Development and assessment of new risk assessment methods
Title of Research:
18_S01-X01

The validation study of EpiSensA (Epidermal Sensitization Assay);the in vitro skin sensitization assay based on reconstructed humanepidermis
Principal Investigator:
Hideyuki Mizumachi, PhD (Safety Science Research Laboratory, Kao Corporation)
2606, Akabane, Ichikai-Machi, Haga-Gun, Tochigi 321-3497, Japan(tel) +81-70-3297-2574, (e-mail) mizumachi.hideyuki@kao.com
Collaborators:
Sho Suzuki (Safety Science Research Laboratory, Kao Corporation)
Makoto Mizuno, Megumi Sakuma, PhD, Momoko Shibata (KOSÉ Corporation)
Mika Watanabe, Michiyo Yasuda, Michika Kajiwara (Hatano Research Institute, Food and Drug
Safety Center)
Shin-ichi Watanabe, Junko Ueno (LION Corporation)
Summary of Research:
Lipophilic chemicals are difficult to correctly evaluate by existing in vitro tests because these tests
employ aqueous-phase systems. To overcome the limitation, we focused on a reconstructed
human epidermis (RhE) and developed the Epidermal Sensitization Assay (EpiSensA) based on
the expression of four marker genes related to induction of skin sensitization. Based on thecomparison with the results of animal test, we confirmed that EpiSensA has better predictive
performance for a variety of chemicals including lipophilic chemicals than existing in vitro tests.
Therefore, the validation study of EpiSensA was started from July 2018 at JaCVAM (JapaneseCenter for the Validation of Alternative Methods) to adopt it for OECD test guideline. We havereported that the validation management team (VMT) concluded the technical transfer from thelead laboratory to three participating laboratories (Food and Drug Safety Center, KOSÉ
Corporation and LION Corporation) was successfully completed.
For evaluation of within laboratory reproducibility (WLR), three laboratories tested 15 codedchemicals in three independent experiments during Phase I study, and target criteria wasestablished at 85% by the VMT. Several protocol modifications and additional experiments wereperformed as appropriate, and the mean WLR resulted in 91% and satisfied the target criteria. TheVMT concluded that the Phase I study was successful. Regarding subsequent Phase II study forevaluation of between laboratory reproducibility (BLR), three laboratories tested 12 codedchemicals once, and target criteria was established at 80%. The BLR was calculated using 27 test
chemicals including Phase I and Phase II chemicals, and the final prediction for the chemicals thatwere tested 3 times in each laboratory was based on the median classification. As a result, theBLR was 89% and satisfied the target criteria. In addition, protocol modification was proposed toavoid the potential cross-contamination effect of volatile strong sensitizers. Furthermore, hazard
predictive performances at participating laboratories were evaluated using 27 test chemicals, theperformances were similar to that of the lead laboratory. From these results, the VMT concluded
that the Phase II study was successful, and the protocol modification was accepted.
Timeline: April 1, 2018Topics:
Presentations at 2018,2019, 2020, and 2021 JCIA-LRI Workshop
Publications:
The 34th Annual Meeting of the Japanese Society for Alternatives to Animal Experiments,
Okinawa and On-line, Japan, Nov. 2021.