Genomic Allergen Rapid Detection test

Topic: Sensitisation

Test Method Number:

TM2011-09 (EU)

Short Name of TM:

GARD

Year received:

2011

Responsible Organisation:

EURL ECVAM - European Union

Protocol(s)/SOP(s):

GARDskin Assay Protocol

General Comments:

Please note that the GARDskin Assay Protocol available in the link above is a revised version provided by the test method developer after completion of the ESAC peer review to address comments made by the ESAC.

Method Description

The Genomic Allergen Rapid Detection (GARD) is a transcriptomics-based in vitro assay proposed to assess the skin sensitisation potential/potency of chemicals.

GARD addresses the third key event of the skin sensitisation Adverse Outcome Pathway (activation of dendritic cells), step 5 (biochemical pathways related to skin sensitisation) and step 6 (immune recognition of chemical allergens and maturation of dendritic cells (DCs)).

The test method has two elements: the so-called GARDskin to assess skin sensitisation potential (first submission in October 2011) and GARDpotency to assess skin sensitisation potency (first submission in July 2018).

The Genomic Allergen Rapid Detection (GARD) is a transcriptomics-based in vitro assay proposed to assess the skin sensitisation potential/potency of chemicals.

The test method is based on the nCounter system and measures the expression level of a panel of genes in the human myeloid cell line MUTZ-3 exposed to chemicals. In GARDskin, the expression of a panel of 200 genes (the GARD Prediction Signature, GPS) is used as input to a prediction model based on a Support Vector Machine (SVM) trained with 38 chemicals. This model classifies chemicals as skin sensitising or non-sensitising. The GARDpotency can be considered as second-tier of a testing strategy, following GARDskin. Thus, in GARDpotency, the model sub-categorises sensitisers into GHS/CLP categories 1A (strong/extreme sensitisers) or 1B (weak/moderate sensitisers) based on the expression of a panel of 52 genes (the GARD Potency Prediction Signature, GPPS).

