Beckman Coulter's iTAg MHC Tetramer-CMV is for the identification and enumeration of cytomegalovirus (CMV) -specific CD8+ lymphocytes in whole blood by flow cytometry, and for the assessment of CMV-specific immune status in immunosuppressed stem cell transplant recipients. The assay is limited to individuals with the following HLA types: A0101, A0201, B0702, B0801, B*3501.

Device Description

iTAg™ MHC Tetramer CMV is similar to existing CD (cluster differentiation) technology, measuring subsets of an individual's total leukocyte population. The tetramer kits include five tetramers specific for particular CD3+CD8+ cell receptors. While 5 alleles are provided for this assay, an individual's analysis may use up to 4 of these 5 tetramers. Tetramers enumerate CD3+CD8+ subsets by flow cytometry, similar to antibodies: Same specimen (whole blood), indication (identification and enumeration of lymphocyte populations), platform (flow cytometry), fluorochromes, Flow-Count Fluorospheres, and accessory reagents. The assay components include: Vials of anti-CD8 FITC, Vials of anti-CD4 PE, Vials of anti-CD3 PC5, Vials of Flow-Count Beads, Vials of lysing agent, Vials of fixative, Up to 5 vials of individual Tetramers labeled with PE, Vials of negative Tetramer labeled with PE.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study information for the iTAg MHC Tetramer-CMV device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance:

Performance Metric	Acceptance Criteria (Implied)	Reported Device Performance
Specificity	No significant interference from common interferents.	No significant interference from common interferents (Monocytes, granulocytes, platelets, red blood cells). No significant interference from similar viral response (EBV). Tetramers were specific for identified alleles.
Linear Range	Acceptable correlation between expected and actual values.	Deming regression analysis showed acceptable correlation. Upper limit varied by allele (119 to >300 cells/µL).
Accuracy and Recovery	Acceptable recovery for cells/µL and % tetramer positive.	All tetramers demonstrated acceptable recovery. Overall percent recovery across three tetramers was 96%.
Analytical Sensitivity	Defined lower limit of detection.	1.0 cell/µL for absolute counts. 0.2% tetramer positive.
Reproducibility	Acceptable CV ranges for intra- and inter-laboratory testing.	Intra-laboratory: 1.3% CV to 16.3% CV. Inter-laboratory (Beckman Coulter facilities): 0.9% CV to 13.3% CV. Inter-laboratory (Beckman Coulter + two external sites): 2.6% CV to 29.6% CV.
Instrument Comparison	Comparable results and interchangeability between specified flow cytometers; acceptable correlation.	BD FACSCalibur vs. BCI EPICS-XL (Absolute Counts): Comparable results, interchangeable. Deming regression: y = 0.9697x - 0.3255, r = 0.9978. BD FACSCalibur vs. BCI EPICS-XL (% Tetramer Positive): Comparable results, interchangeable. Deming regression: y = 0.9800x - 0.0152, r = 0.9982. BCI FC500 vs. BCI EPICS-XL (Absolute Counts): Comparable results, interchangeable. Deming regression: y = 0.9812X + 0.1527, r = 0.9921. BCI FC500 vs. BCI EPICS-XL (% Tetramer Positive): Comparable results, interchangeable. Deming regression: y = 1.0426X - 0.0448, r = 0.995. Imprecision (Absolute Counts): Comparable between instruments, averaged < 10% CV for all samples.
Clinical Utility	Demonstrate utility for monitoring CMV-specific CD8+ T cells to assess immune status and risk in specific populations.	The data demonstrate utility for Beckman Coulter's iTAg MHC Tetramer-CMV in monitoring CMV-specific CD8+ T cells to assess immune status and risk of recurrent or persistent CMV infection or CMV disease (CMVD) in immunosuppressed stem cell transplant recipients, allowing clinicians to further refine pre-emptive therapeutic strategies in appropriate high-risk populations.
Predicate Device Equivalence	Good correlation with predicate device.	Good correlation between the iTAg MHC Tetramer-CMV and the predicate device.

