Phase I Study of Validation on EpiSensA to Evaluate Skin Sensitizing Potential of Chemicals

EpiSensA is an in vitro skin sensitization test using four marker genes (ATF3, GCLM, DNAJB4, and IL-8) expressed in reconstructed human epidermis (RhE). Early work has indicated that EpiSensA has better predictive performance for a variety of chemicals including lipophilic chemicals and pre/pro-haptens than existing in vitro tests. The validation study was started by JaCVAM in 2018. Transferability to three participating laboratories (Food and Drug Safety Center, KOSÉ Corporation and LION Corporation) was evaluated using 3 sensitizers and 1 non-sensitizer. The 4 chemicals exhibited good reproducibility in two repetitions, and in all laboratories were accurately predicted in concordance with LLNA reference results. The validation management team (VMT) concluded that the technical transfer from the lead laboratory was completed successfully. For evaluation of within laboratory reproducibility (WLR), three laboratories test 15 coded chemicals in three independent experiments each. This Phase I was conducted in three parts (Phase I-A, I-B, and I-C), each including 5 chemicals. Regarding Phase I-A, two out of three laboratories did not meet the target criteria of WLR (>85%) established by the VMT. Consequently, aspects of the protocol were revised and then were approved by the VMT; i) statistically determined acceptance criteria of vehicle control, ii) clarified criteria of retesting at a low dilution rate and iii) retesting when internal control gene fails to meet the criteria. After reanalysis and retesting based on the revised protocol, all laboratories met the target WLR criteria. In the subsequent Phase I-B, all laboratories showed 100% WLR according to the revised protocol. Finally, the mean WLR using 10 coded test chemicals was 93% and satisfied the target criteria. Currently, the Phase I-C study is under evaluation. This study received a research grant from the Japanese Society for Alternative to Animal Experiments and the Long-range Research Initiative.

Impact/Purpose

The Japanese Center for the Validation of Alternative Methods (JaCVAM) is committed to promoting the principles of the 3Rs (i.e., reduction, refinement and replacement) in animal research and to the establishment of new alternative skin sensitization testing guidelines through international collaboration. This work describes an international effort to develop an OECD test guideline for the EpiSensA test, a novel test for screening chemicals for the potential to cause allergic skin sensitization.

Citation

Kojima, H., M. Watanabe, M. Kajiwara, M. Yasuda, M. Ikezumi, K. Uno, N. Imai, M. Sakuma, M. Shibata, S. Watanabe, J. Ueno, T. Ashikaga, D. Basketter, C. Eskes, S. Hoffmann, T. Kim, D. Lehmann, M. Miyazawa, H. Mizumachi, T. Sozu, AND M. Takeyoshi. Phase I Study of Validation on EpiSensA to Evaluate Skin Sensitizing Potential of Chemicals. 11th World Congress on Alternatives and Animal Use in the Life Science, n/a, Maastricht, NETHERLANDS, August 23 - 27, 2020.