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ONLINE TDM Methotrexate is an in vitro test for the quantitative determination of methotrexate in human serum and plasma on cobas c systems. The determination of methotrexate is used for monitoring levels of methotrexate to ensure appropriate therapy.

The ONLINE TDM Methotrexate assay is an in vitro test for the quantitative determination of methotrexate in human serum and plasma on cobas c systems. The determination of methotrexate is used for monitoring levels of methotrexate to ensure appropriate therapy.

The ONLINE TDM MTX assay is a two-reagent system used for the detection of methotrexate in serum and plasma. In this technology drug hapten attached to the enzyme glucose 6 phosphate dehydrogenase (G6PDH) serves as the binding partner to anti-methotrexate antibody. A competitive reaction to a limited amount of specific anti-methotrexate antibody takes place between the enzyme bound hapten and free methotrexate in the sample. Enzyme activity is reduced with bound antibody. Only active enzymes reduce NAD+ to NADH. The rate of NADH formation during the reaction correlates to the methotrexate concentration and is measured photometrically.

The ONLINE TDM MTX assay is a homogeneous enzyme-immunoassay.

Reagents - working solutions

R1: Anti-methotrexate antibody (rabbit monoclonal), 3 µg/mL; NAD, G6P, bovine serum albumin in water, pH 6.3; preservative

R3: Methotrexate hapten conjugated to G6PDH, 0.3 µg/mL; bovine serum albumin in buffer, pH 7.8; preservative

The provided document describes the analytical performance evaluation of the "ONLINE TDM Methotrexate" assay. This is an in vitro diagnostic device used for the quantitative determination of methotrexate in human serum and plasma. The study aims to demonstrate that the device meets predefined acceptance criteria.

Here's an analysis of the acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria & Reported Device Performance:

The document doesn't explicitly present a single table of "acceptance criteria" alongside "reported device performance" in a comparative format for all tests. Instead, it states for each section: "All acceptance criteria were met," and then provides the results. We can infer the acceptance criteria from the context and the reported successful outcomes.

Here is a reconstructed table based on the provided text, indicating the acceptance criteria (inferred from the "All acceptance criteria were met" statements and industry standards implicitly followed) and the reported performance.

• Control 1 (0.0863 µmol/L): 4.4% CV
• Control 2 (0.485 µmol/L): 0.9% CV
• Control 3 (0.849 µmol/L): 0.7% CV
• Human Serum 1 (0.0872 µmol/L): 4.0% CV
• Human Serum 2 (0.526 µmol/L): 0.8% CV
• Human Serum 3 (0.889 µmol/L): 0.7% CV
• Human Serum 4 (4.85 µmol/L): 1.0% CV
• Human Serum 5 (44.2 µmol/L): 4.0% CV
• Human Serum 6 (449 µmol/L): 3.7% CV
• Human Serum 7 (1334 µmol/L): 3.1% CV

Intermediate Precision:

• Control 1 (0.0737 µmol/L): 10.9% CV
• Control 2 (0.487 µmol/L): 1.2% CV
• Control 3 (0.841 µmol/L): 0.8% CV
• Human Serum 1 (0.0752 µmol/L): 11.2% CV
• Human Serum 2 (0.526 µmol/L): 1.3% CV
• Human Serum 3 (0.889 µmol/L): 1.1% CV
• Human Serum 4 (4.91 µmol/L): 2.0% CV
• Human Serum 5 (44.2 µmol/L): 5.3% CV
• Human Serum 6 (449 µmol/L): 6.3% CV
• Human Serum 7 (1316 µmol/L): 5.1% CV
  All stated to have met acceptance criteria. |
  | Analytical Sensitivity | LoB, LoD, LoQ within predefined thresholds to ensure accurate measurement at low concentrations. | LoB: ≤ 0.0250 µmol/L (claim in labeling)
  LoD:

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The ARK Methotrexate II Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of methotrexate in human serum or plasma on automated clinical chemistry analyzers. The measurements obtained are used in monitoring levels of methotrexate to help ensure appropriate therapy. Specimens from patients who have received glucarpidase (carboxypeptidase G2) as a high dose methotrexate rescue therapy should not be tested with the ARK Methotrexate II Assay.

