EUROIMMUN ANTI-PLA2R ELISA (IGG)

K132195 · Euroimmun Us, Inc. · PGV · Jun 27, 2014 · Microbiology

Device Facts

• Record ID: K132195
• Device Name: EUROIMMUN ANTI-PLA2R ELISA (IGG)
• Applicant: Euroimmun Us, Inc.
• Product Code: PGV · Microbiology
• Decision Date: Jun 27, 2014
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.5780
• Device Class: Class 2

Indications for Use

The EUROIMMUN Anti-PLA2R ELISA (IgG) test kit is intended for the qualitative or semiquantitative determination of IgG class autoantibodies against phospholipase A2 receptor (PLA2R) in human serum. It is used as an aid in the diagnosis of primary membranous glomerulonephritis (pMGN), in conjunction with other laboratory and clinical findings.

Device Story

The EUROIMMUN Anti-PLA2R ELISA (IgG) is an in vitro diagnostic test for human serum samples. It utilizes a microwell plate coated with recombinant PLA2R antigen to capture anti-PLA2R IgG antibodies. The assay follows a standard ELISA workflow: sample incubation, washing to remove unbound components, incubation with peroxidase-labeled anti-human IgG conjugate, further washing, and addition of TMB chromogen/substrate. A stop solution is added, and the plate is read photometrically at 450nm with a reference wavelength (620-650nm). The device is intended for use in clinical laboratories by trained personnel. Results are reported qualitatively or semi-quantitatively (RU/ml or ratio) to assist clinicians in diagnosing pMGN. The test provides an objective measurement of autoantibody levels, aiding in the differentiation of primary from secondary membranous glomerulonephritis.

Clinical Evidence

Clinical study of 560 samples (275 pMGN, 285 controls). Sensitivity for pMGN was 66.9% (95% CI: 61.0–72.4%) and specificity was 99.6% (95% CI: 98.1–100.0%). Analytical performance included precision (CVs <12% for positive/borderline), linearity (2–1500 RU/mL), and LoD (2.2 RU/mL). Cross-reactivity testing with 65 sera from various autoimmune/inflammatory conditions showed no interference.

Technological Characteristics

Microwell ELISA plate coated with recombinant PLA2R (type M). Reagents: peroxidase-labeled anti-human IgG conjugate, TMB substrate, stop solution (0.5 M sulfuric acid). Requires microwell plate reader (450nm/620-650nm). Manual or automated processing. No specific materials standards cited. Shelf-life 12 months at 2-8°C.

Indications for Use

Indicated for the qualitative or semi-quantitative detection of IgG autoantibodies against PLA2R in human serum to aid in the diagnosis of primary membranous glomerulonephritis (pMGN). For prescription use only.

Regulatory Classification

Identification

An anti-phospholipase A2 receptor immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoantibodies in human blood samples that react with phospholipase A2 receptor. The measurements aid in the diagnosis of primary membranous glomerulonephritis (pMGN), in conjunction with other laboratory and clinical findings.

Special Controls

Anti-phospholipase A2 receptor (b) immunological test system must comply with the following special controls:

