TPP by PANBIO, INC. | FDA 510(k) Summary

The TpP™ EIA employs a murine monoclonal antibody (MAb), specific for soluble fibrin polymer, as a capture antibody immobilized on a microtiter plate (MTP). This MAb recognizes a conformational epitope present only on the TpP™ entities but which is absent from fibrinogen and degradation products of fibrin and fibrinogen. During the first incubation phase TpP™ in human plasma specimens bind to the capture antibody. Afterwards the plate is rinsed, and a conjugate, another murine monoclonal antibody, labeled with horseradish peroxidase (HRP) is added to the well. This peroxidase conjugated MAb binds to a separate site on the TpP™ molecule during a second incubation period. Excess enzyme conjugated MAb is washed out and a subsequent application and incubation with tetramethylbenzidine (TMB) substrate follows. The reaction after TMB incubation is terminated with dilute sulfuric acid. The level of the TpP™ present in the specimen sample is determined colorimetrically from the enzymatic activity of detection MAb conjugate. The intensity of the color is proportional to the concentration of TpP™. Calibrator standard is provided with the kit.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study information for the ABS, Inc. TpP™ EIA, extracted and organized as requested:

Acceptance Criteria and Device Performance

Acceptance Criteria Category	Specific Criteria/Metric	Reported Device Performance
Linear Reportable Range	Not explicitly stated as an acceptance criterion, but a performance metric.	0 to 40 µg/mL
Minimum Detectable Level	Not explicitly stated as an acceptance criterion, but a performance metric.	0.177 µg/mL
Interference	No significant interference from common substances (Hemoglobin, Bilirubin, Triglycerides, Urokinase).	No significant interference observed with tested substances at specified concentrations.
Precision	Not explicitly stated as acceptance criteria, but performance metrics.	Sample A (23.64 µg/mL): - Within-Run CV: 1.50% - Total Precision CV: 10.15% Sample B (7.91 µg/mL): - Within-Run CV: 3.70% - Total Precision CV: 10.80%
Normal Range/Cutoff	Establishment of an effective cutoff value for risk assessment.	Best estimate cutoff: 6.65 µg/mL (determined by percentile evaluation)
Correlation with F1.2	Positive correlation with F1.2 following surgery.	Positive correlation of 0.58 (p=0.008) observed immediately following surgery. TpP™ levels remained elevated longer than F1.2.
Monitoring Anticoagulant Efficacy	Ability to distinguish patients with inadequate anticoagulant therapy.	In 4 out of 25 PTCA patients with thrombotic complications, TpP™ values never returned to normal after heparinization.
Substantial Equivalence	Substantially equivalent to Organon Teknika Corporation's immunochemical assay Thrombonostika F1.26 (K9911434).	Data and information demonstrate substantial equivalence to Thrombonostika F1.26.

