(458 days)
Immunoassay for the in vitro quantitative determination of thyroglobulin in human serum and plasma. Determination of Tg is used as an aid in monitoring for the presence of persistent or recurrent/metastatic disease in patients who have differentiated thyroid cancer (DTC) and have had thyroid surgery (with or without ablative therapy). The electrochemiluminescence immunoassay "ECLIA" is intended for use on cobas e immunoassay analyzers.
The Tg II immunoassay makes use of a two-step, double antigen sandwich principle using a biotinylated monoclonal Tg-specific antibody and monoclonal Tg-specific antibodies labeled with a ruthenium complex. The Tg II immunoassay is intended for the in vitro quantitative determination of thyroglobulin in human serum and plasma. Determination of Tg is used to aid in monitoring for the presence of persistent or recurrent/metastatic disease in patients who have differentiated thyroid cancer (DTC) and have had thyroid surgery (with or without ablative therapy). It is intended for use on the cobas e immunoassay analyzers. Results are determined via a calibration curve which is instrument-specifically generated by 2-point calibration and a master curve provided via the reagent barcode or e-barcode.
The Elecsys Tg II device is an immunoassay intended for the in vitro quantitative determination of thyroglobulin in human serum and plasma, used as an aid in monitoring for the presence of persistent or recurrent/metastatic disease in patients who have differentiated thyroid cancer (DTC) and have had thyroid surgery.
Here's an analysis of its acceptance criteria and the study that proves the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
The provided document doesn't explicitly list "acceptance criteria" for all performance measures in a comparative table against the reported performance. However, based on the studies conducted and their results, one can infer the implicit acceptance criteria by observing the measured performance and statements like "All deviations from linearity met the specification" or "Non-significant interferences were defined as %interferences within ± 10 %".
Below is a table summarizing the reported device performance, with inferred acceptance criteria where direct ones are not explicitly stated, but are implied by the reported "met specifications" or similar statements.
| Performance Characteristic | Inferred Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Clinical Performance | ||
| Sensitivity | High sensitivity required for monitoring recurrent/metastatic disease (e.g., >90%). | 98.91% (91/92) with 95% CI: (94.10%; 99.81%) |
| Specificity | Acceptable specificity for the intended use (the exact value is not explicitly stated as an initial acceptance criterion, but the reported value is presented as performance). | 53.42% (234/438) with 95% CI: (48.74%; 58.05%) |
| Negative Predictive Value (NPV) | High NPV desired for ruling out disease (-ve result, truly -ve). | 99.89% with 95% CI: (99.42%; 99.98%) (calculated at 4.99% prevalence) |
| Positive Predictive Value (PPV) | Acceptable PPV for the intended use. | 10.03% with 95% CI: (9.16%; 11.03%) (calculated at 4.99% prevalence) |
| Analytical Performance | ||
| Limit of Blank (LoB) | Must be very low (e.g., in the picogram/mL range) to detect low levels of Tg. No explicit criterion given, but the reported value is the outcome of the study designed to determine it. | 0.02 ng/mL (Determined according to CLSI EP17-A2) |
| Limit of Detection (LoD) | Must be very low, enabling early detection of disease recurrence. No explicit criterion given, but the reported value is the outcome of the study designed to determine it. | 0.04 ng/mL (Determined according to CLSI EP17-A2) |
| Limit of Quantitation (LoQ) | %CV of within-laboratory precision ≤ 20% and %bias within ±15%. | 0.1 ng/mL (%CV for samples around this level ranged from 7.56% to 4.00% for repeatability, and within-laboratory CVs were 9.34%, 8.75%, 5.67% for HS1, HS2, HS3 respectively, all below 20%. Bias not explicitly shown in summary table but met criteria.) |
| Linearity | Deviations from linearity ≤ ±10% for values ≥0.3 ng/mL and within ±0.03 ng/mL for values <0.3 ng/mL. | All deviations from linearity met the specification. |
| Measuring Range | To cover a broad range of clinically relevant Tg concentrations. | 0.1 ng/mL – 500 ng/mL. Extended measuring interval is 500 – 5,000 ng/mL for 1:10 diluted samples. |
| High-Dose Hook Effect | No hook effect within clinically relevant high concentrations (e.g., up to 120,000 ng/mL or higher, implying reliable readings even at very high concentrations). | No hook effect observed up to ≥ 120,000 ng/mL Tg. |
| Matrix Comparison | Performance with Li-heparin, K2-EDTA, and K3-EDTA plasma should be similar to serum. | Matrix comparison studies showed that performance of Elecsys Tg II assay with these matrices are similar. |
| Biotin Interference | Non-significant interference, generally defined as %interference within ± 10%. | Biotin interference claim is set to 1200 ng/mL in labeling (meaning up to this concentration, interference is acceptably low, i.e., within ±10%). |
