Predicate Devices

Not Found

Reference Devices

Not Found

AI/ML (Artificial Intelligence / Machine Learning)

No
The summary describes a molecular diagnostic assay using T2 Magnetic Resonance (T2MR) for direct detection of Candida species. The detection method is based on species-specific probes attached to superparamagnetic particles and subsequent T2MR detection of amplification products. There is no mention of AI or ML in the device description, intended use, performance studies, or any other section. The analysis of the signal appears to be based on established T2MR principles and thresholds, not learned algorithms.

Therapeutic

No.
The T2Candida Panel and T2Dx® Instrument is a diagnostic device used for the direct detection of Candida species in blood for the presumptive diagnosis of candidemia; it does not directly treat or prevent a disease.

Diagnostic

Yes

The "Intended Use / Indications for Use" section explicitly states, "The T2Candida Panel is indicated for the presumptive diagnosis of candidemia." This directly indicates its diagnostic purpose.

SaMD (Software as a Medical Device)

No

The device description clearly states that the system is comprised of the T2Candida Panel (a molecular diagnostic assay) and the T2Dx® Instrument, which is a physical instrument that performs the assay steps. This indicates the presence of significant hardware components beyond just software.

IVD (In Vitro Diagnostic)

Yes, this device is an IVD (In Vitro Diagnostic).

Here's why:

Intended Use: The intended use explicitly states that the device is for the "direct detection of Candida species in EDTA human whole blood specimens from patients with symptoms of, or medical conditions predisposing the patient to, invasive fungal infections." This clearly indicates that the device is intended to be used in vitro (outside the body) to examine a human specimen (whole blood) for diagnostic purposes (detecting Candida species for the presumptive diagnosis of candidemia).
Device Description: The description details a "qualitative molecular diagnostic assay that employs a whole blood compatible PCR amplification followed by T2 magnetic resonance (T2MR) detection." This describes a laboratory test performed on a biological sample, which is characteristic of an IVD.
Specimen Type: The device uses "EDTA human whole blood specimens," which are biological samples collected from a patient for in vitro analysis.
Diagnostic Purpose: The device is indicated for the "presumptive diagnosis of candidemia," which is a diagnostic application.

The information provided aligns perfectly with the definition of an In Vitro Diagnostic device.

PCCP (Predetermined Change Control Plan) Authorized

N/A

Overview

Intended Use / Indications for Use

The T2Candida Panel and T2Dx® Instrument is a qualitative T2 Magnetic Resonance (T2MR®) assay for the direct detection of Candida species in EDTA human whole blood specimens from patients with symptoms of, or medical conditions predisposing the patient to, invasive fungal infections. The T2Candida Panel identifies five species of Candida and categorizes them into the following three species groups:

1. Candida albicans and/or Candida tropicalis,
1. Candida parapsilosis
1. Candida glabrata and/or Candida krusei

The T2Candida Panel does not distinguish between C. albicans and C. tropicalis. The T2Candida Panel does not distinguish between C. glabrata and C. krusei.

The T2Candida Panel is indicated for the presumptive diagnosis of candidemia. The T2Candida Panel is performed independent of blood culture. Concomitant blood cultures are necessary to recover organisms for susceptibility testing or further identification.

The T2Candida positive and negative External Controls are intended to be used as quality control samples with the T2Candida Panel when run on the T2Dx® instrument system. These controls are not intended for use with other assays or systems.

Product codes (comma separated list FDA assigned to the subject device)

PII, NSU

Device Description

The T2Candida panel and T2Dx® Instrument is comprised of the T2Candida Panel performed on the T2Dx® Instrument. The T2Candida Panel is a qualitative molecular diagnostic assay that employs a whole blood compatible PCR amplification followed by T2 magnetic resonance (T2MR) detection. The T2Candida Panel is performed on the T2Dx Instrument which executes all steps after specimen loading. A K2 EDTA whole blood specimen is loaded onto the T2Candida Sample Inlet, which is then placed on the T2Candida Base along with the T2Candida Reagent Pack. The Reagent Pack contains the internal control, amplification reagent, enzyme and the probe-coupled superparamagnetic particles for each Candida target. Three milliliters of the blood specimen is transferred to the T2Dx® Instrument where lysis of the red blood cells, concentration and lysis of the Candida cells and amplification of the Candida DNA takes place. Amplification products are detected by T2MR detection using species-specific probes which are attached to the superparamagnetic particles. At the end of each assay, the T2Dx® Instrument uses a bleach solution to neutralize all liquids on the cartridge to mitigate the risk of amplicon contamination. The assay provides an identification of Candida albicans and/or Candida tropicalis, Candida parapsilosis, and Candida glabrata and/or Candida krusei. The test does not distinguish between C. albicans and C. tropicalis. The test does not distinguish between C. glabrata and C. krusei.

Mentions image processing

Not Found

Mentions AI, DNN, or ML

Not Found

Input Imaging Modality

Not Found

Anatomical Site

whole blood specimens

Indicated Patient Age Range

adult patients

Intended User / Care Setting

For prescription use only.

Description of the training set, sample size, data source, and annotation protocol

Not Found

Description of the test set, sample size, data source, and annotation protocol

Description of the training set, sample size, data source, and annotation protocol:

