KoCVAM-led validation of KeraSkin™ Phototoxicity Assay for inclusion in OECD TG 498

Phototoxicity (or photoirritation) is defined as an acute toxic response elicited by topically or systematically administered photoreactive chemicals after the exposure of the body to environmental light. Korean Center for the Validation of Alternative Methods (KoCVAM) developed and optimized an in vitro phototoxicity test method using KeraSkin™, a reconstructed human epidermis model (RhE), (KeraSkin™ Phototoxicity Assay) as a ‘me-too’ test method in a previous study. KeraSkin™ Phototoxicity Assay was added to the OECD Workplan for inclusion in OECD test guideline (TG) 498. This study, conducted based on OECD Performance Standard No. 356 by one lead laboratory and four participating laboratories, aimed to validate the relevance and reliability of the KeraSkin™ Phototoxicity Assay for regulatory application in the safety assessment of cosmetics and drugs. Based on the test results, the 12 reference chemicals showed 91.7% to 100% within-lab reproducibility and 100% between-lab reproducibility in all participating labs. Further, the predictive capacity for the 12 reference chemicals calculated based on the total number of runs (144) showed 100% sensitivity (72/72), 98.6% specificity (71/72), and 99.3% accuracy (143/144). Overall predictive capacity (32 test chemicals) calculated based on the total number of runs (164) showed 97.6% (80/82) sensitivity, 97.6% (80/82) specificity, and 97.6% (160/164) accuracy. KeraSkin™ Phototoxicity Assay thus fulfills the requirements to be included as a ‘me-too’ test method in OECD TG 498.