Tag Archive for: Quantitative potency assessment

Skin Sensitization Potency Assessments of Fragrance Materials using GARDskin Dose-Response

Joint poster with Research Institute for Fragrance Materials (RIFM),
Presented at the 2021 RIFM annual meeting & 2021 ACT annual meeting 

Mihwa Na, Ulrika Mattson, Robin Gradin, Henrik Johansson, Andy Forreryd, Anne Marie Api, Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA., SenzaGen AB, Lund, Sweden

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Conclusion

  • GARDskin Dose-Response closely approximated the potency categories of 9/12 fragrance materials tested.
  • Based on results from this dataset, GARDskin Dose-Response appears useful for potency assessment for weak sensitizers and may constitute a promising strategy for deriving a point of departure for quantitative risk assessments.

Abstract

Several New Approach Methods for hazard identification of skin sensitizers have been developed and incorporated as OECD Test Guidelines. However, the methods for potency assessment are still lacking. GARDskin (OECD TGP 4.106) was initially developed to identify skin sensitizers by monitoring transcriptional patterns of a biomarker signature in a dendritic like cell line.

The predictive capacity of GARDskin has been demonstrated previously, with 95.8% accuracy, 91.7% positive predictive value, and 100.0% negative predictive value (1 false positive, n=24) (Johansson, Gradin et al. 2019). To derive potency information, a strategy based on dose-response measurements in GARDskin, referred to as the GARDskin Dose-Response assay, has recently been proposed. The readout of the assay corresponds to the lowest concentration required to exceed the binary classification threshold in GARDskin. This concentration correlates with local lymph node assay (LLNA) EC3 and human no observed effect level (NOEL) values and linear regression models have been established to exploit these relationships for potency predictions.

In this blinded study, 12 fragrance materials (10 very weak sensitizers and 2 weak sensitizers) were evaluated in GARDskin Dose-Response. Results were evaluated by comparing predicted values to the reference potency categories. Three of the very weak sensitizers were predicted as non-sensitizers by GARDskin Dose-Response. For the remaining nine materials which were predicted as sensitizers, the predicted EC3 and NOEL values closely approximated the reference data for most materials. Based on results from this dataset, GARDskin Dose-Response appears useful for potency assessment for weak sensitizers and may constitute a promising strategy for deriving a point of departure for quantitative risk assessments.

Quantitative Sensitizing Potency Assessment Using GARD™skin Dose-Response

Poster presented at the 2021 World Congress on Alternatives and Animal Use in the Life Sciences

Henrik Johansson, Robin Gradin, Andy Forreryd, Joshua Schmidt
SenzaGen AB, Lund, Sweden. SenzaGen Inc., Raleigh, NC.

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Conclusion

  • As an adaptation from the GARDskin assay, GARDskin Dose-Response is suitable for quantitative skin sensitizing potency assessment of chemicals.
  • The experimental readout, referred to as cDV0, corresponds to the lowest dose required to elicit a positive response in GARDskin. As such, experimental protocols are analogous to the LLNA, in which the cDV0 corresponds to the EC3-value.
  • The cDV0 may be used to directly monitor sensitizing potency, or further used to extrapolate LLNA EC3-values, estimation of Human potency categories, or CLP 1A/1B classifications.

Abstract

Proactive identification and characterization of sensitization hazards are central aspects of risk assessment of chemicals. Current legislations and trends in predictive toxicology advocate a transition from in vivo methods to non-animal alternatives, with a number of methods for hazard assessment of skin sensitizers currently available. However, non-animal methods capable of providing quantitative assessment of sensitizing potency are currently lacking.

