Implementation Insights Paul A. Keown · 2018-04-01 · 11/14/2016 1 Implementation Insights...
Transcript of Implementation Insights Paul A. Keown · 2018-04-01 · 11/14/2016 1 Implementation Insights...
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Implementation Insights
Vancouver General Hospital, BC
Challenges we faced
Will vary depending on what your starting point is (SBT vs Serology)
• Space
• Training
- Bench and analysis
• Computerization
• Integration into LIMS
Work-flow integration
• How much change do you need to take the lab from molecular to NGS?
➡ still need pre- and post-pcr areas, so not much change from current set up
➡ tissue or sample collection will probably stay the same as current methods (ACD blood, BMT with multiple transfusions?)
➡DNA extractions will also probably stay the same (note the use of EDTA in elution buffer)
➡ computerization might be an issue
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Challenges with space• Currently we are still running SSO/SSP, our sequencing
core has moved into the old serology lab
➡ Bench height and width is different
➡ Benches dimension need to be able to take equipment (size and weight…a MiSeq weighs more than Terasaki typing plates)!
• Freezer/fridge space
➡ Do you keep individual loci amplicon? Or only pooled samples? How long are libraries good for?
Challenges with Training
• Staff training involves;
➡ bench/hands on training
➡ analysis resulting training
➡ Also, disseminating information to clinics and physicians.
Challenges with trainingBench work;
• Remarkably similar to current molecular techniques.
• Micro-volumes require additional experience to achieve consistency
• Multiplex of high number of samples can be confusing and will require more care awareness during processing
• Many more steps involved in library preparation (compared to SSO/SSP), time-management is more relevant
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Bench Training
• Walk through protocol and technology
• 3 test runs (non-valuable samples; with smaller batch sizes initially),
• 3 real runs (with standard batch size, concordance with SSO/SSP)
• All QC tests passed for all 6 runs
• Training schedule ~5 months
Actions to overcome bench challenges
• Practice good micro-pipetting technique on non-valuable samples
• Develop monitoring procedures, and good practice, to ensure no sample mix up when handling many samples
• Protocols and workflows which are more flexible will permit technicians to develop a time management plan that works for them
Challenges with training
Analysis;
• Previous experience with SBT data and the associated software makes the learning curve less steep
• level of competence comes with analysis of a POOR run not a good run!
• Simplified workflow of analysis is essential to maintain consistency across calls
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Actions to overcome challenges with analysis training
• Familiarization with software
• Lab meetings to show how the software looks, how to navigate through analysis pipeline, examples of results, examples of reports, integration into current reporting procedure
• Clear SOP (even better, cheat sheets!)
• Practise datasets (good and bad data). Compare analysis with trainee and trainer, work through challenging calls together
Challenges with equipment
• Due to the significantly higher throughput capabilities of the technology, even simple things will need to be re-assessed;
• ordering reagents and supplies will be more frequent. Plan accordingly
• Multichannel pipettes will have to be maintained regularly and calibrated (which is an ASHI standard)
CONNECTIVITY
• Computer specification for software will vary depending on software used;
• Most can be run on a stand alone desktop, either as individual licenses or as client servers
• Some will require a dedicated server to run software
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Challenges with connectivity
• Standard hospital computers are not 64-bit.
• Data storage requirements for an Immunology lab for the last 40 years ~ 500mb/month, current data storage requirements for an Immunology lab ~100gb/month
• Data storage security concerns
Optimal multiplexing strategy
• Optimal multiplexing strategy;
➡expected sample throughput,
➡ frequency of testing,
➡ the assay TAT,
➡ the degree of batching (for regions of high genomic complexity, higher read depth can be used to compensate to improve accuracy)
• for batching samples, there must exist guidelines for standard multiplexing and read depth to ensure equivalence of test results.
• Validation of barcodes
DATA REPORTING
• Clinical interpretation: Seamless, unambiguous, clinically relevant interpretation for end user
• Clinical report generation; ‘What to include and what not to include’…intronic differences, variants of unknown significance
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Integration with LIMS
• Automatic transfer of fastq files to data analysis software
• Direct import from analysis software to Histotrac (or equivalent)
• Update of
Tie- breakers
• All methods tested were excellent and easily implementable in the lab
• Customer support is critical
• Although cost is of course important, should not be the deciding factor
• Tech feedback
Top 5 reasons to go NGS
• The learning curve might be steep, depending on where you start from (serology, SBT), but easily streamlined for a medium-large throughput lab
• One pass testing; no need to go back and order additional tests (careful with those class 2’s!)
• Maintain autonomy from other sequencing labs, business model
• Creating a pre-to-post transplant continuum
• Cos all your friends are doing it!