Isolates: Isolates were obtained from a reference laboratory and a clinical laboratory. The ITS region of each isolate was sequenced to confirm its identification; for all isolates the BLAST results of the determined sequence showed > 99.2% similarity to C. albicans, C. tropicalis, C. krusei, C. glabrata or C. parapsilosis, as appropriate.
Blood specimens: Three K2EDTA tubes containing 4 mL of blood in each tube were drawn from patients for whom blood cultures were ordered at three clinical sites. Thirty-four percent of specimens were obtained from patients determined to have some level of immunocompromise. Tubes were transported to T2Biosystems within 24 hours of collection under refrigeration conditions. In the event that a blood culture (from the same patient draw as the K2EDTA tubes) was determined to be Candida positive for the patient blood specimen, the contrived specimen's T2 analytical result was declared invalid and not analyzed as part of the T2 study.
Spiking: Contrived samples were spiked with a specific concentration of Candida based on Table 13 to represent clinically relevant organism concentrations; a majority of samples contained Candida levels near the limit of detection. Cell bullets were prepared for each isolate and stored frozen. The concentration of organism in the cell bullets was determined by colony count. The colony count was used to assign an organism concentration value to guide contrived sample preparation. Cell viability and cell death was evaluated by comparing cell counts obtained before and after a single freeze/thaw cycle. Results were consistent with minimal cell death after a single freeze/thaw cycle. Within 48 hours of specimen draw, contrived samples were prepared using a randomized organism list to determine the species and strain to be used each day of preparation. Cell bullets were diluted to appropriate levels and the concentration was verified by colony count testing: three replicates, each in 4 mL of K2EDTA blood, were prepared for each organism/inoculum concentration. For each three-tube set, one tube was retained by T2 Biosystems for quality control purposes and the remaining two tubes were distributed to a testing site. Duplicate samples were shipped to assure the availability of a sample in the event one of the sample tubes was damaged during transit or otherwise malfunctioned. Only one sample was tested by the site, the untested sample was discarded.
In addition to positive spiked samples, an additional 50 un-spiked blood specimens were sent to testing sites as blinded negative samples.
Contrived samples and negative samples were distributed across four clinical sites within 24 hours of preparation and analyzed with the T2Candida Panel and T2Dx Instrument within 48 hours of receipt. Instructions for performance of contrived sample testing specified that as part of the loading procedure, refrigerated (i.e. controls and contrived) samples should be allowed to equilibrate to room temperature for ~20 minutes prior to loading. In all cases, samples were tested within five hours of equilibration to room temperature.

Summary of Performance Studies (study type, sample size, AUC, MRMC, standalone performance, key results)

Clinical Sensitivity Study (Contrived Samples):
- Study type: Clinical Sensitivity using contrived samples
- Sample size: 250 positive samples (50 unique Candida isolates of each of the five T2Candida targets spiked into whole blood) and 50 unspiked negative blood specimens.
- Key results:
  - Out of 900 organism channel results (250 spiked and 50 negative samples), Positive Percent Agreement (PPA) across all organism concentrations was 94.0% for the A/T and P channels and 88.0% for the K/G channel.
  - PPA for samples spiked at concentrations ≥ LoD showed 97.4% to 100.0% PPA across all detection channels.
  - All 50 negative samples gave negative results for all channels.
  - A single false positive result (1/250, 0.4%) was seen in the parapsilosis channel with C. krusei.
Clinical Specificity Study (Prospective Samples):
- Study type: Clinical Specificity using a prospective comparison of T2Candida Panel results with blood culture results.
- Sample size: 1501 blood specimens from adult patients.
- Key results:
  - Specificity for the A/T channel: 98.8% (1479/1497)
  - Specificity for the P channel: 99.2% (1487/1499)
  - Specificity for the K/G channel: 99.2% (1499/1500)
  - The T2Candida Panel correctly detected 2/4 specimens that had corresponding blood cultures positive for C. albicans, 2/2 for C. parapsilosis, and 1/1 for C. glabrata.
  - T2Candida Panel indicated 31 positive detections in 29 patient specimens for which Candida was not detected in corresponding blood cultures (false positives). Chart review for these cases indicated: one sample from a patient with proven intra-abdominal candidiasis (no positive blood cultures); six patients receiving anti-fungal therapy; four patients colonized with Candida species.

Key Metrics (Sensitivity, Specificity, PPV, NPV, etc.)

Clinical Sensitivity (from contrived samples):

A/T channel: 94/100 (94.0%)
P channel: 47/50 (94.0%)
K/G channel: 88/100 (88.0%)

Clinical Specificity (from prospective samples):

A/T channel: 1479/1497 (98.8%)
P channel: 1487/1499 (99.2%)
K/G channel: 1499/1500 (99.9%)

Limit of Detection (LoD):

C. albicans: 2 CFU/mL
C. tropicalis: 1 CFU/mL
C. parapsilosis: 3 CFU/mL
C. glabrata: 2 CFU/mL
C. krusei: 1 CFU/mL

Overall Incidence of Candida: 0.3% (4/1501) in prospective study.

Predicate Device(s): If the device was cleared using the 510(k) pathway, identify the Predicate Device(s) K/DEN number used to claim substantial equivalence and list them here in a comma separated list exactly as they appear in the text. List the primary predicate first in the list.

Not Found

Reference Device(s): Identify the Reference Device(s) K/DEN number and list them here in a comma separated list exactly as they appear in the text.

Not Found

Predetermined Change Control Plan (PCCP) - All Relevant Information for the subject device only (e.g. presence / absence, what scope was granted / cleared under the PCCP, any restrictions, etc).

Not Found

Regulation Number and Section

§ 866.3960 Nucleic acid-based device for the amplification, detection, and identification of microbial pathogens directly from whole blood specimens.

(a)
Identification. A nucleic acid-based device for the amplification, detection, and identification of microbial pathogens directly from whole blood specimens is a qualitative in vitro device intended for the amplification, detection, and identification of microbial-associated nucleic acid sequences from patients with suspected bloodstream infections. This device is intended to aid in the diagnosis of bloodstream infection when used in conjunction with clinical signs and symptoms and other laboratory findings.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Premarket notification submissions must include detailed device description documentation, including the device components, ancillary reagents required but not provided, and a detailed explanation of the methodology, including primer/probe sequence, design, and rationale for sequence selection.
(2) Premarket notification submissions must include detailed documentation from the following analytical and clinical performance studies: Analytical sensitivity (limit of detection), reactivity, inclusivity, precision, reproducibility, interference, cross reactivity, carryover, and cross contamination.
(3) Premarket notification submissions must include detailed documentation from a clinical study. The study, performed on a study population consistent with the intended use population, must compare the device performance to results obtained from well-accepted reference methods.
(4) Premarket notification submissions must include detailed documentation for device software, including, but not limited to, software applications and hardware-based devices that incorporate software.
(5) The device labeling must include limitations regarding the need for culture confirmation of negative specimens, as appropriate.
(6) A detailed explanation of the interpretation of results and acceptance criteria must be included in the device's 21 CFR 809.10(b)(9) compliant labeling.
(7) Premarket notification submissions must include details on an end user device training program that will be offered while marketing the device, as appropriate.
(8) As part of the risk management activities performed as part of your 21 CFR 820.30 design controls, you must document an appropriate end user device training program that will be offered as part of your efforts to mitigate the risk of failure to correctly operate the instrument.