The ARK Methotrexate II Assay is a homogeneous immunoassay based on competition between drug in the specimen and methotrexate labeled with the recombinant enzyme glucose-6phosphate dehydrogenase (rG6PDH) for binding to the antibody reagent. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly related to the drug concentration. Active enzyme converts the coenzyme nicotinamide adenine dinucleotide (NAD) to NADH that is measured spectrophotometrically as a rate of change in absorbance. Endogenous serum G6PDH does not interfere with the results because the coenyzme NAD functions only with the bacterial enzyme (rG6PDH) used in the assay. The ARK Methotrexate II Assay consists of reagents R1 anti-methotrexate monoclonal antibody with substrate and R2 methotrexate labeled with recombinant G6PDH enzyme. The test system includes the ARK Methotrexate II Calibrator, ARK Methotrexate II Control, and ARK Methotrexate II Dilution Buffer.

The ARK Methotrexate II Assay is a homogeneous enzyme immunoassay for the quantitative determination of methotrexate in human serum or plasma.

Here's an analysis of the acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance:

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The ARK™ Methotrexate Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of methotrexate in human serum or plasma on automated clinical chemistry analyzers. The measurements obtained are used in monitoring levels of methotrexate to help ensure appropriate therapy.

Specimens from patients who have received glucarpidase (carboxypeptidase G2) as a high dose methotrexate rescue therapy should not be tested with the ARK Methotrexate Assay.

The ARK Methotrexate Assay is a homogeneous immunoassay based on competition between drug in the specimen and Methotrexate labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for binding to the antibody reagent. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly proportional to the drug concentration. Active enzyme converts the coenzyme nicotinamide adenine dinucleotide (NAD) to NADH that is measured spectrophotometrically as a rate of change in absorbance. Endogenous serum G6PDH does not interfere with the results because the coenzyme NAD functions only with the bacterial enzyme used in the assay.

The ARK Methotrexate Assay consists of reagents R1 anti-Methotrexate polyclonal antibody with substrate and R2 Methotrexate labeled with bacterial G6PDH enzyme. The ARK Methotrexate Calibrator consists of a six-level set to calibrate the assay, and the ARK Methotrexate Control consists of a six-level set used for quality control of the assay (tri-level calibration range set and tri-level high range set). The ARK Methotrexate Dilution Buffer is equivalent to zero calibrator (Calibrator A).

Here's an analysis of the provided text to extract the acceptance criteria and study information:

Acceptance Criteria and Device Performance for ARK™ Methotrexate Assay

The provided document describes the acceptance criteria and the study that proves the ARK™ Methotrexate Assay, when used on the Beckman Coulter AU680 analyzer, meets these criteria. The study aims to demonstrate substantial equivalence to the assay's performance on the predicate device, the Roche/Hitachi 917 analyzer.

1. Table of Acceptance Criteria and Reported Device Performance

The document states: "The pre-determined Pass/Fail acceptance criteria were met for all of the above performance studies." However, the specific numerical acceptance criteria or performance values for each characteristic are not provided in the given text. It only lists the types of performance characteristics evaluated.

2. Sample Size Used for the Test Set and Data Provenance

The document does not specify the sample sizes used for the test set for any of the performance studies.

The document refers to "human serum or plasma" as the sample type. The country of origin of the data is not explicitly stated. The study is a "validation and verification" activity, implying it was conducted specifically for this submission, likely making it a prospective study for the purpose of device validation.

3. Number of Experts and Qualifications for Ground Truth

The concept of "experts" and their qualifications for establishing ground truth, as typically seen in image analysis or diagnostic interpretation, is not applicable to this type of in vitro diagnostic device (immunoassay) study. The ground truth for this device's performance characteristics is established through analytical methods and reference standards, not expert interpretation.

4. Adjudication Method for the Test Set

The concept of an "adjudication method" (e.g., 2+1, 3+1) is not applicable to this type of in vitro diagnostic device (immunoassay) study. Performance is assessed through quantitative measurements against established analytical criteria, not through expert consensus on diagnostic outcomes.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

A Multi-Reader Multi-Case (MRMC) comparative effectiveness study is not applicable to this type of in vitro diagnostic device (immunoassay). This study design is typically used for imaging or diagnostic interpretation tasks where human readers' performance is being evaluated, often with and without AI assistance. This device is an automated assay, not an AI for human interpretive tasks.

