Optimizing an integrated testing strategy for evaluating skin sensitization potential of pharmaceutical intermediates

Occupational exposure to chemicals resulting in skin sensitization and/or respiratory sensitization is an important concern in the chemical industry and especially in the pharmaceutical industry. Hazard classification of these chemicals is readily determined through various animal models, but these models have become undesirable. Alternative methods involving cell-based technology and the development in understanding key events in skin sensitization have advanced the science to begin moving away from the use of in vivo models or animal testing in hazard classification. This research evaluated alternative testing strategies to predict whether pharmaceutical intermediates are skin sensitizers. These alternative testing strategies determined if the in vivo models currently in use could be replaced with in silico and in vitro models. This research included validation of in vitro sensitization assays that may be used for pharmaceutical intermediates to evaluate the skin sensitization potential. Additionally, this research proposed in vitro assay(s) for both skin and respiratory sensitization by leveraging cell types and analyzing cytokines in the adverse outcome pathway (AOP) for sensitization. Problem Statement: Are there single or multiple in vitro or non-animal assays that can be used to determine the sensitization potential of pharmaceutical intermediates so that these materials are handled appropriately in an occupational setting? •Aim 1: Validate an integrated testing strategy to determine the skin sensitization potential of pharmaceutical process intermediates. •Aim 1a: Once Aim 1 is met, replace the use of the in vivo local lymph node assay (LLNA) with alternative in vitro assays, potentially resulting in the reduction of animal testing. oHypothesis: One or more in vitro assays in combination with a structural activity relationship (SAR) analysis could be used to potentially determine whether or not a chemical is a skin sensitizer. oThese in vitro assays may be optimized alone or in combination with each other to determine if a pharmaceutical intermediate can be classified as a skin sensitizer with derived potency. A tiered approach for skin sensitizers will be proposed and validated. Ultimately, adoption of this tiered approach will reduce and, in the future, eliminate the need for in vivo testing for sensitization. •Aim 2: Characterize the potential link between immune response and the development of respiratory sensitization through skin exposure to novel chemical intermediates. oHypothesis 2: There is overlap in immune responses between T-helper cells 1 and 2 with respect to interleukin (IL)-18 as an immunoregulatory cytokine that determines if chemical intermediates can produce respiratory sensitization through skin exposure. oUsing the IVSA investigate a potential AOP for chemicals that may be respiratory sensitizers through skin exposure and also look at gene expression of several cytokines which may be involved in produce occupational asthma and analyzed gene expression of several cytokines which may be involved in respiratory sensitization: IL-4, IL-6, IL-12, IL-13 and Thymic Stromal Lympoprotein (TSLP).Ph.D.Includes bibliographical reference