Summary

0

EVALUATION OF AUTOMATIC CLASS III DESIGNATION FOR T2Candida Panel and T2Dx® Instrument

DECISION SUMMARY

A. DEN Number:

DEN140019

B. Purpose for Submission:

De Novo request for evaluation of automatic class III designation for the T2Candida Panel and T2Dx® Instrument

C. Measurands:

The assay amplifies and detects nucleic acids of the following species: Candida albicans and/or Candida tropicalis Candida parapsilosis Candida krusei and/or Candida glabrata

D. Type of Test:

The T2Candida Panel, performed on the T2Dx® Instrument, is a molecular diagnostic assay for the detection of the above listed Candida species from whole blood specimens obtained from patients with signs and symptoms of invasive Candida infection.

E. Applicant:

T2 Biosystems, Inc.

F. Proprietary and Established Names:

T2Candida Panel and T2Dx® Instrument

G. Regulatory Information:

1. Regulation section:
  21 CFR 866.3960
1. Classification:
  Class II
1. Product code(s):

1

PII

NSU

1. Panel:
  83- Microbiology

H. Intended Use:

1. Intended use(s):
  The T2Candida Panel and T2Dx® Instrument is a qualitative T2 Magnetic Resonance (T2MR®) assay for the direct detection of Candida species in EDTA human whole blood specimens from patients with symptoms of, or medical conditions predisposing the patient to, invasive fungal infections. The T2Candida Panel identifies five species of Candida and categorizes them into the following three species groups:
1. Candida albicans and/or Candida tropicalis,
1. Candida parapsilosis
1. Candida glabrata and/or Candida krusei

The T2Candida Panel does not distinguish between C. albicans and C. tropicalis. The T2Candida Panel does not distinguish between C. glabrata and C. krusei.

The T2Candida Panel is indicated for the presumptive diagnosis of candidemia. The T2Candida Panel is performed independent of blood culture. Concomitant blood cultures are necessary to recover organisms for susceptibility testing or further identification.

The T2Candida positive and negative External Controls are intended to be used as quality control samples with the T2Candida Panel when run on the T2Dx® instrument system. These controls are not intended for use with other assays or systems.

1. Indication(s) for use:
  Same as Intended Use
1. Special conditions for use statement(s):
  For prescription use only.
1. Special instrument requirements:
  The T2Candida Panel is performed on the T2Dx® Instrument.

2

I. Device Description:

The T2Candida panel and T2Dx® Instrument is comprised of the T2Candida Panel performed on the T2Dx® Instrument. The T2Candida Panel is a qualitative molecular diagnostic assay that employs a whole blood compatible PCR amplification followed by T2 magnetic resonance (T2MR) detection. The T2Candida Panel is performed on the T2Dx Instrument which executes all steps after specimen loading. A K2 EDTA whole blood specimen is loaded onto the T2Candida Sample Inlet, which is then placed on the T2Candida Base along with the T2Candida Reagent Pack. The Reagent Pack contains the internal control, amplification reagent, enzyme and the probe-coupled superparamagnetic particles for each Candida target. Three milliliters of the blood specimen is transferred to the T2Dx® Instrument where lysis of the red blood cells, concentration and lysis of the Candida cells and amplification of the Candida DNA takes place. Amplification products are detected by T2MR detection using species-specific probes which are attached to the superparamagnetic particles. At the end of each assay, the T2Dx® Instrument uses a bleach solution to neutralize all liquids on the cartridge to mitigate the risk of amplicon contamination. The assay provides an identification of Candida albicans and/or Candida tropicalis, Candida parapsilosis, and Candida glabrata and/or Candida krusei. The test does not distinguish between C. albicans and C. tropicalis. The test does not distinguish between C. glabrata and C. krusei.

J. Standard/Guidance Document Referenced (if applicable):

. IEC 61010-1:2001, (Second Edition). Safety requirements for electrical equipment for measurement control and laboratory use - General requirements. 2001
. IEC61010-2-010:2003 (Second Edition). Safety requirements for electrical equipment for measurement, control, and laboratory use - Part 2-010. Particular requirements for laboratory equipment for the heating of materials. 2003
IEC 61010-2-081:2001 (First Edition) + A1:2003. Safety requirements for electrical . equipment for measurement, control and laboratory use - Part 2-081: Particular requirements for automatic and semiautomatic laboratory equipment for analysis and other purposes. 2001
. IEC 61010-2-101:2002 (Second Edition). Safety requirements for electrical equipment for measurement, control, and laboratory use. Particular requirements for in vitro diagnostic (IVD) medical equipment. 2002.
. IEC 61326-1:2005. Electrical equipment for measurement, control and laboratory use -EMC requirements - Part 1: General requirements. 2005
. IEC 61326-2-6:2005. Electrical equipment for measurement, control and laboratory use -EMC requirements - Part 2-6: Particular requirements - In vitro diagnostic (IVD) medical equipment. 2005
. CISPR 11:2003 Group 1 Class A. Industrial, scientific and medical equipment -Radiofrequency disturbance characteristics – Limits and methods of measurement. 2003
. CLSI MM03-A2. Molecular Diagnostic Methods for Infectious Diseases: Approved Guideline. 2008
CLSI EP17-A2. Protocols for Determination of Limits of Detection and Limits of . Quantitation: Approved Guideline. 2013.