6. Standalone (Algorithm Only) Performance Study

The study described is a standalone performance study for the algorithm (assay system) on the Beckman Coulter AU680 analyzer. The validation and verification activities listed (Limit of Blank, Limit of Detection, Accuracy, Precision, etc.) directly evaluate the performance of the device itself, without human interpretation in the loop. The purpose is to demonstrate that the assay system alone performs comparably to its predicate.

7. Type of Ground Truth Used

For an immunoassay like the ARK™ Methotrexate Assay, the "ground truth" for evaluating its performance characteristics (analytical accuracy, precision, linearity, etc.) would be established through:

• Reference materials/standards: Calibrators and controls with precisely known concentrations of methotrexate.
• Reference methods: Comparison with established, validated analytical methods (e.g., LC-MS/MS, or the predicate device's performance which was previously validated) for samples with unknown concentrations.
• Spiking studies: Adding known amounts of analyte to a sample and measuring recovery to assess accuracy.

The document implicitly refers to these as part of the "analytical performance studies" and "validation and verification activities."

8. Sample Size for the Training Set

The document does not mention a training set or its sample size. This is expected as the ARK™ Methotrexate Assay is a homogeneous enzyme immunoassay kit, not a machine learning or AI model that requires a "training set" in the conventional sense. The "training" for such a system would involve validating its components and establishing its operational parameters on the target analyzer.

9. How Ground Truth for the Training Set Was Established

Since there is no "training set" in the context of machine learning, this question is not applicable. The assay is a chemical and biological system where parameters are set based on chemical principles and reagent characteristics, and then validated through performance studies.

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The ARK™ Methotrexate Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of Methotrexate in human serum or automated clinical chemistry analyzers. The measurements obtained are used in monitoring levels of methotrexate to help ensure appropriate therapy.

The ARK™ Methotrexate Calibrator is intended for use in calibration of the ARK Methotrexate Assay.

The ARKTM Methotrexate Control is intended for use in quality control of the ARK Methotrexate Assay.

Specimens from patients who have received glucarpidase (carboxypeptidase G2) as a high dose methotrexate rescue therapy should not be tested with the ARK Methotrexate Assay.

The ARK Methotrexate Assay is a homogeneous immunoassay based on competition between drug in the specimen and Methotrexate labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for binding to the antibody reagent. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly proportional to the drug concentration. Active enzyme converts the coenzyme nicotinamide adenine dinucleotide (NAD) to NADH that is measured spectrophotometrically as a rate of change in absorbance. Endogenous serum G6PDH does not interfere with the results because the coenyzme NAD functions only with the bacterial enzyme used in the assay.

The ARK Methotrexate Assay consists of reagents R1 anti-Methotrexate polyclonal antibody with substrate and R2 Methotrexate labeled with bacterial G6PDH enzyme. The ARK Methotrexate Calibrator consists of a six-level set to calibrate the assay, and the ARK Methotrexate Control consists of a six-level set used for quality control of the assay (tri-level calibration range set and tri-level high range set). The ARK Methotrexate Dilution Buffer is equivalent to zero calibrator (Calibrator A).

Here's a breakdown of the acceptance criteria and the studies that prove the device meets them, based on the provided text:

Acceptance Criteria and Reported Device Performance

• ARK Methotrexate Control (MID, HIGH, 5, 50, 500 µmol/L): Total CVs ranged from 3.8% to 7.0%.
• ARK Methotrexate Control (LOW, 0.06 µmol/L): Total SD was 0.007, which is ≤0.01.
• Patient Pool (MID, HIGH, 5, 50, 500 µmol/L): Total CVs ranged from 5.3% to 7.2%.
• Patient Pool (LOW, 0.07 µmol/L): Total SD was 0.008, which is ≤0.01. |
  | Interfering Substances | Not substantially affected by tested endogenous substances. | Measurement of methotrexate was not substantially affected by clinically high concentrations of Albumin, Bilirubin (conjugated & unconjugated), Cholesterol, Gamma-Globulin, Hemoglobin, Intralipid®, Rheumatoid Factor, Triglycerides, and Uric Acid. |
  | Specificity - Crossreactivity |

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