The Validation of GARDskin

Johansson A, Agemark M, Gradin R, Larne O, Appelgren H, Forreryd A, Jerre A, Edwards A, Hoepflinger V, Burleson F, Gehrke H, Roggen E, Johansson H
SenzaGen, Lund, Sweden, Burleson Research Technologies, Morrisville, US, Eurofins, Munich, Germany

Introduction
The prevalence of allergic contact dermatitis (ACD) is estimated to >20% in the western world. Not only the individual is affected, but downstream socioeconomic effects are high. To minimize exposure, chemicals must be safety tested. Traditional testing strategies like the murine local lymph node assay (LLNA) comprise animals, but the regulatory authorities, public opinion and economic interests require animal-free models. The Genomic Allergen Rapid Detection skin (GARDskin) is an in vitro assay addressing this need. Here, we present the results of the GARDskin ring trial (OECD TGP 4.106) for validity of the assay.

Conclusions
Transfer study
Transferability: 100%

Validation study
Reproducibility:
WLR: 82 – 89%BLR: 92% (92 – 100%)

Test performance
Accuracy: 94%Sensitivity: 93%Specificity: 96%

A blinded ring trial was performed to assess the functionality of the GARDskin assay. The data demonstrates that GARDskin is a powerful tool for assessment of chemical skin sensitizers, with a predictive accuracy of 94% and excellent reproducibility between laboratories.

Poster

Conclusive data on predictive performance of GARD™ in highly regarded scientific journal

SenzaGen announces today that research on the conformal prediction of the GARD™ assay has been published in the distinguished peer reviewed journal Toxicology in Vitro. The research presented in the publication proves that, as the first in vitro model for prediction of the skin sensitizing potential of chemicals, GARD™ is now capable of providing a statistically valid measure of uncertainty for each individual prediction, thus allowing for classification of skin sensitizers with confidence. Consequently, GARD™ can meet the growing needs of high safety skin sensitization testing and particularly since there is now proof that all chemical reactivity domains, as well as pre- and pro-haptens are within GARD’s applicability domain. 

In the publication, Predicting skin sensitizers with confidence — Using conformal prediction to determine applicability domain of GARD™, a research group from Lund University, Swetox and SenzaGen reports its successful work on implementing a mathematical framework based on conformal prediction into GARD™ for the purpose of defining the applicability domain of the assay, something often neglected by test developers. Investigation of historical data within the framework demonstrates that all hitherto tested chemical reactivity domains, as well as pre- and pro-haptens are within the applicability domain of GARD, and can be predicted with a high degree of confidence. The results of this research demonstrate that the multivariate genomic biomarker signature, the unique technology of GARD makes it applicable across various chemical reactivity domains.

The mathematical framework in this implementation defines the applicability domain in terms of similarity to the samples used for model development and is capable of providing a statistically valid measure of uncertainty associated with each prediction. Furthermore, it also delivers a warning if a specific test sample is outside the region where the model is capable of generating a reliable prediction. Similar to the field of QSAR modelling, this information should be a minimal requirement for a successful validation also of in vitro models.

As the first in vitro model for prediction of skin sensitizing potential of chemicals, GARD™ is now capable of providing a statistically valid measure of uncertainty for each individual prediction, thus allowing for classification of skin sensitizers with even higher confidence. These scientific findings will benefit the chemical industry by providing better guidance of what test to use for different substances in different chemical domains and demonstrates the even broader applicability of GARD.

Full article:  Predicting skin sensitizers with confidence — Using conformal prediction to determine applicability domain of GARD Forreryd A., Norinder U., Lindberg T., Lindstedt M.  
https://www.sciencedirect.com/science/article/pii/S0887233318300237?via%3Dihub


For more information:
Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Telephone: +46 768 284822

 

About GARD™
GARD is a group of tests for assessing chemical skin sensitizers. The tests make use of genetic biomarkers for more than 200 genes which cover the entire immune reaction and are relevant to predicting the risk of hypersensitivity. The tests have over 90% reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75%. SenzaGen’s tests are also capable of measuring the potency of a substance’s allergenic properties. Consequently, GARD tests provide a much more comprehensive basis for determining whether a substance should be classified as an allergen than current testing methods.

