Utilize the input text as a context reference, choose the right relationship between 'Sanofi' and 'Regeneron Pharmaceuticals' from the options.
Options: developer, owner of, creator, legal form

Elsewhere, French drugmaker Sanofi (NasdaqGM: GCVRZ - news ) advanced as it said it has entered into a research agreement with Regeneron Pharmaceuticals (NasdaqGS: REGN - news ) and will invest $2.17bn to develop new cancer treatments together.
owner of