*Classification.* Class II (special controls). The special controls for this device are:(1) Design verification and validation must include: (i) A detailed description of the device that includes: (A) A detailed description of all parts of the test system, including a description of the assay parts in the kit and all required ancillary reagents; (B) A detailed description of instrumentation and equipment, and illustrations or photographs of non-standard equipment or methods if applicable; (C) Detailed documentation of the device software, including standalone software applications and hardware-based devices that incorporate software where applicable; (D) A detailed description of appropriate internal and external quality controls that are recommended or provided. The description must identify those control elements that are incorporated into the recommended testing procedures; (E) Detailed specifications for sample collection, processing, and storage; (F) A detailed description of methodology and assay procedure; and (G) Detailed specification of the criteria for test results interpretation and reporting. (ii) Information that demonstrates the performance characteristics of the device, including: (A) Device precision/reproducibility data generated from within-run, between-run, between-day, between-lot, between-operator, between-instruments, between-site, and total precision for multiple nonconsecutive days as applicable. A well-characterized panel of patient samples or pools from the intended use population that covers the device measuring range must be used; (B) Device linearity data generated from patient samples covering the assay measuring range if applicable; (C) Information on traceability to a reference material and description of value assignment of calibrators and controls if applicable; (D) Device analytical sensitivity data, including limit of blank, limit of detection, and limit of quantitation if applicable; (E) Device analytical specificity data, including interference by endogenous and exogenous substances, as well as cross-reactivity with samples derived from patients with other autoimmune diseases or conditions; (F) Device instrument carryover data when applicable; (G) Device stability data including real-time stability under various storage times and temperatures; (H) Specimen stability data including stability under various storage times, temperatures, freeze-thaw, and transport conditions where appropriate; (I) Method comparison data generated by comparison of the results obtained with the device to those obtained with a legally marketed predicate device with similar indication of use. Patient samples from the intended use population covering the device measuring range must be used; (J) Specimen matrix comparison data if more than one specimen type or anticoagulant can be tested with the device. Samples used for comparison must be from patient samples covering the device measuring range; (K) A description of how the assay cut-off (the medical decision point between positive and negative) was established and validated as well as supporting data; (L) A clinical performance assessment established by comparing data generated by testing samples from the intended use population and differential diagnosis groups with the device to the clinical diagnostic standard. Diagnosis of pMGN must be based primarily on clinical history, physical examination, laboratory tests (including urinalysis), and renal biopsy. Membranous glomerulonephritis is considered to be idiopathic/primary when no secondary cause can be elucidated on the basis of clinical and laboratory criteria. The differential diagnosis groups must include secondary membranous glomerulonephritis, membranoproliferative glomerulonephritis, lupus nephritis, focal segmental glomerulosclerosis, IgA nephritis, diabetic nephropathy, systemic lupus erythematosus, systemic sclerosis, and Goodpasture syndrome. Diagnosis of autoimmune and immune-mediated diseases that are associated with membranous glomerulonephritis must be based on established diagnostic criteria and clinical evaluation. For all samples, clinical criteria, including demographic information, must be considered in the differentiation between pMGN and secondary membranous glomerulonephritis. The clinical validation results must demonstrate correlation clinical sensitivity and clinical specificity between the test values and the presence or absence of pMGN. The data must be summarized in tabular format comparing the interpretation of results to the disease status; and (M) Expected/reference values generated by testing an adequate number of samples from apparently healthy normal individuals. (iii) Identification of risk mitigation elements used by the device, including a description of all additional procedures, methods, and practices incorporated into the directions for use that mitigate risks associated with testing. (2) The label required under § 809.10(a) and labeling required under § 809.10(b) of this chapter must include warnings relevant to the assay including: (i) A warning statement that explains: The device is for use by laboratory professionals in a clinical laboratory setting; (ii) A warning statement that explains: The test is not a standalone test but an adjunct to other clinical information. A diagnosis of pMGN or secondary MGN should not be made based on a single test result. The clinical symptoms, results on physical examination, and laboratory tests ( *e.g.,* serological tests), when appropriate, should always be taken into account when considering the diagnosis of primary versus secondary MGN;(iii) A warning statement that explains: Absence of circulating PLA2R autoantibody does not rule out a diagnosis of pMGN; and (iv) A warning statement that explains: The assay has not been demonstrated to be effective for monitoring the stage of disease or its response to treatment. (3) The labeling required under § 809.10(b) of this chapter must include a description of the protocol and performance studies performed in accordance with paragraph (b)(1)(ii) of this section and a summary of the results.

Predicate Devices

• EUROIMMUN Anti-PLA2R IFA (IgG) (k132379)

Submission Summary (Full Text)

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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
ASSAY ONLY TEMPLATE

A. 510(k) Number:
k132195

B. Purpose for Submission:
New assay

C. Measurand:
Anti-PLA2R antibodies

D. Type of Test:
Qualitative or semi-quantitative enzyme immunoassay

E. Applicant:
EUROIMMUN US INC

F. Proprietary and Established Names:
EUROIMMUN Anti-PLA2R ELISA (IgG)

G. Regulatory Information:
1. Regulation section:
21 CFR §866.5780 Anti-phospholipase A2 receptor immunological test system
2. Classification:
Class II
3. Product code:
PGV-Anti-phospholipase A2 receptor
4. Panel:
Immunology (82)

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H. Intended Use:

1. Intended use(s):

The EUROIMMUN Anti-PLA2R ELISA (IgG) test kit is intended for the qualitative or semi-quantitative determination of IgG class autoantibodies against phospholipase A2 receptor (PLA2R) in human serum. It is used as an aid in the diagnosis of primary membranous glomerulonephritis (pMGN), in conjunction with other laboratory and clinical findings.