3

CLSI EP07-A2. Interference Testing in Clinical Chemistry. 2007 ●
. CLSI EP05-A2. Evaluation of Precision Performance of Quantitative Measurement Methods. 2005
CLSI EP25-A. Evaluation of Stability of In Vitro Diagnostic Reagents. 2013.
LIS01-A2. Standard Specification for Low Level Protocol to Transfer Messages Between Clinical Laboratory Instruments and Computer Systems; Approved Standard - Second Edition. Maintained by CLSI. 2009
. LIS02-A2. Standard Specification for Transferring Information Between Clinical Laboratory Instruments and Information Systems; Approved Standard - Second Edition. Maintained by CLSI. 2008
. ISTA 7E. Testing Standard for Thermal Transport Packaging Used in Parcel Delivery System Shipment. 2010
ISTA 2A. Partial Simulation Performance Test (ASTM D5276 Drop Test). 2011. ●
CLSI EP12-A2. User Protocol for Evaluation of Qualitative Test Performance: Approved . Guideline - Second Edition. 2014.

K. Test Principle:

In the T2Candida Panel and the T2Dx® Instrument a single pair of pan-Candida primers hybridizes to conserved sequences within the 5.8S and 26S ribosomal RNA operon of Candida species and amplify the intervening transcribed spacer 2 sequence (ITS2) released from the lysed Candida cells contained in the specimen. The primers are mixed in a ratio such that an asymmetric produces a predominantly single stranded nucleic acid after amplification. The primers are designed to also amplify the internal control. Speciesspecific and internal control-specific probes provide the specificity of the assay. The instrument detects the amplified PCR product directly in the whole blood matrix by amplicon-induced agglomeration of superparamagnetic particles to which the speciesspecific and internal control-specific probes are attached. The detection method measures the spin-spin relaxation signals of water molecules. For these measurements, the T2Dx Instrument utilizes a small permanent magnet and a specialized radio frequency coil to measure the T2MR signal from the water molecules. T2MR measures the disorder of the nuclear spins of the water molecules contained in the sample and this disorder is directly proportional to the superparamagnetic particle clustering state. The T2Dx® Instrument reports a positive or negative result for each detection channel [C. albicans/C. tropicalis (A/T), C. parapsilosis (P), C. krusei/ C. glabrata (K/G) and internal control (IC)].

L. Performance Characteristics:

1. Analytical performance:

a. Precision/Reproducibility

A multicenter reproducibility study was performed to determine the run to run, reagent lot, day to day, and site to site reproducibility. Testing was performed at three sites (two external and one internal) with a panel of three Candida species (C. albicans, C. parapsilosis and C. glabrata), each tested at two concentrations (1 - 2X

4

LoD. 3 - 4X LoD) using two reagent lots. Testing was performed for six nonconsecutive days with two runs and two operators per day. Organisms were tested in triplicate. A total of 108 data points were determined for each analyte at each concentration.

The organisms were prepared in fresh negative human blood samples and the concentration of organisms that were spiked in the samples was confirmed using colony count testing. Spiked samples were prepared by T2 Biosystems, deidentified and shipped to the testing sites under refrigerated conditions and stored at 2 - 8° C until testing. Reproducibility results were acceptable with a range of 95.4 to 100% agreement with expected results for each Candida species tested. A summary of the results is shown in Table 1 below.

Of the total 830 tests obtained, an analysis was conducted to assess the rate of invalid results. instrument failure or false positives. Those were as follows:

Invalid Results: 13/830 tests (1.6%) Instrument Failures: 17/830 tests (2.1%) False Positive: 3/830 (0.4%)

| Organism Detected | No. Not
Detected | %
Agreement
with
Expected |
|----------------------------------| | C.
parapsilosis | 1 – 2 X LoD | Site 1 | | | | | | | C.
parapsilosis | 3-4 X LoD | Site 1 | 36 | | | | | | | C. glabrata | 1-2 X LoDa | | | | | | | C. glabrata | 3-4 X LoD | | | | | | | C. albicans | 1-2 X LoDb | | | | | | | Concentration | Test site | No.
---------------|-----------|-----------------|---------------------|------------------------------------|
| 36 | 0 | |
| Site 2 | 36 | 0 | 108/108 |
| Site 3 | 36 | 0 | 100% |
| All sites | 108 | 0 | |
| 0 | |
| Site 2 | 36 | 0 | 108/108 |
| Site 3 | 36 | 0 | 100% |
| All sites | 108 | 0 | |
| Site 1 | 35 | 1 | |
| Site 2 | 34 | 2 | 105/108 |
| Site 3 | 36 | 0 | 97.2% |
| All sites | 105 | 3 | |
| Site 1 | 36 | 0 | |
| Site 2 | 35 | 1 | 106/108 |
| Site 3 | 35 | 1 | 98.1% |
| All sites | 106 | 2 | |
| Site 1 | 35 | 1 | |
| Site 2 | 35 | 1 | 103/108 |
| Site 3 | 33 | 3 | 95.4% |
| All sites | 103 | 5 | |

Table 1. Summary of Reproducibility Results Across Sites, Reagents and Operators

5

| | 3-4 X LoD | Site 1 | 35 | 1 | 107/108
99.1% |
|----------|-----------|-----------|-----|-----|------------------|
| | | Site 2 | 36 | 0 | |
| | | Site 3 | 36 | 0 | |
| | | All sites | 107 | 1 | |
| Negative | N/A | Site 1 | 0 | 36 | 108/108
100% |
| | | Site 2 | 0 | 36 | |
| | | Site 3 | 0 | 36 | |
| | | All sites | 0 | 108 | |

ª Two false positive results in the P channel

b One false positive result in the P channel

b. Linearity/assay Reportable Range:
Not Applicable
Traceability, Stability, Expected Values (controls, calibrators, or methods): C.
The T2Candida Panel and T2Dx® Instrument require two types of controls, the internal control and the external controls. The Internal Control (IC) is introduced into each specimen during sample processing on the T2Dx® instrument; the pan-Candida primers are designed to amplify the target Candida species and the internal control DNA. The IC is designed to report on the presence of any inhibitors in the clinical specimen and on any instrument-related errors. The signal cut-off for the IC is a 66(4) (b)(4) If the IC signal is below its cutoff and if the patient specimen is negative for all Candida targets, the specimen result cannot be determined and the IC result will be flagged as "Invalid" by the software resulting in an invalid test. If any of the Candida targets is determined to be positive. the specimen will be reported as positive for that target, regardless of the performance of the IC.

