PERSONALIZED ONCOGENOMICS IN GASTROINTESTINAL
CARCINOMAS, Sheffield
et al.
ORIGINAL
ARTICLE
Personalized oncogenomics in the
management of gastrointestinal carcinomas—
early experiences from a pilot study
B.S. Sheffield MD,* B. Tessier-Cloutier MD,* H. Li-Chang MD,† Y. Shen PhD,‡ E. Pleasance PhD,‡
K. Kasaian PhD,‡ Y. Li PhD,‡ S.J.M. Jones PhD,‡ H.J. Lim MD PhD,§ D.J. Renouf MD,§ D.G. Huntsman MD,*
S. Yip MD PhD,* J. Laskin MD,§ M. Marra PhD,‡|| and D.F. Schaeffer MD PhD*
ABSTRACT
Background Gastrointestinal carcinomas are genomically complex cancers that are lethal in the metastatic
setting. Whole-genome and transcriptome sequencing allow for the simultaneous characterization of multiple
oncogenic pathways.
Methods
We report 3 cases of metastatic gastrointestinal carcinoma in patients enrolled in the Personalized
Onco-Genomics program at the BC Cancer Agency. Real-time genomic profiling was combined with clinical expertise
to diagnose a carcinoma of unknown primary, to explore treatment response to bevacizumab in a colorectal cancer,
and to characterize an appendiceal adenocarcinoma.
Results In the first case, genomic profiling revealed an IDH1 somatic mutation, supporting the diagnosis of
cholangiocarcinoma in a malignancy of unknown origin, and further guided therapy by identifying epidermal growth
factor receptor amplification. In the second case, a BRAF V600E mutation and wild-type KRAS profile justified the
use of targeted therapies to treat a colonic adenocarcinoma. The third case was an appendiceal adenocarcinoma
defined by a p53 inactivation; Ras/raf/mek, Akt/mtor, Wnt, and notch pathway activation; and overexpression of
ret, erbb2 (her2), erbb3, met, and cell cycle regulators.
Summary We show that whole-genome and transcriptome sequencing can be achieved within clinically effective
timelines, yielding clinically useful and actionable information.
Key Words Oncogenomics, genomics, cholangiocarcinoma, colonic adenocarcinoma, appendiceal adenocarcinoma,
targeted therapy, personalized medicine, bevacizumab
Curr Oncol. 2016 Dec;23(6):e571-e575
INTRODUCTION
Gastrointestinal (gi) carcinomas are molecularly heterogeneous and usually lethal at advanced stages1,2. Although
some predictive single-gene assays are available, approaches
that are capable of simultaneously interrogating multiple
genetic loci within finite biopsy samples will increasingly
be required. Whole-genome sequencing (wgs) and rna
sequencing provide a comprehensive catalog of somatic
mutations and gene expression measurements and can be
of particular use in the clinical management of molecularly
complex cancers such as gi carcinomas. We and others have
www.current-oncology.com
reported on the real-time clinical use of sequencing in the
diagnosis and treatment of advanced tumours3–7.
The interdisciplinary Personalized Onco-Genomics
(pog) program at the BC Cancer Agency was conceived
with the goal of using whole-genome analysis for clinical
oncologic care. A pilot project aimed to address the frequency with which clinically informative results might
be obtained through the application of whole-genome
analysis. The pog program currently represents the largest
precision medicine endeavor in Canada, and it has resulted
in the first genomic definitions of rare cancer types such
as peritoneal mesothelioma8 and, in the present report,
Correspondence to: Brandon S. Shefield, Abbotsford Regional Hospital and Cancer Centre, 32900 Marshall Road, Abbotsford, British Columbia V2S 0C2
E-mail: brandon.s.shefield@gmail.com n DOI: http://dx.doi.org/10.3747/co.23.3165
Current Oncology, Vol. 23, No. 6, December 2016 © 2016 Multimed Inc.
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P E R S O NA L IZED ONCOGENOMICS IN GASTROINTESTINAL CARCINOMAS, Sheffield et al.
appendiceal adenocarcinoma. Patients with incurable
advanced cancers, good performance status, and limited
remaining conventional treatment options are eligible for
enrolment. Whole-genome sequencing, rna sequencing,
and amplicon-based panel sequencing are performed on
contemporaneous fresh-frozen biopsies, together with tumour dna from archival formalin-fixed paraffin-embedded
tissue and germline dna from blood. A team of genome scientists, physicians, and computational biologists discusses
each case and generates a treatment plan within a typical
turnaround-time of 4–6 weeks from sample procurement.
Since 2012, more than 500 patients have been enrolled
in the pog program. During that time, a number of challenges emerged—mostly related to fresh and fresh-frozen
tissue acquisition, tumour genomic heterogeneity, and
turnaround reporting time. We recently reported a detailed overview of our experiences of implementing wgs
in clinical applications9.
