# Presentation: 036324

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

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

## 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

## 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?**

## Outline

**Disease-Context Validation **
**	****- ****	****Analytical Validation**
**	****-****	****Clinical validation**
**Regulatory Perspectives of Validation Background**
**Tools and Solutions**
**Public Perspective of Validation**
**A Hypothetical Example**
**Summary**

## 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**

## 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

## 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
- Samples should mimic the molecular composition and concentration of real clinical samples

## 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_

## 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

## 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.

## 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.**

## Pipeline Concept: From discovery to prevalidation to validation

- Convenience
- Set

- Prevalidation
- Reference Set

- Validation
- Set

- “Entry
- Fee”

- Anything
- Theoretically
- Interesting or
- identified
- Via profile

- Screening or Diagnostic
- Sensitivity = >40%
- Specificity = 80%
- Analytical scale up possible
- Potentially marketable
- Any stage cancer*

- Screening
- Sensitivity = ≥60%
- Specificity = 90%
- Diagnostic
- Has to match colonoscopy (>95% sensitivity; 99% specificity

- *Higher “cost” for frozen tissue samples, they are rarer

## Regulatory Review Intended Use

- 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.

***FDA device classification and review is driven by***
***the intended use of the device and the associated risk***

## 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**

## Regulatory Aspects of Validation

- Source: Kessler’s Presentation

## 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

## 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?

## 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

## 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**

## 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**

## Public Perspectives of Validation

## 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**

## Biomarkers in Health Care

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

## Slide 24

## 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****	**