The external controls are provided in a kit and include both positive and negative controls prepared in a whole blood matrix. The T2 positive external control includes two blends of Candida species which can interrogate each T2Candida detection channel. The T2Candida A/P/G positive external control is comprised of a blend of C. albicans, C. parapsilosis and C. glabrata. The T/P/K positive external control is comprised of a blend of C. tropicalis, C. parapsilosis and C. krusei. The Candida concentration in the positive external controls is at least 3-5X LoD. The T2 negative external control is a whole blood specimen free of any Candida cells.

As noted in sections 3a and 3b below, clinical studies were conducted using prospectively collected specimens and contrived specimens. During the clinical and analytical studies for the T2Candida assay, fresh whole blood external controls were used; a positive and negative control was run each day of the contrived and prospective arms of the study; positive controls alternated between the APG and the TPK controls. A summary of the quality control test results across all sites is listed in Table 2 below.

6

| Target

Species	Site	No. Tested	No. Positive	No. Negative	No. Invalid
A/P/G
controla	Site 1	67	67	0	0
	Site2	68	66	1c	1
	Site 3	56	56	0	0
	Site 4	49	46	0	3
	Site 5	99	97	0	2
	Site 6	16	15	1c	0
	Site 7	11	10	0	1
	All Sites	366	357 (97.5%)	2 (0.6%)	7 (1.9%)
T/P/K
Controlb	Site 1	69	67	0	2
	Site2	73	72	0	1
	Site 3	58	56	0	2
	Site 4	60	58	0	2
	Site 5	102	98	0	4
	Site 6	13	12	0	1
	Site 7	14	13	0	1
	All Sites	389	376 (96.7)	0	13 (3.3%)
Negative
Control	Site 1	138	0	136	2
	Site2	140	2d	137	1
	Site 3	115	3d	109	3
	Site 4	109	2d	105	2
	Site 5	200	4d	194	2
	Site 6	29	0	25	4
	Site 7	26	0	24	2
	All Sites	757	11 (1.4%)	730 (96.4%)	16 (2.1%)

Table 2. Summary of Quality Control Testing, Including Testing Performed During the Clinical (Prospective and Contrived) Testing Arms.

a A/P/G control contains: C. albicans, C. parapsilosis and C. glabrata.

b T/P/K control contains C. tropicalis, C. parapsilosis and C. krusei.

C One of three channels negative.

d One of three channels positive.

Fresh vs. Frozen Control Equivalence. Due to the limited shelf life of the fresh whole blood external controls, the positive and negative controls will be provided in a separate package as frozen whole blood external controls containing the same organism blends as is found in the fresh whole blood controls. These controls are intended to be stored at -20° C, thawed and equilibrated to room temperature prior to testing. In order to evaluate the equivalence of the frozen external controls with the fresh whole blood external controls, a study was conducted with two lots each of fresh and frozen controls using 65 samples (each, fresh and frozen) of the A/P/G positive control, 65 samples (each, fresh and frozen) of the T/P/K positive control and 65 samples (each, fresh and frozen) of the negative control. Results confirmed the equivalence of the fresh and frozen controls. Results for each of the three channels (A/T, P, K/G) are shown in Table 3 below.

7

| Control | Lot | No tested | A/T
Channel
Pos (%) | P
Channel
Pos (%) | K/G
Channel
Pos (%) | IC Pos
(%) | Invalid |
|--------------------|-----|-----------|---------------------------|-------------------------|---------------------------|---------------|---------|
| A/P/G
Fresh | 1 | 65 | 65 (100) | 65 (100) | 65 (100) | 65
(100) | 0 |
| A/P/G
Fresh | 2 | 65 | 65 (100) | 65 (100) | 65 (100) | 65
(100) | 0 |
| A/P/G
Frozen | 1 | 65 | 65 (100) | 65 (100) | 64 (98.5) | 65
(100) | 0 |
| A/P/G
Frozen | 2 | 65 | 65 (100) | 65 (100) | 64 (98.5) | 65
(100) | 0 |
| T/P/K
Fresh | 1 | 65 | 64 (98.5) | 65 (100) | 64(98.5) | 65
(100) | 0 |
| T/P/K
Fresh | 2 | 65 | 64 (98.5) | 65 (100) | 64(98.5) | 65
(100) | 0 |
| T/P/K
Frozen | 1 | 65 | 65 (100) | 65 (100) | 65 (100) | 65
(100) | 0 |
| T/P/K
Frozen | 2 | 65 | 65 (100) | 64 (98.5) | 65 (100) | 65
(100) | 0 |
| Negative
fresh | 1 | 65 | 0 | 0 | 0 | 65
(100) | 9* |
| Negative
fresh | 2 | 65 | 0 | 0 | 0 | 65
(100) | 0 |
| Negative
frozen | 1 | 65 | 0 | 0 | 0 | 65
(100) | 3* |
| Negative
frozen | 2 | 65 | 0 | 0 | 0 | 65
(100) | 3* |

Table 3. Control Lots 1 and 2, Fresh vs. Frozen Equivalence

*Invalid tests were repeated and provided negative results.

External Control Reproducibility. The lot-to-lot reproducibility of the frozen external controls was further assessed by evaluating the T2 signal obtained from four production lots of the frozen controls. Ten replicates of each of the three frozen controls (A/P/G positive, T/P/K positive and negative) from each of the four lots were evaluated. The average T2 signal, %CV and % positive was evaluated for each lot. Results indicated that the four lots provided equivalent results.

Frozen Control Stability. The stability of the frozen positive and negative controls was also assessed. Three lots of each of the three controls (A/P/G positive, T/P/K positive and negative) were tested using the T2Candida Panel after 0 days, 30 days and 60 days of storage at -20° C. For each time point, the mean of the measured T2 signals from the A/T, P and K/G channels for each of the controls was expected to be statistically equivalent to the mean T2 signals measured in those channels on Day 0. At the time of clearance, all controls showed acceptable performance for at least 60 days.