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

The document does not explicitly state a specific sample size for a "test set" in the context of typical algorithm validation (e.g., retrospective images for AI). Instead, the "Summary of Studies" describes a series of analytical performance evaluations using various samples.

Sample Size: Not explicitly stated as a single number.
- Linear Range, Accuracy and Recovery, Analytical Sensitivity: "the sample tested" (for linearity), "three tetramers" (for recovery), "samples" (for sensitivity).
- Reproducibility: Not specified beyond the general nature of samples for intra- and inter-laboratory tests.
- Expected Reference Range: "apparently healthy CMV sero-negative donors" and "apparently healthy CMV sero-positive donors" – the number of donors is not specified.
- Clinical Data: "samples were HLA-typed and tested for CMV immune status by immunoassay" from "immunosuppressed stem cell transplant recipients." The precise number of clinical samples is not specified.
Data Provenance:
- The studies were performed at Beckman Coulter Inc. facilities, and some inter-laboratory reproducibility studies involved "two external sites."
- The clinical data involved "immunosuppressed stem cell transplant recipients" and "apparently healthy CMV sero-negative donors" and "CMV sero-positive donors," indicating human biological samples.
- The nature of the studies (e.g., "Expected Reference Range," "Clinical Data") implies prospective collection or analysis of these donor/patient samples, though not explicitly stated as "prospective" or "retrospective" in a research study design sense. It's likely prospective collection of fresh samples/blood for laboratory characterization.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications:

This information is not provided in the document. The studies described are methodologic performance evaluations (e.g., linearity, reproducibility, sensitivity) and instrument comparisons, not evaluations of a diagnostic algorithm against human expert interpretation. The "ground truth" for these types of studies is typically derived from established laboratory methods, reference materials, or a "gold standard" instrument/assay.

4. Adjudication Method for the Test Set:

This information is not applicable and not provided. There's no mention of expert adjudication for establishing ground truth, as the studies focus on analytical performance rather than diagnostic accuracy based on human interpretation.

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

This information is not applicable and not provided. The device (iTAg MHC Tetramer-CMV) is a laboratory assay (an automated differential cell counter in the context of its classification) that identifies and enumerates specific cell populations using flow cytometry. It is not an AI-powered diagnostic imaging device that human readers would interpret or use an AI assistant with. Therefore, an MRMC study comparing human readers with or without AI assistance is not relevant to this device.

6. Standalone (Algorithm Only) Performance:

Yes, the studies describe standalone performance. The iTAg MHC Tetramer-CMV, being a laboratory assay, is evaluated for its inherent analytical capabilities (specificity, linearity, accuracy, sensitivity, reproducibility, instrument comparability) without explicit human intervention in the measurement process itself, beyond standard laboratory procedures for sample handling and instrument operation. The results reported (e.g., 96% recovery, CVs, regression coefficients) are precisely the standalone performance of the assay and the associated flow cytometry system.

7. Type of Ground Truth Used:

The ground truth used for the analytical studies described appears to be a combination of:

Expected values/reference methods: For linearity, accuracy, and recovery studies, the "expected values" or comparison against established methods serve as the ground truth.
Established laboratory techniques: The enumeration of cell populations and determination of characteristics like specificity likely rely on well-defined flow cytometry principles and expert validation of populations.
CMV serological status and HLA typing: For the clinical utility aspect, the samples were "HLA-typed and tested for CMV immune status by immunoassay," which would serve as the ground truth for classifying patients for the clinical utility assessment.
Reference instruments: For instrument comparison, the "BD FACSCalibur flow cytometer" and "BCI EPICS-XL flow cytometer" and "BCI FC500 flow cytometer" serve as the reference/comparative ground truth.

8. Sample Size for the Training Set:

This information is not provided and is likely irrelevant in the context of this device. The iTAg MHC Tetramer-CMV is a reagent kit used with flow cytometers, not a machine learning or AI algorithm that requires a "training set" in the conventional sense. Its performance is based on the biochemical and physical properties of the tetramers and the established analytical capabilities of flow cytometry.