The GARDskin assay is a next-generation in vitro assay for hazard assessment of skin sensitizers, currently progressing towards regulatory acceptance. Recently, the GARDskin Dose-Response (DR) testing strategy was introduced, in which test chemicals are evaluated by the GARDskin assay in a titrated range of concentrations, in order to investigate the dose-response relationship between GARDskin classifications and test chemical concentration. As such, it provides a quantitative estimation of sensitizing potency, referred to as cDV0, which corresponds to the least required dose able to generate a positive response in the GARDskin assay. The cDV0 value obtained for a test chemical may be viewed as an analogue to the LLNA EC3 value, based on which further hazard characterization and risk assessment may be performed. Statistically significant correlation between the GARDskin DR cDV0 and the LLNA EC3, as well as with human No Expected Sensitization Induction level (NESIL) estimations has been confirmed, thus enabling direct extrapolation between the different metrics.

Here, we further illustrate how these results can be used on their own to facilitate direct potency-associated ranking of test chemicals. Furthermore, we demonstrate how obtained cDV0 values can be extrapolated to LLNA EC3 values with a 95% confidence interval, thereby also facilitating potency-associated subcategorization of test chemicals according to UN GHS classification criteria. Lastly, we illustrate how results generated with GARDskin DR can be directly incorporated into existing strategies for Quantitative Risk Assessment using an entirely in vitro setup.

Quantitative Sensitizing Potency Assessment Using GARD™skin Dose-Response

Poster presented at SOT 2021

Henrik Johansson, Robin Gradin, Andy Forreryd, Joshua Schmidt
SenzaGen AB, Lund, Sweden. SenzaGen Inc., Raleigh, NC.

Download a copy

 

Conclusion

  • As an adaptation from the GARDskin assay, GARDskin Dose-Response is suitable for quantitative skin sensitizing potency assessment of chemicals.
  • The experimental readout, referred to as cDV0, corresponds to the lowest dose required to elicit a positive response in GARDskin. As such, experimental protocols are analogous to the LLNA, in which the cDV0 corresponds to the EC3-value.
  • The cDV0 may be used to directly monitor sensitizing potency, or further used to extrapolate LLNA EC3-values, estimation of Human potency categories, or CLP 1A/1B classifications.

Abstract

Proactive identification and characterization of sensitization hazards are central aspects of risk assessment of chemicals. Current legislations and trends in predictive toxicology advocate a transition from in vivo methods to non-animal alternatives, with a number of methods for hazard assessment of skin sensitizers currently available. However, non-animal methods capable of providing quantitative assessment of sensitizing potency are currently lacking.

The GARDskin assay is a next-generation in vitro assay for hazard assessment of skin sensitizers, currently progressing towards regulatory acceptance. Recently, the GARDskin Dose-Response (DR) testing strategy was introduced, in which test chemicals are evaluated by the GARDskin assay in a titrated range of concentrations, in order to investigate the dose-response relationship between GARDskin classifications and test chemical concentration. As such, it provides a quantitative estimation of sensitizing potency, referred to as cDV0, which corresponds to the least required dose able to generate a positive response in the GARDskin assay. The cDV0 value obtained for a test chemical may be viewed as an analogue to the LLNA EC3 value, based on which further hazard characterization and risk assessment may be performed. Statistically significant correlation between the GARDskin DR cDV0 and the LLNA EC3, as well as with human No Expected Sensitization Induction level (NESIL) estimations has been confirmed, thus enabling direct extrapolation between the different metrics.

Here, we further introduce the GARDskin DR protocols, as proposed in a standardized testing strategy. By studying a concentration range of 6 concentration points titrated from the experimentally derived GARD input concentration in biological duplicates, a test chemical-specific cDV0 is established by linear interpolation. We illustrate how these results can be used on their own to facilitate direct potency-associated ranking of test chemicals. Furthermore, we demonstrate how obtained cDV0 values can be extrapolated to LLNA EC3 values with a 95% confidence interval, thereby also facilitating potency-associated subcategorization of test chemicals according to UN GHS classification criteria. Lastly, we illustrate how results generated with GARDskin DR can be directly incorporated into existing strategies for Quantitative Risk Assessment using an entirely in vitro setup.