About SenzaGen
SenzaGen makes it possible to replace animal experiments with in vitro genetic testing to determine the allergenicity of the chemicals we come into contact with in our daily lives, such as for example in cosmetics, pharmaceuticals, food products and dyes. The company’s patented tests are the most reliable on the market and provide more information than traditional evaluation methods. We ourselves sell the tests in Sweden and the USA, and we sell through partners in several other countries. Over the next few years the company will expand geographically, make alliances with more distribution partners and launch further unique tests. SenzaGen has its headquarters in Lund in Sweden and a subsidiary in San Francisco, USA. For more information visit www.senzagen.com

News post as pdf

Predicting skin sensitizers with confidence – Using conformal prediction to determine applicability domain of GARD

Toxicol In Vitro.  Jan 30 2018,  [Epub ahead of print];48:179-187. doi: 10.1016/j.tiv.2018.01.021.

Andy Forreryd, Ulf Norinder, Tim Lindberg, Malin Lindstedt.

Abstract

GARD – Genomic Allergen Rapid Detection is a cell based alternative to animal testing for identification of skin sensitizers. The assay is based on a biomarker signature comprising 200 genes measured in an in vitro model of dendritic cells following chemical stimulations, and consistently reports predictive performances ~90% for classification of external test sets. Within the field of in vitro skin sensitization testing, definition of applicability domain is often neglected by test developers, and assays are often considered applicable across the entire chemical space. This study complements previous assessments of model performance with an estimate of confidence in individual classifications, as well as a statistically valid determination of the applicability domain for the GARD assay. Conformal prediction was implemented into current GARD protocols, and a large external test dataset (n = 70) was classified at a confidence level of 85%, to generate a valid model with a balanced accuracy of 88%, with none of the tested chemical reactivity domains identified as outside the applicability domain of the assay. In conclusion, results presented in this study complement previously reported predictive performances of GARD with a statistically valid assessment of uncertainty in each individual prediction, thus allowing for classification of skin sensitizers with confidence.

KEYWORDS:
Applicability domain; Conformal prediction; GARD; In vitro assay; Skin sensitization

PMID: 29374571     DOI: 10.1016/j.tiv.2018.01.021

Article on line

SenzaGen signs its first global licensing agreement with Eurofins BioPharma Product Testing Munich

Lund, 15 February, 2018 – SenzaGen (Nasdaq First North: SENZA) announces today that the company has signed a global licensing agreement with the leading contract research organization Eurofins BioPharma Product Testing Munich (Eurofins BPT Munich), to market the GARD™ test to its clients. GARD™ is a genome-based test, with higher accuracy than other available test methods that gives the customers important safety information whether chemical substances are at risk of causing allergies in humans.

Eurofins BioPharma Product Testing is the largest network of harmonized bio/pharmaceutical GMP/GLP product testing laboratories worldwide with 30 facilities all over the world, providing comprehensive laboratory services for the world’s major pharmaceutical, biopharmaceutical and medical device companies. The Munich subsidiary of Eurofins BioPharma Product Testing was part of the successful ring trial in the validation of GARDskin™, which was completed in the autumn of 2017.

Under the terms of the agreement, Eurofins BPT Munich will immediately include GARDskin™ and the add on test GARDpotency™ as a leading diagnostic tool in its chemical safety testing services to clients in the cosmetic, chemical and pharmaceutical industries worldwide.

“This new license agreement with such a major and strong partner provides an important stepping stone in the global marketing of GARD and it is also a hallmark of the high quality and relevance of GARD. We are very pleased to sign this important deal, in particular since Eurofins BPT Munich is a leading player in chemical safety testing, with a pronounced mission to contribute to global health and safety,” says SenzaGen’s CEO Anki Malmborg Hager.

GARDskin has the potential to meet the increasing demands in the cosmetics, chemicals and pharmaceutical industries for reliable, animal-free testing methods to assess the allergy-inducing properties of chemical substances. The test is in the process of obtaining regulatory approval and inclusion in international test guidelines.

 

For more information:
Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Telephone: +46 768 284822

 

About Eurofins BioPharma Product Testing, Munich
Eurofins BPT Munich is part of the world’s largest network of biopharmaceutical GMP/GLP testing laboratories. With more than 30 years of experience Eurofins BPT Munich provides a comprehensive testing portfolio to its clients in the fields of biopharma product testing, medical device testing and human safety testing.

Eurofins BPT Munich is a leader in in vitro and ex vivo safety testing. By offering its clients a comprehensive set of alternative in vitro and ex vivo test methods Eurofins BPT Munich provides the full service toxicological evaluation under GLP.

