PLAC TEST REAGENT KIT,CALIBRATOR KIT, LP-PLA2 CONTROL KIT, MODEL(S) 90107,90109,90109

K072599 · Diadexus, Inc. · NOE · Dec 20, 2007 · Immunology

Device Facts

• Record ID: K072599
• Device Name: PLAC TEST REAGENT KIT,CALIBRATOR KIT, LP-PLA2 CONTROL KIT, MODEL(S) 90107,90109,90109
• Applicant: Diadexus, Inc.
• Product Code: NOE · Immunology
• Decision Date: Dec 20, 2007
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.5600
• Device Class: Class 2

Intended Use

The PLAC® Test Reagent Kit is a turbidimetric immunoassay for the quantitative determination of Lp-PLA₂ (lipoprotein-associated phospholipase A₂) in human plasma or serum on automated clinical chemistry analyzers, to be used in conjunction with clinical evaluation and patient risk assessment as an aid in predicting risk for coronary heart disease, and ischemic stroke associated with atherosclerosis. The PLAC® Test Calibrator Kit is intended to establish points of reference that are used in the determination of values in the measurement of Lp-PLA₂ by the PLAC® Test Reagent Kit. The Lp-PLA₂ Control Kit is intended for use as a quality control tool to monitor the performance within the clinical range of the PLAC® Test Reagent Kit, a turbidimetric immunoassay for the quantitative determination of Lp-PLA₂.

Device Story

The PLAC® Test is a quantitative turbidimetric immunoassay for measuring Lp-PLA₂ levels in human serum or plasma. The device utilizes latex microparticles coated with mouse monoclonal antibodies (2C10 and 4B4) that bind to Lp-PLA₂ in the sample, causing agglutination. The degree of turbidity is measured by an automated clinical chemistry analyzer (validated on Hitachi® 917) at 570 nm. The concentration is interpolated from a standard curve generated by a five-level calibrator set using a spline curve fit. The test is performed in professional clinical laboratories. Results are used by clinicians alongside other clinical evaluations to assess patient risk for coronary heart disease and ischemic stroke. The device provides a quantitative value that assists in identifying patients at higher risk, potentially guiding clinical decision-making regarding cardiovascular health management.

Clinical Evidence

No new clinical data were generated. Substantial equivalence is supported by analytical performance data, including a minimum detection limit of 4.0 ng/mL, intra-assay precision (1.6-2.4% CV), total precision (1.8-3.2% CV), and linearity (96-472 ng/mL). A method comparison study between the turbidimetric immunoassay and the predicate ELISA method showed a correlation coefficient of r = 0.95 with a slope of 1.02.

Technological Characteristics

Turbidimetric immunoassay using latex microparticles coated with mouse monoclonal antibodies (2C10 and 4B4). Reagents: R1 (Tris-based buffer), R2 (coated latex beads). Detection: Automated clinical chemistry analyzer (570 nm). Calibration: 5-level recombinant Lp-PLA₂. Linearity: 7-500 ng/mL. Stability: 16 months at 2-8°C. Software: Spline curve fitting for concentration interpolation.

Indications for Use

Indicated for use in patients as an aid in predicting risk for coronary heart disease and ischemic stroke associated with atherosclerosis. Used for quantitative determination of Lp-PLA2 in human plasma or serum.

Regulatory Classification

Identification

A low-density lipoprotein immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein in serum may aid in the diagnosis of disorders of lipid (fat) metabolism and help to identify young persons at risk from cardiovascular diseases.

Predicate Devices

• diaDEXUS PLAC Test (k062234)
• diaDEXUS PLAC Test (k050523)
• diaDEXUS PLAC Test (k030477)

Submission Summary (Full Text)

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# 510(k) Summary

This summary of 510(k) safety and effectiveness information is being submitted in accordance with the requirements of 21 CFR 807.92.

