Exploration of the GARD® applicability domain – Sensitization assessment of UVCBs

U. I. Torstensdotter Mattson, C. Humfrey, O. Larne, H. Johansson, L. Sweet SenzaGen, Lund, Sweden, Lubrizol, Derbyshire, United Kingdom, Lubrizol, Ohio, United States of America Introduction The GARD – Genomic Allergen Rapid Detection – platform is a state of the art in vitro assay for assessment of chemical sensitizers. The GARD®skin assay is a powerful […]

U. I. Torstensdotter Mattson, C. Humfrey, O. Larne, H. Johansson, L. Sweet
SenzaGen, Lund, Sweden, Lubrizol, Derbyshire, United Kingdom, Lubrizol, Ohio, United States of America

Introduction
The GARD – Genomic Allergen Rapid Detection – platform is a state of the art in vitro assay for assessment of chemical sensitizers. The GARD®skin assay is a powerful tool for assessment of chemical sensitizers, with a predictive accuracy of 94%. In this study, four UVCB test items, provided by Lubrizol and selected based on existing in vivo data (internal Lubrizol data), were evaluated. Sensitizing hazard was assessed using the GARD®skin assay, and the GARD®potency assay further subcategorized the sensitizers into strong (1A) or weak (1B) sensitizers according to GHS/CLP classification. Here we show the importance of using appropriate vehicles in order to predict a correct classification of Test items.

 

Conclusion
A UVCB Test item with poor water and DMSO solubility was assessed using a mixture of vehicles with different polarity indexes (DMF and Glycerol 1:1). This experimental vehicle mixture classified the UVCB as a skin sensitizer, being consistent with the in vivo data. This case study demonstrates the broadening of the applicability domain of the GARD -assay when assessing UVCBs.

Poster dowload

The Validation of GARD®skin

Sandberg P, 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. […]

Sandberg P, 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 (GARD®skin) is an in vitro assay addressing this need. Here, we present the results of the GARD®skin ring trial (OECD TGP 4.106) for validity of the assay. In addition, we show data for GARD®potency – a complementary assay developed to categorize identified senitizers as CLP 1A or 1B.

 

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.
In addition, we show that GARDpotency accurately assesses potency of identified sensitizers.

Poster download

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

Objective GARD – Genomic Allergen Rapid Detection – is a state of the art non-animal based technology platform for classification of skin sensitizing chemicals. The assay has proven to be reliable and highly accurate for identification of skin sensitizing chemicals, and consistently reports predictive performances > 90% across external test sets. The aim of the […]

Objective
GARD – Genomic Allergen Rapid Detection – is a state of the art non-animal based technology platform for classification of skin sensitizing chemicals. The assay has proven to be reliable and highly accurate for identification of skin sensitizing chemicals, and consistently reports predictive performances > 90% across external test sets. The aim of the current project is to complement assessments of average model performance with an estimate of uncertainty involved in each individual prediction, thus allowing for classification of skin sensitizers with confidence.

Results
An Internal validation procedure was initially performed on samples in the GARD training set (n=38) using the strategy described in Fig. 3A. Results from this exercise is summarized in Fig. 4A. Conformal prediction by definition allows the user to determine a reasonable and acceptable significance level to guarantee a maximum error rate in predictions. The significance level was set to 15%, i.e. the model was allowed to make a maximum of 15% errors. Performance of the conformal predictor was measured by validity and efficiency. A model was valid if the number of prediction errors did not exceed the significance level, while efficiency corresponded to the percentage of single class predictions. Internal validation of the training data resulted in a valid and highly effective model (92% single classifications, 1 empty, 2 both), indicating that the ambitious significance level was at a reasonable level for the GARD® assay. Following internal validation, samples in a large external test set (n =70) was classified within the CP framework as described in Fig. 3B, which resulted in generation of a valid and highly efficient model (99% single classifications, 0 empty, 1 both) (Fig.4B). Additional data on model performance is illustrated in Table 1.

Poster download

The use of GARDskin for sensitization evaluation of cosmetic ingredients and ‘real-life’ mixtures

Renato Ivan de Ávila, Tim Lindbergh, Malin Lindstedt and Marize Campos Valadares Lab. of Education and Research in Pharmacology and Cellular Toxicology, Faculty of Pharmacy, Federal University of Goiás, Goiânia, Goiás, Brazil. Department of Immunotechnology, Medicon Village, Lund University, Lund, Sweden.   Introduction Genomic fingerprints in dendritic cells after chemical exposure is a recent strategy […]

Renato Ivan de Ávila, Tim Lindbergh, Malin Lindstedt and Marize Campos Valadares
Lab. of Education and Research in Pharmacology and Cellular Toxicology, Faculty of Pharmacy, Federal University of Goiás, Goiânia, Goiás, Brazil.
Department of Immunotechnology, Medicon Village, Lund University, Lund, Sweden.

