Parion Sciences of Durham has licensed an experimental treatment for dry-eye disease to Shire, PLC, of Lexington, Massachusetts. The entirety of the agreement was not made public, but Shire will pay $20 million upfront and an additional $20 million if near-term milestones are reached. Additional payments, totaling as much as $535 million, would be made for future achievements. In exchange, Shire will have exclusive worldwide development and commercialization rights, with Parion retaining an option to co-fund in exchange for royalties. The product of interest is a molecule, P-321, which inhibits the reabsorption of fluid on the eye by epithelial sodium channels, which are proteins that regulate ionic flow. Prescription products now available for dry eyes treat ocular inflammation. P-321 is currently undergoing mid-stage Phase 2 patient studies, so further clinical trials are required, by the United States Food and Drug Administration, to demonstrate safety and efficacy.