The case vignettes that follow address the application
of the pog approach to common diagnostic and treatment
problems in gi carcinomas and illustrate how genomic
profiling yielded clinically important and biologically relevant information. These reports highlight the possibilities
and potential applications of molecular technology in the
future of routine cancer care.
METHODS
Ethics, Privacy, and Consent
Informed written consent for sequencing and publication of clinical and genomic data was obtained for each
patient in the program. All protocols and procedures
in the program, including the consent procedure, were
approved by the University of British Columbia Research
Ethics Committee (no. H12-00137). Raw sequencing data
are maintained within a secure computing environment
at Canada’s Michael Smith Genome Sciences Centre, and
clinical data are maintained by physicians and a dedicated
research team at the BC Cancer Agency.
Tumour Sampling
Metastatic or recurrent tumours were sampled under imaging guidance. The samples were frozen and embedded
in optimal-cutting-temperature compound for dna and
rna extraction and were also prepared as frozen sections
for histologic correlation. In addition, tumour dna and rna
were extracted from formalin-fixed paraffin-embedded
tissue from earlier (usually primary) lesions. Matching
normal dna was extracted from peripheral blood leucocytes. Paired-end dna and rna sequencing libraries were
generated at the Genome Sciences Centre, and sequencing
was performed using the HiSeq platform (version 3: Illumina, San Diego, CA, U.S.A.). Simultaneously, targeted
deep sequencing was performed using the Ion AmpliSeq
oncogene panel platform (Life Technologies, Carlsbad, CA,
U.S.A.) and the Ion Torrent PGM sequencing platform (Life
Technologies). Coverage for wgs was 80–100× on frozen
tumour tissue and 40× for dna from archival formalin-fixed
paraffin-embedded tissue and germline dna from blood. A
minimum of 500× coverage was required for the targeted
amplicon reads.
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Bioinformatic Analysis
Reads were aligned to the human genome (reference:
GRCh37-lite) using the BWA software application (version
0.5.710). Reads from multiple lanes were merged and duplicatemarked using the Picard application (version 1.38, http://
sourceforge.net/projects/picard/). Variants were called
using mpileup and subsequently filtered with varFilter
(SAMtools, version 0.1.1711). The tumour sample was
compared with the normal sample to identify somatic
copy-number variants [CNAseq (version 0.0.6, http://
www.bcgsc.ca/platform/bioinfo/software/cnaseq)], loss
of heterozygosity events [APOLLOH (version 0.1.112 )],
single nucleotide variants [SAMtools (version 0.1.17),
MutationSeq (version 1.0.213), Strelka (version 0.4.6.214)],
and small insertions and deletions (Strelka). The rna sequencing reads were analyzed with JAGuaR15 to include
alignments to a database of exon junction sequences and
subsequent repositioning onto the genomic reference. The
rna sequencing data were processed using the Genome
Sciences Centre’s wtss (whole-transcriptome shotgun
sequencing) pipeline coverage analysis (version 1.1)
with the “stranded” option to determine gene and exon
read counts and normalized expression level. Expressed
variants were called with SNVMix2 (version 0.12.1-rc116 )
and SAMtools (version 0.1.13). Gene expression in the
tumour was compared with a compendium of normal
tissues and with one or more normal libraries of the same
tissue type to identify upregulated and downregulated
genes. Genomic and rna sequencing tumour data were
also both assembled using Trans-ABySS (version 1.4.317 )
to identify structural variants and fusion genes. Variants
were annotated to genes using the Ensembl database
(version 59,6918 ).
Genes were linked to cancer pathways using cosmic
(Wellcome Trust Sanger Institute, Genome Campus,
Hinxton, U.K.), kegg (Kanehisa Laboratories, University
of Tokyo, Tokyo, Japan), and Ingenuity Pathway Analysis
(Qiagen, Redwood City, CA, U.S.A.), and linked to drugs
using DrugBank and the Therapeutic Target Database.
Literature review for drug–target combinations and
pharmacogenetics was integrated to identify potential
therapeutic recommendations. For the analysis of germline
variants predisposing to gi cancers, genes with germline
variants were compared against a compiled list of gi cancer
predisposition genes (Table i); the list of genes was compiled from a parallel study of next-generation sequencing
of germline dna in hereditary gi tumours.
RESULTS AND DISCUSSION
In Cases of Diagnostic Uncertainty,
Molecular Studies Can Aid in Diagnosis
and Guide Targeted Treatment
Patient 1, a previously well 33-year-old woman, presented
with increasing back pain and new-onset leg weakness.
Computed tomography imaging showed multiple vertebral
and pelvic lytic lesions, together with extensive intraabdominal and retroperitoneal lymphadenopathy. The only
visceral mass seen on imaging was a large hepatic lesion.