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d. Detection Limit:

LoD testing was performed using two strains of each species targeted by the T2Candida Panel and performed on the T2Dx® Instrument. LoD testing consisted of an initial screening phase and a confirmatory phase. In the initial screening phase triple or double spiked samples (A/G/P or T/K) were prepared at 5 concentrations (8, 4, 2, 0.5) than the control components.

1. Comparison Studies:
- a. Method Comparison with Predicate Device: Not Applicable
- b. Matrix Comparison: Not Applicable

3. Clinical Studies:

a. Clinical Sensitivity:
Because of the low prevalence of Candida-positive blood cultures from clinical specimens (prevalence 99.2% similarity to C. albicans, C. tropicalis, C. krusei, C. glabrata or C. parapsilosis, as appropriate.

Blood specimens. Three K2EDTA tubes containing 4 mL of blood in each tube were drawn from patients for whom blood cultures were ordered at three clinical sites. Thirty-four percent of specimens were obtained from patients determined to have some level of immunocompromise. Tubes were transported to T2Biosystems within 24 hours of collection under refrigeration conditions. In the event that a blood culture (from the same patient draw as the K2EDTA tubes) was determined to be Candida positive for the patient blood specimen. the contrived specimen's T2 analytical result was declared invalid and not analyzed as part of the T2 study.

Spiking. Contrived samples were spiked with a specific concentration of Candida based on Table 13 below to represent clinically relevant organism concentrations; a majority of samples contained Candida levels near the limit of detection.

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| Organism (LoD*) | LoD showed 97.4 to 100.0% PPA across all detection channels.

All 50 negative samples gave negative results for all channels. A single false positive result (1/250, 0.4%) was seen in the parapsilosis channel with C. krusei.

	Table 14. Contrived Specimen Performance by Detection Channel

| Detection

Channel	PPA	95 %CI	NPA	95%CI
A/T	94/100 (94.0%)	87.5-97.2	200/200 (100.0%)	98.1-100.0
P	47/50 (94.0%)	83.8-97.9	249/250 (99.6%)	97.8-99.9
K/G	88/100 (88.0%)	80.2-93.0	200/200 (100.0%)	98.1-100.0

Abbreviations: PPA, Positive percent agreement; NPA, Negative percent agreement; A/T, C. albicans/C. tropicalis channel; P, C. parapsilosis channel; K/G, C. krusei, C. glabrata channel

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| Detection
Channel | LoD included a portion of the samples spiked at 1-10 CFUmL (depending on the LoD of the species) and all samples spiked at 11-30 CFU/mL and 31-100 CFU/mL).

°The calculations of PPA at False Positives. The T2Candida Panel indicated 31 positive detections in 29 patient specimens for which Candida was not detected in corresponding blood cultures. A chart and case history review was conducted for those patients. This review revealed that one sample was obtained from a patient who had proven intra-abdominal candidiasis with no positive blood cultures. In addition, six patients were receiving anti-fungal therapy and four patients were colonized with Candida species. Repeat testing of 26 of the 29 false positive specimens using a specimen drawn at the same time as the original specimen were negative for Candida by the T2Candida assay. Three specimens were unavailable for retesting.

Other clinical supportive data (when a. and b. are not applicable): C. Not Applicable
1. Clinical cut-off:

5. Expected values/Reference range:

The overall incidence of Candida species as determined by the T2Candida Panel and T2Dx® Instrument in direct blood specimens in patients tested during this study was 0.3% (4/1501). All clinical specimens collected during this study were collected between August, 2013 and October 2013 and April 2014.

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M. Instrument Name:

T2Candida Panel and T2Dx® Instrument

N. System Descriptions:

1. Modes of Operation:
  The system operates in a fully automated mode with limited user intervention. Reagent packs, samples and cartridges are loading manually but all processing and analysis steps are controlled and monitored by the system.

2. Software:

FDA has reviewed applicant's Hazard Analysis and software development processes for this line of product types:

Yes X or No ______________________________________________________________________________________________________________________________________________________________

Level of Concern: Moderate

Software Description:

The T2Dx instrument software controls the following:

T2Dx instrument interactions with peripheral devices and systems (e.g. printer, ● barcode reader, portable memory device, service laptop computer and LIS system)
T2Dx® instrument system diagnostics, including alarms and error notifications ●
. T2Dx® instrument graphical user interface. including touch screen prompts that guide an operator through the steps associated with loading and unloading test cartridges/patient specimens on the T2Dx® instrument and obtaining test results
T2Dx internal operating temperatures
Operating parameters (e.g. time, temperature, etc.) of various T2Dx instrument . subsystems.
Initiation of workflows, scheduling of specimens for processing and monitoring ● of workflow implementation
Determination of the result
Administrative functions (e.g. Require Operator ID, Positive Sample Counter, . Archive Results, Shutdown OS, and Restart Application)

This T2Dx® instrument software is designed and intended to interface with the T2Candida workflow software.

Device Hazard Analysis:

A list of potential hazards was developed by conducting a bottom up analysis of potential failure modes. Potential failure modes were identified including those which could lead

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to invalid or incorrect results. The RPN value for these potential hazards exceeded the threshold, which triggered a mitigation action. As a result, solutions were implemented to verify that risks were reduced.

Architecture Design Chart:

The T2Dx instrument software and T2Candida workflow software architecture design chart was provided along with a summary of software architecture illustrations and references to description of each illustration.

Software Requirements Specification (SRS):

The software requirements for T2Dx® instrument and the T2Candida panel were based on discussions with potential users, site visits, and a review of current, similar diagnostic systems. The Software Requirements Specifications (SRS) were developed using these findings.

Software Design Specification (SDS):

Requirements defined in the SRS document are implemented according to the design specifications described.

Traceability Analysis:

A traceability matrix which links requirements, specifications, hazards, mitigations and verification & validation testing for the software was acceptable.

Software Development Environment Description:

Software development life cycle plan and software development configuration management plan for the T2Dx® instrument software and the T2Candida workflow software was acceptable.