Eurofins BPT Munich offers clients the flexibility to choose from its fee-for-service, FTE, and the award-winning Professional Scientific Services® (PSS) service models in order to meet clients’ specific project needs.
For more information please visit:     www.eurofins.com/human-safety-testing

 

About GARD
GARD is a group of tests for assessing chemical skin sensitizers. The tests make use of genetic biomarkers for more than 200 genes which cover the entire immune reaction and are relevant to predicting the risk of hypersensitivity. The tests have up to 90% reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75%. SenzaGen’s tests are also capable of measuring the potency of a substance’s allergenic properties. Consequently, GARD tests provide a much more comprehensive basis for determining whether a substance should be classified as an allergen than current testing methods.

About SenzaGen
SenzaGen makes it possible to replace animal experiments with in vitro genetic testing to determine the allergenicity of the chemicals we come into contact with in our daily lives, such as for example in cosmetics, pharmaceuticals, food products and dyes. The company’s patented tests are the most reliable on the market and provide more information than traditional evaluation methods. We ourselves sell the tests in Sweden and the USA, and we sell through partners in several other countries. Over the next few years the company will expand geographically, make alliances with more distribution partners and launch further unique tests. SenzaGen has its headquarters in Lund in Sweden and a subsidiary in San Francisco, USA. For more information visit www.senzagen.com

 

This information is information that SenzaGen is obliged to make public pursuant to the EU Market Abuse Regulation. The information was submitted for publication, through the contact person set out above on the 15 February, 2018 at 10:30.

 SenzaGen AB are listed on Nasdaq First North in Stockholm and FNCA is the company’s Certified Adviser. For more information, please visit www.senzagen.com

 

Press release as pdf

SenzaGen’s final validation report of GARDskin™ submitted to regulatory authorities – reveals highest test prediction accuracy in the field

Lund, January 12, 2018 – SenzaGen (Nasdaq First North: SENZA) announces today that the company has submitted the final report for the validation of GARDskin™ to the regulatory authorities. Global regulatory approval and recommendation by ECVAM and OECD on the use of GARDskin is expected in April 2019. The final result presented in the report shows an unprecedented over all prediction accuracy of 93,8% in determining whether chemical substances are at risk of causing allergies. This proves that GARDskin™ outperforms all current available validated methods.

 

The analysis of the data has been performed by an independent validation statistics consultant, according to the regulatory requirements. This analysis is the base for the official report now sent in to ECVAM. The data shows that the mean accuracy from all three independent laboratories (Eurofins BioPharma Product Testing in Germany, Burleson’s Research Technologies in the United States and SenzaGen’s own laboratory in Lund) is very high, reaching an accuracy of 93,8%.

The validation has included a large number of coded chemicals unknown to the validation laboratories, to enable the blinded testing demanded in this process. All laboratory results have been provided in a blinded manner to an external validating statistics consultant, who has now decoded the identity of the chemicals to compare the GARD classification performed at each lab, and analysed the prediction accuracy of GARD in classifying compounds as non-sensitizers or sensitizers. The validation report also includes data on the robustness of the test platform and its transferability.

The results in this report constitutes the basis for the evaluation of SenzaGen’s tests in the ECVAM Scientific Committee and within the OECD for regulatory approval and Test Guideline recommendation on the use of GARDskin. The regulatory decision from OECD is expected in April 2019. GARDpotency™, which is based on the same biological platform, is being validated in parallel with GARDskin™, and is thus expected to be approved and recommended at the same time.

“These excellent validation results underpin the potential for GARD testing to become a game changer in in vitro allergy testing. We have long been aware of its high performance, and the validation now also provided by independent laboratories is of course very satisfying. Importantly, the validation has highlighted the simplicity of assay transfers to other labs. This adds to the confidence of further laboratories around the world to set up our unique assay,” says Anki Malmborg Hager, CEO of SenzaGen.

A comprehensive report of the results will be presented at the Society of Toxicology’s 57th Annual Meeting 11-15 March in San Antonio, US.

 

For more information:
Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Telephone: +46 768 284822

 

About GARD
GARD is a group of tests for assessing chemical skin sensitizers. The tests make use of genetic biomarkers for more than 200 genes which cover the entire immune reaction and are relevant to predicting the risk of hypersensitivity. The tests have up to 90% reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75%. SenzaGen’s tests are also capable of measuring the potency of a substance’s allergenic properties. Consequently, GARD tests provide a much more comprehensive basis for determining whether a substance should be classified as an allergen than current testing methods.

