I have a potential client who is embarking on early development of a protein for dermal administration. The receptor target is HUMAN specific; preliminary in vitro data shows good dermal penetration (prototype formulation) and receptor binding. However, there are no known animal models with the same target receptor. Does anyone have experience with the development of a therapeutic agent for which there is no known animal model to use for safety/toxicity testing? The client is looking for specific expertise and experience with this unique regulatory pathway.