Biopsies of the liver and vertebral lesions showed a
moderately differentiated adenocarcinoma (Figure 1)
Current Oncology, Vol. 23, No. 6, December 2016 © 2016 Multimed Inc.
PERSONALIZED ONCOGENOMICS IN GASTROINTESTINAL CARCINOMAS, Sheffield et al.
TABLE I Genes associated with predisposition to gastrointestinal cancer
AKAP12
CASP10
FHIT
MAP3K6
NAT2
PXN
SLC22A4
AKR7A3
CDH1
FOXF1
APC
CDKN2A
GAB2
MET
NEK1
RHNO1
SMAD4
MCCC1
PALB2
RNF43
SPINK1
ARID1A
CFTR
GREM1
MLH1
PLAU
RUNX3
STK11
ATM
CHEK2
HIC1
MSH2
PMS1
SCARF2
TGFR2
BAX
CTHRC1
HPP1
MSH3
PMS2
SCG5
TNFRSF12
BCL2L10
CTNNA1
HSPA5
MSH6
PRR5
SCTR
TMEFF2
BMPR1A
DLC1
IDH1
MSR1
PRSS1
SDHB
TP53
BRCA1
EPCAM
IDH2
MTUS1
PSCA
SDHC
BRCA2
FAT4
ITIH2
MUTYH
PTEN
SDHD
a cholangiocarcinoma-specific chemotherapy regimen of
gemcitabine and cisplatin. Erlotinib was also prescribed
based on the detection of epidermal growth factor receptor copy-number gain and overexpression. Erlotinib has
been shown to provide benefit in the treatment of biliary
tract cancers21.
Real-Time Genomic Profiling Characterizes
the Molecular Basis of Treatment Resistance
and Predicts Treatment Response
FIGURE 1 (A) Computed tomography images for patient 1 show lytic
vertebral lesions and an intrahepatic mass. No other visceral mass
was identified. (B) The tumour consisted of a moderately differentiated
adenocarcinoma of uncertain origin. Hematoxylin and eosin staining,
200× original magnification. (C) Intrahepatic cholangiocarcinoma was
diagnosed, based on the detection, by whole-genome and targeted
amplicon sequencing, of a p.Arg132Cys mutation in the IDH1 gene,
which was validated by conventional sequencing.
that lacked a site-specific immunohistochemical expression profile. Amplicon-based panel sequencing, wgs, rna
sequencing, and Sanger sequencing independently confirmed the presence of a somatic heterozygous mutation
in the IDH1 gene, resulting in a p.Arg132Cys amino acid
change. Such IDH1 mutations have been identified in up
to a quarter of intrahepatic cholangiocarcinomas, but are
rare elsewhere19,20.
Clinical, pathologic, and genetic correlation thus
yielded a diagnosis of cholangiocarcinoma. Genomic profiling provided a rationale for treatment of the patient with
Current Oncology, Vol. 23, No. 6, December 2016 © 2016 Multimed Inc.
Patient 2, a 30-year-old woman, presented with worsening abdominal pain secondary to a colonic obstruction.
She underwent a right hemicolectomy for a microsatellitestable pT3N2b low-grade colonic adenocarcinoma and
was subsequently found to have synchronous hepatic and
para-aortic lymph node metastases.
The patient underwent whole-genome profiling performed on her primary tumour (archival) and liver metastasis (fresh-frozen) after disease progression on treatment
with folfiri (f luorouracil–leucovorin–irinotecan) and
bevacizumab. In both the archival primary and frozen
metastatic tumours, a BRAF V600E mutation and wildtype
KRAS alleles were detected, which provided a rationale for
the use of sorafenib and cetuximab22.
Of particular interest, disease progression during
bevacizumab treatment had occurred in her hepatic lesions, while her residual extrahepatic disease regressed
(Figure 2). Sequencing showed high-level amplification
and overexpression of vascular endothelial growth factor A
[vegfa (the target of bevacizumab)] in the hepatic lesions
but not elsewhere. The vegfa overexpression likely contributed to treatment resistance in the hepatic lesions and
might have arisen because of selection for and expansion
of a pre-existing clone with amplified vegfa. Results from
animal models have also suggested that bevacizumab
resistance can arise as a result of vegf overexpression and
activation of other oncogenic pathways23,24.
In addition to suggesting initial treatments, genomic
profiling could be used to monitor vegf gene amplification
and activation of other resistance pathways, allowing for
optimization of systemic treatment with bevacizumab
and other agents in patients with colorectal cancer—a
concept that could be achieved by targeting synergistic
pathways or by using alternative therapeutic targets when
resistance develops.