The assigned 510(k) number is: __K072599

## General Information

Name and Address of Applicant diaDexus, Inc. 343 Oyster Point Blvd. South San Francisco, CA 94080

DEC 2 0 2007

Contact Person Julie Blacklock 650-246-6400 Telephone [phone] Facsimile

Date Prepared September 13, 2007

## Trade Name

PLAC® Test Reagent Kit PLAC® Test Calibrator Kit Lp-PLA2 Control Kit

## Common Name

Turbidimetric Immunoassay for the Quantitative Determination of Lp-PLA2 (Lipoprotein-Associated Phospholipase A2) in Human Plasma or Serum

Calibrators for use with Lp-PLA2 Turbidimetric Immunoassay

Controls for use with Lp-PLA2 Turbidimetric Immunoassay

## Classification Name

TEST, SYSTEM, IMMUNOASSAY, LIPOPROTEIN-ASSOCIATED PHOSPHOLIPASE A2 (21 CFR 866.5600, Product Code NOE)

CALIBRATOR, SECONDARY (21 CFR 862.1150, Product Code JIT)

LIPOPROTEIN, LOW-DENSITY, ANTIGEN, ANTISERUM, CONTROL (21 CFR 866.5600, Product Code DFC)

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# Legally Marketed Device to which Equivalency is Claimed

PLAC® Test (k062234)

# Description of Device

The diaDexus PLAC® Test assay consists of separately packaged reagents, calibrators and controls for the measurement of Lp-PLA2 in serum or plasma on automated clinical chemistry analyzers.

- PLAC® Test Reagent Kit .
- R1 Tris-based buffer solution
- R2 Suspension of latex microparticles coated with mouse monoclonal antibodies specific to Lp-PLA2 (2C10 and 4B4).
- PLAC® Test Calibrator Kit .

Five level set of Lp-PLA2 calibrators made with recombinant Lp-PLA2 in a protein stabilizing buffer and used to calibrate the PLAC assay.

- Lp-PLA2 Control Kit .
Two level set of Lp-PLA2 controls made with recombinant Lp-PLA2 in a protein stabilizing buffer and used for quality control of the PLAC assay.

The diaDexus PLAC® Test is based on turbidimetric immunoassay technology utilizing two Lp-PLA2-specific monoclonal antibodies (2C10 and 4B4) coated to latex microparticles. A set of Lp-PLA2 calibrators is used to plot a standard curve of absorbance (y-axis) versus Lp-PLA2 concentration in ng/mL (x-axis) from which the Lp-PLA2 concentration in the test sample can be determined. The concentration of LD-PLA2 in each sample and control is then interpolated from the standard curve using a spline curve fit with appropriate calibration curve fitting software. The kit expiration date and storage conditions are indicated on the package.

# Characterization of Rare Reagents

## Antigen

The antigen used in the diaDexus turbidimetric immunoassay PLAC® Test is purified recombinant Lp-PLA2 (DDX-RA). Antigen preparations were characterized using SDSpolyacrylamide gels under reducing and non-reducing conditions and Western blot analysis using an anti-Lp-PLA2 antibody, to demonstrate consistency with the molecular weight of the antigen reported in the literature.

## Antibodies

The monoclonal anti-Lp-PLA2 antibodies (2C10 and 4B4) used in the preparation of the coated microparticles were characterized for purity and reactivity in a series of procedures including Paragon gel electrophoresis, SDS-PAGE, size exclusion

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chromatography, isotyping and enzyme immunoassay. These results demonstrated that the monoclonal antibodies bind to the Lp-PLA2 antigen quantitatively and specifically.

#### Intended Use Statements

#### REAGENT KIT

The PLAC® Test Reagent Kit is a turbidimetric immunoassay for the quantitative determination of Lp-PLA2 (lipoprotein-associated phospholipase A2) in human plasma or serum on automated clinical chemistry analyzers, to be used in conjunction with clinical evaluation and patient risk assessment as an aid in predicting risk for coronary heart disease, and ischemic stroke associated with atherosclerosis.

#### CALIBRATOR KIT

The PLAC® Test Calibrator Kit is intended to establish points of reference that are used in the determination of values in the measurement of Lp-PLA2 by the PLAC® Test Reagent Kit.

#### CONTROL KIT

The Lp-PLA2 Control Kit is intended for use as a quality control tool to monitor the performance within the clinical range of the PLAC® Test Reagent Kit, a turbidimetric immunoassay for the quantitative determination of Lp-PLA22

#### Comparison of Technological Characteristics

The chart below describes the similarities and differences between the device and the predicate, PLAC® Test ELISA kit.