9. How the Ground Truth for the Training Set Was Established:

This information is not provided and likely irrelevant for the same reasons as (8). As it's not an AI/ML device, the concept of a "training set" and associated ground truth establishment for model training does not apply.

Summary

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AUG 1 - 2005

510(k) Summarv

General information:

Device Generic Name: Automated Differential Cell Counter

Device Trade Name: iTAg MHC Tetramer-CMV

Device Classification: 21 CFR 864.5220

Applicant Name and Address	Beckman Coulter, Inc.7330 Carroll Rd.San Diego, CA 92121
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Device Description:

Tetramers enumerate CD3+CD8+ subsets by flow cytometry, similar to antibodies: Same specimen (whole blood), indication (identification and enumeration of lymphocyte populations), platform (flow cytometry), fluorochromes, Flow-Count Fluorospheres, and accessory reagents. The assay components include:

. Vials of anti-CD8 FITC
. Vials of anti-CD4 PE
Vials of anti-CD3 PC5 .
Vials of Flow-Count Beads ●
. Vials of lysing agent
. Vials of fixative
Up to 5 vials of individual Tetramers labeled with PE .
. Vials of negative Tetramer labeled with PE

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Image /page/1/Picture/0 description: The image shows the logo for Beckman Coulter. The logo consists of a circular graphic on the left and the company name on the right. The graphic is a black circle with two curved white lines inside. The company name is written in a bold, sans-serif font, with "BECKMAN" on top and "COULTER" below.

Summary of Studies

Specificity: There was no significant interference from common interferents such as Monocytes, graulocytes, platelets and red blood cells. There was no significant interference from similar viral response (EBV). The tetramers were specific for the identified alleles.

Linear Range: The Deming regression analysis showed acceptable correlation between the expected and actual values for absolute counts of CMV tetramer positive cells. The upper limit of the linear range for tetramer-positive cells varied by allele depending on the sample tested, but ranged from 119 to >300 cells per microliter.

Accuracy and Recovery: All of the tetramers tested demonstrated acceptable recovery based on the percent recovery for cells per microliter and % tetramer positive. The overall percent recovery across three tetramers was 96%.

Analytical Sensitivity: Functional assay sensitivity was determined to be 1.0 cell per microliter for absolute counts and 0.2% tetramer positive.

Reproducibility:

Intra-laboratory (within-lab) assay reproducibility ranged between 1.3% CV . and 16.3% CV.
Inter-laboratory (between-lab) assay reproducibility ranged from 0.9% CV to . 13.3% CV when performed at Beckman Coulter Inc. facilities, and from 2.6% CV to 29.6% CV when performed at the Beckman Coulter Inc. and two external sites.

Expected Reference Range: The expected reference range based on apparently healthy CMV sero-negative donors was 0 to 0.8 tetramer cells per microliter. The reference range determined for apparently healthy CMV sero-positive donors was 0 to 46.6 cells per microliter.

Instrument comparison: BD FACSCalibur flow cytometer and the BCI EPICS-XL flow cytometer were tested. The flow cytometers were shown to give comparable results and can be used interchangeably. The Deming regression analysis showed good correlation between the BD FACSCalibur flow cytometer and the BCI EPICS-XL flow cytometer for tetramer absolute counts with an equation of y =0.9697x -0.3255, r = 0.9978, where y is the BD FACSCalibur flow cytometer and x is the BCI EPICS-XL flow cytometer.

The Deming regression analysis also showed good correlation between the flow cvtometers for % tetramer positive with an equation of y = 0.9800x -0.0152, r = 0.9982, where y is the BD FACSCalibur flow cytometer and x is the BCI EPICS-XL flow cytometer.

In addition to the above study, BCI FC500 flow cytometer and the BCI EPICS-XL flow cytometers were tested. The flow cytometers were shown to give comparable results and can be used interchangeably. The Deming regression analysis showed acceptable correlation between the BCI FC500 flow cytometer and the BCI EPICS-

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XL flow cytometer for CMV tetramer+ absolute counts with an equation of y = 0.9812X +0.1527, r = 0.9921, where y is the BCI FC500 flow cytometer and x is the BCI EPICS-XL flow cytometer.