| Endogenous Substance and Pharmaceutical Interference | Non-significant interferences, defined as %interferences within ± 10 % at tested concentrations. | Non-significant interferences observed for Bilirubin, Hemoglobin, Intralipid, Biotin, IgG, Albumin, and 17 commonly used pharmaceuticals, and special drugs at tested concentrations (e.g., Iodide, Amiodarone, L-T4, etc.). |
| HAMA Interference | No significant HAMA interference (e.g., recovery within acceptable range, like ±10-20%). | No significant HAMA interference at 805 µg/L HAMA. |
| Cross-Reactivity | Cross-reactivity should be minimal (e.g., within a small percentage). | TSH: Within ±0.36% at 1000 mIU/L. TBG: Within ±0.0001% at 200000 ng/mL. |
| Stability | ||
| Shelf-life Stability | Reagent stable for the stated shelf-life (e.g., 15 months). | Data support a shelf-life of up to 15 months at 2-8°C. |
| Reagent After Opening | Reagent stable for a specified duration after first opening (e.g., 84 days) when stored at 2-8°C. | Up to 84 days (12 weeks) after opening, stored at 2-8°C. |
| On-board Reagent Stability | Reagent stable for a specified duration on the analyzer (e.g., 28 days). | Up to 28 days (4 weeks). |
| Sample Stability | Samples stable for specified durations under different storage conditions (e.g., 14 days at 2-8°C, 24 months at -20°C). | 14 days at 2-8°C, 14 days at 15-25°C, and 24 months at -20 (± 5)°C for serum, Li-Heparin plasma, K2-EDTA and K3-EDTA plasma. |
Study Information:
2. Sample Size Used for the Test Set and Data Provenance
-
Clinical Performance Study (Combined Cohorts):
- Sample Size: 530 samples available for analysis.
- Data Provenance:
- Origin: Collected from 9 sites across the U.S.
- Nature:
- Longitudinal Cohort: Serum samples collected from subjects 4-12 weeks post-thyroidectomy (with/without radioiodine ablation) and at 4 additional time points (6, 12, 18, 24 months post-surgery/ablation).
- Cross-sectional Cohort: Samples collected from subjects with structural disease at a single visit. This cohort was used to increase the number of observations from patients with structural disease.
-
Reference Range Study:
- Sample Size: 244 healthy males and 219 healthy females (total 463).
- Data Provenance: Not explicitly stated (e.g., age range is given, but not country of origin, retrospective/prospective).
-
Expected Values in DTC post-thyroidectomy:
- Sample Size: 127 subjects with differentiated thyroid cancer (100 female; 27 male) with no evidence of disease for 4 or more years post-total/near total thyroidectomy.
- Data Provenance: Not explicitly stated.
-
Precision (Within-laboratory): 84 runs for each sample.
-
Reproducibility (Site-to-site): 146-149 runs for each sample.
-
LoB, LoD, LoQ, Linearity, Hook Effect, Interference, Cross-reactivity, Stability Studies: Varying number of samples/replicates as described in the respective sections (e.g., LoB/LoD: 5 native samples, 2 replicates/run, 6 runs over 4 days; LoQ: 7 low-level human serum samples, 5 replicates/run, 1 run/day over 5 days).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number of experts or their specific qualifications for establishing the ground truth of "structural disease" in the clinical study. However, the definition of structural disease is provided:
- Ground Truth Definition: "Structural disease was defined as evidence of disease on ultrasound, cross sectional or functional imaging, or biopsy proven disease as determined by the investigator."
- Implied Experts: This definition suggests that the "investigator" (likely a medical professional such as an endocrinologist, radiologist, or pathologist, depending on the type of evidence) determined the presence of structural disease. The number of such investigators involved in determining ground truth per patient or across the study is not specified.
4. Adjudication Method for the Test Set
The document does not explicitly describe an adjudication method (e.g., 2+1, 3+1) for establishing the ground truth of structural disease. It states that structural disease was "determined by the investigator." This implies a single determination rather than a consensus or adjudicated process among multiple experts for each case.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not explicitly done. The study focuses on the standalone performance of the Elecsys Tg II assay rather than comparing human reader performance with and without AI assistance. The device itself is an immunoassay, not an AI imaging interpretation tool that would typically involve human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the studies presented are primarily standalone (algorithm only) performance evaluations. The Elecsys Tg II is an automated immunoassay system, and its performance (sensitivity, specificity, precision, accuracy, linearity, stability, etc.) is measured directly on biological samples without active human interpretation assistance in the analytical or clinical performance reported here. The "results are determined via a calibration curve which is instrument-specifically generated."