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PERSONALIZED ONCOGENOMICS IN GASTROINTESTINAL CARCINOMAS, Sheffield et al.
FIGURE 2 (A,B) Computed tomography images of the hepatic metastases in patient 2 that progressed during treatment with bevacizumab.
(C,D) A para-aortic lymph node metastasis that decreased in size during
the same period. Sequencing demonstrated amplification of vascular
endothelial growth factor A in the liver lesions, but not in the primary
tumour, which had been sampled before bevacizumab treatment.
Genomic Profiling Provides a Comprehensive
Understanding of Poorly Characterized
Malignancies
Bona fide non-mucinous high-grade appendiceal adenocarcinomas are associated with poor prognosis. These
rare neoplasms are neither neuroendocrine tumours nor
low-grade appendiceal mucinous neoplasms. Little is
known about their molecular abnormalities beyond the
low frequency of both KRAS mutations and microsatellite
instability, and some differences relative both to low-grade
mucinous carcinomas and to colorectal carcinomas25,26.
Patient 3, a 38-year-old woman, presented with pelvic
pain. Imaging showed bilateral ovarian masses with diffuse
omental nodules and ascites, and an appendiceal mass was
noted on laparoscopy. Although a primary gynecologic
malignancy was initially suspected, a poorly differentiated
non-mucinous adenocarcinoma was found to be originating in the appendix (Figure 3).
The patient was treated with the folfiri and folfox
(f luorouracil–leucovorin–oxaliplatin) regimens with
good response and underwent cytoreductive surgery and
hyperthermic intraperitoneal chemotherapy. Genomic
profiling was used to explore her cancer after liver metastases developed.
The tumour had broad areas of copy-number change
and loss of heterozygosity. As observed in other high-grade
tumours25, the tumour was KRAS wild-type and microsatellite stable. Inactivation of p53 was evident, as was activation
of the Ras/raf/mek, Akt/mtor, Wnt, and notch pathways.
From a therapeutic standpoint, the tumour showed overexpression of several targetable receptor tyrosine kinases,
including ret, erbb2 (her2), erbb3, and met. Other abnormalities included overexpression of several cell cycle
regulators that could render the tumour amenable to cell
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FIGURE 3 (A,B) Images of the adenocarcinoma arising in the appendix. (C,D) Dysplastic epithelium lining the appendix gave rise to an
adenocarcinoma, which, in areas, is poorly differentiated.
cycle inhibitors, and overexpression of histone deacetylases
and topoisomerases that could warrant use of histone
deacetylase and topoisomerase IIα inhibitors respectively.
O u r a na l y si s c on f i r m s t hat a lt houg h poorl ydifferentiated appendiceal adenocarcinomas are complex
at a molecular level, they could present several opportunities for targeted treatments.
Summary
A complete set of genomic findings from the preceding
3 cases, as well as previously published cases from the
pog program, can be viewed online at the Web site of
the International Cancer Genome Consortium (https://
www.ebi.ac.uk/ega/studies; studies EGAD00001001308,
EGAD00001001307, and EGAD00001001309).
CONCLUSIONS
With improvements in sequencing technology, sample
procurement 27, and interpretation of genomic variants28,
we are in the process of learning how to apply genomic data
to the treatment of individual patients. These early experiences in our pilot project have shown that real-time genomic
profiling of gi tumours can yield a wealth of biologic and
clinically important information, and hence improve the
understanding and management of these cancers at the level
of the individual patient. As we learn from these experiences
and interrogate further tumours at earlier stages, we expect
that significant improvements in outcomes will result from
sequencing and collaborations within multidisciplinary
teams. The Personalized Onco-Genomics program continues to explore the utility and clinical integration of novel
molecular technologies, with the ultimate goal of providing
precision cancer treatment in Canada.
ACKNOWLEDGMENTS
This work is funded by the BC Cancer Foundation. HLC and
KK receive fellowship funding from the Canadian Institutes of
Health Research.
Current Oncology, Vol. 23, No. 6, December 2016 © 2016 Multimed Inc.
PERSONALIZED ONCOGENOMICS IN GASTROINTESTINAL CARCINOMAS, Sheffield et al.
CONFLICT OF INTEREST DISCLOSURES
We have read and understood Current Oncology’s policy on disclosing conflicts of interest, and we declare that we have none.
AUTHOR AFFILIATIONS
*Department of Pathology and Laboratory Medicine, University of
British Columbia, Vancouver, BC; †Royal Victoria Regional Health
Centre, Department of Pathology and Laboratory Medicine,
Barrie, ON; ‡Canada’s Michael Smith Genome Sciences Centre,
BC Cancer Agency, § Division of Medical Oncology, BC Cancer
Agency, and ||Department of Medical Genetics, University of
British Columbia, Vancouver, BC.
13.
14.
15.
16.
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