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| | Predicate<br>PLAC® Test<br>k062234 | Device |
|---------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Intended Use | REAGENT KIT<br>The diaDexus PLAC® Test is an<br>enzyme immunoassay for the<br>quantitative determination of Lp-PLA2<br>(lipoprotein-associated phospholipase<br>A2) in human plasma and serum, to be<br>used in conjunction with clinical<br>evaluation and patient risk assessment<br>as an aid in predicting risk for coronary<br>heart disease, and ischemic stroke<br>associated with atherosclerosis.<br><br>(Calibrators included in kit.) | REAGENT KIT<br>The PLAC® Test Reagent Kit is a<br>turbidimetric immunoassay for the<br>quantitative determination of Lp-PLA2<br>(lipoprotein-associated phospholipase A2) in<br>human plasma or serum on automated<br>clinical chemistry analyzers, to be used in<br>conjunction with clinical evaluation and<br>patient risk assessment as an aid in<br>predicting risk for coronary heart disease,<br>and ischemic stroke associated with<br>atherosclerosis.<br><br>CALIBRATOR KIT<br>The PLAC® Test Calibrator Kit is intended<br>to establish points of reference that are used<br>in the determination of values in the<br>measurement of Lp-PLA2 by the PLAC®<br>Test Reagent Kit. |
| Intended Use | CONTROL KIT<br>The Lp-PLA2 Controls are intended for<br>use with the diaDexus PLAC® Test, an<br>enzyme immunoassay for the<br>quantitative determination of Lp-PLA2<br>in human plasma and serum. The Lp-<br>PLA2 Controls are intended as a<br>Quality Control tool to monitor Lp-<br>PLA2 clinical laboratory results. Two<br>levels of Controls are provided to<br>monitor the performance within the<br>clinical range of the assay. | CONTROL KIT<br>The Lp-PLA2 Control Kit is intended for use<br>as a quality control tool to monitor the<br>performance within the clinical range of the<br>PLAC® Test Reagent Kit, a turbidimetric<br>immunoassay for the quantitative<br>determination of Lp-PLA2. |
| Methodology | Microplate Enzyme immunoassay<br>(ELISA) | Latex particle-enhanced turbidimetric<br>immunoassay (particle agglutination) |
| Detection<br>Method | Microplate spectrophotometer read at<br>450 nm | Automated clinical chemistry analyzers<br>read at 570 nm |
| Analyte<br>Sample | Lp-PLA2<br>Serum, EDTA-plasma, heparin-plasma | Same<br>Same |
| Reagent<br>Components | Dual monoclonal antibody sandwich<br>ELISA:<br>• anti-Lp-PLA2 mAb (2C10) coated<br>stripwells<br>• Wash Buffer<br>• Enzyme Conjugate : anti-Lp-<br>PLA2 mAb (4B4)-HRP<br>• TMB Substrate Solution<br>• Stop Solution | Two-reagent system:<br>• R1: Tris-based buffer solution<br>• R2: Suspension of anti-Lp-PLA2<br>(mAbs 2C10 and 4B4) coated latex<br>beads |
| | Predicate<br>PLAC® Test<br>k062234 | Device |
| Calibration | Six calibrators made with recombinant<br>Lp-PLA₂ in a buffered protein matrix<br>(included in ELISA kit) | Five calibrators made with recombinant<br>Lp-PLA₂ in a buffered protein matrix (sold<br>separately) |
| Calibration<br>Levels | 0, 50, 100, 250, 500, 1000 ng/mL | 0, 50, 100, 250, 500 ng/mL |
| Quality<br>Control | • 2 levels<br>• Recombinant Lp-PLA₂ in a<br>buffered protein matrix | Same |
| Risk to<br>Patients | Minimal risk | Same |
| Laboratory<br>Environment | Professional laboratory | Same |

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# Performance Characteristics - Analytical

#### Sensitivity

The minimum detection limit is 4.0 ng/mL, as calculated by interpolation of the mean plus two standard deviations of 20 replicates of the 0 ng/mL Lp-PLA2 calibrator from the standard curve.

# Precision

Intra-assay precision (n=80) ranged from 1.6 %CV to 2.4 %CV throughout assay range (69 to 450 ng/mL).