7. The Type of Ground Truth Used
- Clinical Performance Study: The ground truth for the clinical performance study (sensitivity, specificity, NPV, PPV) was based on structural disease (SD+ or SD-). This was determined by:
- Evidence of disease on ultrasound.
- Cross-sectional or functional imaging.
- Biopsy-proven disease.
- These were "determined by the investigator."
- Analytical Studies: For analytical performance (LoB, LoD, LoQ, linearity, interference, stability), the ground truth generally involved:
- Reference standards/materials: e.g., CRM 457.
- Known analyte concentrations: Obtained by spiking or using characterized serum pools.
- Clinical laboratory standards: (e.g., CLSI guidelines).
8. The Sample Size for the Training Set
The document does not mention a separate "training set" for the Elecsys Tg II device in the context of machine learning or AI algorithms. As an immunoassay, the "training" analogous to an AI system would be the development and optimization of the assay reagents, protocols, and calibration curves. The provided information relates to the validation of the final product. The "calibration curve" is established for the assay, which is a form of internal "training" for the instrument's interpretation of signal to concentration.
9. How the Ground Truth for the Training Set Was Established
As noted above, for an immunoassay, there isn't a "training set" in the typical AI sense. The development of the assay relies on establishing accurate measurements against recognized reference standards and materials (e.g., CRM 457, characterized serum pools with known thyroglobulin concentrations). These standards serve as the "ground truth" to ensure the assay accurately quantifies thyroglobulin. The assay is then calibrated using these standards to accurately relate the measured signal (chemiluminescent emission) to the thyroglobulin concentration in patient samples.
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Image /page/0/Picture/0 description: The image shows the logo of the U.S. Food and Drug Administration (FDA). On the left is the Department of Health & Human Services logo. To the right of that is the FDA logo, with the letters "FDA" in a blue square. To the right of the blue square is the text "U.S. FOOD & DRUG ADMINISTRATION" in blue.
September 30, 2023
Roche Diagnostics Phil Williams Regulatory Affairs Program Manager 9115 Hague Road Indianapolis, Indiana 46250
Re: K221890
Trade/Device Name: Elecsys Tg II Regulation Number: 21 CFR 866.6010 Regulation Name: Tumor-Associated Antigen Immunological Test System Regulatory Class: Class II Product Code: MSW Dated: April 21, 2023 Received: April 21, 2023
Dear Phil Williams:
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. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. 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. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. 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
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requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (OS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.
For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).
Sincerely,
Ying Mao -S
Ying Mao, Ph.D. Branch Chief Division of Immunology and Hematology Devices OHT7: Office of In Vitro Diagnostics Office of Product Evaluation and Quality Center for Devices and Radiological Health
Enclosure
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Indications for Use
510(k) Number (if known) K221890
Device Name Elecsys Tg II
Indications for Use (Describe)
Immunoassay for the in vitro quantitative determination of thyroglobulin in human serum and plasma. Determination of Tg is used as an aid in monitoring for the presence of persistent or recurrent/metastatic disease in patients who have differentiated thyroid cancer (DTC) and have had thyroid surgery (with or without ablative therapy). The electrochemiluminescence immunoassay "ECLIA" is intended for use on cobas e immunoassay analyzers.
| Type of Use (Select one or both, as applicable) | |
|---|---|
| Prescription Use (Part 21 CFR 801 Subpart D) | Over-The-Counter Use (21 CFR 801 Subpart C) |
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K221890
510(k) Summary
| Submitter Name | Roche Diagnostics | |
|---|---|---|
| Address | 9115 Hague RoadIndianapolis, IN 46250 | |
| Contact | Phil WilliamsEmail: phil.williams@roche.com | |
| Date Prepared | May 19, 2023 | |
| Device Trade Name | Elecsys Tg II (08906556160) | |
| Common Name | Tumor-associated antigen immunological test system | |
| Classification Name | System, Test, Thyroglobulin | |
| Regulation Number | 866.6010 | |
| Product Codes,Regulation Numbers | MSW | |
| Legally Marketed PredicateDevices | K002905Access® Thyroglobulin Reagents on the Access® Immunoassay | MSW |
DEVICE DESCRIPTION SUMMARY 1.
The Tg II immunoassay makes use of a two-step, double antigen sandwich principle using a biotinylated monoclonal Tg-specific antibody and monoclonal Tg-specific antibodies labeled with a ruthenium complex. The Tg II immunoassay is intended for the in vitro quantitative determination of thyroglobulin in human serum and plasma. Determination of Tg is used to aid in monitoring for the presence of persistent or recurrent/metastatic disease in patients who have differentiated thyroid cancer (DTC) and have had thyroid surgery (with or without ablative therapy). It is intended for use on the cobas e immunoassay analyzers. Results are determined via a calibration curve which is instrument-specifically generated by 2-point calibration and a master curve provided via the reagent barcode or e-barcode.