Track Approval Status

Submission
Validation
Peer-review
Recommendation
Regulatory acceptance/Standards

Submission

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Date	Stage	Comment
Oct 2011	Receipt of presubmission	Presubmission (TPF) of GARD (for discriminating sensitisers from non-sensitisers; later called GARDskin) received.
Nov 2011	Assessment of presubmission	Submitter notified of GARD presubmission assessment outcome and invited to send a full submission.
May 2013	Receipt of full submission	Full submission (TST) of GARD (for discriminating sensitisers from non-sensitisers; later called GARDskin) received.
Dec 2013	Assessment of full submission	Submitter notified of full submission assessment outcome and invited to submit a revised full submission.
Jan 2015	Receipt of revised full submission	Revised full submission (TST) of GARD (for discriminating sensitisers from non-sensitisers; later called GARDskin) received.
Sep 2015	Assessment of revised full submission	Formal assessment of revised GARD full test submission was conducted by EURL ECVAM. Submitter informed of the intention of not progressing the test submission further at this stage. Response from the submitter to EURL ECVAM's comments were received on 07/10/2015 and discussed by teleconference 20/11/2015. The submitter decided to conduct an external validation study of the GARD.
Jan 2018	Receipt of revised full submission	A second revised full submission of the now called GARDskin was received, following an externally-conducted prospective validation study. Following an initial screen of the submission, EURL ECVAM requested on 24/01/2018 the submission of the results of the validation study in Excel format. Excel files were received on 29/05/2018 and 12/06/2018. Knowing of the intention of the submitter to provide both the GARDskin and GARDpotency for assessment, EURL ECVAM informed the submitter that the GARD would not undergo two separate assessments and peer-reviews on the skin and potency elements and that, therefore, EURL ECVAM could not formally commence an evaluation until a complete dossier had been received.
Jul 2018	Assessment of revised full submission	During the period April-July 2018, EURL ECVAM nevertheless carried out a preliminary assessment of the GARDskin. All replies provided by the test submitter to comments made by EURL ECVAM were assessed and the outcome communicated to the submitter (see below).
Jul 2018	Receipt of full submission	Full submission of GARDpotency was received.
Oct 2018	Stopped	There are a number of challenging scientific, technical and legal aspects that require particular attention before proper evaluation of GARD can commence. These are as follows: 1) a suitable agreement needs to be put in place and appropriate arrangements made to provide EURL ECVAM access to the web-based GARD Data Analysis Application (GDAA) software hosting the data analysis and the Support Vector Machine-based prediction model, and its source codes; 2) it is unclear if a web-based prediction software (to process a user's experimental data) that is under the control of the method provider would be acceptable to regulatory authorities and implementable under Good Laboratory Practice (GLP); and finally, 3) elements of the GARD method are protected by patent which may impede the development and validation of similar methods. Most of the issues described above require resolution at the level of the OECD, and the JRC (EURL ECVAM) is actively involved in the relevant discussions and expert groups. In addition, good progress is being made within the OECD project to develop a set of three Defined Approaches for skin sensitisation into a new Test Guideline, two of which address potency-based classification. EURL ECVAM will wait for the eventual outcome of the discussions at the OECD before taking a decision on whether to commence evaluation of the GARD.
Aug 2019	Receipt of revised full submission	In December 2018, the test submitter notified EURL ECVAM that a number of inaccuracies were found in the GARD potency test submission. A revised full submission was received in August 2019, while the assessment of the GARD by EURL ECVAM was on hold.
Dec 2019	Assessment of revised full submission	The scientific, technical and legal aspects described above have been or are currently being addressed as follows: 1) a Non-Disclosure Agreement is being put in place between the JRC and the method developer; 2) Discussions on the implementation of GARD in a GLP environment are ongoing at OECD level; 3) IPR issues will be considered under the terms of the recently published OECD Guidance Document No. 298 on the "Guiding Principles on Good Practices for the Availability/Distribution of Protected Elements in OECD Test Guidelines". On the basis of the above, EURL ECVAM decided to reinitiate the evaluation of the GARD. EURL ECVAM is mandating its Scientific Advisory Committee (ESAC) to develop the evalution framework for the GARD, considering all the novel elements it is bringing to the field of regulatory toxicology (e.g. use of toxicogenomics data and complex algorithms).
May 2020	Assessment finalised	A formal assessment of the revised test submission was conducted by EURL ECVAM. The decision to proceed with peer review by the EURL ECVAM Scientific Advisory Committee (ESAC) was communicated to the test submitter in April 2020.

Validation

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Date	Stage	Comment	Documents/Links
Jul 2018	Finalised	Validation study was performed externally and not coordinated by EURL ECVAM. See Submission step.

Peer-review

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Date	Stage	Comment	Documents/Links
Jun 2020	Ongoing	First meeting of the ESAC Working Group on the GARD
Sep 2020	Ongoing	Second meeting of the ESAC Working Group on the GARD to discuss with the test submitter specific aspects of the GARD submission and to clarify what additional information the Working Group needed to conduct a proper scientific assessment of the GARD prediction model.
May 2021	Ongoing	The ESAC Working Group on the GARD met another 16 times between September 2020 and May 2021 to discuss additional information provided by the test submitter and to complete their peer review of the GARDskin and GARDpotency test methods. Due to the situation with the COVID-19 pandemic and the impossibility of organising face-to-face meetings, all 18 ESAC Working Group meetings had to be organised virtually.
Jul 2021	Finalised	ESAC Opinion on the Scientific Validity of the GARDskin and GARDpotency Test Methods endorsed by the ESAC by written procedure on 8th July 2021.	ESAC Opinion on the Scientific Validity of the GARDskin and GARDpotency Test Methods GARD peer review documents

Recommendation

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Date	Stage	Comment	Documents/Links
Jul 2021	Not applicable

Regulatory acceptance/Standards

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Date	Stage	Comment	Documents/Links
Apr 2016	Drafting of new regulatory standard/guideline	Project approved by the OECD Working Group of the National Coordinators of the Test Guidelines Programme (WNT) and included in the OECD TGP Work Plan in 2016. Validation studies of GARDskin and GARDpotency conducted between 2017 and 2019 and followed by the OECD expert group on skin sensitisation. Outcome of validation studies evaluated by EURL ECVAM (see Submission step) and peer reviewed by the ESAC (see Peer-review step).