 

About SenzaGen
SenzaGen makes it possible to replace animal experiments with in vitro genetic testing to determine the allergenicity of the chemicals we come into contact with in our daily lives, such as for example in cosmetics, pharmaceuticals, food products and dyes. The company’s patented tests are the most reliable on the market and provide more information than traditional evaluation methods. We ourselves sell the tests in Sweden and the USA, and we sell through partners in several other countries. Over the next few years the company will expand geographically, make alliances with more distribution partners and launch further unique tests. SenzaGen has its headquarters in Lund in Sweden and a subsidiary in San Francisco, USA. For more information visit www.senzagen.com 

The information was provided by the contact person for publication on 12 January 2018 at 08:45.

SenzaGen AB are listed on Nasdaq First North in Stockholm and FNCA is the company’s Certified Adviser. For more information, please visit www.senzagen.com

SenzaGen reports positive results from ring trial in the validation of GARDskin™

Lund, 14th December 2017 – SenzaGen (Nasdaq First North: SENZA) today reports highly positive results from the final laboratory stage in the validation of GARDskin™. The results form an important part of the evidence in the approval process for the validation by ECVAM and OECD International Regulatory Authorities. In the recently completed evaluation, GARDskin continues to exhibit high accuracy and excellent reproducibility of test results, both within laboratories and between different laboratories. These data suggest that GARDskin outperforms all currently available validated methods.

The comprehensive laboratory evaluation of GARDskin, which is required for final regulatory validation, has produced excellent results. Three independent laboratories (Eurofins BioPharma Product Testing in Germany, Burleson’s Research Technologies in the United States and SenzaGen’s own laboratory in Lund) have carried out blind analyses of a large number of chemicals. The process has been repeated on several different occasions, in accordance with the OECD validation process. The purpose is to validate the transferability, robustness and reproducibility of the test, in order to demonstrate that GARDskin can deliver reliable results with higher accuracy than existing tests, even when used in external laboratories.

The results will be presented in detail at SOT, the International Society of Toxicology Conference, in Texas in March, and subsequently in scientific publications.

“The validation study provides convincing evidence that GARDskin works well even when the test method is used in external laboratories. The results reinforce the scientific basis for GARDskin in the process of obtaining regulatory approval and inclusion in international test guidelines. We are delighted with the outcome which shows that GARD consistently outperforms all existing validated test methods,” says SenzaGen’s CEO, Anki Malmborg Hager.

The results from the completed validation study constitute an important part of the basis for the forthcoming evaluation of SenzaGen’s tests in the ECVAM Scientific Committee and within the OECD. Regulatory approval and recommendation on the use of GARDskin are expected from the OECD in April 2019. GARDpotency™, which is based on the same biological platform, is being validated in parallel with GARDskin, and is thus expected to be approved and recommended at the same time.

GARDskin will have significant potential to meet the increasing demand in the cosmetics, chemicals and pharmaceutical industries for reliable, animal-free testing methods to assess the allergy-inducing properties of chemical substances.

For more information:
Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Telephone: +46 768 284822

About GARD
GARDis a group of tests for assessing chemical skin sensitizers. The tests make use of genetic biomarkers for more than 200 genes which cover the entire immune reaction and are relevant to predicting the risk of hypersensitivity. The tests have up to 90% reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75%. SenzaGen’s tests are also capable of measuring the potency of a substance’s allergenic properties. Consequently, GARD
tests provide a much more comprehensive basis for determining whether a substance should be classified as an allergen than current testing methods.

About SenzaGen
SenzaGen makes it possible to replace animal experiments with in vitro genetic testing to determine the allergenicity of the chemicals we come into contact with in our daily lives, such as for example in cosmetics, pharmaceuticals, food products and dyes. The company’s patented tests are the most reliable on the market and provide more information than traditional evaluation methods. We ourselves sell the tests in Sweden and the USA, and we sell through partners in several other countries. Over the next few years the company will expand geographically, make alliances with more distribution partners and launch further unique tests. SenzaGen has its headquarters in Lund in Sweden and a subsidiary in San Francisco, USA. For more information visit www.senzagen.com

This information is information that SenzaGen is obliged to make public pursuant to the EU Market Abuse Regulation. The information was submitted for publication, through the contact person set out above on the 14 December 2017 at 08:30.