2. INTENDED USE/INDICATIONS FOR USE
Immunoassay for the in vitro quantitative determination of thyroglobulin in human serum and plasma. Determination of Tg is used as an aid in monitoring for the presence of persistent or
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recurrent/metastatic disease in patients who have differentiated thyroid cancer (DTC) and have had thyroid surgery (with or without ablative therapy).
The electrochemiluminescence immunoassay "ECLIA" is intended for use on cobas e immunoassay analyzers.
INDICATIONS FOR USE COMPARISON 3.
The Elecsys Tg II is substantially equivalent to the Access® Thyroglobulin Reagents on the Access® Immunoassay Systems. Both test systems are for the quantitative determination of thyroglobulin levels in human serum and plasma and used as an aid in the monitoring for the presence of local and metastatic thyroid tissue in patients who have thyroid cancer and have had thyroid surgery.
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TECHNOLOGICAL COMPARISON 4.
| Item | Predicate(Beckman Access, K002905) | Candidate Device(Elecsys Tg II) |
|---|---|---|
| Test Principle | The Access Thyroglobulin assay is asimultaneous one-step immunoenzymatic("sandwich") assay.A sample is added to a reaction vessel,along with a biotinylated mixture of fourmonoclonal Tg antibodies, streptavidincoated paramagnetic particles, andmonoclonal anti-Tg antibody alkalinephosphatase conjugate. The biotinylatedantibodies and the serum or plasmathyroglobulin binds to the solid phase,while the conjugate antibody reacts witha different antigenic site on thethyroglobulin molecule. After incubationin a reaction vessel, materials bound tothe solid phase are held in a magneticfield while unbound materials are washedaway. Then, the chemiluminescentsubstrate Lumi-Phos* 530 is added to thevessel and light generated by the reactionis measured with a luminometer. Thelight production is directly proportionalto the concentration of thyroglobulin inthe sample. The amount of analyte in thesample is determined from a stored,multi-point calibration curve. | Sandwich principle. Total duration ofassay: 18 minutes.• 1st incubation: Tg from 35 µL ofsample, a biotinylated monoclonalTg-specific antibody and monoclonalTg-specific antibodies labeled with aruthenium complex a) react to form asandwich complex.• 2nd incubation: After addition ofstreptavidin-coated microparticles, thecomplex becomes bound to the solidphase via interaction of biotin andstreptavidin.• The reaction mixture is aspiratedinto the measuring cell where themicroparticles are magneticallycaptured onto the surface of theelectrode. Unbound substances arethen removed with ProCell/ProCellM. Application of a voltage to theelectrode then induceschemiluminescent emission which ismeasured by a photomultiplier.• Results are determined via acalibration curve which is instrument-specifically generated by 2 pointcalibration and a master curveprovided via the reagent barcode or ebarcodea) Tris(2,2'-bipyridyl)ruthenium(II)-complex (Ru(bpy) ) |
| Instrument | Access® Immunoassay Systems | cobas e immunoassay analyzers |
| Item | Predicate(Beckman Access, K002905) | Candidate Device(Elecsys Tg II) |
| ReagentComposition | R1: Access Thyroglobulin Reagent TestPacks: Cat# 33860. 100 determinations,50 tests/packR1a: Dynabeads Paramagnetic particlescoated with streptavidin, suspended in aTris-buffered saline, surfactant, bovineserum albumin (BSA) <0.1%sodiumazide 0.1% ProClin** 300.R1b: Mouse monoclonal anti-thyroglobulin-alkaline phosphatase(bovine) conjugate in a Tris buffer, withprotein (bovine), <0.1%sodium azide0.1% ProClin** 300.R1c: Mouse monoclonal anti-thyroglobulin antibodies coupled tobiotin in a HEPES buffer with protein(bovine and mouse), < 0.1% sodiumazide, and 0.05% ProClin 300 | The reagent rackpack:• M Streptavidin-coatedmicroparticles (transparent cap),1 bottle, 6.5 mL: Streptavidin-coated microparticles 0.72mg/mL; preservative.• R1 Anti-Tg-Ab |
| Sample Type/Matrix | Serum and (heparinized) plasma | Serum, Li-Heparin, K2-EDTA, andK3-EDTA |
| Calibrator | Access Thyroglobulin Calibrators | Tg II CalSet |
| Calibration Interval | Calibration is required every 56 days orwhenever new lot numbers of reagentsare placed into use | Renewed calibration is recommendedas follows:• after 1 month (28 days) when usingthe same reagent lot• after 7 days (when using the samereagent kit on the analyzer)• as required: e.g. quality controlfindings outside the defined limits |
| Controls | Commercial control materials | PreciControl Universal, PreciControlTS, or other suitable control material |