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THANK YOU
Introduction
• For clinical purposes, NGS has all but replaced it’s methodological predecessor, Sanger sequencing.
• It’s faster, cheaper but ALONE, is it sensitive and specific enough to catch every variant while avoiding false-positives?
Is cost a barrier to introduction of NGS in HLA labs?
•
Pro’s Con’s
Pushing Transplant diagnostics into the 21st century
High set up costs
Comparable to current molecular testing costs
More complex training than current molecular testing techniques
Fewer supplementary assaysMinor pipetting error could result in loss of amplicon and consequently
no data
Limits repeated testing (especially hi-res repeats when Ab detected)
Steep learning curve for data analysis
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Interesting article
• The Scientist Q&A: Confirming NGS results with Sanger (Ambry Genetics CEO, Aaron Elliot)
• http://www.the-scientist.com/?articles.view/articleNo/47224/title/Q-A--Confirming-Next-Gen-Sequencing-Results-with-Sanger/
Is cost a barrier to introduction of NGS in HLA labs?
• multi-plexing is a double edged sword; if it works, drastically lowers cost, but if theres an error, lose a lot in terms of reagent and time
• higher start-up costs
• cost of positive/negative controls (for each library preparation as well as for each sequencing instrument run)
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Costs
• Evaluation costs
• Validation/accreditation costs
• Capital equipment costs
• Tech costs…training costs
Capital Equipment InvestmentInstrument Cost*
Illumina MiSeq $100,000
Illumina MiSeq Support (Years 2 & 3) $34,000
Size selection equipment (Optional) $10,000
Plate fluorometer (Optional) $20,000
qPCR machine (Optional) $30,000
5x PCR machine $35,000
64-bit computer with 16+ GB RAM $3,000
1-2x Liquid handler (Optional, pre & post PCR) $50,000+ (each)
*Based on figures from four US Labs, rounded to $1,000
workflow integration• Upstream integration
• Sample collection and DNA extractions
• Library preparation workflows
• Sample batching
• Liquid handling automation
• Data processing and analysis workflows
• Data transfer automation
• Analysis automation
• Long term data storage
• Approval workflow and tracking
• LIMS integration
• Export to NMDP standard
• Import directly into LIMS
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Work-flow integration
• multiple QC steps; initially time-consuming but in the long run, will save bench time. Eventually QC steps can be pared down to minimum.
• to confirm or not to confirm…with different assay
• typing takes longer than antibodies…consequence on activation of patient
• labs not previously engaged in HLA typing could become involved in testing, as the workflow is fairly simple and indeed not drastically different for a wide range of diagnostic tests (cancer panel vs hla panel)…however interpretation is KEY
Automation
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Work-flow integration
• WHAT IS OUR CURRENT TAT FOR NGS?
• Currently not suitable for deceased donor typing
Challenges in data interpretation
• Can be summarised in 3 words; TIME, WORKLOAD, AMBIGUITIES
• Average time spent analysing and interpreting NGS data…time allotment
• data analysis is still a bottle-neck…partly because batches can be so large
• very few ambiguities…gone are the days of ‘chains’
Challenges in data interpretation
• determining QC characteristics
• associations
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Challenges in data interpretation
• loss of 2nd allele in homozygous!
• determining true homozygousity
• drop outs…
• amplicon coverage- accurate pooling required
Challenges in data interpretation
• Submission of new alleles to CTR dictionary
• getting used to no chains!
• G group problem is now the reverse of the problem before (cant match too specific vs cant match not specific enough)
NGS Data Analysis Approaches
• Reference- bases alignment, followed by HLA call based on the variants detected during alignment
• call is only as good at the alignment, coverage often insufficient
• Database based approach against known alleles
• novel allele detection and homozygous alleles are difficult to detect
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Complex genetics
• Duplications
• High level of segmental duplications
• Lots of similar genes and lots of similar pseudogenes
• Duplicated segments can be more similar within an individual than they are to the corresponding segments of a reference genome
Complex genetics
• Particularly DRB
• Tandem repeats can still be problematic (however no other technique has overcome this issue fully)
However…
• Many alleles are already known (even partially), both in terms of sequence and frequencies within a population
• HLA regions is relatively small, with a high degree of linkage disequilibrim, therefore many haplotypes have been described
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Validation requirements
• 50 samples (plus 20 blind), over 3 runs
• Set up as you would routine testing (run size, sample type)
• Evaluation of;
• Run to run variability
• Tech to tech variability
Quality Testing
• Must evaluate potential allele dropouts
• Documentation for;
• Sample preparation
• Monitor fidelity of barcoding methods
• rotate control samples with different barcode sequences
• Instrument performance measures
• internal control sample for instrument run performance
Quality Testing
• Analytic performance criteria
• Incorporating vendor specifications
• Base quality, read length, average coverage, uniformity of coverage
• Independently validate software program
• Ensure genotyping algorithms are appropriate for sequencing strategy and sequencing error modalities
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• KNOW YOUR ASSAY’S LIMITATIONS!