Study Details

Sample sizes used for the test set and the data provenance:
- Normal Range Determination:
  - Total Subjects: 140
  - Site #1: 115 healthy volunteers (Country of origin not specified, but the submission is from an American company, suggesting US)
  - Site #2: 8 healthy volunteers and 17 outpatients (Country of origin not specified, but the submission is from an American company, suggesting US)
  - Provenance: Retrospective/Cross-sectional for establishing normal range.
- Clinical Study (Aortic Aneurysm):
  - Total Patients: 90
  - Location: Johns Hopkins Medical School, Baltimore, MD (USA)
  - Provenance: Prospective (patients recruited "who were undergoing procedures to repair aortic aneurysm").
- Clinical Study (PTCA):
  - Total Patients: 25
  - Location: Philadelphia Heart Institute (USA)
  - Provenance: Prospective (patients "administered systemic heparin").
- Interference Testing: Not specified as a patient population, but involved normal plasma samples, likely from the US.
- Precision Testing: Two samples (A & B) tested with replicates across multiple runs, likely laboratory-prepared or pooled human plasma from the US.
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The document does not specify the number or qualifications of experts used to establish the ground truth for the test sets.
- For the normal range, the "best estimate of an effective cutoff value was determined to be 6.65 µg/mL by employing a percentile evaluation," implying a statistical method rather than individual expert consensus on specific cases.
- For the clinical studies, ground truth for patient outcomes (e.g., thrombotic complications, post-surgical recovery, hypercoagulable state) would have been established by attending physicians/medical staff based on clinical presentation and other diagnostic tests, but no specific "experts" for ground truth adjudication are mentioned in the context of this device's evaluation.
Adjudication method (e.g. 2+1, 3+1, none) for the test set:
- No adjudication method (e.g., 2+1, 3+1) is mentioned or described for establishing ground truth for any of the test sets. Clinical outcomes likely served as the de facto "ground truth" for the efficacy studies.
If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- No MRMC comparative effectiveness study was conducted or mentioned. This device is an in-vitro diagnostic (IVD) assay, not an AI-assisted diagnostic imaging or interpretation tool that would involve human "readers."
If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, this is an IVD assay, which by nature operates in a standalone mode, providing a quantitative result without direct "human-in-the-loop" interpretation for each specific test result beyond the clinical application of the measured value (e.g., a physician interpreting the 6.65 µg/mL cutoff). The performance metrics (linearity, precision, interference, correlation) represent the standalone performance of the assay.
The type of ground truth used (expert consensus, pathology, outcomes data, etc):
- Normal Range: Statistical percentile evaluation of healthy individuals.
- Aortic Aneurysm Study: Clinical outcomes (post-surgical changes, correlation with F1.2 levels, which is a recognized marker for fibrin formation).
- PTCA Study: Clinical outcomes (occurrence of "serious thrombotic complications" and assessment of anticoagulant therapy efficacy based on these complications).
- Interference, Linearity, Precision: Laboratory-derived ground truth based on spiking known concentrations/substances and standard reference methods.
The sample size for the training set:
- Training Set (for Normal Range/Cutoff): 140 subjects (115 healthy volunteers, 8 healthy volunteers, 17 outpatients) were used for determining the effective cutoff value of 6.65 µg/mL. This can be considered the dataset used to "train" or establish the normal operating parameters and cutoff for the assay.
- For the correlation and efficacy studies, these were essentially "validation" sets for the established operational characteristics.
How the ground truth for the training set was established:
- For the normal range/cutoff determination, the ground truth was established by:
  - Identifying subjects as "healthy volunteers" or "outpatients" (implying a clinical assessment of their health status).
  - Performing the TpP™ EIA on their plasma samples.
  - Employing a "percentile evaluation" method to determine the statistical distribution of TpP™ levels in these populations and derive the "best estimate of an effective cutoff value" (6.65 µg/mL). This is a statistical, rather than case-by-case, ground truth establishment.

Summary

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OCT 1 8 1996

K962176

AMERICAN BIOGENETIC SCIENCES, INC.

1539 North Ironwood Drive, South Bend, IN 46635 · Tel: (219) 271-3415 Fax: (219) 271-3423 Premarket Notification Summary

TpP™ EIA

The ABS, Inc. TpP™ EIA is an enzyme linked immunoassay for the quantitative determination of soluble fibrin polymers in human plasma. It is indicated as an aid in assessing the risk of intravascular thrombosis and monitoring the efficacy of anticoagulant (heparin) therapy. The TpP™ EIA employs a murine monoclonal antibody (MAb), specific for soluble fibrin polymer, as a capture antibody immobilized on a microtiter plate (MTP). This MAb recognizes a conformational epitope present only on the TpP™ entities but which is absent from fibrinogen and degradation products of fibrin and fibrinogen. During the first incubation phase TpP™ in human plasma specimens bind to the capture antibody. Afterwards the plate is rinsed, and a conjugate, another murine monoclonal antibody, labeled with horseradish peroxidase (HRP) is added to the well. This peroxidase conjugated MAb binds to a separate site on the TpP™ molecule during a second incubation period. Excess enzyme conjugated MAb is washed out and a subsequent application and incubation with tetramethylbenzidine (TMB) substrate follows. The reaction after TMB incubation is terminated with dilute sulfuric acid. The level of the TpP™ present in the specimen sample is determined colorimetrically from the enzymatic activity of detection MAb conjugate. The intensity of the color is proportional to the concentration of TpP™. Calibrator standard is provided with the kit.

The data and information in this submission demonstrate that American Biogenetic Sciences' TpP™ EIA is substantially equivalent to Organon Teknika Corporation's immunochemical assay Thrombonostika F1.26, K9911434. KQ1 | | 434

These devices are similar in their intended use and methodology. Both utilize enzyme conjugated antibodies that bind to the analyte and react with the substrate TMB to directly measure species in blood which reflect activation of the coagulation system. These devices are dissimilar in that F1.2 tests measure a molecular entity which is generated in the penultimate stage of fibrin formation, i.e. during the conversion of prothrombin to thrombin. Although prothrombin is converted to thrombin, the latter is not necessarily coincident with fibrin (clot) formation. This is due to multiple inhibitors and substrates of thrombin. TpP™ consists of polymeric soluble fibrin entities which ultimately form fibrin in a clot. TpP™ is, therefore, coincident with fibrin formation as well as an indicator of thrombin activity.

These differences are not considered significant and have no effect on the safety and effectiveness of the product.

In order to determine the expected normal range for the TpP™ EIA, as well as to determine an effective cutoff point, several control populations were tested at several sites.