| Traceability/Standardization | Calibrators are traceable to the EuropeanCommunity Bureau of Reference (BCR)CRM 457 thyroglobulin standard | Standardized against CRM (CertifiedReference Material) 457, of the BCR(Community Bureau of Reference) ofthe European Union. |
| Reagent Stability | Stable until the expiration date stated onthe label when stored at 2 to 10°C. | up to the stated expiration date(unopened at 2-8 °C)84 days (12 weeks) after opening,stored at 2-8 °C |
| Reagent On-BoardStability | After initial use, the pack is stable at 2 to10°C for 28 days. | 28 days (4 weeks) |
| Measuring Range | 0.1 – 500 ng/mL | 0.1 ng/mL – 500 ng/mL |
| Item | Predicate(Beckman Access, K002905) | Candidate Device(Elecsys Tg II) |
| Lower Limits ofMeasurement | The lowest detectable level of Tgdistinguishable from zero (AccessThyroglobulin Calibrator S0) with 95%confidence is 0.1 ng/mL. This value isdetermined by processing a complete six-point calibration curve, controls and tenreplicates of the zero calibrator inmultiple assays. The analytical sensitivityvalue is calculated from the curve at thepoint that is two standard deviations fromthe fitted zero calibrator signal. | Limit of Blank = 0.02 ng/mLLimit of Detection = 0.04 ng/mLLimit of Quantitation = 0.1 ng/mL |
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ડ. CLINICAL AND ANALYTICAL STUDIES SUMMARY & CONCLUSIONS
A reference range study was performed with 244 apparently healthy male subjects between 22 and 79 years of age and 219 apparently healthy female subjects between 22 and 77 years of age. Reference intervals (2.5th and 97.5th percentiles) together with medians are presented in the following table:
| N | 2.5th percentile | Median=50th percentile | 97.5th percentile | |
|---|---|---|---|---|
| Males | 244 | 3.3 ng/mL | 15.1 ng/mL | 63.2 ng/mL |
| Females | 219 | 3.9 ng/mL | 18.3 ng/mL | 104 ng/mL |
| Males and Females | 463 | 3.6 ng/mL | 16.6 ng/mL | 77.3 ng/mL |
Study for the expected values obtained from a total of 127 subjects with differentiated thyroid cancer (100 female; 27 male) with no evidence of disease for 4 or more years following total/near total thyroidectomy was conducted. The percentage of measurements below the LoQ of 0.1 ng/ml was 80.3%. The 95th percentile was 0.786 ng/mL (95% of patients had results <0.786 ng/mL).
A prospective, multi-center study was conducted on the cobas e 411 analyzer to assess the clinical performance of Elecsys Tg II. Samples were collected from 9 sites across the U.S. 530 samples were available for analysis.
Serum samples were collected from subjects in the longitudinal cohort within 4 - 12 weeks following total or near total thyroidectomy but before radioiodine ablation (if planned). Thyroglobulin levels were measured at 4 additional time points (approximately 6 months, 12 months, 18 months, and 24 months post-surgery/radioiodine ablation), 5 planned longitudinal visits per patient.
Samples from the cross-sectional cohort (structural disease positive) were used to increase the number of observations from patients with structural disease in the longitudinal cohort due to the
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low prevalence of structural disease in the longitudinal cohort. Subjects from the cross-sectional cohort had only 1 single visit.
The longitudinal and the cross-sectional cohorts were combined to increase the prevalence to determine a more precise estimate for sensitivity and NPV (negative predictive value). NPV and PPV (positive predictive value) estimates were adjusted based on the real-world prevalence of structural disease observed in the longitudinal cohort (4.99 % = 23/461).
Structural disease was defined as evidence of disease on ultrasound, cross sectional or functional imaging, or biopsy proven disease as determined by the investigator.
| Tg Concentration | SDa)+ | SD- | ||
|---|---|---|---|---|
| Elecsys Tg II | ≥0.2 ng/mL | 91 | 204 | 295 |
| <0.2 ng/mL | 1 | 234 | 235 | |
| Total | 92 | 438 | 530 |
The combined data of 530 samples are presented in the table below:
a) SD = structural disease
Sensitivity and specificity for the combined data were calculated for Elecsys Tg II assay result < 0.2 ng/mL as a negative result and Elecsys Tg II assay result ≥ 0.2 ng/mL as a positive result. Estimates of sensitivity and specificity along with two-sided 95% confidence intervals are presented in the table below. Prevalence of structural disease (SD+) in the longitudinal part of the clinical study was 4.99% (23/461). NPV and PPV were calculated for the prevalence of 4.99% along with two-sided 95% confidence intervals and results of the calculations are presented in the table below.