Issues to consider
• inclusion of positive control sample, library QC
• use of phiX for cross lot QC, run QC
Top 5 reasons to go NGS
• The learning curve might be steep, depending on where you start from (serology, SBT), but easily streamlined for a medium-large throughput lab
• one pass testing; no need to go back and order additional tests (careful with those class 2’s!), auto-antibody issue
• Cos all your friends are doing it
• potential for …epitope etc, rejection assay that detects donor-derived cell-free DNA in recipient plasma (Journal of Molecular Diagnostics)
Circulating cell-free DNA enables noninvasive diagnosis of heart transplant rejection. De Vlaminck et al. Sci Transl Med. 2014 Jun 18;6(241)
• ?maintain autonomy from (cancer) other sequencing labs, business model
• Creating a pre-to-post transplant continuum?
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Single Molecule, Real-Time (SMRT®) Sequencing
Unique capability to reveal the unknown
High
Accuracy� Achieves >99.999% consensus accuracy
� Lack of systematic sequencing errors
2 High Coverage
Uniformity
Lack of GC content or sequence
complexity bias
3 Sequence
native DNA� No DNA amplification
� Epigenome characterization
4Very Long
Read lengthsSingle Molecule Real Time Sequencing is
capable of generating long reads
to enable resolution of variation
1
Roche’s Single Molecule Real-Time Sequencer
Accessible Benefits of Single Molecule Real-Time Sequencing
Products in development and not available for global distribution. For Research Use Only.
Not for use in diagnostic procedures.
SMRT® is a trademark of Pacific Biosciences
� Long read lengths
� High accuracy
� Sensitivity to detect minor variants at low frequencies
� Simultaneous base-modification detection
� High coverage uniformity
� Short run times (minutes to few hours)
� Analytically validated workflows and analysis algorithms
� An optional, simplified supplied and supported compute
pipeline
Designed To Deliver:
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LOCATION
SPACE• ASHI Standards require (wipe tests for both);
• Pre-PCR and
• Thermocyclers, vortexer, centrifuge (no change from current molecular requirements)
• Post-PCR areas
• DNA quantitation equipment, thermocyclers, vortexer, centrifuge, library preparation auxiliary equipment, sequencer
• DNA extraction area
EQUIPMENT (specific)
• Auxiliary equipment (not just the sequencer) is required for any HLA kit on the market
• DNA quantitation (and qualitation) equipment (fluorometers, spectrophotometers, gel equipment, RT-PCR etc)
• Library preparation equipment (magnetic stands for beads (remarkably expensive!), Pippin prep), thermocyclers)
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Challenges with space• Currently we are still running SSO/SSP, our sequencing
core has moved into the old serology lab
• Bench height is different
• Benches dimension need to be able to take equipment (size and weight…a MiSeq weighs more than Terisaki plates)!
• Freezer/fridge space
• Do you keep individual loci amplicon? Or only pooled samples? How long are libraries good for?
DNA quantitation equipment
Equipment (standard)
• Vortexers (plate and tube)
• Centrifuges (plate and tube)
• Amplification thermocyclers
• Multichannel pipette
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Other equipment
Challenges with equipment
• Due to the significantly higher throughput capabilities of the technology, even simple things will need to be re-assessed;
• ordering reagents and supplies will be more frequent. Plan accordingly
• Multichannel pipettes will have to be maintained regularly and calibrated (which is an ASHI standard), but when pipetting for heavy loads and with microvolumes, any tiny variability will cause samples to fail
Equipment (general)
• Liquid handlers are highly recommended for both Pre- and Post-PCR steps
• Budget allowing (otherwise, get the 1 for Pre-PCR)
• Are programmable for other uses within the laboratory
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Challenges with equipment
• Sequencers and liquid handlers have relatively large footprints, and can be very heavy and sensitive
• Must be on weight bearing bench
• No located on the same bench as a centrifuge or high-traffic area as vibrations can affect both the sequencer and the liquid handler
• Highly recommended NOT to move sequencers (alignment of internal optics) or liquid handlers (alignment and very heavy) unless absolute need..pick a permanent place
Equipment (specific)
TRAINING
• Staff training involves;
• bench/hands on training
• analysis resulting training
• Also, disseminating information to clinics and physician. Whilst the reported typings (if remaining at 4 digits) will look the same, the loss of chains and the ambiguities (no more XX) will need to be clarified with the programs
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Challenges with training
• Bench work;
• Remarkably similar to current molecular techniques. Micro-volumes require additional experience to achieve consistency
• Multiplex of high number of samples can be confusing and will require more care awareness during processing
• Many more steps involved in library preparation (compared to SSO/SSP), time-management is more relevant
Actions to overcome bench challenges
• Practice good micro-pipetting technique on non-valuable samples
• Develop monitoring procedures, and good practice, to ensure no sample mix up when handling many samples (do not overwhelm the tech…identify a suitable number of multiplex-able sample and use that as a standard)
• Protocols and workflows which are more flexible will permit technicians to develop a time management plan that works for them
Challenges with training
• Analysis;
• Previous experience with SBT data and the associated software makes the learning curve less steep
• level of competence comes with analysis of a POOR run not a good run!