SenzaGen AB are listed on Nasdaq First North in Stockholm and FNCA is the company’s Certified Adviser. For more information, please visit www.senzagen.com

Malin Lindstedt, founder of SenzaGen and GARD, is awarded the NYTÄNKAREN 2017 (INNOVATIVE THINKER 2017) prize by the Swedish foundation Research Without Animal Experiments

SenzaGen’s co-founder, Professor Malin Lindstedt, has been awarded the Nytänkaren 2017 (Innovative Thinker 2017) Prize and SEK 400,000 by the Swedish fundation for Research Without Animal Experiments for her work on the development of animal-free testing methods. The prize was awarded today, 16 October at a ceremony at Research Without Animal Experiments offices in Stockholm.

Professor Malin Lindstedt receives the prize for her successful development of advanced testing methods that can reduce and replace the use of animals in the risk assessment of chemicals and consumer products. Malin Lindstedt works at Lund University’s Department of Immunotechnology, where she has directed the research that lies behind the series of allergy tests based on cell-based gene analysis that are now marketed under the name GARD. Under her direction, a research team started by developing a test for skin allergies. They then went on to develop a test to determine which substances can cause respiratory allergies, and most recently a test that can analyze proteins associated with food allergies.

While working on the development of the technology behind GARD, Malin Lindstedt founded SenzaGen, the company which is now responsible for making this technology available on the global market. The first test to be developed, GARDskin, is already seeing limited use. GARDskin is at the present time undergoing a validation process for inclusion in the OECD Chemical Test Guidelines, which would result in the method achieving its international breakthrough as an eligible method that meets regulatory requirements for the risk assessment of chemicals.

The prize from Research Without Animal Experiments highlights the practicability of using advanced methods to continue to reduce and replace the use of animals in the risk assessment of chemicals and consumer products both inside and outside Sweden. With the NYTÄNKAREN prize and its associated funding, Research Without Animal Experiments wishes particularly to support the research team’s ambitions to continue their development of allergy tests.

 

News about the prize can be viewed on the Research Without Animal  Experiments website:

http://forskautandjurforsok.se/knappar-pa-startsidan/nytankaren-2017/

 

For more information

Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Telephone: +46 768 284822

All laboratory elements completed in the regulatory part of the validation process for SenzaGen’s GARDskin allergy test

Lund, 6th October, 2017. SenzaGen (Nasdaq First North: SENZA) announces today that all laboratory elements in the validation of GARDskin have been completed according to plan. After data processing and statistical analysis, the results will be compiled and reported to the international regulatory authorities ECVAM and OECD. The results of the analysis will also be published in conjunction with the submission of this report.

The purpose of this final step of the validation process is to document reproducibility in the use of GARDskin. Three laboratories (Eurofins in Germany, Burleson’s Research Technologies in the USA and Senzagen’s own laboratory) have independently carried out tests of 28 coded chemicals on three separate occasions, and this work has now been completed.

The validation element for reproducibility follows evaluations demonstrating that GARDskin can be set up in laboratories other than SenzaGen’s own (transferability). The results of these evaluations were published at the European Toxicology Conference EuroTox in Bratislava in September 2017, showing 100% transferability.

“Every step in the validation process brings us closer to our goal of establishing GARD as the new global industry standard for animal-free toxicological testing and as the natural choice for screening new drug candidates to make it possible at an early stage to weed out substances that are harmful and will not be usable as medicines,” says SenzaGen’s CEO, Anki Malmborg Hager.

After all the results from the different stages of the validation process have been compiled and reported, an assessment will take place in the ECVAM Scientific Committee and within the OECD. Regulatory approval and the OECD’s recommendations concerning the use of GARDskin are expected in April 2019. GARDpotency, which is based on the same biological platform, is to be evaluated in parallel with GARDskin, and is thus expected to be approved and recommended at the same time.

 

For more information:
Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Telephone: +46 768 284822

About GARD
GARD is a group of tests for assessing chemical skin sensitizers. The tests make use of genetic biomarkers for more than 200 genes which cover the entire immune reaction and are relevant to predicting the risk of hypersensitivity. The tests have up to 90% reliability.

This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75%. SenzaGen’s tests are also capable of measuring the potency of a substance’s allergenic properties. Consequently, GARD tests provide a much more comprehensive basis for determining whether a substance should be classified as an allergen than current testing methods.