 

Introduction
Genomic fingerprints in dendritic cells after chemical exposure is a recent strategy in in vitro techniques for skin sensitization hazard. Within this perspective, Genomic Allergen Rapid Detection (GARDskinTM), an assay based on a support vector machine (SVM) model, was developed for identifying contact allergens using a myeloid cell line as a surrogate for dendritic cells. Predictive system behind the GARDskin™ consists on the transcriptional quantitative analysis of 200 genes, referred as the GARDskin™ prediction signature. Mechanistically, GARDskin™ is linked to key event 3 “Activation of DCs”, as defined by the Adverse Outcome Pathways for skin sensitization published in 2012 by OECD (https://read.oecd-ilibrary.org/environment/the-adverse-outcome-pathway-for-skin-sensitisation-initiated-by-covalent-binding-to-proteins_9789264221444-en#page1)

 

Resluts
Information declared on the label and lawsone and PDD levels found in ten commercial henna-based hair coloring cosmetics are show in Table 1. Since all products analyzed were declared as henna cosmetics by the manufactures, the presence of LAW, the main active phytochemical of henna, was then expected in all samples. However, HPLC analysis showed no LAW level in the product nº 2, suggesting falsification. Furthermore, the presence of PPD was declared on the products nº 2 and 8 only by the manufactures. However, this substance was detected in all products, suggesting undisclosed adulteration.

Poster:
The use of GARDskin for sensitization evaluation of cosmetic ingredients and ‘real-life’ mixtures

Scientific study shows that GARDskin™ is the most accurate test for skin sensitization of chemical substances

Lund, 31 July 2018 – SenzaGen (Nasdaq First North: SENZA) announces today that a new scientific study shows that GARDskin™ can provide producers and contract laboratories with a single test for evaluating substances, with an increased accuracy as compared with the recommended combination of current market leading methods. The reason for this recommendation by regulatory authorities is the relatively low accuracy of the currently available individual methods. The positive results from the published study shows that GARDskin™ could be established as the first animal-free standalone test and thereby become a new global standard for toxicological evaluation of chemical substances.

There are more and more countries banning animal testing of ingredients and final products within the cosmetics industry. Also other industries are facing a growing demand for accurate animal-free test methods. The primary forces driving this development are stricter regulatory demands and an urge to reduce the use of animals in experimental testing.

A new scientific study confirms that SenzaGen´s test method GARDskin™ is more accurate than the other animal free methods (DPRA, KeratinoSens (ARE-Nrf2 luciferase) and h-CLAT) on the market today, for skin sensitization testing. Due to the relatively low accuracy of these methods, regulatory authorities recommend a combination of them, in order to better predict the skin sensitization activity of a substance. However, not even a combination of these tests show the same high level of accuracy as displayed by GARDskin™.

”This recently published scientific study shows that GARDskin™ can give producers and contract laboratories a possibility to use one single test to evaluate their substances with even better accuracy than a combination of several test methods. GARDskin™ has the potential to make testing of chemicals more efficient with respect to time, resources and quality”, says SenzaGen CEO Anki Malmborg Hager.

The scientific study was carried out by Dr David W Roberts at the School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University in the UK. The results are published in the scientific journal Regulatory Toxicology and Pharmacology and can be accessed via this link :  “Is a combination of assays really needed for non-animal prediction of skin sensitization potential? Performance of the GARD™ (Genomic Allergen Rapid Detection) assay in comparison with OECD guideline assays alone and in combination” 

 

For more information:
Anki Malmborg Hager, CEO, SenzaGen AB
Email: anki.malmborg.hager@senzagen.com
Phone: +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 percent reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75 percent. 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 http://www.senzagen.com.

The information was submitted for publication, through the contact person set out above on the 31 July 2018 at 08.50.

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

Attached file

SenzaGen receives patent protection for GARDskin™ in China

Lund, July 11th 2018 - SenzaGen (Nasdaq First North: SENZA) announces today that the Chinese Patent Office (CPO) has granted a patent for GARDskin™, the company's test that analyses the risk that chemical substances will induce skin allergies. The tests in the GARD™ portfolio outperform all currently available traditional validated methods, while at the same time eliminating the need for laboratory animals, as they are performed in test tubes (in vitro). Taken in conjunction with the recruitment of a Business Development Coordinator for the Asian market, this patent strengthens SenzaGen's future market opportunities in Asia.

The recently granted Chinese patent covers the analytical methods and genetic signatures that form the basis of SenzaGen’s GARDskin™ technology. The patent is valid until October 2031.

“China is a potentially important future market for us, and patent protection in China is another confirmation of our technology’s merits and a new milestone in establishing our unique GARDskin™ test method as a global industry standard. This complements European patent protection and further strengthens our potential in the global market of in vitro tests,” says SenzaGen CEO, Anki Malmborg Hager.

A vital part of SenzaGen’s business development is relations with contract laboratories, industry, government agencies and NGOs concerned with alternative testing methods. The market for in vitro methods is growing rapidly, although experiments on animals are still permitted for allergy tests in some parts of the world. Asia is a huge market and is growing fast, and it is therefore essential for SenzaGen to prepare the way for a future introduction of its tests there.

The announcement from the Chinese Patent Office relates to Chinese Patent No. CN 103429756 B entitled: “Analytical methods and arrays for use in the identification of agents inducing sensitization in human skin”. Corresponding patent applications are currently being processed by the patent authorities in Brazil, Canada, Hong Kong, India, South Korea and the United States. 

For more information, please contact:
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 percent reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75 percent. 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 http://www.senzagen.com.

The information was submitted for publication, through the contact person set out above on July 11th 2018 at 08:50

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

Attached file

SenzaGen’s final validation report for the animal-free allergy test GARDpotency™ has been submitted to the regulatory authorities

Lund, July 9, 2018. SenzaGen (Nasdaq First North: SENZA) announces today that the company has submitted the official validation report for GARDpotency™ to the relevant regulatory authorities as a complement to the validation of GARDskin™. GARDpotency™ is the first animal-free allergy test on the market that can be used to evaluate chemicals according to the EU's CLP classification. Other initiatives to measure potency today, including animal tests, only reach an accuracy of 55%-69%. Therefore, we at SenzaGen are extremely happy to be able to present the final results of the report showing that our test can classify CLP Class 1A and 1B chemical substances, quantifying the risk of causing allergies with an accuracy of 82 percent, as determined by three laboratories. Results from the validation demonstrate that the performance of GARDskin™ together with GARDpotency™ exceeds all currently available validated methods. Worldwide approval and recommendation from ECVAM (the EU Reference Laboratory for Alternatives to Animal Testing) and OECD regarding the use of GARDskin™ and GARDpotency™ are expected in 2019.

GARDpotency™ is based on the same biological platform as GARDskin™ and both tests are expected to be approved and recommended at the same time. Together with GARDpotency™, which complements GARDskin™, SenzaGen’s allergy test will be unique on the market, as it is the only test that offers animal-free tests of chemicals in line with the EU’s CLP classification. The CLP classification follows the Global Harmonized System, GHS, developed by the UN to create common criteria for the classification and labelling of chemicals.

The EU Chemicals Agency ECHA, which regulates chemical use based on the REACH Regulation, requires that chemicals that may induce sensitivity (sensitization) must be potency-classified according to CLP. This has so far only been possible with a so-called LLNA (Local Lymph Node Assay) evaluation, which is an in vivo test using animals. SenzaGen’s GARD™ test platform is based on human cells in vitro and genomic biomarkers, constantly delivering better accuracy than animal tests.

“Potency is extremely difficult to measure. We are therefore very happy to be able to report these results. In view of the impressive validation results for GARDpotency™, we look forward to receiving the authorities’ response regarding GARDskin™ and GARDpotency™ in 2019. As a consequence of these good results, we are planning to communicate sales targets for the coming years during the second half of this year. A positive response would make our allergy test the first animal-free test that can be used for classification in accordance with CLP, the EU’s standard,” says Anki Malmborg Hager, CEO of Senzagen.

The results from the validation report will be presented at forthcoming scientific conferences.

For more information, please contact:
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 percent reliability. This compares with the current predominant test method, experiments on mice, which has an accuracy of 70-75 percent. 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 http://www.senzagen.com.

The information was submitted for publication, through the contact person set out above on the 6 July 2018 at 08:50

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

Attached file

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 […]

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 […]

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 […]

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

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