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There were a total of 140 subjects used (115 healthy volunteers from Site #1, 8 healthy volunteers and 17 outpatients from site #2). The best estimate of an effective cutoff value was determined to be 6.65 µg/mL by employing a percentile evaluation.

A clinical study was conducted at Johns Hopkins Medical School, Baltimore, MD. Ninety (90) patients were recruited from a population of adults of both sexes, age 17 and older who were undergoing procedures to repair aortic aneurysm. There was a positive correlation (0.58, p=0.008) for the increase in the two analytes following surgery. The mean value for all F1.2 patients started to decrease at 6 hours which is further confirmed by a lower correlation coefficient of 0.3 (p=0.19) as calculated for the increase in TpP™ and F1.2 after 6 hours. As F1.2 approached normal levels at t=12 hours post surgery TpP™ levels remained elevated and consequently the correlation between the ratios at 12 hours postsurgery decreased to 0.23 (p=0.31). From these results it can be concluded that elevations of TpP™ and F1.2 are correlated immediately following surgery and TpP™ levels persist at an elevated level for longer time periods. This physiological response suggests that ToP™ could serve as an alternative but equivalent marker to F1.2 for evaluating patients in a hypercoagulable state and as an aid to assess patients at risk of intravascular thrombosis.

The utility of the TpP™ EIA to distinguish patients with increased risk of thrombosis during a surgical procedure (PTCA) was evaluated at the Philadelphia Heart Institute. In the study, 25 PTCA patients were administered systemic heparin to achieve an activated clotting time of >300 seconds. Four (4) of the 25 patients proceeded to serious thrombotic complications The TpP™ values for these four patients never returned to normal values indicating active thrombosis. High TpP™ levels post heparinization suggest that the anticoagulant therapy was not adequate to maintain normal hemostatic function. From this data it may be concluded that the TpP™ EIA could serve as an aid in monitoring the efficacy of anticoagulant (heparin) therapy.

The performance of the TpP™ EIA was confirmed by linearity, precision, and interference testing. Results are reported below.

Linear Reportable Range :	0 to 40 µg/ml
Minimum Detectable Level:	0.177 µg/mL
Interference:	The TpP™ EIA has been evaluated with potential interfering substances. This interference study utilized a dose response method utilizing Hemoglobin (5, 2.5, 1, 0.5, 0.1 mg/mL), Bilirubin (0.2, 0.1, 0.05, 0.025, 0.01 mg/mL), Triglycerides (400, 250, 200, 125, 50 mg/dL), and Urokinase (1000, 500, 400, 200, 100 NIHU/ml). No significant interference was observed between normal plasma samples and normal plasma samples spiked with the noted level of analyte (interferent).

Linear Reportable Range :

0 to 40 µg/ml

Minimum Detectable Level:

0.177 µg/mL

Interference:

The TpP™ EIA has been evaluated with potential interfering substances. This interference study utilized a dose response method utilizing Hemoglobin (5, 2.5, 1, 0.5, 0.1 mg/mL), Bilirubin (0.2, 0.1, 0.05, 0.025, 0.01 mg/mL), Triglycerides (400, 250, 200, 125, 50 mg/dL), and Urokinase (1000, 500, 400, 200, 100 NIHU/ml). No significant interference was observed between normal plasma samples and normal plasma samples spiked with the noted level of analyte (interferent).

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Precision

Variability was determined by testing two samples over 10 days, one run per day, with replicates of 2 in each run. A single manufactured lot of kits, one kit utilized for each run, was employed. The concentrations were calculated from a calibration curve, with sample A, mean=23.64 µg/mL, selected well above the pathological cutoff and sample B, mean=7.91 µg/mL, selected near the pathological cutoff. Assay variances, standard deviation and coefficient of variation, were determined according to the NCCLS guideline EP5-T2.

Sample	Mean TpPTMvalue (µg/mL)	Within-RunStandardDeviation	Within-RunCoefficient ofVariation (%)	Total PrecisionStandardDeviation	Total PrecisionCoefficient ofVariation (%)
A	23.64	0.36	1.50	2.40	10.15
B	7.91	0.29	3.70	0.85	10.80

Regulation Number and Section

§ 864.7320 Fibrinogen/fibrin degradation products assay.

(a)
Identification. A fibrinogen/fibrin degradation products assay is a device used to detect and measure fibrinogen degradation products and fibrin degradation products (protein fragments produced by the enzymatic action of plasmin on fibrinogen and fibrin) as an aid in detecting the presence and degree of intravascular coagulation and fibrinolysis (the dissolution of the fibrin in a blood clot) and in monitoring therapy for disseminated intravascular coagulation (nonlocalized clotting in the blood vessels).(b)
Classification. Class II (performance standards).