Verification and Validation Testing:

Based on the Software Requirements Specification ("SRS") and Software Design Specifications ("SDS"), software verification test plans were devised to verify that the software meets the requirements. Each element of the SRS was tested and found to meet the requirements. This was accomplished via a series of system, software integration, and code inspection activities:

Unit level code inspection performed by an independent reviewer and associated ● unit/integration level automated or manual functional testing of code
Module level (integrated software and hardware) functional testing ●
System level performance verification
. System level validation

Revision Level History:

A software revision history record for the T2Dx® instrument software and T2Candida

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workflow software was acceptable.

Unresolved Anomalies:

The T2Dx software release version 1.0.0.9 contains three unresolved anomalies. Impact analysis of these unresolved anomalies on device safety or effectiveness was acceptable.

EMC Testing:

The electrical safety of the T2Dx Instrument has been verified in accordance with the following standards:

Safety requirements for electrical equipment for measurement, control, and laboratory use (Safety).

. IEC 61010-1:2001 (Second Edition): Safety requirements for electrical equipment for measurement, control, and laboratory use - Part 1: General requirements
IEC 61010-2-010: 2003 (2nd Ed): 100562844BOX-004: Safety requirements for ● electrical equipment for measurement, control, and laboratory use - Part 2-010: Particular requirements for laboratory equipment for the heating of materials
IEC 61010- 2 - 081: 2001 (1st Edition) + A1:2003 : Safety requirements for electrical equipment for measurement, control, and laboratory use - Part 2-081: Particular requirements for automatic and semi-automatic laboratory equipment for analysis and other purposes
IEC 61010-2-101: 2002 (ed.1): Safety requirements for electrical equipment for . measurement, control and laboratory use - Part 2-101: Particular requirements for in vitro diagnostic (IVD) medical equipment

Electromagnetic Compatibility (EMC)

IEC 61326-1:2005: Electrical equipment for measurement, control and laboratory ● use, control and laboratory use - EMC requirements - Part 1: General requirements
IEC 61326-2-6:2005: Electrical equipment for measurement, control and ● laboratory use - EMC requirements - Part 2-6: Particular requirements - In vitro diagnostic (IVD) medical equipment
1. Specimen Identification:

The T2Dx® instrument interfaces with a handheld digital imager scanner. The barcode reader can be used to identify:

the type of assay;
assay component lot numbers; ●
the specimen being analyzed; ●
the T2Dx® instrument operator, if the operator uses barcode identification. ●
1. Specimen Sampling and Handling:

Blood should be collected in K2EDTA vacutainer tubes; the minimum volume for testing is 3 mL. Specimens should be tested as soon as possible after collection and should be

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held at room temperature (15 - 25°C) for no longer than 12 hours or for up to one day at 2 - 8° C. Holding specimens longer than one day at 2 - 8° C may result in a decrease of viable organisms in the specimen. Blood specimens should be at room temperature at the time of testing and should be inverted a minimum of 8-10 times to ensure sample homogeneity. Samples that are not visually homogenous should not be tested. The vacutainer tubes are uncapped and placed on the T2Candida Sample Inlet. The specimen and sample inlet are inserted into the instrument.

1. Calibration:
  Calibration routines are performed automatically and require no user intervention
1. Quality Control:
  Users are recommended to follow all laboratory procedures, local, state, and/or federal requirements and accrediting organizations guidelines for the testing of all external positive and negative control materials regardless of source.

The following recommendations are provided which relate to external quality control testing at least once per month:

A single POSITIVE (APG or TPK) control tube of either multiplex blend and a ● single NEGATIVE control tube from the T2Candida External Controls kit is run at least once every 30 days in order to verify the continuing performance of the T2Dx® instrument and the T2Candida panel reagents. Users should alternate the multiplex blend POSITIVE control tube with each OC check.
. A POSITIVE APG, a POSITIVE TPK control tube and a NEGATIVE control tube from the T2Candida External Controls kit should be run when either of the following events occurs
- o A new reagent lot is received into the laboratory
- o Significant maintenance (including software upgrades) to the T2Dx Instrument
. A single NEGATIVE control tube from the T2Candida External Controls kit should be run upon completion of the T2Dx® instrument decontamination procedure.

O. Other Supportive Instrument Performance Characteristics Data Not Covered In The "Performance Characteristics" Section above:

Not Applicable

P. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Parts 801 and 809 and the specials controls.

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Q. Identified Risks and Required Mitigations:

Identified Risks	Required Mitigations
Incorrect identification of a pathogenic microorganism by the device can lead to improper patient management	Special Controls (1), (2), (3), (4), (5)
Failure to correctly interpret test results	Special Control (6)
Failure to correctly operate the instrument	Special Controls (7) and (8)

R. Benefit/Risk Analysis:

| Summary of
the Benefit(s) | The primary benefit provided by the T2Candida Panel and T2Dx® Instrument is the
earlier diagnosis of candidemia and early initiation of appropriate antifungal treatment.
Symptoms of candidemia may be nonspecific, and difficult to differentiate from other
infectious causes of disease. Early diagnosis of candidemia may be associated with
decreased morbidity and mortality for some patients. Additionally, negative testing
may provide additional clinician confidence when delaying empiric therapy or
discontinuing empiric antifungal therapy. Patients may experience fewer side effects
from antifungal therapy, and there may be additional benefits to antimicrobial
stewardship programs |

------------------------------

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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| Summary of
the Risk(s) | False positive and false negative results resulting from incorrect identification of a
pathogenic organism by the device, failure to correctly interpret test results, or failure
to correctly operate the instrument are the primary risks associated with use of the
T2Candida Panel and T2Dx® Instrument.

A false positive result may result in unnecessary antifungal therapy, with associated
toxicities and side effects, including potential allergic reaction. Additionally, patients
may undergo unnecessary imaging studies to identify potential organ system
involvement or have alternative testing delayed due to a presumptive diagnosis of
candidemia. Because established treatment guidelines also recommend indwelling
central line removal for certain Candida infections, unnecessary line removal could
occur as a result of a false positive result. These side effects from antifungal therapy
are generally reversible, and additional laboratory testing is often ordered
simultaneously with evaluation for Candida . Unnecessary imaging increases potential
radiation exposure, but many critically ill patients may obtain these scans as part of
their evaluation.