The Deming regression analysis also showed acceptable correlation between the flow cytometers for CMV tetramer+ percent with an equation of y = 1.0426X -0.0448, r = 0.995, where y is the BCI FC500 flow cytometer and x is the BCI EPICS-XL flow cytometer.

The imprecision for CMV tetramer+ absolute counts was comparable between instruments and averaged less than 10% CV for all samples tested.

Clinical Data: The samples were HLA-typed and tested for CMV immune status by immunoassay. The data demonstrate utility for Beckman Coulter's iTAg MHC Tetramer-CMV in monitoring CMV-specific CD8+ T cells to assess immune status and risk of recurrent or persistent CMV infection or CMV disease (CMVD) in immunosuppressed stem cell transplant recipients, allowing clinicians to further refine pre-emptive therapeutic strategies in appropriate high-risk populations.

Conclusion

The data generated demonstrates acceptable non-clinical (laboratory) performance, and good correlation between the iTAg MHC Tetramer-CMV and the predicate device.

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Public Health Service

AUG 1 - 2005

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

Beckman Coulter, Inc. c/o Ms Mara Caler 7330 Carroll Rd. San Diego, CA 92121

Re: K051122

Trade/Device Name: iTAg MHC Tetramer - CMV Regulation Number: 21 CFR 864.5220 Regulation Name: Automated differential cell counter Regulatory Class: Class II Product Code: GKZ Dated: April 29, 2005 Received: May 2, 2005

Dear Ms Caler:

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

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to such additional controls. Existing major regulations affecting your device can be found in 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 requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

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

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Page 2 -

If you desire specific information about the application of labeling requirements to your device, or questions on the promotion and advertising of your device, please contact the Office of In Vitro Diagnostic Device Evaluation and Safety at (240) 276-0484. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its Internet address http://www.fda.gov/cdrh/industry/support/index.html

Sincerely yours,

lobatz Beckerh

Robert L. Becker, Jr., MD, P/ Director Division of Immunology and Hematology Office of In Vitro Diagnostic Device Evaluation and Safety Center for Devices and Radiological Health

Enclosure

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Indications for Use 15/102

510(k) Number (if known):_

Device Name:__ iTAg MHC Tetramer CMV assay

Indications For Use:

Beckman Coulter's iTAg MHC Tetramer-CMV is for the identification and eoumeration of cytomegalovirus (CMV) -specific CD8+ lymphocytes in whole blood by flow cytometry, and for the assessment of CMV-specific immune status Blood by non cylomony in immunosuppressed stem cell transplant and nets. The assay is limited to individuals with the following HLA types: A0101, A0201, B0702, B0801,B*3501.

(a) Classification name: Automated Cell Counter, 21 CFR 864.5220

(b) Classification. Class II

Prescription Use _ V

AND/OR

Over-The-Counter Use

(Part 21 CFR 801 Subpart D)

(21 CFR 801 Subpart C)

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

Concurrence of CDRH, Office of Device Evaluation (ODE)

Page 1 of of

Maria M Chan

Division Sign-Off

Office of In Vitro Diagnostic Device Evaluation and Safety

510(k) K051122

CONFIDENTIAL

Regulation Number and Section

§ 864.5220 Automated differential cell counter.

(a)
Identification. An automated differential cell counter is a device used to identify one or more of the formed elements of the blood. The device may also have the capability to flag, count, or classify immature or abnormal hematopoietic cells of the blood, bone marrow, or other body fluids. These devices may combine an electronic particle counting method, optical method, or a flow cytometric method utilizing monoclonal CD (cluster designation) markers. The device includes accessory CD markers.(b)
Classification. Class II (special controls). The special control for this device is the FDA document entitled “Class II Special Controls Guidance Document: Premarket Notifications for Automated Differential Cell Counters for Immature or Abnormal Blood Cells; Final Guidance for Industry and FDA.”