| Clinical Performance Measures | Estimate | 95% CI |
|---|---|---|
| Sensitivity | 98.91% (91/92) | (94.10%; 99.81%) |
| Specificity | 53.42% (234/438) | (48.74%; 58.05%) |
| Prevalence | 4.99% (23/461) | (3.35%; 7.37%) |
| Negative Predictive Value (NPV) | 99.89% | (99.42%; 99.98%) |
| Positive Predictive Value (PPV) | 10.03% | (9.16%; 11.03%) |
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The pre-defined suppressed Tg concentrations according to the ATA Response Classification categories: Excellent Response, Indeterminate Response and Biochemical Incomplete Response are presented in the table below:
| Excellent Response = $Tg < 0.2$ ng/mL |
|---|
| Indeterminate Response = $Tg \ge 0.2$ ng/mL AND $Tg < 1.0$ ng/mL |
| Biochemical Incomplete Response = $Tg \ge 1.0$ ng/mL |
The results from the clinical study demonstrated that at Tg concentrations > 1.0 ng/mL (corresponding to ATA "Biochemical Incomplete Response"), the probability of structural disease was much higher than the probability of structural disease for Tg concentrations <0.2 ng/mL (corresponding to ATA "Excellent Response").
Within-laboratory precision of the Elecsys Tg II assay was evaluated using Elecsys reagents, samples, and controls in accordance with the CLSI document EP05-A3: 2 runs per day in duplicate each for 21 days (n = 84). The following results were obtained:
| Sample | N | Mean | Repeatability(Within Run) | Between-Run | Between-Day | Within-Laboratory | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| SD | %CV | SD | %CV | SD | %CV | SD | %CV | |||
| HS 1b) | 84 | 0.129 | 0.010 | 7.56 | 0.000 | 0.000 | 0.007 | 5.49 | 0.012 | 9.34 |
| HS 2 | 84 | 0.145 | 0.009 | 5.86 | 0.000 | 0.000 | 0.009 | 6.50 | 0.013 | 8.75 |
| HS 3 | 84 | 0.228 | 0.009 | 4.00 | 0.004 | 1.81 | 0.008 | 3.59 | 0.013 | 5.67 |
| HS 4 | 84 | 1.67 | 0.045 | 2.67 | 0.015 | 0.908 | 0.025 | 1.50 | 0.053 | 3.20 |
| HS 5 | 84 | 38.7 | 0.503 | 1.30 | 0.000 | 0.000 | 0.460 | 1.19 | 0.682 | 1.76 |
| HS 6 | 84 | 235 | 4.52 | 1.92 | 0.000 | 0.000 | 2.90 | 1.23 | 5.37 | 2.28 |
| HSPc) 7 | 84 | 459 | 7.76 | 1.69 | 5.00 | 1.09 | 4.39 | 0.958 | 10.2 | 2.23 |
| PCUd) 1 | 84 | 24.1 | 0.267 | 1.11 | 0.038 | 0.156 | 0.308 | 1.28 | 0.409 | 1.70 |
| PCU 2 | 84 | 84.4 | 0.865 | 1.02 | 0.509 | 0.603 | 1.03 | 1.22 | 1.44 | 1.71 |
| PC TSe) | 84 | 1.05 | 0.016 | 1.55 | 0.000 | 0.000 | 0.019 | 1.79 | 0.025 | 2.37 |
b) HS = Human Serum
c) HSP = Human Serum Pool
d) PCU = PreciControl Universal
d) PC TS = PreciControl TS
Site-to-site reproducibility study was conducted on 3 cobas e 411 analyzers at 3 sites using 3 lots of reagents (2 reagent lots per site). The following samples and controls were tested in 5 replicates per run, in a single run per day, for 5 days according to the CLSI document EP05-A3 (n=150). The overall reproducibility (imprecision) data are summarized in the following table:
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| Repeatability | Between-Day | Between-Lot | Between-Lab | Total | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sample | N | Mean | SD | CV[%] | SD | CV[%] | SD | CV[%] | SD | CV[%] | SD | CV[%] |
| HS 01 | 148 | 0.217 | 0.016 | 7.56 | 0.014 | 6.66 | 0.014 | 6.49 | 0.014 | 6.45 | 0.030 | 13.6 |
| HS 02 | 148 | 0.315 | 0.021 | 6.62 | 0.022 | 7.14 | 0.012 | 3.77 | 0.022 | 6.88 | 0.039 | 12.5 |
| HS 03 | 146 | 2.00 | 0.076 | 3.79 | 0.090 | 4.52 | 0.012 | 0.622 | 0.067 | 3.34 | 0.136 | 6.81 |
| HS 04 | 148 | 39.7 | 1.26 | 3.17 | 2.02 | 5.08 | 0.541 | 1.36 | 1.53 | 3.86 | 2.88 | 7.26 |
| HP 05 | 149 | 261 | 11.0 | 4.20 | 12.1 | 4.64 | 8.02 | 3.07 | 13.4 | 5.15 | 22.6 | 8.67 |