About SenzaGen
SenzaGen makes it possible to replace animal experiments with in vitro genetic testing to determine the allergenicity of the chemicals we come into contact with in our daily lives, such as for example in cosmetics, pharmaceuticals, food products and dyes. The company’s patented tests are the most reliable on the market and provide more information than traditional evaluation methods. We ourselves sell the tests in Sweden and the USA, and we sell through partners in several other countries. Over the next few years the company will expand geographically, make alliances with more distribution partners and launch further unique tests. SenzaGen has its headquarters in Lund in Sweden and a subsidiary in San Francisco, USA. For more information visit www.senzagen.com 

The information was provided by the contact person for publication on October 6 at 11:30.

SenzaGen is presenting at hosted session at the EUROTOX Congress in Bratislava

SenzaGen new Chief Scientific officer Hernik Appelgren will give a presentation on 21st century testing for skin sensitisation and updates on application of the GARD platform at The 53rd  European Congress of the European Societies of Toxicology, EUROTOX, on the 12th of Sept. SenzaGen is also Exhibiting at the congress and presenting two posters

The meeting promises scientific sessions houndreds of abstract presentations, exhibitors meetings, continuing education courses, awards presentations, receptions,  and  an exhibition area for exhibitors offering you the latest information on services and technology
Presentation details
Tuesday 12 Sep 10-11 AM | 
Memories, Hotel Sheraton
21st Century Sensitisation testing: Can one test be stand alone? Regulatory challenges and GARD applications update
.

Presented by: Henrik Appelgren, Chief Scientific Officer and regulatory expert at SenzaGen

Allergy is a growing health problem in humans. The data requirements for the assessment of sensitisation in chemical legislations have been based on animal assays, which until now have served as the golden standard. However, in vitro assays have been developed which need to be combined in order to address all key events for sensitisation to fulfil the demands in e. g., Reach. However, The Genomic Allergen Rapid Detection Skin (GARDskin) assay addresses all the key regulatory questions regarding sensitisation, including potency – How? This session we will give an update on the validation status and the different applications of GARD.

Posters
ID 668 | Session 2 | Board no P-04-02-07 | Monday, Sept 11 from 15:00
Transferability of the GARDskin assay to two independent laboratories.

ID 438 | Session 4 | Board number P-09-02-31 | Tuesday, Sept 12 from 15:00
The GARD platform for potency assessment of skin sensitizing chemicals

Skin Sensitization: Challenging the Conventional Thinking – A Case Against 2 Out of 3 as Integrated Testing Strategy

Toxicological Sciences, Volume 159, Issue 1, 1 September 2017, Pages 3–5, https://doi.org/10.1093/toxsci/kfx115
Published: 27 June 2017

Henrik Johansson,  Robin Gradin

Background

Recent years have seen a surge in development of alternative methods for assessment of skin sensitizers. This has been in order to meet the regulatory and industrial demand for accurate safety assessment without the use of animal experimentation, and to address societal expectations. Today, 3 such assays are formally validated and have achieved OECD Guideline status (EC, 201320142015). However, partly due to insufficient predictive capacity, none of the validated assays have received a recommendation for use as a stand-alone method. In addition, there is a view that accurate hazard identification must be based upon an assessment of several key events in the relevant Adverse Outcome Pathway (AOP).

For these reasons it is proposed that tests are used in combinations, forming so-called Integrated Testing Strategies (ITSs), to address deficiencies in the performance of individual methods and to incorporate end points that reflect several key events in the AOP (Hartung etal., 2013Jaworska and Hoffmann, 2010Rovida etal., 2015). Although such ITSs may be configured in a number of ways, one heavily advocated approach relies on the majority vote of individual assays, often referred to as a 2 out of 3 ITS. That is, the identification of hazard is dependent upon the chemical eliciting a positive response in at least 2 of 3 test methods. This approach is based on the view that this will provide an increased weight of evidence and thereby greater confidence in hazard characterization and risk assessment.

Here, we present arguments opposing the claimed benefits of 2 out of 3 ITSs by examining the theoretical probability propagation of combined outcomes, simulated predictions generated by hypothetical assays, and actual data obtained from recently published literature. We argue that the added value of combining the top-performing assay with other assays with less predictive accuracy is overestimated, if present, and may actually be detrimental.

Link to full article