• Simplified workflow of analysis is essential to maintain consistency across calls
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Actions to overcome challenges with analysis training
• Familiarization with software
• Lab meetings to show how the software looks, how to navigate through analysis pipeline, examples of results, examples of reports, integration into current reporting procedure
• Clear SOP (even better, cheat sheets!)
• Practise datasets (good and bad data). Compare analysis with trainee and trainer, work through challenging calls together
ADDITIONAL
• During the validation phase of assay development, it is important to test assay performance using reference material
• Positive control material
• Must establish what constitutes a ‘fail’ or a ‘pass’ positive control
• Requirement to include a Negative control
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Bench Training
• Walk through protocol and technology
• 3 test runs (non-valuable samples; with smaller batch sizes initially),
• 3 real runs (with standard batch size, concordance with SSO/SSP)
• All QC tests passed for all 6 runs
Equipment Training
• Monitoring sequencing runs
• SOP will outline run metrics, positive control for sequencing portion of protocol (cross run variability)
• Maintenance of sequencers (do not knock bench while machine is running etc, wash maintenance schedule)
CONNECTIVITY
• Computer specification for software will vary depending on software used;
• Most can be run on a stand alone desktop, either as individual licenses or as client servers
• Some will require a dedicated server to run software
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Challenges with connectivity
• Standard hospital computers are not 64-bit.
• Data storage requirements for an Immunology lab for the last 40 years ~ 500mb/month, current data storage requirements for an Immunology lab ~350gb/month
• Data storage security concerns (there is a paper published that individuals could be identified from anonymous NGS data; Science 2013. 339:321-4. ‘Identifying personal genomes by surname inference)
BIOINFORMATICS
• essential to have a strategy to detect and investigate false…
Challenges of Bioinformatics
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COST COMPARISON
• Demonstrating cost effectiveness of clinical NGS is key to payor reimbursement, hospital uptake
OTHER CHALLENGES
• The question is not technological ‘can it be done’ but rather practical ‘how can NGS technology be developed into a mainstream clinical typing tool?’
• Quality control standardisation…lack thereof…current NGS technologies have higher error rates and novel error modes compared to traditional sequencing…
• what is an appropriate orthogonal technology? i mean, we ‘assume’ SSO/SSP is ‘right’. What is the true measure of truth
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• BMT samples; the way we request samples may need to change…what if the patient has had multiple transfusions and we are not detecting patient cells but donor DNA
• DNA often low, cell count low in certain types malignancies
How we overcame challenges
FLOW DIAGRAMS OF VENDORS
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Illumina TruSight
Life Technologies (Thermo Fisher) NXType
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FLOW DIAGRAMS IN PRACTICE
• CAP NGS checklist recommends orthogonal analytical confirmation of all encountered mutations from an assay before the mutation is reported as clinically actionable (is this relevant for HLA…possibly not)
• FDA-Cleared instrumentation…
• Optimal multiplexing strategy; includes taking into account the following …expected sample throughput, frequency of testing, the assay TAT, the degree of batching (for regions of high genomic complexity, higher read depth can be used to compensate to improve accuracy)…for batching samples, there must exist guidelines for standard multiplexing and read depth to ensure equivalence of test results.
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DATA REPORTING
• Clinical interpretation: Seamless, unabiguous, clinically relevant interpretation for end user
• Clinical report generation; ‘What to include and what not to include’…intronic differences, variants of unknown significance
Raw reads (DAT files, BCL files)
Deconvoluted reads (FASTQ files)
Alignment to reference genome
Aligned reads (BAM files)Coverage calculations, local alignment
Demultiplexing
On target alignment
Variation analysis
Filtration
Clinical report
‘Truth’
Parallel analysis of control samples
QC raw and QC passed run yield,read quality, run parameters
QC barcoding deconvolution, sample read distribution
QC alignment (mapping quality),library complexity
QC coverage depth, coverage uniformity,allellelic frequency,
strand bias, GC content
QC controls