| HSP 06 | 148 | 407 | 14.0 | 3.43 | 17.8 | 4.37 | 10.6 | 2.61 | 20.4 | 5.01 | 32.2 | 7.92 |
| HSP 07 | 149 | 464 | 17.6 | 3.79 | 19.3 | 4.16 | 0.000 | 0.000 | 18.5 | 3.98 | 32.0 | 6.89 |
| PCU 1 | 149 | 24.2 | 1.16 | 4.80 | 1.79 | 7.43 | 0.892 | 3.70 | 1.26 | 5.20 | 2.63 | 10.9 |
| PCU 2 | 148 | 93.0 | 4.31 | 4.63 | 4.62 | 4.97 | 3.32 | 3.57 | 3.10 | 3.34 | 7.78 | 8.36 |
| PC TS | 149 | 1.08 | 0.034 | 3.15 | 0.045 | 4.23 | 0.033 | 3.08 | 0.017 | 1.57 | 0.068 | 6.30 |
The Limit of Blank (LoB) was determined according to CLSI EP17-A2. Five analyte-free samples including native human serum samples and serum pools were measured in two replicates per run, six runs distributed over 4 days using three reagent lots on one analyzer. The LoB of the Elecsys Tg II assay is set to 0.02 ng/mL.
The Limit of Detection (LoD) was determined according to CLSI EP17-A2. Five native samples with low-analyte concentration were measured in two replicates per run, six runs distributed over 4 days, using three reagent lots on one analyzer. The LoD of the Elecsys Tg II assay is set to 0.04 ng/mL.
The Limit of Quantitation (LoQ) was determined according to CLSI EP17-A2. Seven low-level human serum samples (HS) were measured in five replicates with one run per day over 5 days using three reagent lots on one analyzer. The acceptance criteria were %CV of within-laboratory precision ≤ 20% and %bias within ±15%. The LoQ of the Elecsys Tg II assay is set to 0.1 ng/mL.
The linearity study for Elecsys Tg II assay was conducted on the cobas e 411 analyzer with 3 lots of reagent using two native, unmodified human serum samples (low, high) mixed in different proportions. A weighted linear regression was performed in accordance with the CLSI document EP06-Ed2. All deviations from linearity met the specification of ±10% for values ≥0.3 ng/mL and within ±0.03 ng/mL for values <0.3 ng/mL. Results of the regression analysis are presented in the table below.
The extended measuring interval is 500 - 5.000 ng/mL for manually or automatically 1:10 diluted samples. Samples with Tg concentrations above the analytical measuring range can be diluted with Diluent MultiAssay. The recommended dilution is 1:10 (either automatically by the analyzers or manually). The concentration of the diluted sample must be ≥ 40 ng/mL. After
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manual dilution, multiply the result by the dilution factor of 10. After dilution by the analyzers. the software automatically takes the dilution into account when calculating the sample concentration.
Three matrix comparison studies were conducted: Li-heparin plasma vs serum. K2-EDTA plasma vs serum, and K3-EDTA plasma vs serum. Each matrix comparison study included 65 pairs that cover the analytical measuring interval. Matrix comparison studies showed that performance of Elecsys Tg II assay with these matrices are similar.
The high-dose hook effect was assessed in three replicates. Three human serum samples (single donors) were spiked with analyte (human Tg) to achieve high Thyroglobulin concentrations. For each sample, a dilution series was performed. The hook concentration reported corresponds to the highest analyte concentration that generates a signal ≥ 10% above the upper limit of the measuring range. There was no hook effect up to ≥ 120000 ng/mL Tg.
The effect on quantitation of Tg in the presence of biotin was tested with native human serum samples. The interfering pool was diluted into the dilution pool in 10% increments. The recovery for each sample was calculated by comparison to the control (unspiked) sample. The biotin interference claim is set to 1200 ng/mL in labeling.