False negative results could result in delayed diagnosis of candidemia, or delayed
initiation of empiric antifungal therapy. An incorrect identification could result in
inappropriate anti-fungal therapy. As a result, the patient could experience a delay in
effective anti-fungal therapy. However, these risks can be mitigated through
appropriate labelling and do not exceed the current standard of care when used with
traditional blood culture. |
|----------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Summary of
Other Factors | None |
| Conclusions
Do the
probable
benefits
outweigh the
probable risks? | The anticipated probable benefits of the T2Candida Panel and T2Dx® Instrument
likely outweigh the anticipated potential risks in light of the special controls and the
applicable general controls. The T2Candida panel is the first of its kind, and represents
a potential for patient benefit through more rapid diagnosis of candidemia. Potential
risks associated with false positive or false negative results may be mitigated by use of
traditional blood cultures, which would be necessary to recover the organism for
further identification and susceptibility testing even without the T2Candida panel.

Data obtained from additional studies with contrived specimens demonstrated high
sensitivity. However, the prospective clinical study found that the sensitivity for C. albicans , the most prevalent species of Candida , is low, but given the small number of
positive prospective samples (4), it is difficult to determine how the T2 will perform in
real-world use. |

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S. Conclusion:

The information provided in this de novo submission is sufficient to classify this device into class II under regulation 21 CFR 866.3960. FDA believes that special controls, along with the applicable general controls, provide reasonable assurance of the safety and effectiveness of the device type. The device is classified under the following:

Product Code:	PII, NSU
Device Type:	Nucleic acid-based device for the amplification, detection and
identification of microbial pathogens directly from whole blood
specimens.
Class:	II (special controls)
Regulation:	21 CFR 866.3960

(a) Identification. A nucleic acid-based device for the amplification, detection and identification of microbial pathogens directly from whole blood specimens is a qualitative in vitro device intended for the amplification, detection, and identification of microbial-associated nucleic acid sequences from patients with suspected bloodstream infections. This device is intended to aid in the diagnosis of bloodstream infection when used in conjunction with clinical signs and symptoms and other laboratory findings.
(b) Classification. Class II (special controls). A nucleic acid-based device for the amplification, detection and identification of microbial pathogens directly from whole blood specimens must comply with the following special controls:
1. Premarket notification submissions must include detailed device description documentation, including the device components, ancillary reagents required but not provided, and a detailed explanation of the methodology, including primer/probe sequence, design, and rationale for sequence selection.
1. Premarket notification submissions must include detailed documentation from the following analytical and clinical performance studies: Analytical sensitivity (Limit of Detection), reactivity, inclusivity, precision, reproducibility, interference, cross reactivity, carry-over, and cross contamination.
1. Premarket notification submissions must include detailed documentation from a clinical study. The study, performed on a study population consistent with the intended use population, must compare the device performance to results obtained from well-accepted reference methods.

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1. Premarket notification submissions must include detailed documentation for device software, including, but not limited to, software applications and hardware-based devices that incorporate software.
1. The device labeling must include limitations regarding the need for culture confirmation of negative specimens, as appropriate.
1. A detailed explanation of the interpretation of results and acceptance criteria must be included in the device's 21 CFR 809.10(b)(9) compliant labeling.
1. Premarket notification submissions must include details on an end user device training program that will be offered while marketing the device, as appropriate.
1. As part of the risk management activities performed as part of your 21 CFR 820.30 design controls, you must document an appropriate end user device training program that will be offered as part of your efforts to mitigate the risk of failure to correctly operate the instrument.

Intended Use / Indications for Use

Product codes (comma separated list FDA assigned to the subject device)

Device Description

Mentions image processing

Mentions AI, DNN, or ML

Input Imaging Modality

Anatomical Site

Indicated Patient Age Range

Intended User / Care Setting

Description of the training set, sample size, data source, and annotation protocol

Description of the test set, sample size, data source, and annotation protocol

Summary of Performance Studies (study type, sample size, AUC, MRMC, standalone performance, key results)

Key Metrics (Sensitivity, Specificity, PPV, NPV, etc.)

Predicate Device(s): If the device was cleared using the 510(k) pathway, identify the Predicate Device(s) K/DEN number used to claim substantial equivalence and list them here in a comma separated list exactly as they appear in the text. List the primary predicate first in the list.

Reference Device(s): Identify the Reference Device(s) K/DEN number and list them here in a comma separated list exactly as they appear in the text.

Predetermined Change Control Plan (PCCP) - All Relevant Information for the subject device only (e.g. presence / absence, what scope was granted / cleared under the PCCP, any restrictions, etc).

§ 866.3960 Nucleic acid-based device for the amplification, detection, and identification of microbial pathogens directly from whole blood specimens.

EVALUATION OF AUTOMATIC CLASS III DESIGNATION FOR T2Candida Panel and T2Dx® Instrument

DECISION SUMMARY

A. DEN Number:

B. Purpose for Submission:

C. Measurands:

D. Type of Test:

E. Applicant:

F. Proprietary and Established Names:

G. Regulatory Information:

H. Intended Use:

I. Device Description:

J. Standard/Guidance Document Referenced (if applicable):

K. Test Principle:

L. Performance Characteristics:

1. Analytical performance:

a. Precision/Reproducibility

Table 1. Summary of Reproducibility Results Across Sites, Reagents and Operators

d. Detection Limit:

3. Clinical Studies:

Table 19. Cut-off values for Candida and IC Channels

5. Expected values/Reference range:

M. Instrument Name:

N. System Descriptions:

2. Software:

Software Description:

Device Hazard Analysis:

Architecture Design Chart:

Software Requirements Specification (SRS):

Software Design Specification (SDS):

Traceability Analysis:

Software Development Environment Description:

Verification and Validation Testing:

Revision Level History:

Unresolved Anomalies:

EMC Testing:

O. Other Supportive Instrument Performance Characteristics Data Not Covered In The "Performance Characteristics" Section above:

P. Proposed Labeling:

Q. Identified Risks and Required Mitigations:

R. Benefit/Risk Analysis:

S. Conclusion: