer: Systematic review of different strategies.

Cancer Treat Rev 2019 Feb 27;73:41-53. Epub 2018 Dec 27.

Niguarda Cancer Center, Grande Ospedale Metropolitano Niguarda, Milan, Italy; Università degli Studi di Milano, Dipartimento di Oncologia ed Emato-Oncologia, Milano, Italy. Electronic address:

Background: Despite advances in precision oncology and immunotherapy of tumors, little progress has been made in metastatic colorectal cancer (mCRC) in recent years. Therefore, making the most of available therapies is a necessity. Several studies, based on the pulsatile behavior of RAS clones under EGFR blockade, investigated whether readministration of EGFR-targeted agents is effective beyond second line.

Methods: A systematic review of studies of retreatment with anti-EGFR monoclonal antibodies has been performed from January 2005 to December 2018 according to PRISMA criteria from PubMed, ESMO and ASCO meetings libraries and Clinicaltrial.gov. Efficacy has been evaluated as objective response rate and survival in available publications. In addition, type and incidence of side effects occurring during on anti-EGFR retreatment have been considered.

Results: 26 publications have been retrieved, of which 20 full-text articles and 6 abstracts and categorized as for the retreatment strategy into five groups: rechallenge (n = 10), reintroduction (n = 4), sequence (n = 5), dose escalation (n = 1) and mixed (n = 6). Data of efficacy displayed high heterogeneity across different strategies (objective response rate, ORR = 0.0-53.8%; disease control rate, DCR = 24.0-89.7%), with best results in the setting of rechallenge (ORR = 2.9-53.8%; DCR = 40.0-89.7%).

Conclusions: Rechallenge with anti-EGFR provides clinical benefit in molecularly selected mCRC patients beyond second line. Further ctDNA-guided studies comparing this option of treatment with current approved advanced line treatments are warranted.
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http://dx.doi.org/10.1016/j.ctrv.2018.12.006DOI Listing
February 2019

Blood-Based Prediction of Tumor Relapse: The cfDNA Forecast.

Cancer Discov 2018 10;8(10):1213-1215

Massachusetts General Hospital Cancer Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts.

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http://dx.doi.org/10.1158/2159-8290.CD-18-0952DOI Listing
October 2018

Radiologic and Genomic Evolution of Individual Metastases during HER2 Blockade in Colorectal Cancer.

Cancer Cell 2018 07;34(1):148-162.e7

Niguarda Cancer Center, Grande Ospedale Metropolitano Niguarda, Milan 20162, Italy.

Targeting HER2 is effective in 24% of ERBB2 amplified metastatic colorectal cancer; however, secondary resistance occurs in most of the cases. We studied the evolution of individual metastases during treatment to discover spatially resolved determinants of resistance. Circulating tumor DNA (ctDNA) analysis identified alterations associated with resistance in the majority of refractory patients. ctDNA profiles and lesion-specific radiographic reports revealed organ- or metastasis-private evolutionary patterns. When radiologic assessments documented progressive disease in target lesions, response to HER2 blockade was retained in other metastases. Genomic and functional analyses on samples and cell models from eight metastases of a patient co-recruited to a postmortem study unveiled lesion-specific evolutionary trees and pharmacologic vulnerabilities. Lesion size and contribution of distinct metastases to plasma ctDNA were correlated.
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http://dx.doi.org/10.1016/j.ccell.2018.06.004DOI Listing
July 2018

Efficacy of Sym004 in Patients With Metastatic Colorectal Cancer With Acquired Resistance to Anti-EGFR Therapy and Molecularly Selected by Circulating Tumor DNA Analyses: A Phase 2 Randomized Clinical Trial.

JAMA Oncol 2018 Apr 12;4(4):e175245. Epub 2018 Apr 12.

Symphogen A/S, Ballerup, Denmark.

Importance: Acquired resistance to anti-EGFR therapy (epidermal growth factor receptor) is frequently due to RAS and EGFR extracellular domain (ECD) mutations in metastatic colorectal cancer (mCRC). Some anti-EGFR-refractory patients retain tumor EGFR dependency potentially targetable by agents such as Sym004, which is a mixture of 2 nonoverlapping monoclonal antibodies targeting EGFR.

Objective: To determine if continuous blockade of EGFR by Sym004 has survival benefit.

Design, Setting, And Participants: Multicenter, phase 2, randomized, clinical trial comparing 2 regimens of Sym004 with investigator's choice from March 6, 2014, through October 15, 2015. Circulating tumor DNA (ctDNA) was analyzed for biomarker and tracking clonal dynamics during treatment. Participants had wild-type KRAS exon 2 mCRC refractory to standard chemotherapy and acquired resistance to anti-EGFR monoclonal antibodies.

Interventions: Participants were randomly assigned in a 1:1:1 ratio to Sym004, 12 mg/kg/wk (arm A), Sym004, 9 mg/kg loading dose followed by 6 mg/kg/wk (arm B), or investigator's choice of treatment (arm C).

Main Outcomes And Measures: Overall survival (OS). Secondary end points included preplanned exploratory biomarker analysis in ctDNA.

Results: A total of 254 patients were randomized (intent-to-treat [ITT] population) (median age, 63 [range, 34-91] years; 63% male; n = 160). Median OS in the ITT population was 7.9 months (95% CI, 6.5-9.9 months), 10.3 months (95% CI, 9.0-12.9 months), and 9.6 months (95% CI, 8.3-12.2 months) for arms A, B, and C, respectively (hazard ratio [HR], 1.31; 95% CI, 0.92-1.87 for A vs C; and HR, 0.97; 95% CI, 0.68-1.40 for B vs C). The ctDNA revealed high intrapatient genomic heterogeneity following anti-EGFR therapy. Sym004 effectively targeted EGFR ECD-mutated cancer cells, and a decrease in EGFR ECD ctDNA occurred in Sym004-treated patients. However, this did not translate into clinical benefit in patients with EGFR ECD mutations, likely owing to co-occurring resistance mechanisms. A subgroup of patients was defined by ctDNA (RAS/BRAF/EGFR ECD-mutation negative) associated with improved OS in Sym004-treated patients in arm B compared with arm C (median OS, 12.8 and 7.3 months, respectively).

Conclusions And Relevance: Sym004 did not improve OS in an unselected population of patients with mCRC and acquired anti-EGFR resistance. A prospective clinical validation of Sym004 efficacy in a ctDNA molecularly defined subgroup of patients with refractory mCRC is warranted.

Trial Registration: clinicaltrialsregister.eu Identifier: 2013-003829-29.
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http://dx.doi.org/10.1001/jamaoncol.2017.5245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5885274PMC
April 2018

Parallel Evaluation of Circulating Tumor DNA and Circulating Tumor Cells in Metastatic Colorectal Cancer.

Clin Colorectal Cancer 2018 03 1;17(1):80-83. Epub 2017 Nov 1.

Niguarda Cancer Center, Grande Ospedale Metropolitano Niguarda, Milan, Italy. Electronic address:

Background: Tissue biopsy is the gold standard for tumor genotyping, but it is an invasive procedure providing a single snapshot into tumor heterogeneity. Liquid biopsy approaches, encompassing the analysis of circulating tumor DNA (ctDNA) or circulating tumor cells (CTCs), have been proposed as an alternative, with the potential of providing a comprehensive portrait of the tumor molecular landscape. In metastatic colorectal cancer (mCRC), both CTCs and ctDNA analysis have been investigated, but comparative analyses are limited.

Methods: We collected blood samples from 20 consecutive patients with mCRC with at least 1 of the following inclusion criteria: high tumor burden (> 1 metastasis), intact colonic primary tumor, disease progression at the time of sampling, ≤ 2 cycles of cytotoxic chemotherapy of current treatment course, and time between last chemotherapy cycle ≥ 4 weeks.

Results: Nineteen of 20 samples displayed the appropriate quality for CTC analysis. CTCs could be isolated in 7 (36.8%) of 19 evaluable patients. The median number of CTCs was 0 (range, 0-73). In 2 patients, we isolated > 1 CTC, and in five, we found 1 CTC. We retrieved ctDNA in all samples, with a median amount of 732,573 GE/mL (range, 174,774-174,078,615 GE/mL). Concordance between ctDNA and tissue for RAS, BRAF, and ERBB2 alterations was found in 11 (84.6%) of 13 cases.

Conclusions: In this cohort, we show that ctDNA was detectable in all cases, whereas CTCs were detectable in one-third of the cases. ctDNA analysis was achieved with a smaller amount of blood sampling and allowed molecular characterization. Our data indicate that ctDNA is a readily available candidate for clinical application in mCRC.
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http://dx.doi.org/10.1016/j.clcc.2017.10.017DOI Listing
March 2018

Inactivation of DNA repair triggers neoantigen generation and impairs tumour growth.

Nature 2017 12 29;552(7683):116-120. Epub 2017 Nov 29.

Candiolo Cancer Institute - FPO, IRCCS, Candiolo 10060, Turin, Italy.

Molecular alterations in genes involved in DNA mismatch repair (MMR) promote cancer initiation and foster tumour progression. Cancers deficient in MMR frequently show favourable prognosis and indolent progression. The functional basis of the clinical outcome of patients with tumours that are deficient in MMR is not clear. Here we genetically inactivate MutL homologue 1 (MLH1) in colorectal, breast and pancreatic mouse cancer cells. The growth of MMR-deficient cells was comparable to their proficient counterparts in vitro and on transplantation in immunocompromised mice. By contrast, MMR-deficient cancer cells grew poorly when transplanted in syngeneic mice. The inactivation of MMR increased the mutational burden and led to dynamic mutational profiles, which resulted in the persistent renewal of neoantigens in vitro and in vivo, whereas MMR-proficient cells exhibited stable mutational load and neoantigen profiles over time. Immune surveillance improved when cancer cells, in which MLH1 had been inactivated, accumulated neoantigens for several generations. When restricted to a clonal population, the dynamic generation of neoantigens driven by MMR further increased immune surveillance. Inactivation of MMR, driven by acquired resistance to the clinical agent temozolomide, increased mutational load, promoted continuous renewal of neoantigens in human colorectal cancers and triggered immune surveillance in mouse models. These results suggest that targeting DNA repair processes can increase the burden of neoantigens in tumour cells; this has the potential to be exploited in therapeutic approaches.
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http://dx.doi.org/10.1038/nature24673DOI Listing
December 2017

Genotyping tumour DNA in cerebrospinal fluid and plasma of a HER2-positive breast cancer patient with brain metastases.

ESMO Open 2017 9;2(4):e000253. Epub 2017 Oct 9.

Investigative Clinical Oncology (INCO), Candiolo Cancer Institute-FPO, IRCCS, Candiolo, Italy.

Background: Central nervous system (CNS) involvement contributes to significant morbidity and mortality in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC) and represents a major challenge for clinicians. Liquid biopsy of cerebrospinal fluid (CSF)-derived circulating tumour DNA (ctDNA) harbours clinically relevant genomic alterations in patients with CNS metastases and could be effective in tracking tumour evolution.

Methods: In a HER2-positive mBC patient with brain metastases, we applied droplet digital PCR (ddPCR) and next-generation whole exome sequencing (WES) analysis to measure ctDNA dynamic changes in CSF and plasma collected during treatment.

Results: Baseline CSF-derived ctDNA analysis revealed and mutations as well as and c amplification. Post-treatment ctDNA analysis showed decreased markers level in plasma, consistent with extra-CNS disease control, while increased in the CSF, confirming poor treatment benefit in the CNS.

Discussion: Analysis of ctDNA in the CSF of HER2-positive mBC is feasible and could represent a useful companion for clinical management of brain metastases.
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http://dx.doi.org/10.1136/esmoopen-2017-000253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640139PMC
October 2017

Discovery of methylated circulating DNA biomarkers for comprehensive non-invasive monitoring of treatment response in metastatic colorectal cancer.

Gut 2018 11 5;67(11):1995-2005. Epub 2017 Oct 5.

Department of Oncology, University of Torino, Torino, Italy.

Objective: Mutations in cell-free circulating DNA (cfDNA) have been studied for tracking disease relapse in colorectal cancer (CRC). This approach requires personalised assay design due to the lack of universally mutated genes. In contrast, early methylation alterations are restricted to defined genomic loci allowing comprehensive assay design for population studies. Our objective was to identify cancer-specific methylated biomarkers which could be measured longitudinally in cfDNA (liquid biopsy) to monitor therapeutic outcome in patients with metastatic CRC (mCRC).

Design: Genome-wide methylation microarrays of CRC cell lines (n=149) identified five cancer-specific methylated loci (, , , ). Digital PCR assays were employed to measure methylation of these genes in tumour tissue DNA (n=82) and cfDNA from patients with mCRC (n=182). Plasma longitudinal assessment was performed in a patient subset treated with chemotherapy or targeted therapy.

Results: Methylation in at least one marker was detected in all tumour tissue samples and in 156 mCRC patient cfDNA samples (85.7%). Plasma marker prevalence was 71.4% for , 68.5% for , 69.7% for , 69.1% for and 65.1% for . Dynamics of methylation markers was not affected by treatment type and correlated with objective tumour response and progression-free survival.

Conclusion: This five-gene methylation panel can be used to circumvent the absence of patient-specific mutations for monitoring tumour burden dynamics in liquid biopsy under different therapeutic regimens. This method might be proposed for assessing pharmacodynamics in clinical trials or when conventional imaging has limitations.
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http://dx.doi.org/10.1136/gutjnl-2016-313372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897187PMC
November 2018

Genetic Evolution of Glioblastoma Stem-Like Cells From Primary to Recurrent Tumor.

Stem Cells 2017 11 29;35(11):2218-2228. Epub 2017 Sep 29.

Laboratory of Cancer Stem Cell Research, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy.

Glioblastoma (GBM) is a lethal tumor that displays remarkable genetic heterogeneity. It is also known that GBM contains a cell hierarchy driven by GBM stem-like cells (GSCs), responsible for tumor generation, therapeutic resistance, and relapse. An important and still open issue is whether phylogenetically related GSCs can be found in matched primary and recurrent GBMs, and reflect tumor genetic evolution under therapeutic pressure. To address this, we analyzed the mutational profile of GSCs isolated from either human primary GBMs (primary GSCs) or their matched tumors recurring after surgery and chemoradiotherapy (recurrent GSCs). We found that recurrent GSCs can accumulate temozolomide-related mutations over primary GSCs, following both linear and branched patterns. In the latter case, primary and recurrent GSCs share a common set of lesions, but also harbor distinctive mutations indicating that primary and recurrent GSCs derive from a putative common ancestor GSC by divergent genetic evolution. Interestingly, TP53 mutations distinctive of recurrent GSCs were detectable at low frequency in the corresponding primary tumors and likely marked pre-existent subclones that evolved under therapeutic pressure and expanded in the relapsing tumor. Consistently, recurrent GSCs displayed in vitro greater therapeutic resistance than primary GSCs. Overall, these data indicate that (a) phylogenetically related GSCs are found in matched primary and recurrent GBMs and (b) recurrent GSCs likely pre-exist in the untreated primary tumor and are both mutagenized and positively selected by chemoradiotherapy. Stem Cells 2017;35:2218-2228.
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http://dx.doi.org/10.1002/stem.2703DOI Listing
November 2017

Emergence of MET hyper-amplification at progression to MET and BRAF inhibition in colorectal cancer.

Br J Cancer 2017 Jul 27;117(3):347-352. Epub 2017 Jun 27.

Department of Oncology, University of Torino, Candiolo (TO) 10060, Italy.

Background: Combined MET and BRAF inhibition showed clinical benefit in a patient with rectal cancer carrying BRAF and MET amplification. However after 4 months, acquired resistance emerged and the patient deceased shortly after disease progression. The mechanism of resistance to this drug combination is unknown.

Methods: We analysed plasma circulating tumour DNA obtained at progression by exome sequencing and digital PCR. MET gene and mRNA in situ hybridisation analyses in two bioptic specimens obtained at progression were used to confirm the plasma data.

Results: We identified in plasma MET gene hyper-amplification as a potential mechanism underlying therapy resistance. Increased MET gene copy and transcript levels were detected in liver and lymph node metastatic biopsies. Finally, transduction of MET in BRAF mutant colorectal cancer cells conferred refractoriness to BRAF and MET inhibition.

Conclusions: We identified in a rectal cancer patient MET gene hyper-amplification as mechanism of resistance to dual BRAF and MET inhibition.
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http://dx.doi.org/10.1038/bjc.2017.196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537500PMC
July 2017

Liquid Biopsies for Monitoring Temporal Genomic Heterogeneity in Breast and Colon Cancers.

Pathobiology 2018 15;85(1-2):146-154. Epub 2017 Jun 15.

Cancer is a spatial and temporal dynamic disease where differently evolving genetic clones are responsible for progression. In this landscape, the genomic heterogeneity of the primary tumours can be captured by deep-sequencing representative spatial samples. However, the recognition of genetic alterations responsible for tumour evolution remains a challenging task. Recently, the "liquid biopsy" was recognized as a powerful real-time approach for the molecular monitoring of this dynamic disease. The term "liquid biopsy" generally refers to the use of circulating (cell-free) tumour DNA (ctDNA) and circulating tumour cells (CTCs) as non-invasive biomarkers for the early diagnosis, prognosis, monitoring of clinical progression, and response to treatment in different types of tumours, including the highly genomic heterogeneous breast cancer. The implementation and standardization of both approaches are still needed to achieve the required sensitivity and specificity to successfully analyze heterogenous tumours, but pivotal studies, in particular those concerning colorectal cancer, have shown the feasibility and usefulness of liquid biopsy for monitoring the Darwinian clonal evolution from an early to a metastatic stage.
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http://dx.doi.org/10.1159/000473882DOI Listing
October 2018

Integrating liquid biopsies into the management of cancer.

Nat Rev Clin Oncol 2017 Sep 2;14(9):531-548. Epub 2017 Mar 2.

Candiolo Cancer Institute - Fondazione del Piemonte per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Strada Provinciale 142, Km 3.95, 10060 Candiolo, Torino, Italy.

During cancer progression and treatment, multiple subclonal populations of tumour cells compete with one another, with selective pressures leading to the emergence of predominant subclones that replicate and spread most proficiently, and are least susceptible to treatment. At present, the molecular landscapes of solid tumours are established using surgical or biopsy tissue samples. Tissue-based tumour profiles are, however, subject to sampling bias, provide only a snapshot of tumour heterogeneity, and cannot be obtained repeatedly. Genomic profiles of circulating cell-free tumour DNA (ctDNA) have been shown to closely match those of the corresponding tumours, with important implications for both molecular pathology and clinical oncology. Analyses of circulating nucleic acids, commonly referred to as 'liquid biopsies', can be used to monitor response to treatment, assess the emergence of drug resistance, and quantify minimal residual disease. In addition to blood, several other body fluids, such as urine, saliva, pleural effusions, and cerebrospinal fluid, can contain tumour-derived genetic information. The molecular profiles gathered from ctDNA can be further complemented with those obtained through analysis of circulating tumour cells (CTCs), as well as RNA, proteins, and lipids contained within vesicles, such as exosomes. In this Review, we examine how different forms of liquid biopsies can be exploited to guide patient care and should ultimately be integrated into clinical practice, focusing on liquid biopsy of ctDNA - arguably the most clinically advanced approach.
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http://dx.doi.org/10.1038/nrclinonc.2017.14DOI Listing
September 2017

Mutation-Enrichment Next-Generation Sequencing for Quantitative Detection of Mutations in Urine Cell-Free DNA from Patients with Advanced Cancers.

Clin Cancer Res 2017 Jul 17;23(14):3657-3666. Epub 2017 Jan 17.

Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, Texas.

Tumor-derived cell-free DNA (cfDNA) from urine of patients with cancer offers noninvasive biological material for detection of cancer-related molecular abnormalities such as mutations in Exon 2 of A quantitative, mutation-enrichment next-generation sequencing test for detecting mutations in urine cfDNA was developed, and results were compared with clinical testing of archival tumor tissue and plasma cfDNA from patients with advanced cancer. With 90 to 110 mL of urine, the cfDNA test had an analytical sensitivity of 0.002% to 0.006% mutant copies in wild-type background. In 71 patients, the concordance between urine cfDNA and tumor was 73% (sensitivity, 63%; specificity, 96%) for all patients and 89% (sensitivity, 80%; specificity, 100%) for patients with urine samples of 90 to 110 mL. Patients had significantly fewer copies in urine cfDNA during systemic therapy than at baseline or disease progression ( = 0.002). Compared with no changes or increases in urine cfDNA copies during therapy, decreases in these measures were associated with longer median time to treatment failure ( = 0.03). A quantitative, mutation-enrichment next-generation sequencing test for detecting mutations in urine cfDNA had good concordance with testing of archival tumor tissue. Changes in mutated urine cfDNA were associated with time to treatment failure. .
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http://dx.doi.org/10.1158/1078-0432.CCR-16-2592DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5511562PMC
July 2017

Polyclonal Secondary Mutations Drive Acquired Resistance to FGFR Inhibition in Patients with FGFR2 Fusion-Positive Cholangiocarcinoma.

Cancer Discov 2017 03 29;7(3):252-263. Epub 2016 Dec 29.

Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, Massachusetts.

Genetic alterations in the fibroblast growth factor receptor (FGFR) pathway are promising therapeutic targets in many cancers, including intrahepatic cholangiocarcinoma (ICC). The FGFR inhibitor BGJ398 displayed encouraging efficacy in patients with FGFR2 fusion-positive ICC in a phase II trial, but the durability of response was limited in some patients. Here, we report the molecular basis for acquired resistance to BGJ398 in three patients via integrative genomic characterization of cell-free circulating tumor DNA (cfDNA), primary tumors, and metastases. Serial analysis of cfDNA demonstrated multiple recurrent point mutations in the kinase domain at progression. Accordingly, biopsy of post-progression lesions and rapid autopsy revealed marked inter- and intralesional heterogeneity, with different mutations in individual resistant clones. Molecular modeling and studies indicated that each mutation led to BGJ398 resistance and was surmountable by structurally distinct FGFR inhibitors. Thus, polyclonal secondary mutations represent an important clinical resistance mechanism that may guide the development of future therapeutic strategies. We report the first genetic mechanisms of clinical acquired resistance to FGFR inhibition in patients with FGFR2 fusion-positive ICC. Our findings can inform future strategies for detecting resistance mechanisms and inducing more durable remissions in ICC and in the wide variety of cancers where the FGFR pathway is being explored as a therapeutic target. .
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http://dx.doi.org/10.1158/2159-8290.CD-16-1000DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433349PMC
March 2017

Acquired RAS or EGFR mutations and duration of response to EGFR blockade in colorectal cancer.

Nat Commun 2016 12 8;7:13665. Epub 2016 Dec 8.

Candiolo Cancer Institute-FPO, IRCCS, 10060 Candiolo, Torino, Italy.

Blockade of the epidermal growth factor receptor (EGFR) with the monoclonal antibodies cetuximab or panitumumab is effective in a subset of colorectal cancers (CRCs), but the emergence of resistance limits the efficacy of these therapeutic agents. At relapse, the majority of patients develop RAS mutations, while a subset acquires EGFR extracellular domain (ECD) mutations. Here we find that patients who experience greater and longer responses to EGFR blockade preferentially develop EGFR ECD mutations, while RAS mutations emerge more frequently in patients with smaller tumour shrinkage and shorter progression-free survival. In circulating cell-free tumour DNA of patients treated with anti-EGFR antibodies, RAS mutations emerge earlier than EGFR ECD variants. Subclonal RAS but not EGFR ECD mutations are present in CRC samples obtained before exposure to EGFR blockade. These data indicate that clonal evolution of drug-resistant cells is associated with the clinical outcome of CRC patients treated with anti-EGFR antibodies.
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http://dx.doi.org/10.1038/ncomms13665DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155160PMC
December 2016