2. Indication(s) for use:

Same as intended use

3. Special conditions for use statement(s):

For prescription use only

4. Special instrument requirements:

Microwell plate reader capable of measuring OD at 450nm and 620nm for dual wavelength readings.

I. Device Description:

The EUROIMMUN Anti-PLA2R ELISA (IgG) consists of a microwell ELISA plate coated with PLA2R antigen, five calibrators, positive and negative controls, peroxidase-labeled rabbit anti-human IgG conjugate, sample buffer, wash buffer concentrate, TMB chromogen/substrate solution and stop solution.

J. Substantial Equivalence Information:

1. Predicate device name(s):

EUROIMMUN Anti-PLA2R IFA (IgG)

2. Predicate 510(k) number(s):

k132379

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3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended Use | Detection of IgG antibodies against PLA2R | Same |
| Sample | Human Serum | Same |
| Controls | Two controls: positive and negative | Same |
| Reagent preparation | All reagents are ready to use, except for the wash buffer. | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Technology | ELISA | IFA/BIOCHIP TITER PLANE |
| Antigen | Recombinant PLA2R (type M) | PLA2R transfected cells and control-transfected cells |
| Calibrators and controls | Five calibrators: 2, 20, 100, 500 and 1500 RU/ml; Two controls: positive and negative | Two Controls |
| Conjugate | Anti-human IgG labeled with horseradish peroxidase | Fluorescein-labeled anti-human IgG |
| Assay range | 2 - 1500 RU/ml | Not applicable |
| Borderline | ≥14 - <20 RU/ml; ≥0.7 - <1.0 (ratio) | No borderline |
| Cutoff level | 20 RU/ml or 1.0 (ratio) | 1:10 dilution |
| Assay format | Qualitative or semi-quantitative (using either all calibrators or the cut-off calibrator only) | Qualitative |
| Procedure | ELISA: Sample incubation with micro-well antigen coated plate, followed by a wash step, incubation with conjugate, wash step, incubation with substrate, addition of stop solution, photometric reading | IFA: Sample incubation with tissues/cells, followed by a wash step, incubation with conjugate, wash step, embedding, fluorescence microscopy reading |
| Reagents | 96 well microplate, 5, Sample buffer, Wash buffer (10x concentrate), Substrate solution (TMB), Stop solution (0.5 M sulphuric | BIOCHIP slides, Salt for PBS pH 7.2, Tween 20, Embedding medium, Cover glasses |

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| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| | acid) | |
| Sample dilution | 1:101 in sample buffer | 1:10 |

## K. Standard/Guidance Document Referenced (if applicable):

CLSI EP17-A1: Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline

## L. Test Principle:

Patient samples are diluted 1:101 in sample buffer, then 100 μL of each diluted patient sample and pre-diluted controls and calibrators are added to the antigen coated microtiter wells and incubated for 30 minutes at room temperature. After incubation the microtiter well strips are washed with wash buffer to remove unbound antibodies and 100 μL of the anti-human IgG enzyme conjugate reagent is added to each microtiter well. After 30 minute incubation at room temperature, the microtiter wells are again washed three times with 300 μL of wash buffer to remove any unbound enzyme conjugate and 100 μL of the chromogen substrate is added. The strips are incubated for 15 minutes at room temperature and 100 μL stop solution is added. The microtiter plates are placed in an ELISA reader and read at a wavelength of 450 nm and a reference wavelength of between 620 nm and 650 nm within 30 minutes.

## M. Performance Characteristics (if/when applicable):

### 1. Analytical performance:

#### a. Precision/Reproducibility:

##### 1. Repeatability

Repeatability was investigated using samples with values at different points on the calibration curve. Within-run, between-run, between-day and total standard deviations (SD) and coefficients of variation (CV) were calculated based on 150 determinations per sample performed in six different runs on three different days (with two runs per day and 25 replicates per run) according to the package insert with the same lot and by the same technician. EUROIMMUN’s acceptance criterion was that the CV’s show results below 12% for positive and borderline samples. Their acceptance criterion for the ratio-based results was that all qualitative results (positive, borderline, negative) of the samples be in line with the expected result. The following results were obtained:

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| | Semi-quantitative: RU/mL | | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Within-Run | | Within-Run | | Between-Lot | | Total | |
| Sample | Mean (RU/mL) | SD | % | SD | % CV | SD | % CV | SD | % CV |
| 1 | 3 | 0.28 | 9.2 | 0.38 | 12.9 | 0.64 | 22.4 | 0.43 | 14.8 |
| 2 | 17 | 0.57 | 3.3 | 1.04 | 6.4 | 1.25 | 7.5 | 0.95 | 5.7 |
| 3 | 22 | 0.87 | 3.9 | 1.56 | 7.3 | 1.08 | 5.1 | 1.17 | 5.4 |
| 4 | 24 | 0.75 | 3.2 | 1.60 | 6.7 | 1.51 | 6.4 | 1.28 | 5.4 |
| 5 | 884 | 69.95 | 7.9 | 72.49 | 8.3 | 66.51 | 7.6 | 69.65 | 7.9 |
| 6 | 1356 | 65.65 | 4.8 | 33.59 | 2.5 | 45.60 | 3.4 | 48.28 | 3.6 |
| | Qualitative: Ratio | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | Sample 1 | Sample 2 | Sample 3 | Sample 4 | Sample 5 | Sample 6 |
| Mean value (x): | 0.20 | 0.74 | 0.91 | 1.00 | 7.57 | 8.20 |
| Range of values: | 0.16 – 0.25 | 0.68 – 0.81 | 0.76 – 1.27 | 0.83 – 1.17 | 6.34 – 8.22 | 7.45 – 8.72 |
| Expected result: | negative | borderline | borderline | positive | positive | positive |
| % positive: | 0% | 0% | 1% | 52% | 100% | 100% |
| % borderline | 0% | 97% | 99% | 48% | 0% | 0% |
| % negative: | 100% | 3% | 0% | 0% | 0% | 0% |

2. Lot to Lot

Reproducibility between lots was investigated using samples with values at different points on the calibration curve. Within-run, between-run, between-lot and total SD's and %CV's were calculated based on 18 determinations per sample performed in three different runs on three different days (with three runs per lot and two replicates per run, using three lots). EUROIMMUN's acceptance criterion was that the CV's show results below 12% for positive and borderline samples. Their acceptance criterion for the ratio-based results was that all qualitative results (positive, borderline, negative) of the samples be in line with the expected result. The following results were obtained:

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| | Semi-quantitative: RU/mL | | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Within-Run | | Within-Run | | Between-Lot | | Total | |
| Sample | Mean (RU/mL) | SD | % | SD | % CV | SD | % CV | SD | % CV |
| 1 | 3 | 0.45 | 16.4 | 0.15 | 5.4 | 0.33 | 11.9 | 0.31 | 11.2 |
| 2 | 17 | 1.19 | 7.2 | 0.42 | 2.5 | 0.69 | 4.1 | 0.76 | 4.6 |
| 3 | 23 | 1.46 | 6.5 | 0.30 | 1.3 | 0.99 | 4.4 | 0.91 | 4.0 |
| 4 | 26 | 1.78 | 6.7 | 0.85 | 3.2 | 1.37 | 5.2 | 1.33 | 5.0 |
| 5 | 304 | 15.71 | 5.2 | 6.48 | 2.1 | 10.61 | 3.5 | 10.93 | 3.6 |
| 6 | 1260 | 127.19 | 10.1 | 35.80 | 2.8 | 33.53 | 2.7 | 65.51 | 5.2 |
| | Qualitative: Ratio | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | Sample 1 | Sample 2 | Sample 3 | Sample 4 | Sample 5 | Sample 6 |
| Mean value (x): | 0.19 | 0.77 | 0.99 | 1.12 | 5.62 | 8.43 |
| Range of values: | 0.16 – 0.21 | 0.68 – 0.83 | 0.91 – 1.12 | 1.06 – 1.20 | 5.29 – 6.12 | 7.71 – 9.04 |
| Expected result: | negative | borderline | borderline | positive | positive | positive |
| % positive: | 0% | 0% | 28% | 100% | 100% | 100% |
| % borderline | 0% | 94% | 72% | 0% | 0% | 0% |
| % negative: | 100% | 6% | 0% | 0% | 0% | 0% |

## b. Linearity/assay reportable range:

### 1. Linearity

Five sets of 11-step-wise dilutions were prepared by mixing two low and five high analyte samples for proportional dilutions throughout the claimed ranges. The concentrations ranges tested were from a low concentration of 2 RU/mL to high concentrations of 75 RU/mL, 133 RU/mL, 790 RU/mL, 1100 RU/mL, or 1477 RU/mL. The assay was shown to be linear from 2 to 1500 RU/mL.

The regression results from sample sets around the cutoff and throughout the measuring range were:

| Concentration range | Regression and R² |
| --- | --- |
| 2 - 75 RU/mL | y=0.949x + 1.91, R²= 0.995 |
| 2 - 133 RU/mL | y=0.94x + 1.221, R²= 0.991 |
| 2-790 RU/mL | y=1.038x+14.497, R²=0.9843 |
| 2-1100 RU/mL | y=0.9178x+74.938, R²=0.9846 |
| 2-1642 RU/mL | y=1.0913x+51.156, R²=0.9713 |

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# Analytical measuring range

The analytical measuring range is 2 to 1500 RU/mL, from the lowest to the highest concentration calibrators.

c. Traceability, Stability, Expected values (controls, calibrators, or methods):

1. Traceability

There is no internationally recognized standard for autoantibodies to PLA2R. Results of this assay are given in arbitrary values (RU/mL or ratio of sample OD to cutoff control OD). The concentration of the calibrators is linked to the concentrations of master reference materials.

2. Calibrators and controls

The calibrators and controls are derived from human serum, purchased from commercial sources. Human originated material is tested and found negative for HBsAg, anti-HCV, anti-HIV-1 and anti-HIV-2, diluted to the appropriate concentration and stabilized. The calibrators are manufactured by dilution of the human serum with stabilizing buffer and adjusted to match the required performance criteria in use with the corresponding assay lot and the corresponding kit controls. The new lot of calibrator is assayed using a reference panel of at least eight positive and two negative reference sera (distributed over the measurement range). By further dilution or spiking with the original serum, the calibrators are adjusted until the following acceptance criteria are met: At least six of the eight positive sera must be found within the established acceptable ranges. The OD of the negative sera must be below the OD of the calibrator. After the adjustment is completed, the components of the new ELISA kit lot are tested together.

3. Reference panel

The samples used for the reference panel are human sera that are characterized, stabilized, aliquoted and stored frozen until usage. The acceptable range of the reference panel samples is determined as ±3 standard deviations of the mean of 10 runs using different assaylots. The range is set in RU/mL using released lots of the Anti-PLA2R ELISA (IgG). The reference panel is used as a master reference material against which to assign values to new lots.

4. Stability

Three lots of materials were tested with three different concentrations of analyte in real-time and accelerated stability. Claims from real-time stability are below:

a. Shelf-life stability: The sponsor provided data demonstrating the stability of unopened kits for 12 months at 2-8 °C.

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b. Open kit stability: The sponsor provided data demonstrating the stability of the opened kit for 6 months when stored at 2–8°C.

c. Reconstituted reagent stability: The sponsor provided data demonstrating that the reconstituted wash buffer is stable for 28 days (4 weeks).

d. Analytical Sensitivity

1. Limit of Blank

The limit of blank (LoB) was determined according to the recommendations of CLSI standard EP17-A. Six negative samples in the range &lt; 2 RU/mL were each run 12 times (four runs x three replicates) for 72 measurements. LoB was calculated according to formula (1) of EP17-A: LoB = μB + 1.645 × σB. μB = mean of means of blank sample measurements; σB = mean of standard deviations of blank sample measurements. μB = 1.3 RU/mL; σB = 0.3 RU/mL; LoB = 1.8 RU/mL.

2. Limit of Detection

The limit of detection (LoD) was determined according to the recommendations of CLSI standard EP17-A. Nine samples ranging from 2 to 7 RU/mL were each run 12 times (four runs x three replicates) for a total of 108 measurements. LoD was determined according to formula (4) of EP17-A:

LoD = LoB + 1.645 × σs, where σs = mean of standard deviations of low positive sample measurements, here σs = 0.25 RU/mL; LoD = 2.2 RU/mL.

3. Limit of Quantitation

The limit of quantitation (LoQ) is equal to the LoD, which is 2.2 RU/mL.

e. Analytical specificity:

1. Cross reactivity

Cross reactivity was investigated using a panel of 65 clinically characterized sera positive for thyroiditis (5), systemic lupus erythematosus (5), systemic sclerosis (5), Sjögren’s syndrome (5), cANCA (10), pANCA (10), glomerular basement membrane disease (GBM) (10), Hepatitis B surface antigen (10) and rheumatoid arthritis (5). All 65 sera were negative in the Anti-PLA2R ELISA (IgG) assay.

2. Interference

To investigate the influence from hemoglobin, triglycerides and bilirubin, sera with anti-PLA2R concentrations from 12 to 948 RU/mL were spiked with

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potential interfering substances and compared with unspiked sera. The concentrations of interferents were: Hemoglobin 0, 250, 500 and 1000 mg/dL; Triglycerides 0, 500, 1000 and 2000 mg/dL; Bilirubin 0, 10, 20 and 40 mg/dL.

EUROIMMUN's acceptance criterion was that all individual recoveries should be within the range of 70 – 130% and the mean of recoveries for each interferent be within the range of 85 – 115%. All recoveries met the acceptance criteria for recovery to 1000 mg/dL for hemoglobin, 2000 mg/dL for triglyceride and 40 mg/dL for bilirubin.

f. Assay cut-off:

1. Semi-quantitative

20 RU/mL; however, the assay has a borderline range. Results should be interpreted as follows:

&lt;14 RU/mL: negative; ≥14-&lt;20 RU/mL borderline; ≥20 RU/mL positive

2. Ratio-based analysis

Results can be evaluated by calculating a ratio of the OD value of the control or patient sample over the OD value of calibrator 2 (20 U/mL). The ratio is calculated according to the following formula:

$$
\frac{\text{OD of the control or patient sample}}{\text{OD of calibrator 2}} = \text{Ratio}
$$

Results should be interpreted as follows:

&lt;0.7: negative; ≥0.7 to &lt;1.0: borderline; ≥1.0: positive

2. Comparison studies:

a. Method comparison with predicate device:

The samples from the clinical studies total 560 (275 from pMGN patients, 285 from control groups) were investigated for anti-PLA2R antibodies (IgG) using the two test systems EUROIMMUN Anti-PLA2R IFA and EUROIMMUN Anti-PLA2R ELISA (IgG). Note that the IFA test is a qualitative immunofluorescence test for Anti-PLA2R.

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i. Semi-Quantitative (RU/mL):

| | Predicate | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| Anti-PLA2R ELISA (IgG) RU/mL | positive | 184 | 1 | 185 |
| | borderline | 6 | 0 | 6 |
| | negative | 22 | 347 | 369 |
| | Total | 212 | 348 | 560 |

Semi-quantitative, Borderline counted as Positive:

| | Predicate | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| Anti-PLA2R ELISA (IgG) RU/mL | positive | 190 | 1 | 191 |
| | negative | 22 | 347 | 369 |
| | Total | 212 | 348 | 560 |
| Positive Agreement: 184/212 = 86.79%; 95% CI: 81.5–91.0%
Negative Agreement: 347/348 = 99.71%; 95% CI: 98.4–100.0% | | | | |

Semi-quantitative, Borderline counted as Negative:

| | Predicate | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| Anti-PLA2R ELISA (IgG) RU/mL | positive | 184 | 1 | 185 |
| | negative | 28 | 347 | 375 |
| | Total | 212 | 348 | 560 |
| Positive Agreement: 190/212 = 89.62%; 95% CI: 84.7–93.4%
Negative Agreement: 347/348 = 99.71%; 95% CI: 98.4–100.0% | | | | |

ii. Qualitative (Ratio):

| | Predicate | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| Anti-PLA2R ELISA (IgG) Ratio | positive | 184 | 1 | 185 |
| | borderline | 12 | 1 | 13 |
| | negative | 16 | 346 | 362 |
| | Total | 212 | 348 | 560 |

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Qualitative, Borderline counted as Positive:

| | Predicate | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| Anti-PLA2R ELISA (IgG) Ratio | positive | 196 | 2 | 198 |
| | negative | 16 | 346 | 362 |
| | Total | 212 | 348 | 560 |
| Positive Agreement: 184/212 = 86.79%; 95% CI: 88.0–95.6%
Negative Agreement: 347/348 = 99.71%; 95% CI: 98.4–100.0% | | | | |

Qualitative, Borderline counted as Negative:

| | Predicate | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| Anti-PLA2R ELISA (IgG) Ratio | positive | 184 | 1 | 185 |
| | negative | 28 | 347 | 375 |
| | Total | 212 | 348 | 560 |
| Positive Agreement: 196/212 = 92.45%; 95% CI: 88.0–95.6%
Negative Agreement: 347/348 = 99.71%; 95% CI: 98.4–100.0% | | | | |

b. Matrix comparison:

Not applicable

3. Clinical studies:

a. Clinical Sensitivity and Specificity

Clinical studies were performed in cooperation with different sites (see below). In total 560 clinically characterized samples (275 from pMGN patients, 285 from control groups) were investigated for anti-PLA2R antibodies (IgG). Diagnosis of pMGN was based on renal biopsy and was considered to be idiopathic/primary when no secondary cause of MN was suspected on the basis of clinical and laboratory criteria. The samples were drawn within eight weeks after biopsy and before treatment; excluding patients who had been or were currently being treated with immunosuppressive drugs. With the EUROIMMUN Anti-PLA2R ELISA (IgG) using the 5-point calibrated analysis and a cut-off of 20 RU/ml, a sensitivity of 66.9% (95% C.I.: 61.0–72.4%) was found in pMGN, which is within the expected range of approximately 70% of anti-PLA2R as reported in the scientific literature. Specificity was 99.6% (95% C.I.: 98.1–100.0%). The results are shown in the tables below. 95% C.I. are calculated by the exact method. The results for the ratio analysis were calculated based on raw OD, not RU/mL:

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i. Clinical Sensitivity:

| Diagnosis | N (M, W) | Mean age (range, y) | Anti-PLA2R ELISA (IgG) | | |
| --- | --- | --- | --- | --- | --- |
| | | | positive | % | 95% C.I. |
| Primary membranous glomerulonephritis (pMGN) | 275 (188, 87) | 52 (16 – 86) | 184; 5 borderline | 66.9% | 61.0 – 72.4% |

ii. Clinical Specificity:

| Diagnosis | N (M, W) | Mean age (age range, # unknown) | Anti-PLA2R ELISA (IgG) | | |
| --- | --- | --- | --- | --- | --- |
| | | | negative | % | 95% C.I. |
| Secondary membranous glomerulonephritis (sMGN) | 68 (35, 33) | 51 (19 – 80, 2) | 67 | 98.5% | 92.1 – 100.0% |
| Non-membranous glomerulonephritides (GN) | 63 (32, 30, 1 unk) | 44 (16 – 68, 6) | 63 | 100.0% | 94.3 – 100.0% |
| Systemic lupus erythematosus (SLE) | 30 (8, 22) | 64 (50-86) | 30 | 100.0% | 88.4 – 100.0% |
| Systemic sclerosis (SSc) | 30 (6, 24) | 52 (30 – 74) | 30 | 100.0% | 88.4 – 100.0% |
| Psoriasis arthritis (PSA) | 30 (16, 14) | 48 (19 – 73) | 30 | 100.0% | 88.4 – 100.0% |
| Rheumatoid arthritis (RA) | 14 (1, 13) | 53 (29 – 86) | 14 | 100.0% | 76.8 – 100.0% |
| Thyroiditis | 50 (8, 42) | 48 (22 – 90) | 50 | 100.0% | 92.9 – 100.0% |
| Total | 285 | | 284 | 99.6% | 98.1 – 100.0% |

iii. Semi-quantitative Analysis (RU/mL):

| Clinical samples (n = 560) | Clinical diagnosis | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| EUROIMMUN Anti-PLA2R ELISA (IgG) RU/mL | positive | 184 | 1 | 185 |
| | borderline | 5 | 0 | 5 |
| | negative | 86 | 284 | 370 |
| | Total | 275 | 285 | 560 |

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Borderline samples counted as negative:
Sensitivity 184 / 275 = 66.9%; 95% C.I.: 61.0% - 72.4%
Specificity 283 / 285 = 99.6%; 95% C.I.: 98.1% - 100.0%

Borderline samples counted as positive:
Sensitivity 189 / 275 = 68.7%; 95% C.I.: 62.9% - 74.2%
Specificity 284 / 285 = 99.6%; 95% C.I.: 98.1% - 100.0%

iv. Qualitative Analysis (Ratio):

| Clinical Samples (n = 560) | Clinical diagnosis | | | |
| --- | --- | --- | --- | --- |
| | | positive | negative | Total |
| EUROIMMUN Anti-PLA2R ELISA (IgG) Ratio | positive | 181 | 1 | 182 |
| | borderline | 9 | 1 | 10 |
| | negative | 85 | 283 | 288 |
| | Total | 275 | 285 | 560 |

Borderline samples counted as negative:
Sensitivity 181 / 275 = 65.8%; 95% C.I.: 59.9% - 71.4%
Specificity 283 / 285 = 99.3%; 95% C.I.: 97.5% - 99.9%

Borderline samples counted as positive:
Sensitivity 190 / 275 = 69.1%; 95% C.I.: 63.3% - 74.5%
Specificity 283 / 285 = 99.3%; 95% C.I.: 97.5% - 99.9%

b. Other clinical supportive data (when a. and b. are not applicable):
Not applicable

4. Clinical cut-off:

The assay cut-off is based on a ROC analysis of the OD results of 122 samples from primary membranous glomerulonephritis (pMGN) patients (positive group) and 534 samples from patients with nonmembranous glomerulonephritides (GN), other connective tissue diseases and from normal healthy blood donors (negative group). pMGN diagnosis was based on renal biopsy and the samples were drawn within 8 weeks after biopsy and pre-selected for anti-PLA2R positivity. This population was separate from the samples used in the clinical sensitivity and specificity study. The ROC analysis demonstrated optimal sensitivity (96.7%) and specificity (100.0%) at the OD value of 0.228. The cut-off calibrator 2 was established with a nominal value of 20 RU/mL around this cut-off OD.

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5. Expected values/Reference range:

Two studies were performed: the first tested samples from European donors and the second tested samples from US donors.

European donors: The levels of anti-PLA2R antibodies (IgG) were analyzed in a panel of 100 samples from apparently healthy blood donors (83 men and 17 women with an average age of 38 y; age range: 18 – 68 y). There was one positive sample, male, with measurement of 32 RU/ml and a ratio of 1.6.

US donors: The levels of anti-PLA2R antibodies (IgG) were analyzed in a panel of 248 samples from apparently healthy blood donors (151 men, 97 women, mean age 36 y, age range 17 – 50 y). There was one positive sample, The results are shown in the table below. Taken together, these results demonstrate a prevalence of positive results of 0.6% in a normal population.

| European Donors | | |
| --- | --- | --- |
| N | 100 | |
| Positives | 1 | |
| Borderline | 0 | |
| Negatives | 99 | |
| Prevalence | 1.0 % | |
| | RU/mL | Ratio |
| Lowest value | 0 | 0.0 |
| Highest value | 32 | 1.6 |
| Mean value | 2 | 0.1 |
| 95^{th} percentile | 5.05 | 0.3 |
| Std deviation | 3.4 | 0.18 |
| US Donors | | |
| --- | --- | --- |
| N | 248 | |
| Positives | 1 | |
| Borderline | 0 | |
| Negatives | 247 | |
| Prevalence | 0.4% | |
| | RU/mL | Ratio |
| Lowest value | 1 | 0.0 |
| Highest value | 40 | 1.6 |
| Mean value | 2 | 0.1 |
| 95^{th} Percentile | 4.65 | 0.2 |
| Std deviation | 2.8 | 2.8 |

N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

O. Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.