Development of Molecular In Vitro Diagnostics for the - Slide 1

							Development of Molecular
In Vitro Diagnostics for the
 Early Detection of Cancer

      Sudhir Srivastava, Ph.D., MPH
Chief, Cancer Biomarkers Research Group




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         Definition of Validation
   validation - the act of validating; finding or
    testing the truth of something
   determination, finding - the act of determining
    the properties of something, usually by research
    or calculation; "the determination of molecular
    structures"
   authentication, certification - validating the
    authenticity of something or someone

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Meaning of Diagnostic Validation
Fletcher:

   Is the test clearly described?
   Is the true presence or absence of disease
    established for all individuals?
   Is the spectrum of patients with and without
    disease adequate?
   Is assessment of test and disease status conducted
    in an unbiased manner?
   Is the performance summarized by sensitivity and
    specificity?

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                           Outline

 Disease-Context Validation
     -      Analytical Validation
     -      Clinical validation
 Regulatory Perspectives of Validation Background
    Tools and Solutions
 Public Perspective of Validation
 A Hypothetical Example
 Summary
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       Analytical Validation
   Precision (reproducibility)
   Accuracy (clinical samples; compare to
    cleared or gold standard method )
   Limit of Detection
   Potential Interferences
   Software
   Sample preparation / conditions
   Performance around the cut-off
   Potential for carryover or cross-hybridization
   Assay Limitations
   Confidence Intervals
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          Analytical Validation
Precision (Reproducibility):
  Studies should demonstrate that the intended users
   can get reliable results
  Studies should evaluate reproducibility of assay at
   external sites
  Should use clinical samples where possible
  All analytical steps of the assay should be included
  User training should be the same for studies and for
    marketed assay
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             Analytical Validation
Accuracy:
 Real clinical samples

   Compare to a reference method, e.g., bi-
    directional DNA sequencing
   In limited cases (i.e., very rare alleles) may use
    contrived samples
    o   Samples should mimic the molecular composition
        and concentration of real clinical samples

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Clinical Validation /Clinical Utility
May be based on
   New clinical trial data
     Prospectively collected data in a longitudinal study
   Retrospective studies
     Must have appropriate IRB, informed consent
     Sample control well characterized
     Tests standardized across laboratories
   Review of Information in the literature
     e.g., Cytochrome P450 2D6 genotyping assay

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                    Clinical Validation

   Clinical studies are needed to show clinical utility in
       Prospective clinical studies
       Retrospective validation
           Banked samples from prior clinical studies (optimal storage)
       Bridging studies may be done if a platform change or device change
        is necessary after clinical validation

   Clinical Cut-Offs
     Clinical and analytical cut-off points should be described and
      independently validated
     Identify clinical cut-off points in a training set and validate them in
     a test set
     When applicable, literature references may support clinical cut-offs
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    Clinical Validation: Go or No-Go
                 Decision
   Clinical validation studies are expensive.
   Only few biomarkers may succeed.
   There is a need for triage system that allows a
    “Go or No-Go” decision.
   EDRN has developed a mechanism through
    which biomarkers are first tested in Standard
    Reference Samples for the intended use.
   If successful, then a large validation study is
    planned.
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  Standard Reference Samples

 Standard Reference Samples are sets of
samples with cases and controls statistically
powered to allow rapid assessment of
technologies and biomarkers discovered
through a wide variety of technology
platforms.



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   Pipeline Concept: From discovery to
   prevalidation to validation



     Convenience                 Prevalidation               Validation
     Set                         Reference Set               Set


“Entry Anything             Screening or Diagnostic        Screening
Fee” Theoretically          Sensitivity = >40%             Sensitivity = ≥60%
       Interesting or       Specificity = 80%              Specificity = 90%
       identified
       Via profile          Analytical scale up possible   Diagnostic
                            Potentially marketable         Has to match
                            Any stage cancer*              colonoscopy (>95%
                                                           sensitivity; 99%
                                                           specificity
*Higher “cost” for frozen tissue samples, they are rarer
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 Regulatory Review Intended Use
   FDA device classification and review is driven by
the intended use of the device and the associated risk

   The claims made in the intended use will determine the
   type of review and the types of studies that are necessary.
   This is independent of the technology or assay format.

Example:
 The Roche AmpliChip CYP450 test is intended to identify a
  patient's CYP2D6 and CYP2C19 genotype from genomic DNA
  extracted from a whole blood sample. Information about
  CYP2D6 and CYP2C19 genotype may be used as an aid to
  clinicians in determining therapeutic strategy and treatment
  dose for therapeutics that are metabolized by the CYP2D6 and
  CYP2C19 gene products.
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           Types of Intended Use

 Risk Markers: probability – less than 100%, outcome: incidence
 Early Detection Markers: probability – close to 100%, outcome:
  incidence

 Diagnostic Markers: probability: 100%, outcome: disease
 Prognostic Markers:   outcome: survival

 Predictive markers:   outcome: response to therapy


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Regulatory Aspects of Validation



                     Source: Kessler’s Presentation
                                                  15
          Regulatory Mechanisms for
           Discussing IVD Markers
   Determine potential risks of device
       If positive – more diagnostic tests or surgery?
   And, hence, the class – I, II, III
   N.B. 510(k) vs. de novo 510(k)
   If applicable:
     Pre-IDE (Investigational Device Exemption)
     IDE



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             Device Description
   The Biomarker:
     CA125, Mesothelin and HE4
     Linear combination of standardized values

     Focus on change over time in serum

   Sample requirements
   Platform description
   Algorithm description: complex software
    involved?

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    Quality System Regulations
   Design controls
   Design quality in
   Define inputs
   Define outputs
   Controlled environment and processes
   Modern approach toward quality
   Harmonized approach toward quality, ISO,
    GHTF

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    Labeling of in vitro diagnostic
          devices 809.10(b)
   Proprietary and established names
   Intended Use(s)
       The Access OV Monitor assay is … indicated for use in
        the measurement of CA 125 antigen to aid in the
        management of ovarian cancer patients….
   Summary and explanation of test
   Principle of procedures
   Information on reagents
   Information on instruments
   Information on specimen collection and
    preparation
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                Labeling 809.10(b)
                   (continued)
   Procedures
   Results
   Limitations of the procedure
       4. The Access OV Monitor results should be interpreted
        in light of the total clinical presentation…
   Expected values
   Specific performance characteristics
   Bibliography
   Name and place of business
   Date of the package insert
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Public Perspectives of Validation




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Biomarker (Device) In Health
           Care
   Definitive Technology, e.g. Vaccine, X-ray

   Competing Technology, e.g., Sputum Cytology
    and other biomarkers

   Half-Way Technology (Add On),
    e.g., biomarkers

   Cost Saving Technology




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        Biomarkers in Health Care



Considerations for Technology Assessment

   Degree to which technology supports the needs of cancer
    patients and physicians
   Throughput and cost-effectiveness
   Standardization and quality control



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                          Summary
   Diagnostic testing is becoming more complex
       Suggests early interaction with FDA is desirable

   Biomarker Test Development
       Prime Time for FDA Approval of a “Suite of Tests” =
        “Multimarker Strategy” for same indication?


   The “de novo process” brings new technologies,
    whose safety and effectiveness have been established,
    to market faster

   Increased dialogue between Regulatory Agencies and
    developers as science develops
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