The effect of the following endogenous substances and pharmaceutical compounds on assay performance was tested. Interferences were tested up to the listed concentrations of the interferent and non-significant interferences were observed. Non-significant interferences were defined as %interferences within ± 10 %.
| Compound | Concentration tested |
|---|---|
| Bilirubin | ≤ 1128 µmol/L or ≤ 66 mg/dL |
| Hemoglobin | ≤ 0.373 mmol/L or ≤ 600 mg/dL |
| Intralipid | ≤ 2000 mg/dL |
| Biotin | ≤ 4912 nmol/L or ≤ 1200 ng/mL |
| IgG | ≤ 2 g/dL |
| Albumin | 7 g/dL |
Pharmaceuticals interferences were tested by spiking serum samples. Interference testing was performed on 17 commonly used pharmaceuticals. No significant interference with the assay was found. The following special drugs were tested with concentrations shown in the table below.
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| Drug | Concentration (mg/L) |
|---|---|
| Iodide | 0.2 |
| Carbimazole | 30 |
| Thiamazole | 80 |
| Propylthiouracil | 300 |
| Perchlorate | 2000 |
| Propranolol | 240 |
| Amiodarone | 200 |
| Prednisolone | 100 |
| Hydrocortisone | 200 |
| Fluocortolone | 100 |
| Octreotide | 0.3 |
| L-T3 | 0.5 |
| D-T3 | 0.5 |
| L-T4 | 5 |
| D-T4 | 5 |
| Cabozantinib-S-Malate | 4.14 |
| Lenvatinib Mesylate | 0.15 |
Drug interferences are measured based on recommendations given in CLSI guidelines EP07-A3 and EP37-Ed1 and other published literature.
The effect of the presence of human anti-mouse antibodies (HAMA) on the Elecsys Tg II assay was assessed on the cobas e 411 with four replicates. A serum pool with an endogenous analyte concentration (approximately 7 ng/mL) having a high-HAMA concentration and the corresponding serum pool without HAMA were tested. The recovery of the serum pool containing HAMA compared to the serum pool without HAMA was calculated. There was no significant HAMA interference at 805 µg/L HAMA.
The following cross-reactivities were investigated with thyroglobulin concentrations of approximately 5 and 50 ng/mL:
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| Cross-reactant | Concentration tested | Cross-reactivity% |
|---|---|---|
| TSH | 1000 mIU/L | Within ±0.36% |
| TBG | 200000 ng/mL | Within ±0.0001% |
The effect on quantitation of analyte in the presence of anticoagulants with Elecsys Tg II was determined by comparing values obtained from human serum samples and sample pools drawn into Serum, Li-Heparin, K2-EDTA, and K3-EDTA plasma tubes. Sixty five (65) serum/plasma pairs were tested in singleton with one reagent lot. Matrix comparison studies showed that performance of Elecsys Tg II assay with these matrices are similar.
The shelf-life stability of the Elecsys Tg II was conducted. The reagent packs were stored at 2 8°C and the real-time stability was evaluated at baseline and testing timepoints up to 17 months. The data support a shelf-life of the Elecsys Tg II up to 15 months at 2-8°C.
Reagent stability after first opening for the Elecsys Tg II assay was tested on one cobas e 411 analyzer. Elecsys Tg II reagent kits can be used after first opening for up to 84 days (12 weeks) when stored at 2-8°C.
On-board reagent stability for the Elecsys Tg II assay was tested on one cobas e 411 analyzer. Elecsys Tg II reagent kits can be stored on-board the analyzers for up to 28 days (4 weeks).
Lot calibration frequency for the Elecsys Tg II assay was tested on one cobas e 411 analyzer. Calibrations of an Elecsys Tg II reagent is recommended after 28 days (1 month) when using the same reagent lot.
Reagent on-board calibration frequency for Elecsys Tg II assay was tested on one cobas e 411 analyzer. Elecsys Tg II reagent kits can be stored on board of the analyzers for up to 7 days without a new calibration.
The sample stability of serum. Li-Heparin plasma, K2-EDTA and K3-EDTA plasma was evaluated for each sample matrix using Elecsys Tg II assay on one cobas e 411 analyzer. All samples can be stored for 14 days at 2-8°C, 14 days at 15-25°C, and 24 months at -20 (± 5)°C.
§ 866.6010 Tumor-associated antigen immunological test system.
(a)
Identification. A tumor-associated antigen immunological test system is a device that consists of reagents used to qualitatively or quantitatively measure, by immunochemical techniques, tumor-associated antigens in serum, plasma, urine, or other body fluids. This device is intended as an aid in monitoring patients for disease progress or response to therapy or for the detection of recurrent or residual disease.(b)
Classification. Class II (special controls). Tumor markers must comply with the following special controls: (1) A guidance document entitled “Guidance Document for the Submission of Tumor Associated Antigen Premarket Notifications (510(k)s) to FDA,” and (2) voluntary assay performance standards issued by the National Committee on Clinical Laboratory Standards.