Total precision (n=80) ranged from 1.8 %CV to 3.2 %CV throughout assay range (69 to 450 ng/mL).

# Linearity/Assay Range

The average recovery in linearity experiments was 97%, demonstrating linearity of samples over a range of 96 to 472 ng/mL Lp-PLA2.

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# Interfering Substances

No appreciable interference from the addition of the following substances was observed at the noted concentrations:

- . Bilirubin 20 mg/dL
- 500 mg/dL Cholesterol ●
- Hemoglobin 10,000 mg/dL .
- . Triglycerides 3000 mg/dL
- Total Albumin* ~6500 mg/dL .
- * 2.5 g/dL albumin added to plasma pool of presumptively 4 g/dL albumin

# Method Comparison

The turbidimetric immunoassay PLAC Test compared to the cleared PLAC Test (ELISA method) in a correlation study, and analyzed by linear regression, resulted in a correlation coefficient of r = 0.95, with a slope of 1.02.

# Performance Characteristics - Clinical

No new clinical data were generated.

## Conclusions

The latex-particle enhanced turbidimetric immunoassay PLAC Test has the same performance characteristics and clinical utility as the cleared enzyme immunoassay PLAC Test (k062234), and therefore is substantially equivalent.

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DEPARTMENT OF HEALTH & HUMAN SERVICES

Image /page/6/Picture/1 description: The image shows the logo for the Department of Health & Human Services - USA. The logo is a circular seal with the words "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" around the perimeter. Inside the circle is an abstract image of an eagle.

Public Health Service

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

diaDexus, Inc. c/o Robert L. Wolfert, Ph.D. Executive Vice President of Diagnostics 343 Oyster Point Blvd. South San Francisco, CA 94080

DEC 2 0 2007

k072599 Re:

> Trade/Device Name: PLAC® Test Reagent Kit PLAC® Test Calibrator Kit Lp-PLA2 Control Kit

Regulation Number: 21 CFR 866.5600 Regulation Name: Low-density lipoprotein immunological test system Regulatory Class: Class II Product Code: NOE, JIT, JJX Dated: December 11, 2007 Received: December 12, 2007

Dear Dr. Wolfert:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to such additional controls. Existing major regulations affecting your device can be found in Title 21, Code of Federal Regulations (CFR), Parts 800 to 895. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Parts 801 and 809); and good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820).

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#### Page 2 -

This letter will allow you to begin marketing your device as described in your Section 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific information about the application of labeling requirements to your device, or questions on the promotion and advertising of your device, please contact the Office of In Vitro Diagnostic Device Evaluation and Safety at [phone]. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number [phone] or [phone] or at its Internet address at http://www.fda.gov/cdrh/industry/support/index.html.

Sincerely yours,

Jean M. Cooper, M.S., D.V.M.

Jean M. Cooper, M.S., D.V.M. Director Division of Chemistry and Toxicology Office of In Vitro Diagnostic Device Evaluation and Safety Center for Devices and Radiological Health

Enclosure ·

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# Indications for Use

510(k) Number (if known):

Device Name: PLAC® Test Reagent Kit PLAC® Test Calibrator Kit Lp-PLA2 Control Kit

Indication For Use:

The PLAC® Test Reagent Kit is a turbidimetric immunoassay for the quantitative determination of Lp-PLA2 (lipoprotein-associated phospholipase A2) in human plasma or serum on automated clinical chemistry analyzers, to be used in conjunction with clinical evaluation and patient risk assessment as an aid in predicting risk for coronary heart disease, and ischemic stroke associated with atherosclerosis.

The PLAC® Test Calibrator Kit is intended to establish points of reference that are used in the determination of values in the measurement of Lp-PLA2 by the PLAC® Test Reagent Kit.

The Lp-PLA2 Control Kit is intended for use as a quality control tool to monitor the performance within the clinical range of the PLAC® Test Reagent Kit, a turbidimetric immunoassay for the quantitative determination of Lp-PLA2.

Prescription Use X (21 CFR Part 801 Subpart D) And/Or

Over the Counter Use (21 CFR Part 801 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE; CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of In Vitro Diagnostic Device Evaluation and Safety (OIVD)

Carol C. Benson

Division Sign-Off Office of In Vitro Diagnostic Device Evaluation and Safety

510(k) K072599